module no e03 electrical test equipment basic

8/10/2019 Module No E03 Electrical Test Equipment Basic

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DUTY NO 15: TEST INSTRUMENTS

OBJECTIVES

Upon completion of this module, the technician would be able to demonstrate

knowledge and understanding on the following:

1. Safety precautions in test & measurement

2. Basic construction and operation of Multimeter (Digital & Analog)

3. Functional selection, setting of Digital Multimeter

4. Use of digital multimeter and test procedures.5. Theory of Insulation measurement

6. Basic construction and operation of Insulation resistance tester

7. Functional selection, setting of Insulation resistance tester

8. Use of digital Insulation resistance tester and test procedures.

9. Basic construction and operation of Clamp on Ammeter

10. Functional selection, setting & use of Clamp on Ammeter

11. Theory of Earth Resistance measurement

12. Function and operation of Earth Resistance tester

13. Preparation and set-up of Earth Resistance tester

14. Function and operation of Loop tester and RCD tester

15. Preparation and set-up of Loop tester and RCD tester

16. test procedure & circuitry


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TABLE OF CONTENT

1.0.0 Introduct ion.............................................................................. 5

2.0.0 Safety........................................................................................ 6

2.1.0 Causes of Electrocut ion ..........................................................................8

2.2.0 Use of High voltage protection equipment ...........................................8

2.2.1 Clearances ..................................................................................................................9

2.3.0 Section 2 Safety of BS 6626: 1985 .......................................................10

2.3.1. Responsib ili ty ..........................................................................................................102.3.2 Rules or procedure for safe systems at work ........................................................10

2.3.3 Isolation and access for maintenance ....................................................................11

2.3.4 Preparing for main tenance work .............................................................................12

2.3.5 Fire extingu ish ing equipment ..................................................................................13

2.3.6 Testing.......................................................................................................................14

2.3.7 Disposal of scrap......................................................................................................14

3.0.0 Mult imeter .............................................................................. 15

3.1.0 Analog Multimeter..................................................................................16

3.2.0 Digital Multimeter ...................................................................................17

3.2.1 Voltage Measurements.............................................................................................20

3.2.2 Current Measurements.............................................................................................21

3 2 3 Resistance Measurements 21


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4.8.0 Insulation resistance (IR) test on Motor/Generator............................32

5.0.0 Clamp on meter ..................................................................... 34

5.1.0 Theory of operat ion of AC Clamp on meter ........................................35

5.2.0 Theory of operation of AC/DC Clamp on meter..................................36

5.3.0 Specifications of Digital Clamp on meters..........................................37

5.4.0 Advantages of Digital Clamp on meter................................................37

5.5.0 Advantages of Digital over Conventional Type ..................................37

5.6.0 Applications of Digital Clamp on meters.............................................38

5.7.0 Clamp on meter operations (Fluke model 321/322)............................38

5.8.0 Safety Precautions.................................................................................40

6.0.0 Earth tester, Loop tester & Residual Current Device (RCD)

tester................................................................................................ 42

6.1.0 Earth resistance .....................................................................................43

6.2.0 Principle of Earth resis tance test ing ...................................................44

6.3.0 Earth resistance test methods .............................................................46

6.4.0 Earth Loop resistance ...........................................................................47

6.5.0 Earth Loop resistance test ....................................................................48

6.6.0 Digital Earth Loop resis tance tester from Megger (L T5 and L T6) ..48

6.7.0 Applications & Use of Earth Loop resis tance tester..........................49


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1.0.0 IntroductionTesting is performed to verify the integrity of electrical systems. Most of these tests

are non-destructive in nature and can be used to provide a complete look at the status

and age of the equipment. In this module, we will concentrate on the following

electrical tests instruments:

Multimeter (Digital & Analog)

Insulation resistance tester

Clap on Ammeter

Earth resistance tester

Earth loop impedance & RCD tester

In this module included the some specific OEM instruction manuals for the above

mentioned test set. The module basically prepared to train the technicians to read and

interpret the OEM manuals of the test instrument, which is the required to perform the

some of the tasks prescribed in POSS under duty no. 15. In the process, it covers thebasic underpinning knowledge required to perform the required tasks. For gaining the

expertise in the activities, detail study of the Operation & Maintenance manual of

respective test instrument and hands on experience is necessary.

Note:Testing of electrical distribution equipment requires experience and an

understanding of the hazards involved. The test equipment used at your workplace


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2.0.0 SafetyIn the interest of safety, all test equipment should be inspected and tested before

being taken to the job site. There is no need to get to the job and find that the test

equipment does not work.

A thorough visual inspection (i.e., checking for broken meters or knobs, damaged

plugs, or frayed cords) is important.

Always perform an operational check. For example:

On an ohmmeter, short the probes and ensure that you can zero the meter.

A voltmeter can be checked against an AC wall receptacle or a battery.

If a meter has a calibration sticker, check to see if it has been recently calibrated.

For precise measurements, a recently calibrated meter is a more reliable instrument.

Every person who works with electrical equipment should be constantly alert to

the hazards to which personnel may be exposed, and should also be capable of rendering

first aid. The hazards are electric shock, burns, and related hazards.

Safety must be the primary responsibility of all personnel. The installation,

maintenance, and operation of electrical equipment enforce a strict safety code.

Carelessness on the part of the technician or operator can result in serious injury or death

due to electrical shock, falls, burns, flying objects, etc. When an accident has occurred,

investigation almost invariably shows that it could have been prevented by the exercise of


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equipment commonly has more than one source of power. Be certain that all power

sources are de-energized before servicing the equipment. Do not service any equipment

with the power on unless absolutely necessary. Remember that the 115V power supply

voltage is not a low, relatively harmless voltage but is the voltage that has caused more

deaths than any other medium.

Safety can never be stressed enough. There are times when your life literally

depends on it. The following is a listing of common safety precautions that must be

observed at all times:

Use only one hand when turning power switches on or off.

Keep the doors to switch and fuse boxes closed except when working inside or replacing

fuses.

Use a fuse puller to remove cartridge fuses after first making certain that the circuit is

dead.

Ensure that you are qualified and authorised to work on an electrical circuit (LV or HV).

Do not work with energized equipment by yourself; have another person (safety

observer) that is qualified in first aid for electrical shock present at all times.

The person stationed nearby should also know which circuits and switches control the

equipment, and should be given instructions to pull the switch immediately if

anything unforeseen happens.

Always be aware of the nearness of high-voltage lines or circuits. Use rubber gloves


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Do not use bare hands to remove hot vacuum tubes from their sockets. Wear protective

gloves or use a tube puller.

Use a shorting stick (discharge rod) to discharge all high-voltage capacitors.

Make certain that the equipment is properly grounded. Ground all isolated and discharged

circuits of the equipment under test to prevent accidental charging.

Turn off the power before connecting alligator clips to any circuit.

When measuring circuits over 440V, do not hold the insulated test probes with bare

hands.

2.1.0 Causes of ElectrocutionUnsafe Acts:

Accidentally slipping with wrenches, screwdrivers, etc., while working on or

near electrical equipment with live parts (over 50 volts)

Switching off the wrong circuit and then failing to verify that the circuit is de-

energized before beginning work.

Failing to implement lock-out/tag-out procedures or use adequate protective

equipment.

Use of noninsulated tools.

Wearing metal jewelry while working on live circuits.

Using instruments/meters/tools not designed for the system voltage.


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rated for electrical resistance, eye protection, safety shoes, and long sleeves.

Gloves that are approved for protection from electrical shock are made of rubber.

