hioki - grounding measurement

8/11/2019 Hioki - Grounding Measurement

1/36

Peninsula Hotel Jakarta, 19 June 2014

By Diyah Handayani KHIOKI SINGAPORE PTE. LTD


2/36

What is Grounding ?

A grounding is a conducting connection by which anelectrical circuit or equipment is connected to theearth or some conducting body.

Source: IEEE Standard 81


3/36

What is Grounding ?

A conducting connection, between an electricalcircuit or equipment and the earth, or to someconducting body that serves in place of the earth.

Source: NFPA 70-1981; National Electrical Code


4/36

PURPOSE OF GROUNDING

The purpose of a ground besides the protection

of people, plants and equipment is to provide asafe path for the dissipation of fault currents,

lightning strikes, static discharges, EMI and RFI

signals and interference.


5/36

2 TYPE GROUNDING SYSTEM

Earth grounding

is an intentional connection from a circuit conductor,

usually the neutral, to a ground electrode placed in the

earth.

Equipment grounding

ensures that operating equipment within a structure is

properly grounded


6/36

EXAMPLE OF GROUNDING


7/36

Why we must test Ground ?

Poor grounding not only contributes to unnecessary downtime,but a lack of good grounding is also dangerous and increasesthe risk of equipment failure.

Without an effective grounding system,we could be exposed tothe risk of electric shock, not to mention instrumentationerrors,harmonic distortion issues, power factor problems and ahost of possible intermittent dilemmas.

If fault currents have no path to the ground through a properlydesigned and maintained grounding system, they will findunintended paths that could include people.


8/36

GROUND STANDARDS

NFPA and IEEE have recommended a ground resistancevalue of 5.0 ohms or less.

The NEC has stated to "Make sure that system

impedance to ground is less than 25 ohms specified in

NEC 250.56.

The Telecommunications industry has often used 5.0

ohms or less as their value for grounding and bonding.

Communication requires lower signal level with higher

frequency characteristics than 60 Hz Utility requirements


9/36

GROUND RESISTANCE TARGET

Typical values for a power company:

- Generating station: 1 maximum

- Large sub-station: 1 maximum

- Small sub-station: 5

maximum

Water pipe ground should be less than 3 and

frequently less than 1 .

The Telecomunication industry has often used 5or

less as their value for grounding and bonding.


10/36

COMPONENT OF GROUND ELECTRODE


11/36

WHAT AFFECTS THE

GROUNDING RESISTANCE?

First, the NEC code (1987, 250-83-3) requires a minimum ground

electrode length of 2.5 meters (8.0 feet) to be in contact with soil.

But, there are variables that affect the ground resistance of a

ground system:

1. Length/depth of the ground electrode2. Diameter of the ground electrode

3. Number of ground electrodes

4 . Ground system design

5. Soil


12/36

Length/depth of the ground electrode

The dept of the electrode can lower the resistance valueeffectively, Normally doubling the length of the earthelectrode can reduce the resistance by an additionally40%.


13/36

Diameter of the ground electrode

Increasing the diameter of the ground electrode has

very little effect in lowering the resistance. Forexample, you could double the diameter of a groundelectrode and your resistance would only decrease by10 %.


14/36

Number of ground electrodes

Another way to lower ground resistance is to use multipleground electrodes. In this design, more than oneelectrode is driven into the ground and connected inparallel to lower the resistance. For additional electrodes

to be effective, the spacing of additional rods need to beat least equal to the depth of the driven rod.


15/36

GROUND SYSTEM DESIGN

Single ground electrode Multiple ground electrode

Mesh Network Ground Plate


16/36

SOIL

Soil resistance values depend on soil composition,moisture & temperature


17/36

TESTING METHODS

Normally single electrode earthing is used for domestic

applications, but for power generating substations and industrieswe use a grid network with multiple electrodes.

The "3-pole fall of potential" testing method can be used for a

complex earth system. In this technique, the earth grid is

disconnected from the earth electrode. Two auxiliary electrodes

(one current electrode and a second potential electrode) areplaced beside the electrode to be tested at an equal distance in a

straight line. The current passed through the auxiliary current

electrode is to be noted and recorded. In this way, the potential

difference generated between the auxiliary potential electrode and

the current electrode can be measured.

