basic of electrical

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Description

SWER is a good choice for a distribution system when conventional return

current wiring would cost more than SWER's isolation transformers and smallpower losses. Power engineers experienced with both SWER and conventional

power lines rate SWER as equally safe, more reliable, less costly, but with

slightly lower efficiency than conventional lines

Power is supplied to the SWER line by an isolating transformerof up to 300 kVA.

This isolates the grid from ground or earth, and changes the grid voltage

(typically 22 kilovolts line to line) to the SWER voltage (typically 12.7 or 19.1

kilovolts line to earth).

The SWER line is a single conductorthat may stretch for tens or even hundreds

of kilometres, visiting a number of termination points. At each termination point,

such as a customer's premises, current flows from the line, through the primary

coil of a step-down transformer, to earththrough an earth stake. From the earth

stake, the current eventually finds its way back to the main step-down

transformer at the head of the line, completing the circuit. SWER is therefore a

practical example of a phantom loop.The secondary winding of the local transformer will supply the customer with

either single ended single phase (N-0) or split phase(N-0-N) power in the

region's standard appliance voltages, with the 0 volt line connected to a safety

earth that does not normally carry an operating current.
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A large SWER line may feed as many as 80 distribution transformers. Since the

distribution system must carry reactive power(vars), as well as real power

(watts), capacities are measured in volt-amperes, not watts. The transformers

are usually rated at 5 kVA, 10 kVA and 25 kVA. The load densities are usuallybelow 0.5 kVA per kilometer (0.31 kVA per mile) of line. Any single customer's

maximum demand will typically be less than 3.5 kVA, but larger loads up to the

capacity of the distribution transformer can also be supplied.

History

At the end of the 19th century, Nikola Teslademonstrated a single wire was

necessary for power systems, with no need for a wired return conductor (using

the Earth instead).[2]Lloyd Mandenofully developed SWER in New Zealand

around 1925for rural electrification. Although he termed it "Earth Working Single

Wire Line" it was often called "Mandeno s Clothesline." More than 200,000

kilometres have now been installed in Australia and New Zealand. It is

considered safe, reliable and low cost, provided that safety features and earthing

are correctly installed. The Australian standards are widely used and cited. It has

been applied in Saskatchewan, Brazil and Africa, and SWER interties have been

proposed for Alaska and prototyped.

Safety

SWER violates common wisdom about electrical safety, because it lacks a

traditional metallic return to a neutral shared by the generator. SWER's safety is

instead assured because transformers isolate the ground from both the generator

and user.

However, grounding is critical. Significant currents (of the order of 8 amperes)

flow through the ground near the earth point, so a good-quality earth connection

is needed to prevent risk of electric shocknear this point. Separate grounds for
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power and safety are also used. Duplication of the grounds assures that the

system is still safe if either of the grounds are damaged.

A good earth connection is normally a 6 m stake of copper-clad steel driven

vertically into the ground, and bonded to the transformer earth and tank. A goodground resistance is 5-10 ohms.

Other standard features include automatic reclosing circuit breakers (reclosers).

Most faults (overcurrent) are transient. Since the network is rural, most of these

faults will be cleared by the recloser. Each service site needs a rewirable drop

out fuse for protection and switching of the transformer. The transformer

secondary should also be protected by a standard high-rupture capacity (HRC)

fuse or low voltage circuit breaker. A surge arrestor (spark gap) on the high

voltage side is common, especially in lightning-prone areas.

Bare-wire or ground-return telecommunications can be compromised by the

ground-return current if the grounding area is closer than 100 m or sinks more

than 10 A of current. Modern radio, optic fibre channels and cell phone systems

are unaffected.

Low cost: the main advantage

SWER's main advantage is its low cost. It is often used in sparsely populated

areas where the cost of building an isolated distribution line cannot be justified.

Capital costs are roughly 50% of an equivalent two-wire single-phase line. They

can be 70% less than 3-wire three-phase systems. Maintenance costs are

roughly 50% of an equivalent line.

SWER also reduces the largest cost of a distribution network, the number of

poles. Conventional two wire or three wire distribution lines have a higher power

transfer capacity, but can require seven poles per kilometre, with spans of 100 m

to 150 m. SWER's high line voltage and low current permits the use of low-cost

galvanized steelwire. Steel's greater strength permits spans of 400 m or more,

reducing the number of poles to 2.5/km.
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Reinforced concretepoles have been traditionally used in SWER lines because

of their low cost, low maintenance, and resistance to water damage, termitesand

fungus. Local labor can produce them in most areas, further lowering costs.

If the cable contains optic fibre[3]

, or carries RF phone line service, this canfurther amortizethe capital costs.

Reliability: a strength

SWER can be used in a grid or loop, but is usually arranged in a linear or radial

layout to save costs. In the customary linear form, a single-point failure in a

SWER line causes all customers further down the line to lose power. However,

since it has fewer components in the field, SWER has less to fail. For example,

since there is only one line, winds can't cause lines to clash, removing a source

of damage, as well as a source of rural brush fires.

Since the line can't clash in the wind, and the bulk of the transmission line has

low resistance attachments to earth, excessive ground currents from shorts and

geomagnetic storms are far more rare than in conventional metallic-return

systems. So, SWER has fewer ground-fault circuit-breaker openings to interrupt

service.

Power quality: a weakness

SWER lines tend to be long, with high impedance, so the voltage drop along the

line is often a problem, causing poor power quality. Variations in demand cause

variation in the delivered voltage. To combat this, some installations have

automatic variable transformers at the customer site to keep the received voltage

within legal specifications.