A separate leather cover protects the rubber from punctures or other damage. Gloves are

rated as providing protection from certain amounts of voltage. Whenever an individual is

going to be working around exposed conductors, the gloves chosen should be rated for at

least as much voltage as the conductors are carrying. Rubber sleeves are used with gloves

to provide additional protection. The combination of sleeves and gloves protects the

hands and arms from electrical shock.

Rubber blankets and floor mats have many uses. Blankets are used to cover

energized conductors while work is going on around them. They might be used to cover

the energized main busses in a breaker panel before you begin working on a deenergized

breaker. Rubber floor mats are used to insulate workers from the ground. If a worker is

standing on a rubber mat and contacts an energized conductor, the current cannot flow

through the body to the ground, so the worker will not get shocked.

2.2.1 Clearances

Adequate clearances are to be maintained between energized and exposed

conductors and personnel. Where DC voltages are involved, clearances specified shall be

used with specified voltages considered as DC line-to-ground values.

If adequate clearances cannot be maintained from exposed live parts of apparatus

in the normal course of free movement within the area during test then access to that area


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These distances are listed in Table 1.

Voltage Range Minimum Working and(Phase-to-Phase) Kilovol ts Clear Hot Stick Distance

2.1 to 15 2 ft. 0 in.

15.2 to 35 2 ft. 4 in.

35.1 to 46 2 ft. 6 in.

46.1 to 72.5 3 ft. 0 in.

72.6 to 121 3 ft 4 in.

138 to 145 3 ft. 6 in.

161 to 169 3 ft. 8 in.

230 to 242 5 ft. 0 in.

345 to 362 *7 ft. 0 in.

500 to 552 *11 ft. 0 in.

700 to 765 *15 ft. 0 in.

* For voltages above 345 kV, the minimum working and clear hot stick distances

may be reduced provided that such distances are not less than the shortestdistance between the energized part and a grounded surface.

Table 1. OSHA Working And Hot Stick Distances At Various Voltages

2.3.0 Section 2 Safety of BS 6626: 1985

2.3.1. Responsibility

Electrical equipment should be regarded as being capable of giving rise to danger


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Barriers preventing access to enclosures containing live conductors should

normally be kept locked.

Where one person isolates and another does the work, the person responsible for

isolating should demonstrate effectively to the other that the equipment is in fact dead

and safe and that there are adequate safeguards to prevent re energization.

Adequate quantities of suitable locks, cautionary notices and temporary barriers

should be available for use to facilitate safe working and to prevent conductors from

being accidentally electrically charged when persons are working thereon and also to

warn of the presence of any live conductors. Such notices should be clearly legible and

prominently displayed, made from durable; material and kept up-to date. Suitable

precautions should be taken to identify circuits and equipment at the front and back of

switchboards where such identification does not already exist. .

Any disconnectors used for isolation should be locked to prevent movement to the

ON position. Any shutters giving access to live conductors should also be padlocked in

the closed position.

Equipment enclosures frequently contain, circuits having sources of supply

different from that of the main circuit, such as interlocks, alarms, heating and lighting

circuits, etc., and these circuits are not always isolated when the main circuit is

disconnected. Conductors and terminals associated with these circuits should be shrouded

where necessary to prevent accidental contact and identified with warning notices


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associated with the equipment or the work to be performed should be housed in proper

receptacles provided for the purpose, and kept in proper condition.

Adequate lighting either fixed portable, or a combination of both should be

provided as necessary to ensure safe access and working.Portable electrical tools and inspection lamps should preferably be operated from

a system with a voltage no greater than 110 V with either the star point of a three phase

or the mid-point of a single-phase transformer low voltage winding earthed. If mains

voltage portable tools need to be used, they should be of all-insulated or double insulated

construction and the use of a residual current device is recommended. All portable

electrical equipment should be regularly inspected and tested.

NOTE. Further advice on the safe use of portable tools is contained in HMG

publication guidance note PM 32 available from HM Stationery Office.

The ingress of moisture, dirt, vermin etc. into electrical equipment can cause

malfunction and danger. Care should be taken to prevent such ingress whilst work is in

progress, and covers should be replaced as soon as access to the chamber is no longerrequired. Before final closure of any compartment is effected, a careful inspection should

be carried out to make sure no foreign matter or loose material is present.

Before work is undertaken in any chamber containing high voltage conductors,

tests using suitable voltage indicators should be carried out. These should include tests

between .each phase and earth to ensure all conductors are dead. Voltage indicators


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also include instructions for preventing automatic operation when persons are working

within the protected area. The prevention and restoration of automatic operation should

be subject to appropriate safety procedures, for example by including a reference on the

relevant permits to work. The type of fire extinguishers provided for use on or nearelectrical equipment should be compatible with the equipment and safe to use. Further

advice on fire prevention and fire fighting may be obtained from the local Fire Prevention

Officer.

2.3.6 Testing

2.3.6.1 General

Care should be taken when applying test voltages to ensure that they are the

lowest value required for the purpose with the minimum current output. Where

equipment is capable of storing a charge this should be safely discharged after every test.

NOTE 1: Further advice on electrical testing is available: one publication is

Health and Safety Series Booklet No. HSG (13) 'Electrical testing' available from HM

Stationery Office.

NOTE 2: Electrical equipment may be damaged by the application of test voltages

and currents of incorrect value and polarity. Some electronic equipment is particularly

vulnerable (see clause 40).

2.3.6.2 Use of test instruments (oscilloscopes, etc.)

Instruments should be of a type suitable for the measurements that are to be made


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3.0.0 Mult imeterA multimeter measures electrical properties such as AC or DC voltage, current,

and resistance. Rather than have separate meters, a multimeter combines a voltmeter, an

ammeter, and an ohmmeter. Electricians and the general public might use a multimeter

on batteries, components, switches, power sources, and motors to diagnose electrical

malfunctions and narrow down their cause.

It is a black box of electronic circuitry that allows to troubleshoot just about any

type of electrical wiring or device. Simply dial the proper function and scale, touch the

two test leads to the wiring or device in question and check the meter reading. Depending

on the setting, the multimeter will give indication to suggest a broken connection, no

power, poor connections, faulty parts and more.

The two main kinds of a multimeter are analog and digital. A digital multimeter

has an LCD screen that gives a straight forward decimal read out, while an analog display

moves a pointer through a scale of numbers and must be interpreted. Any multimeter will

work over a specific range for each measurement. Select one that is compatible with what

is required, from low-voltage power sources to high-voltage car batteries. Multimeters

are specified with a sensitivity range, so make sure to choose the appropriate one.

Multimeters are handheld devices. Analog multimeters are very cheap but

sometimes difficult to read accurately, especially on resistance scales. Digital output


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3.1.0 Analog Mult imeter

The permanent magnet moving coil analogue multimeters are based on the

galvanometer invented by Arsene dArsonval. This device possesses a stationary

permanent magnet, a moving coil, a spring, and a pointer attached to the coil. Figure

below illustrates the way the equipment works. When a current flows through the coil,

there is an induced force on it due to the created electromagnetic field, and the coil

rotates around its central axis until the induced torque is equal and opposite to the spring

torque. The rotation torque, and consequently the angle the pointer rotates is proportional

to the current. The rotation angle is measured on a calibrated scale, and the amount of

current flowing through the meter can be measured. The dArsonval movement is used


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3.2.0 Digi tal Mult imeter

Figure shows a block diagram of an electronic digital multimeter.

Note that the block diagram divides the instrument into three major sections: the

SIGNAL CONDITIONING section, the ANALOG-TO- DIGITAL CONVERTER

section, and the DISPLAY section.