Measurement of earth resistance and leakage current without

disconnecting the circuit can be done using portable

instruments. The clamp-on type of earth resistance tester can

measure earth resistance and leakage current.


18/36

WHATS A CLAMP ON EARTH TESTER?

Measure Closed Loop Resistance

1

Closed Loop


19/36

Ground Resistance Measurement


20/36

Clamp Earth TesterFT6380 / FT6381

Allows you to hold the displayvalue.

With the bright back light, you can easily

read the measurement value even in dark

locations.

You can store up to 2,000 measurement

values in the field and recall them in your

office later.

No wait time after powering on.

Start measuring instantly without

zero-calibration.

Resistance mode filter: Digital filter gives you

steadier readings.

Current mode filter: Low-pass filter

eliminates harmonics current over 180Hz.

Set the alarm to audible and visually

notify you that the resistance or

current value exceeds the threshold.

Switch between resistance

measurement mode or current

measurement mode.

32mm


21/36

For multiple grounding systems

RnRRRR

RxI

V

1.....

4

1

3

1

2

1

1

1

1

RxI

Vn =


22/36

HIOKI

26mm 20mm

53mm

38mm45%Smaller

How Compact?

Comparison of cross-sectional area of the Jaw


23/36

Access to tight spots

Why Compact?


24/36

Pole

Grounding Electrode

Large Jaw Ground

Clamps: Strugglewith dirt

HIOKI: Easy access to tight spots

At your field, what happens?

Feel the difference


25/36

ACCURACY OF FLAT CORE

View of Core Sensor of Flat Jaw


26/36

ACCURACY OF INTERLOCKING CORE

View of Core Sensor of Interlocking Jaw


27/36

INTERLOCKING CORE

-50%

-40%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50%

0 200 400 600 800 1000 1200 1400 1600

HIOKI

+3

-3

Spec

Spec


28/36

RELIABILITY

R

Voltage

Injection

Current

Detection

I = V/R

R =V/I

Designed to last!

Prevents leakage current

Interlocking Shield Design

R

I = V/R

R =V/ (I+Iflux)

Leakage FluxLeakage Flux

With micro-meter gap

Accurate Reading!!

CT Magnetic Core

Magnetic Shield

VT Magnetic Core

Cross-section view of jaw


29/36

Magnetic Cores

Air Gap

EFFECT OF AIR GAP


30/36

AC CURRENT MEASUREMENT (LEAKAGE

CURRENT)

Wide range: From 1mA to 60Awith Filter ON/OFF

Function

Safe: EN61010 CAT IV 600V


31/36

ENERGY EFFICIENT

Uses only 2 x LR6 Alkaline Batteries

Continuous Usage of up to 35 hours (Backlight &

Bluetooth OFF)

ReducedBy more

than 50%


32/36

SAFETY

CAT IV 600V

Withstand Voltage: AC 7400 Vrms for one minute

Between clamp sensor and casing

Max. Input current: AC 100A continuous, AC 200A for 2

minute (50 / 60Hz)


33/36

Auto Report

Generation

Via email

DOWNLOAD APPS FROM GOOGLE PLAY STORE


34/36

REPORT FUNCTION

Get

Time Stamp

Measuring Data with screen

imageLocation information with map

image

Reports are

Sent via e-mailSynchronized using Cloud servers


35/36

APPLICATIONS

All overhead transmission conductor lines that may be exposed to

lightning should be protected by a means for diverting any electricsurge to earth.

The grounding cables of transmission towers should be tested

frequently.

Transformer earthing terminal measurements should be

conducted to ensure proper contact between the soil and theearth point.

Low earthing wire resistance is most important for motors, power

distribution panels, and control panels.

The earthing of a telecommunication control cabin or signal relay

board is important to reduce stray electrodynamic stress andnoise.

Separate earthing should be provided for PLC and SCADA

instruments in a control panel.

Good earthing is required for petrochemicals pipelines and oilstorage tanks.


36/36

hioki - grounding measurement

Documents