The signal conditioning section provides a dc analog voltage, characteristic of the

applied input, to the analog-to-digital converter section. This task is accomplished by the

input voltage divider, current shunts, ac converter, active filter, and associated switching.

The analog-to-digital (a/d) converter section changes the dc output voltage from the

signal conditioning section to digital information. The a/d converter uses a voltage-to-


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3.2.1 Voltage Measurements

Plug the black test lead into the COM jack.

Plug the red test lead into the V jack.

Set the function/range switch to either DC volts in the upper left, or AC volts

in the upper right.

If you do not know the approximate voltage about to be measured, use the

largest voltage range available.

Connect the free ends of the red and black test leads ACROSS the device to

the measured. Voltage is always measured with the meter in PARALLEL with

the device


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3.2.2 Current Measurements

Turn the power off to the device and discharge any capacitors.

Plug the black test lead into the COM jack.

Plug the red test lead into either the 200 mA jack for small current

measurements, or the 10 A jack for large current measurements.

If you do not know the approximate current about to be measured, use the 10 A

jack.

Set the function/range switch to either DC amperes in the lower right, or AC

amperes in the middle right.

Break open the circuit at the point where you want to measure the current by

removing one of the wires.

Connect the free end of the red test lead to one place at which the wire was

attached.

Connect the free end of the black test lead to the other place at which the wire

was attached.

Current is always measured with the meter in SERIES with the device.

Using the current meter incorrectly will blow the fuse or damage the meter

Reapply the power to the device.

If the LCD displays either "1." or "-1." with all other digits blank, the current is

beyond the selected range. Use the switch to select a larger range.


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Once you know the approximate resistance of the device, and then use the

switch to select the lowest range that will still accommodate the resistance of

the device.

Important note: The most common mistake when using a multimeter is not

switching the test leads when switching between current sensing and any other

type of sensing (voltage, resistance). It is critical that the test leads be in the

proper jacks for the measurement you are making.

3.3.0 Digital vs. Analog Multimeters

Digital multimeters have LCD readouts, do audible continuity testing. Some

digital multimeters also feature auto-ranging and overload protection and other

advantages analog multimeters lack.

Analog multimeters have multiple scales on the dial , a moving needle and many

manual settings on the function switch. It is a tricky spotting the correct scale to read on

the dial, and sometimes have to multiply the reading by 10 or 100 to get your final value

3.4.0 Safety Precautions

Be sure the test leads and rotary switch are in the correct position for the desired

measurement.

Never use the meter if the meter or the test leads look damaged.

Never measure resistance in a circuit when power is applied.


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4.0.0 Insulation resistance tester (Megohmmeter)The Insulation resistance tester (IRT) also known as a megohmmeter, is a portable

instrument used to measure insulation resistance. It is a lightweight, simple and in

minutes can help to determine the damaged installation. Checking the integrity of

insulation is not only a good idea for a new installation, its a tremendous tool in ongoing

maintenance, allowing to spot a problem wiring/equipment, before it creates arcing and

damages the equipment or shuts everything down.

The principle of operation of IRTs is as basic as Ohms Law: V=IR or R=V/I. The

tester generates a known dc voltage (250 V, 500 V, 1k V or higher), chosen by the user,and measures the leakage current from the conductor through the insulation. The

resistance is then calculated. The better the insulation, the lower the leakage current and

the higher the amount of resistance present.

For example, if 500 V is applied and 0.5 mA measured, then R=1 M. If only one

hundredth of that current, 5 A, is measured, then R=100 M

The newest generation of IRTs is microprocessor-based and battery-powered.

They are more precise than the older hand-cranked analog testers.

4.1.0 Analog Megohmmeter

It consists of a hand-driven DC generator and a direct reading ohm meter. A

simplified circuit diagram of this instrument is shown in Figure below


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will tend to set itself at right angles to the field of the permanent magnet. With the test

terminals open, giving an infinite resistance, no current flows in Coil A. Thereby, Coil B

will govern the motion of the rotating element, causing it to move to the extreme counter-

clockwise position, which is marked as infinite resistance.Coil A is wound in a manner to produce a clockwise torque on the moving

element. With the terminals marked "line" and "earth" shorted, giving a zero resistance,

the current flow through the Coil A is sufficient to produce enough torque to overcome

the torque of Coil B. The pointer then moves to the extreme clockwise position, which is

marked as zero resistance. Resistance (R1) will protect Coil A from excessive current

flow in this condition.

When an unknown resistance is connected across the test terminals, line and earth,

the opposing torques of Coils A and B balance each other so that the instrument pointer

comes to rest at some point on the scale. The scale is calibrated such that the pointer

directly indicates the value of resistance being measured.


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Some of the common features are:

Lightweight. Tough and robust

Shrouded safety terminals with right angled test lead connector.

Hands-free operation

Voltage ranges of 250, 500, and 1000 V.

Resistance measurement range of 200 G

Combined insulation & Continuity tester

Default Voltmeter

B di i


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4.3.0 Insulation resistance test

Insulation resistance tests give an indication of the condition of insulation,

particularly with regard to moisture and dirt. The actual value of the resistance varies

greatly in different types of machines, depending on the type, size, voltage rating, etc.

The principal worth of such measurements, therefore, is in the relative values of

insulation resistance of the same apparatus taken under similar conditions at various

times. Such tests usually reveal how well the machine has been maintained.

Measuring insulation resistance is rather straightforward. Identify any two points

between which there is insulation and make a connection with a megohmmeter. Take a

measurement; the measured value represents the equivalent resistance of all the insulation

that exists between the two points and any component resistance that might also be

connected between the two points.


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but much more quickly. It is this current which in most cases determines how long it

takes to make an accurate megohm measurement. When the reading appears to stabilize,

it means that the charging current has decayed to a point where it is negligible with

respect to the leakage current.

The current that flows through the insulation is the leakage current. The voltage

across the insulation divided by the leakage current through it equals the insulation

resistance. Thus, to accurately measure insulation resistance, we must wait until the

dielectric absorption current and the charging current have decayed to the point where

they are truly negligible with respect to the leakage current.

The total current that flows is the sum of the three components just mentioned. It


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Polarization index = resistance after 10 minutes resistance after one minute

The recommended minimum value of polarization index for AC and DC motors and

generators is 2.0. Machines having windings with a lower index are less likely to be

suited for operation.

The polarization index is useful in evaluating windings for:

Buildup of dirt or moisture

Gradual deterioration of the insulation (by comparing results of tests made

earlier on the same machine)

Fitness for overpotential tests


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4.3.4 Insulation Contamination

In order to obtain reliable test figures, windings should be free of dirt and

moisture as both of these contaminants result in a lower value of resistance being

indicated. If a machine has recently been taken out of service, it is likely to be hot and

therefore free from moisture.

However, the windings may be quite dirty from dust and oil in the atmosphere.

Conversely, if the machine has been out of service for some time, the winding insulation

may well have absorbed a certain amount of moisture. Indeed, if the insulation resistance

is indicated as low, it may be necessary to dry out the windings. All of these items must

be taken into consideration when assessing the reliability of insulation resistance readings


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4.4.2 Step voltage test

Various test voltage in steps of (in increasing order), usually for the same period

of time (60 Secs). The insulation values are recorded on the graph. The insulation is

exposed to increased electrical stress that can reveal information about flaws in the

insulation such as pinholes, physical damage or brittleness.

4.4.3 Time resis tance test

This test is carried out to compare the absorption characteristic of contaminated

insulation with the absorption characteristic of good insulation. The test voltage is

applied for the 10 mins and after every 10 secs the data is recorded for first one minute

and then after every one minute. The interpretation of the slope of the plotted graph

determines the condition of the insulation.

The polarisation index is another test in this category for determining the quality

of insulation. This is discussed in earlier part of this chapter.


Be sure the test leads and rotary switch are in the correct position for the desired

measurement.

Never use the meter if the meter or the test leads look damaged.

Never measure insulation resistance in a energised circuit.

Make sure that the systems under test have been completely discharged to


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4.6.0 Insulation resistance (IR) test on Cables

Prior to testing required permits must be secured. All safety precautions should be

observed while testing. Cable must be discharged and disconnected form the equipment

in the field.

IR should be measured as illustrated in the figure below:


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4.7.0 Insulation resistance (IR) test on Transformer

Prior to testing required permits must be secured. All safety precautions should be

observed while testing.

4.8.0 Insulation resistance (IR) test on Motor/Generator


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Measuring insulation resistance is rather straightforward. Identify any two points

between which there is insulation and make a connection with a the test instrument is

often referred to as a Megger, after the manufacturers trademark. Take a measurement;

the measured value represents the equivalent resistance of all the insulation that exists

between the two points and any component resistance that might also be connected

between the two points.Megger s are available in several varieties. Some are powered by

a hand-cranked generator, while others are battery powered. Most common is 500V

output, with some going as high as 10,000V. The power supply, in all cases, is DC.

1kV

500V

250V

100V

50V

OFF

V

k

TEST

M

ZERO

AVO

MEGGERXXXX

IR measurement on Cage type Induction motor


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5.0.0 Clamp on meterA clamp meter (clamp-on ammeter) is a type of ammeter which measures

electrical current without the need to disconnect the wiring through which the current is

flowing.

Clamp meters are also known as tong testers or Amprobes (after Amprobe

Instrument Company, one of the first vendors of such devices).

The most common forms of clamp meter are:

A probe for use with a multimeter.

A self-contained unit.

A built-in part of a specialised multimeter used by electricians.


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other direction.

Only one (1) conductor can be measured at a time, and the cable can either be

bare or insulated. The current in the conductor to be measured is (carefully) segregated

from other current-carrying conductors, and shifted enough so that the jaws of the clamp-

on ammeter can be opened, slipped around the cable, and then closed. As soon as the

jaws close, a clear and accurate reading is registered on the scale. The jaws are insulated,

and the Bakelite handle and shield protect the technician from shock.

5.1.0 Theory of operation of AC Clamp on meter

The meter is operated by the magnetic field set up by the current. Basic

construction of the meter is a clamp on current probes and the ammeter (Analog or

digital) connected to it.

The clamp on current probe works on the principle of current transformer. The

d i h i il f f


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5.2.0 Theory of operation of AC/DC Clamp on meter

More modern designs of clamp-on ammeters utilize a small magnetic field

detector device called a Hall-effect sensor to accurately determine field strength. The two

matched sensors provide an output signal which is independent of the location of the

current conductor in the clamp opening. The conductor does not have to be exactly at the

center of the opening. A battery-operated circuit is required to provide the excitation and

amplification of the signal generated by the HALL-EFFECT sensor

Hall effect principle : AC/DC current sensing is achieved by measuring thestrength of the magnetic field created by a current carrying conductor in a semiconductor

chip using Hall effect principle. When a thin semiconductor is placed at right angle to a

magnetic field (B), and a current (Id) is applied to it, a voltage (Vh) is developed across

the semiconductor. This voltage is known as the Hall voltage, named after the US

scientist Edwin Hall


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Some clamp-on meters contain electronic amplifier circuitry to generate a small

voltage proportional to the current in the wire between the jaws, that small voltage

connected to a voltmeter for convenient readout by a technician. Thus, a clamp-on unit

can be an accessory device to a voltmeter, for current measurement.

5.3.0 Specifications of Digital Clamp on meters

AC Current: It is the measuring value of the alternating current taken by

the load of a clamp on meter

AC Voltage : It is defined as the alternating voltage measured by the

clamp on meter.

DC Current : It is the measuring value of the direct current read by the

clamp on meter

DC Voltage: It is defined as the direct voltage measured by the clamp on

meter

Resistance : It is the resistance offered by the clamp on meter to the

current flow

Frequency range : It is the range of frequency at which the current or

voltage is measured.

Distortion factor: It is defined as a measure of non linear distortion.

Total harmonic distortion : It is defined as the ratio of the sum of the

f ll h i f i b h f d l f


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To avoid possible electric shock or personal injury, and to avoid possible damage

to the Meter or the equipment under test, adhere to the following practices:

Avoid working alone as far as possible, and render the assisstance.


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6.0.0 Earth tester, Loop tester & Residual Current Device(RCD) tester

A practical earth electrode that provides a low ground resistance is not always

easy to obtain. The metallic body in the earth is often referred to as an electrode even

though it may be a water-pipe system, buried strips or plates, or wires. Such

combinations of metallic bodies are called a grid. The earth resistance is the resistance to

current from the electrode into the surrounding earth.

To appreciate why earth resistance must be low, you need only use Ohms Law: E

= R x I where E is volts; R, the resistance in ohms; and I, the current in amperes. Assume

that you have a 4000-V supply (2300 V to ground) with a resistance of 13 (see Fig.

below). Now, assume that an exposed wire in this system touches a motor frame that is

connected to a grounding system which has a 10-ohm resistance to earth.


43/203

installation is of insufficient level and the protection device would thus take too long to

activate. The delay can be disastrous for life and property. It is therefore necessary to

know if the impedance of the path that any fault current would take is low enough to

allow sufficient current to flow in the event of a fault and that any installed protective

device will operate within a safe time limit. The earth loop impedance of each individual

circuit a path from the point of use back to the incoming supply connection point. As

measurement of circuit loop impedance is made with the supply normally on, precautions

must be taken to avoid the possibility of electric shock and danger to personnel working

in the vicinity of the circuit under test.

In IEC 60364, fault loop testing falls under the category of Verifying protection

by automatic supply disconnection. This covers verification of the effectiveness of

protective measures (such as test on RCD), and the test methods applied to measure the

fault loop impedance.

Conventional techniques for measuring loop impedance can often trip RCDs,

preventing further measurement. Often the only way around this is to bridge the RCD

or replace the RCD with an equivalent rated MCB for the duration of the test both of

which are potentially dangerous and time consuming practices. To overcome this

manufacturers of earth loop tester have applied innovative technology to ensure that both

electromechanical and electronic type RCDs do not trip during earth loop impedance

measurements.

d h h h b l h b k i ff i f h h l d


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rusted through, the part below the break is not effective as a part of the earth electrode.

Resistance of Surrounding Earth: An electrode driven into earth of uniform

resistivity radiates current in all directions. Think of the electrode as being surrounded by

shells of earth, all of equal thickness. The earth shell nearest the electrode naturally has

the smallest surface area and so offers the greatest resistance. The next earth shell is

somewhat larger in area and offers less resistance. Finally, a distance from the electrode

will be reached where inclusion of additional earth shells does not add significantly to the

resistance of the earth surrounding the electrode. It is this critical volume of soil that

determines the effectiveness of the ground electrode and which therefore must be

effectively measured in order to make this determination. Ground testing is distinct when

compared to more familiar forms of electrical measurement, in that it is a volumetric

id ti


45/203

consideration.

Because the formulas are complicated, and earth resistivity is neither uniform or

constant, a simple and direct method of measuring earth resistance is needed. This is

where Earth Resistance Tester, a self-contained portable instrument is used. This test

instrument is reliable and easy to use. With it, one can check the resistance of the earth

electrode while it is being installed; and, by periodic tests, observe any changes with

time.

To understand the principle of earth testing, consider the schematic diagram in

Fig. below. As explained earlier with the earth shell diagram, with increased distance

from an electrode, the earth shells are of greater surface area and therefore of lower

resistance. Now, assume that there are three rods driven into the earth some distance apart

and a voltage applied, as shown in Fig. The current between rods 1 and 2 is measured by

an ammeter; the potential difference (voltage) between rods 1 and 3 is measured by a

voltmeter.

Th i f i t l b l tt d i t di t t bt i


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The series of resistance values can be plotted against distance to obtain a curve as

shown in Fig. below. Note that as rod 3 is moved away from rod 1, the resistance values

increase, but the amount of increase gets less and less until a point is reached where the

rate of increase becomes so small that I can almost be considered constant (20 in Fig.).

The earth shells between the two rods (1 and 3) have so great a surface area that they add

little to the total resistance. Beyond this point, as rod 3 approaches the earth shells of rod

2, resistance gradually picks up. Near rod 2, the values rise sharply.

Now, lets say that rod 1 is the earth electrode under test. From a typical earth-

resistance curve, such as Fig. above, what is the resistance to earth of this rod? We call

rod 2 current-reference probe C and rod 3, potential reference probe P (simply forconvenience in identification). The correct resistance is usually obtained if P (rod 3) is

placed at a distance from the center of the earth electrode (rod 1) about 62 percent of the

distance between the earth electrode and C (rod 2). Finally, rod C should be far enough

away from the earth electrode system so that the 62 percent distance is out of the sphere

of influence of the earth electrode.

For the test, the electrode should be isolated from the electrical system that it is

protecting; otherwise, the whole system is tested which (depending on local practices)

may include the pole ground, system neutral, and transformer ground. This obscures the

specific effect of the local ground.

X to the earth electrode it may be better to use all four terminals by a lead from the P1


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X to the earth electrode. it may be better to use all four terminals by a lead from the P1

terminal to the test electrode (connecting it inside the lead from C1). This is a true four

wire test configuration which eliminates all lead resistance from the measurement.

The driven reference rod C should be placed as far from the earth electrode as

practical; this distance may be limited by the length of extension wire available, or the

geography of the surroundings. Leads should be separated and not run close and parallel

to each other, to eliminate mutual inductance.

Potential-reference rod P is then driven at mid point on a straight line between the

earth electrode (X) and C. The subsequent two readings are taken moving the rod P closer

to the earth electrode, say 1 meter and away from the earth electrode by same distance (1

meter). Resistance readings are logged for each of the points and average of the readings

are taken, if the three readings do not differ from each other (within 5%) by large margin.

the earth return path back to the supply transformer and its winding; the phase conductor


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the earth return path back to the supply transformer and its winding; the phase conductor

back to the point of the fault.

6.5.0 Earth Loop resistance test

An earth fault loop test on an installation is performed by switching a known lowvalue of resistance between the phase and earth conductors at the desired point test and

measuring the voltage drop across the resistance. In effect this is simulating a fault

between phase and earth and calculation made around the supply voltage and voltage

drop across the test resistor enable the earth fault loop impedance to be indicated.

The same tester may also be used for the determination of prospective earth fault

current, which is the maximum current able to flow in a phase-earth fault in an

installation, and they may also be used to indicate the prospective short circuit current

which is the maximum current able to flow in the event of a phase-neutral fault.

The earth loop testers available in the market, offer both traditional measuring

techniques and state of the art "non-RCD Tripping" technology.

6.6.0 Digital Earth Loop resistance tester from Megger (L T5 and L T6)

The MEGGER@ L T5 and L T6 Digital Loop Testers have been designed for

quickly, accurately and reliably testing newly established and existing wiring

installations. They are simple to use, both with the standard lead for socket tests and with

the optional safety leads for performing tests on lighting installations and testing earth

V a c 10% and automatically compensate for supply variations The test current up to


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V a.c. 10% and automatically compensate for supply variations. The test current, up to

25 A, is dependent on the impedance of the phase-earth loop being measured and flows

for two half cycles of the supply voltage. The circuit is fuse protected and fitted with an

internal thermal switch to prevent excessive heating caused by tests repeated too

frequently.

Testing is very simple as there is no initial setting up to be done and no

pushbutton to operate. A test is automatically executed in about 4 seconds after the

selector switch is set to a measuring range and connection made to the circuit under test.

(Either step may be performed first.) Neons illuminate to show that there are no open

circuits in the installation wiring and that a correct phase conductor connection exists. If

the earth connection is not present, the test will not be performed.

Use of a large, 3 digit L.C.D. makes measurement readings easy with less

chance of ambiguity. It also results in a much more rugged and robust test instrument

that, because of its strong plastic case, will withstand the rough treatment expected of an

installation engineer's tool.

The lightweight, hand-held tester also incorporates a fold-away support

stand/suspension hook for use when the operator requires both hands for using the "flying

leads".

6.7.0 Applications & Use of Earth Loop resistance tester


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6.8.0 Residual Current devices (RCDs)


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6.8.0 Residual Current devices (RCDs)

Increasingly in modern installations, earth leakage circuit breakers are used to

provide protection in additional to conventional fuses and circuit breakers. These devices

are referred to by a variety of different names including RCD (Residual Current Device),

RCCB (Residual Current Circuit Breaker), ELCH (Earth Leakage Circuit Breaker) and

GFI (Ground Fault Interrupt), to name but a few.

The devices operate by sensing when the current in the phase and neutral

conductors within an installation are not equal and opposite. Any imbalance would imply

that an additional path existed for the flow of current, invariably through the earth due to

excessive leakage and/or a fault situation.

pressed even though a real ground fault may not cause it to trip.


52/203

p g g y p

RCD testers are designed to simulate a range of fault currents, with restrictions on

the duration of the fault current, and to time the operation of the device. This will indicate

the ability of the RCD to interrupt a particular fault current within time certain limits to

ensure protection against fire, damage and electrocution.

6.10.0 Digi tal RCD tester from Megger (CBT3 and CBT4)

The CBT3 and CBT4 are hand-held instruments for testing residual current

protective devices (RCDs) in wiring installations. The instruments are connected through

a normal mains socket outlet or directly via the RCDs terminals. Neon lamp indicate if

there are no open circuits in the installation and if the phase connections are correct.

A rotary switch selects the RCD rating from one of six values available and a

Membrane push-buttons are used to select the type of test. The 'ABC' key selects


53/203

p yp y

type of breaker to be tested. The phase key selects the point on the a.c. waveform from

where the test will start, i.e. the positive or negative zero crossing point. The 'I' key, will

allow one of three current multipliers or a 150 mA specific test to be selected. The test

key will initiate a test.

The 4 digit LCD shows the time value that the RCD takes to trip. For a successful

'no trip' test the maximum time of test current flow is given. For unsuccessful tests on 'B'

and 'C' type devices the display shows the word 'FAIL' as the test result.

The instrument circuit is microprocessor controlled and will always assume the

default setting when switched on or when the rotary switch is moved out of the stand-byposition. The maximum current that can flow is 500 mA. The instrument has a thermal

cut out to prevent overheating caused by rapidly repeated tests at high current. Also, it is

hardware and software protected against hazardous live voltages. If in the event prior to a

test the earth neutral potential is greater than 50 V,' or a test current causes earth potential

to rise greater than 50 V above neutral, the instrument will then turn the test current off

within 40 ms and show >50 V on the display. The rotary switch has a 'Standby' position

which, when selected (with the instrument connected to the supply), renders the LCD

blank but the microprocessor in the reset state.



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y

There is an inherent safety problem in earth resistance testing that requires care

and planning by the user of the earth resistance test set.

The possibility exists that a fault in the power system will cause a high current to

flow into the ground system while the test is in progress. This may cause unexpected high

voltages to appear at the current and voltage probes and also at the terminals of the test

set.

This risk must be evaluated by the person responsible for the tests, taking into

account the fault current available and expected step-and-touch potentials. IEEE Standard

80 entitled IEEE Guide for Safety in AC Substation Grounding fully covers thissubject. It is recommended that the operator should wear rubber protective gloves while

handling connections and use a rubber safety mat while operating the earth resistance test

set.

Following safety precautions must be taken before and while performing the earth

loop impedance test or testing RCD.

Safety Warnings and Precautions recommended by manufacturer must be

read and understood before the instrument is used. They must be observed

during use.

Continuity of protective conductors and earthed equipotential bonding of

new or modified installations must be verified before carrying out RCD

7.0.0 Attachments


55/203

7.1.1 Fluke multimeter manual

7.12 Megger Manual BM80

7.13 Fluke Clamp on meter Instruction sheet

7.14 Megger Digital Earth Tester

7.15 Megger Digi tal Loop Tester

7.16 Megger RCD Tester


56/203

80 Series IIIMultimeters

Users Manual

October 1997 Rev.4, 6/021997-2002 Fluke Corporation, All rights reserved. Printed in U.S.A.

All product names are trademarks of their respective companies.

Lifetime Limited Warranty


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y

Each Fluke 20, 70, 80, 170 and 180 Series DMM will be free from defects in material and workmanship for its lifetime. As used herein,

lifetime is defined as seven years after Fluke discontinues manufacturing the product, but the warranty period shall be at least ten years from

the date of purchase. This warranty does not cover fuses, disposable batteries, damage from neglect, misuse, contamination, alteration,

accident or abnormal conditions of operation or handling, including failures caused by use outside of the products specifications, or normal

wear and tear of mechanical components. This warranty covers the original purchaser only and is not transferable.

For ten years from the date of purchase, this warranty also covers the LCD. Thereafter, for the lifetime of the DMM, Fluke will replace theLCD for a fee based on then current component acquisition costs.

To establish original ownership and prove date of purchase, please complete and return the registration card accompanying the product, or

register your product onhttp://www.fluke.com.Fluke will, at its option, repair at no charge, replace or refund the purchase price of a

defective product purchased through a Fluke authorized sales outlet and at the applicable international price. Fluke reserves the right to

charge for importation costs of repair/replacement parts if the product purchased in one country is sent for repair elsewhere.

If the product is defective, contact your nearest Fluke authorized service center to obtain return authorization information, then send the

product to that service center, with a description of the difficulty, postage and insurance prepaid (FOB Destination). Fluke assumes no risk

for damage in transit. Fluke will pay return transportation for product repaired or replaced in-warranty. Before making any non-warranty

repair, Fluke will estimate cost and obtain authorization, then invoice you for repair and return transportation.

THIS WARRANTY IS YOUR ONLY REMEDY. NO OTHER WARRANTIES, SUCH AS FITNESS FOR A PARTICULAR PURPOSE, ARE

EXPRESSED OR IMPLIED. FLUKE SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL

DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, ARISING FROM ANY CAUSE OR THEORY. AUTHORIZED RESELLERS ARE

NOT AUTHORIZED TO EXTEND ANY DIFFERENT WARRANTY ON FLUKES BEHALF. Since some states do not allow the exclusion or

limitation of an implied warranty or of incidental or consequential damages, this limitation of liability may not apply to you. If any provision of

this warranty is held invalid or unenforceable by a court or other decision-maker of competent jurisdiction, such holding will not affect the

validity or enforceability of any other provision.

Fluke Corporation Fluke Europe B.V.

P.O. Box 9090 P.O. Box 1186Everett WA 5602 B.D. Eindhoven

2/02 98206-9090 The Netherlands
http://www.fluke.com/http://www.fluke.com/http://www.fluke.com/


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i

Table of Contents

Title Page

Introduction.................................................................................................................... 1

Safety Information ...................................... ............................................. ...................... 1

Your Meters Features ............................................. ............................................. ......... 4

Power-Up Options .......................................... ............................................. ............. 11

Automatic Power-Off................................................................................................. 11

Input Alert Feature ............................................ ............................................. ....... 12

Making Measurements ........................................ ............................................. ............. 12

Measuring AC and DC Voltage................................................................................. 12

Testing for Continuity................................................................................................ 14

Measuring Resistance ............................................ ............................................. ..... 16

Using Conductance for High Resistance or Leakage Tests ..................................... 18

Measuring Capacitance............................................................................................ 18

Testing Diodes.......................................................................................................... 21

Measuring AC or DC Current.................................................................................... 22Measuring Frequency............................................................................................... 25

Measuring Duty Cycle............................................................................................... 27

Determining Pulse Width ........................................... ............................................. .. 28

80 Series IIIUsers Manual

A l B G h 28


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ii

Analog Bar Graph ......................................... ............................................. .................... 28

Model 87 Bar Graph.................................................................................................. 28

Models 83 and 85 Bar Graph.... ............................................. ................................... 29

4-1/2 Digit Mode (Model 87) .......................................................................................... 29

MIN MAX Recording Mode ............................................ ............................................. ... 30

Touch Hold

Mode....................................................................................................... 32Relative Mode................................................................................................................ 32

Zoom Mode (Models 83 and 85)....................................... ........................................ 32

Uses for the Zoom Mode (Models 83 and 85)........................................................... 33

Maintenance ........................................... ............................................. .......................... 33

General Maintenance................................................................................................ 33

Testing the Fuses...................................................................................................... 34

Replacing the Battery................................................................................................ 35

Replacing the Fuses ............................................ ............................................. ........ 35

Service and Parts........................................................................................................... 36

Specifications................................................................................................................. 41


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iii

List of Tables

Table Title Page

1. International Electrical Symbols ......................................................................................... 2

2. Inputs ................................................................................................................................. 4

3. Rotary Switch Positions ..................................................................................................... 5

4. Pushbuttons ....................................................................................................................... 6

5. Display Features ................................................................................................................ 9

6. Estimating Capacitance Values Over 5 Microfarads.......................................................... 20

7. Functions and Trigger Levels for Frequency Measurements............................................. 268. MIN MAX Functions ........................................................................................................... 31

9. Replacement Parts............................................................................................................. 38

10. Accessories........................................................................................................................ 40

11. Models 85 and 87 AC Voltage Function Specifications...................................................... 42

12. Model 83 AC Voltage Function Specifications ................................................................... 43

13. DC Voltage, Resistance, and Conductance Function Specifications ................................. 44

14. Current Function Specifications ......................................................................................... 45

15. Capacitance and Diode Function Specifications................................................................ 47

16. Frequency Counter Specifications ..................................................................................... 47

17. Frequency Counter Sensitivity and Trigger Levels............................................................. 4818. Electrical Characteristics of the Terminals ......................................................................... 49

19. MIN MAX Recording Specifications ................................................................................... 50



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iv


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v

List of Figures

Figure Title Page

1. Display Features (Model 87 Shown).......................................................... 82. Measuring AC and DC Voltage.................................................................. 133. Testing for Continuity................................................................................. 154. Measuring Resistance ............................................................................... 17

5. Measuring Capacitance............................................................................. 196. Testing a Diode ......................................................................................... 217. Measuring Current..................................................................................... 238. Components of Duty Cycle Measurements ............................................... 279. Testing the Current Fuses......................................................................... 3410. Battery and Fuse Replacement ................................................................. 3711. Replaceable Parts ..................................................................................... 39



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vi

Introduction

Introduction In this manual a Warning identifies conditions and


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1

Introduction

Warning

Read "Safety Information" before you use

the meter.

Except where noted, the descriptions and instructions in

this manual apply to Series III Models 83, 85, 87, and

87/E multimeters. Model 87 is shown in all illustrations.

Safety Information

This meter complies with:

EN61010.1:1993

ANSI/ISA S82.01-1994 CAN/CSA C22.2 No. 1010.1-92

1000 V Overvoltage Category III, Pollution Degree 2

600 V Overvoltage Category IV, Pollution Degree 2

UL3111-1

Use the meter only as specified in this manual, otherwise

the protection provided by the meter may be impaired.

In this manual, a Warningidentifies conditions and

actions that pose hazards to the user. A Caution

identifies conditions and actions that may damage the

meter or the equipment under test.

International symbols used on the meter and in this

manual are explained in Table 1.

Warning

To avoid possible electric shock or personal

injury, follow these guidelines:

Do not use the meter if it is damaged.

Before you use the meter, inspect the

case. Look for cracks or missing plastic.

Pay particular attention to the insulationsurrounding the connectors.

Make sure the battery door is closed and

latched before you operate the meter.

Replace the battery as soon as the

battery indicator () appears.

80 Series III

Users Manual

Table 1. International Electrical Symbols


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2

Table 1. International Electrical Symbols

AC (Alternating Current) Earth ground

DC (Direct Current) Fuse

AC or DC Conforms to European Union directives

Refer to the manual for information

about this feature.

Conforms to relevant Canadian

Standards Association directives

Battery Double insulated

Inspected and licensed by TV Product Services.

Safety Information

Remove test leads from the meter before Caution


66/203

3

Remove test leads from the meter before

you open the battery door.

Inspect the test leads for damaged

insulation or exposed metal. Check the

test leads for continuity. Replace

damaged test leads before you use the

meter.

Do not use the meter if it operates

abnormally. Protection may be impaired.

When in doubt, have the meter serviced.

Do not operate the meter around

explosive gas, vapor, or dust.

Use only a single 9 V battery, properlyinstalled in the meter case, to power the

meter.

When servicing the meter, use only

specified replacement parts.

To avoid possible damage to the meter or to

the equipment under test, follow these

guidelines:

Disconnect circuit power and dischargeall high-voltage capacitors before testing

resistance, continuity, diodes, or

capacitance.

Use the proper terminals, function, and

range for your measurements.

Before measuring current, check the

meters fuses. (See "Testing the Fuses".)

80 Series III

Users Manual

To protect yourself, use the following guidelines: Table 2. Inputs


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4

p y g g

Use caution when working with voltages above 30 V

ac rms, 42 V ac peak, or 60 V dc. Such voltages

pose a shock hazard.

When using the probes, keep your fingers behind thefinger guards.

Connect the common test lead before you connect

the live test lead. When you disconnect test leads,

disconnect the live test lead first.

Avoid working alone.

When measuring current, turn off circuit power

before connecting the meter in the circuit. Rememberto place the meter in series with the circuit.

Your Meters Features

Tables 2 through 5 briefly describe your meters features

and give page numbers where you can find more detailed

information about the features.

p

Terminal Description Page

A Input for 0 A to 10.00 Acurrent measurements

22

mA A Input for 0 A to 400 mAcurrent measurements

22

COM Return terminal for allmeasurements

NA

V Input for voltage,continuity, resistance,

diode, capacitance,

frequency, and duty

cycle measurements

V:12

:16

:21:18Frequency: 25

Duty cycle: 27


Table 3. Rotary Switch Positions


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5

Switch Position Function Page

AC voltage measurement 12

DC voltage measurement 12

mV400 mV dc voltage range 12

Continuity test 14

Resistance measurement 16

Capacitance measurement 18

Diode test 21mAA

DC or AC current measurements from 0 mA to 10.00 A 22

A DC or AC current measurements from 0 A to 4000 A 22

80 Series III

Users Manual

Table 4. Pushbuttons


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6

Button Function Button Function Page

(Bluebutton)

mA/A, APower-up

Selects capacitance.

Switches between dc and ac current.Disables automatic power-off feature.

18

2211

Any switchposition

Power-up

Starts recording of minimum and maximum values. Steps the display throughMIN, MAX, AVG (average), and present readings.

Enables high-accuracy 1-second response time for MIN MAX recording.

30

30

Any switchposition

Switches between the ranges available for the selected function. To return toautoranging, hold the button down for 1 second.

Manually selecting a range causes the meter to exit the Touch Hold, MINMAX, and REL (relative) modes.

See ranges inspecifications.

Power-up For servicing purposes only. NA

Any switchposition

MIN MAXrecording

Frequency

counter

Touch Hold captures the present reading on the display. When a new, stablereading is detected, the meter beeps and displays the new reading.

Stops and starts recording without erasing recorded values.

Stops and starts the frequency counter.

32

30

25


Table 4. Pushbuttons (cont)


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7

Button Function Button Function Page

Model 87:yellow button

Models 83,85: gray

button

Any switchposition

Turns the backlight on and off.

For Model 87, hold the yellow button down for one second to enter the4-1/2 digit mode. To return to the 3-1/2 digit mode, hold the button downonly until all display segments turn on (about one second).

NA

29

Continuity

MIN MAXrecording

Power-up

Turns the continuity beeper on and off.

On Model 87, switches between 250 s and 100 ms or 1 s responsetimes.

Disables the beeper for all functions.

14

30

NA

(Relativemode)

Any switchposition

Power-up

Stores the present reading as a reference for subsequent readings. Thedisplay is zeroed, and the stored reading is subtracted from allsubsequent readings.

For Models 83 and 85, enables zoom mode for the bar graph.

32

32

Any switchposition

Power-up

Starts the frequency counter.

Press again to enter duty cycle mode.

Provides >4000 Minput impedance for the 400 mV dc range.

25

27

NA

80 Series III

Users Manual

6 7 8 9


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8

13

6 7 8 9

5

1010

10

1

2

3

4

12

11

iy1f.eps

Figure 1. Display Features (Model 87 Shown)


Table 5. Display Features


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9

Number Feature Indication Page

Polarity indicator for the analog bar graph. 28

Relative (REL) mode is active. 32

The continuity beeper is on. 14

- Indicates negative readings. In relative mode, this sign indicates that thepresent input is less than the stored reference. 32 The battery is low. Warning: To avoid false readings, which could lead

to possible electric shock or personal injury, replace the battery as soon

as the battery indicator appears.

35

AUTO The meter is in autorange mode and automatically selects the range with thebest resolution.

NA

100 msMAX MIN AVG

Indicators for minimum-maximum recording mode. 30

Touch Hold is active. 32

AC DC Indicator for ac or dc voltage or current. AC voltage and current is displayed asan rms (root mean square) value. 12,22

80 Series III

Users Manual

Table 5. Display Features (continued)


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10


A, A, mA A: Amperes (amps). The unit of current.A: Microamp. 1 x 10-6or 0.000001 amperes.

mA: Milliamp. 1 x 10-3or 0.001 amperes.

22

V, mV V: Volts. The unit of voltage.mV: Millivolt. 1 x 10-3or 0.001 volts.

12

F, nF F: Farad. The unit of capacitance.F: Microfarad. 1 x 10-6or 0.000001 farads.

nF: Nanofarad. 1 x 10-9 or 0.000000001 farads.

18

nS S: Siemen. The unit of conductance.nS: Nanosiemen. 1 x 10-9 or 0.000000001 siemens.

18

% Percent. Used for duty cycle measurements. 27

, M, k : Ohm. The unit of resistance.M: Megohm. 1 x 106or 1,000,000 ohms.

k: Kilohm. 1 x 103or 1000 ohms.

16

Hz, kHz, MHz Hz: Hertz. The unit of frequency.kHz: Kilohertz. 1 x 103or 1000 hertz.

MHz: Megahertz. 1 x 106or 1,000,000 hertz.

25


Table 5. Display Features (continued)


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11


4000 mV Displays the currently selected range. See specificationsfor ranges for each

function.

Analog bar graph Provides an analog indication of the present inputs. 28

The input (or the relative value when in relative mode) is too largefor the selected range. For duty cycle measurements OL is

displayed when the input signal stays high or low.

Duty cycle: 27

Power-Up Options

Holding a button down while turning the meter onactivates a power-up option. Table 4 includes the power-

up options available. These options are also listed on the

back of the meter.

Automatic Power-Off

The meter automatically turns off if you do not turn therotary switch or press a button for 30 minutes. To disable

automatic power-off, hold down the blue button while

turning the meter on. Automatic power-off is always

disabled in MIN MAX recording mode.

80 Series III

Users Manual

Input Alert Feature Measuring AC and DC Voltage


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12

If a test lead is plugged into the mA/Aor Aterminal, but

the rotary switch is not correctly set to the mA/Aor A

position, the beeper warns you by making a chirping

sound. This warning is intended to stop you from

attempting to measure voltage, continuity, resistance,capacitance, or diode values when the leads are plugged

into a current terminal. Placing the probes across (in

parallel with) a powered circuit when a lead is plugged into

a current terminal can damage the circuit you are testing

and blow the meters fuse.This can happen because the

resistance through the meters current terminals is very

low, so the meter acts like a short circuit.

Making MeasurementsThe following sections describe how to take

measurements with your meter.

Voltage is the difference in electrical potential between

two points. The polarity of ac (alternating current) voltage

varies over time, while the polarity of dc (direct current)

voltage is constant over time. The meter presents ac

voltage values as rms (root mean square) readings. Therms value is the equivalent dc voltage that would produce

the same amount of heat in a resistance as the measured

sinewave voltage. Models 85 and 87 feature true rms

readings, which are accurate for other wave forms (with

no dc offset) such as square waves, triangle waves, and

staircase waves.

The meters voltage ranges are 400 mV, 4 V, 40 V, 400 V,

and 1000 V. To select the 400 mV dc range, turn the

rotary switch to mV.

To measure ac or dc voltage, set up and connect the

meter as shown in Figure 2.

Making Measurements

The following are some tips for measuring voltage:

AC Voltage


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When you measure voltage, the meter acts

approximately like a 10 M(10,000,000 )

impedance in parallel with the circuit. This loading

effect can cause measurement errors in high-

impedance circuits. In most cases, the error isnegligible (0.1% or less) if the circuit impedance is

10 k(10,000 ) or less.

For better accuracy when measuring the dc offset of

an ac voltage, measure the ac voltage first. Note the

ac voltage range, then manually select a dc voltage

range equal to or higher than the ac range. This

procedure improves the accuracy of the dc

measurement by ensuring that the input protection

circuits are not activated.

M IN MAX R AN GE H OLD H

HzREL

mAA

mV

V

V

OFF

!

!

1000V MAX

400mA MAXFUSED

10A MAXFUSED

PEAKMINMAX

A

CAT II

V

87 TRUERMSMULTIMETER

M IN M AX R AN GE H OL DH

HzREL

mAA

mV

V

V

OFF

!

!

A COM VmA A

A COM VmA A

1000V MAX

400mA MAXFUSED

10A MAXFUSED

PEAKMINMAX41/2 DIGITS

1 Second

41/2 DIGITS

1 Second

A

CAT II

Switch Box

V

+

g

DC Voltage

III

87 TRUERMSMULTIMETERIII

iy2f.eps

Figure 2. Measuring AC and DC Voltage

80 Series III

Users Manual

Testing for Continuity The continuity function detects intermittent opens andshorts lasting as little as 1 millisecond (0.001 second).


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14

Caution


the equipment under test, disconnect circuit

power and discharge all high-voltagecapacitors before testing for continuity.

Continuity is the presence of a complete path for current

flow. The continuity test features a beeper that sounds if a

circuit is complete. The beeper allows you to perform

quick continuity tests without having to watch the display.

To test for continuity, set up the meter as shown in

Figure 3.

Pressto turn the continuity beeper on or off.

g ( )

These brief contacts cause the meter to emit a short beep.

Making Measurements

For in-circuit tests turn circuit power off


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15

M IN M AX R AN GE HO LD H

HzREL

mAA

mV

V

V

OFF

!

!

1000VMAX

400mAMAX

FUSED10AMAX

FUSED

PEAK MIN MAX

A

CATII

Activatescontinuity

beeper

ON(closed)

MI N MAX R ANG E H OL DH

HzREL

mAA

mV

V

V

OFF

!

!

1000VMAX

400mAMAXFUSED

10AMAXFUSED

PEAK MIN MAX4 1/2 DIGITS1 Seconds4 1/2 DIGITS

1 Seconds

A

CATII

OFF(open)

A COM VmA A

For in circuit tests, turn circuit power off.

87 TRUE RMS MULTIMETERIII87 TRUE RMS MULTIMETERIII

iy4f.eps

Figure 3. Testing for Continuity

80 Series III

Users Manual

Measuring Resistance

C ti

The following are some tips for measuring resistance:

Because the meters test current flows through all


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Caution


the equipment under test, disconnect circuit

power and discharge all high-voltagecapacitors before measuring resistance.

Resistance is an opposition to current flow. The unit of

resistance is the ohm (). The meter measures resistance

by sending a small current through the circuit. Because

this current flows through all possible paths between the

probes, the resistance reading represents the total

resistance of all paths between the probes.

The meters resistance ranges are 400 , 4 k, 40 k,400 k, 4 M, and 40 M.

To measure resistance, set up the meter as shown in

Figure 4.

Because the meters test current flows through all

possible paths between the probe tips, the measured

value of a resistor in a circuit is often different from

the resistors rated value.

The test leads can add 0.1 to 0.2 of error to

resistance measurements. To test the leads, touch

the probe tips together and read the resistance of the

leads. If necessary, you can use the relative (REL)

mode to automatically subtract this value.

The resistance function can produce enough voltage

to forward-bias silicon diode or transistor junctions,

causing them to conduct. To avoid this, do not use

the 40 Mrange for in-circuit resistancemeasurements.

Making Measurements

In-Circuit Resistance Measurements

Isolating a Potentiometer


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MI N MA X R AN GE HOL DH

HzREL

mAA

mV

V

V

OFF

!

!

A COM VmA A

1000VMAX

400mAMAX

FUSED10AMAX

FUSED

PEAK MIN MAX

A

CAT II

Circuit Power

OFF

Disconnect

1 2

3

1 3 2

Disconnect

Isolating a Resistor4 1/2 DIGITS

1 Seconds

87 TRUE RMS MULTIMETERIII

iy6f.eps

Figure 4. Measuring Resistance

80 Series III

Users Manual

Using Conductance for High Resistance orLeakage Tests

The following are some tips for measuring conductance:

High-resistance readings are susceptible to electrical


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Conductance, the inverse of resistance, is the ability of a

circuit to pass current. High values of conductance

correspond to low values of resistance.

The unit of conductance is the Siemen (S). The meters

40 nS range measures conductance in nanosiemens

(1 nS = 0.000000001 Siemens). Because such small

amounts of conductance correspond to extremely high

resistance, the nS range lets you de

module no e03 electrical test equipment basic

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