When used with distributed generation, SWER is substantially more efficient than

when it is operated as a single-ended system. For example, some rural

installations can offset line losses and charging currents with local solar power,

wind power, small hydroor other local generation. This can be an excellent value
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for the electrical distributor, because it reduces the need for more lines. (Kashem

and Ledwich)

After some years of experience, the inventor (Mandeno, below) advocated a

capacitorin series with the ground of the main isolation transformer to counteractthe inductive reactance of the transformers, wire and earth return path. The plan

was to improve the power factor, reduce losses and improve voltage

performance due to reactive powerflow. Though theoretically sound, this is not

standard practice.

Upgrading a SWER line

Transformers need not be permanently installed. It is perfectly possible to place

maximum-indicating thermometers in them, and install larger transformers as

needed, moving the smaller ones to other positions.

As demand grows, a well-designed SWER line can be substantially upgraded

without new poles. The first step may be to replace the steel wire with more

expensive copper-clad or aluminum-clad steel wire.

If more capacity is needed, a second SWER line can be run on the same poles to

provide two SWER lines 180 degrees out of phase. This requires more insulators

and wire, but doubles the power without doubling the poles. Many standard

SWER poles have several bolt holes to support this upgrade. This configuration

causes most ground currents to cancel, reducing shock hazards, and

interference with communication wirelines.

Conventional two phaseservice is also possible with a two-wire upgrade: Though

less reliable, it is more efficient and conforms to standard distribution practices.

As more power is needed the lines can be upgraded to match the load, from

single wire SWER to two wire, single phase and finally to three wire, three phase.

This ensures a more efficient use of capital and makes the initial installation more

affordable.

Customer equipment installed before these upgrades will all be single phase, and

can be reused after the upgrade. If moderate amounts of three-phaseare
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needed, it can be economically synthesized from two-phase with on-site

equipment.

Use in interties

In 1981 a high-power 8.5 mile prototype SWER intertie was successfully installed

from a coal plant in Bethel, Alaskato Napakiak, Alaska. It operates at 80 kV, and

has special lightweight fiberglass poles that form an A-frame. The poles can be

carried on lightweight snow machines, and most poles can be installed with

hand-tools on permafrost without extensive digging. Erection of "anchoring" poles

still required heavy machinery, but the cost savings were dramatic.

The phase conductor also carries a bundle of optic fibres within the steel armor

wire [4], so the system supplies telecommunications as well as power.

Researchers at the University of Fairbanks estimate that a network of such

interties, combined with coastal wind turbines, could substantially reduce

Alaska's dependence on increasingly expensive diesel fuel for power generation.

[5]Alaska's state economic energy screening survey advocated further study of

this option, in order to use more of the state's underutilized power sources. [6]

Regulatory issues

Many national electrical regulations (notably the U.S.) require a metallic return

line from the load to the generator. In these jurisdictions, each SWER line must

be approved by exception.

Use for HVDC systems

Many HVDCsystems using submarine power cablesare (or were until their

expansion to bipolar schemes) single wire earth return systems. In order to avoid

electrochemical corrosion, the ground electrodes of such systems are situated

apart from the converter stations and not in the proximity of the transmission
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cable. The electrodes can be situated in the sea or on land. As cathodes, bare

copper wires can be used in the sea or on land. As anodes, graphite rods dug in

the ground, or titanium grids in the sea are used. In order to avoid

electrochemical corrosion (and passivationof titanium surfaces) the currentdensity at the surface of the electrodes may be only small and therefore large

electrodes are required. The advantage of such schemes is saving money for a

second conductor, because the saltwater is an excellent conductor. Some

ecologists claim bad influences of electrochemical reactions, but they do not

occur on very large underwater electrodes

Earthing system

Contents

[hide]

1 IEC nomenclature

o 1.1 TN network

o 1.2 TT network

o 1.3 IT network

2 Properties

o 2.1 Cost

o 2.2 Safetyo 2.3 Electromagnetic compatibility

3 Regulations

4 Application examples 5 See also

6 Reference

In electricity supplysystems, an earthingsystem defines the electrical potentialof

the conductors relative to that of the Earth's conductive surface. The choice of
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earthing system has implications for the safetyand electromagnetic compatibility

of the power supply. Note that regulations for earthing (grounding) systems vary

considerably between different countries.

A protective earth(PE) connection ensures that all exposed conductive surfacesare at the same electrical potential as the surface of the Earth, to avoid the risk of

electrical shock if a person touches a device in which an insulation fault has

occurred. It also ensures that in the case of an insulation fault, a high fault

current flows, which will trigger an overcurrent protection device (fuse, MCB) that

disconnects the power supply.

A functional earthconnection serves a purpose other than providing protection

against electrical shock. In contrast to a protective earth connection, a functional

earth connection may carry a current during the normal operation of a device.

Functional earth connections may be required by devices such as surge

suppression and electromagnetic-compatibility filters, some types of antennas

and various measurement instruments. Generally the protective earth is also

used as a functional earth, though this requires care in some situations.

IEC nomenclature

International standardIEC 60364distinguishes three families of earthing

arrangements, using the two-letter codes TN, TT, and IT.

The first letter indicates the connection between earthand the power-supply

equipment (generator or transformer):

T : direct connection of a point with earth (French: terre);

I : no point is connected with earth (isolation), except perhaps via a high impedance.

The second letter indicates the connection between earth and the electrical

device being supplied:

T : direct connection with earth, independent of any other earth connection in thesupply system;

N : connection to earth via the supply network.
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TN network

In a TNearthing system, one of the points in the generatoror transformeris

connected with earth, usually the star point in a three-phase system. The body of

the electrical device is connected with earth via this earth connection at the

transformer.

The conductor that connects the exposed metallic parts of the consumer is called

protective earth(PE). The conductor that connects to the star point in a three-

phasesystem, or that carries the return current in a single-phasesystem, is

called neutral(N). Three variants of TN systems are distinguished:

TN-S : PE and N are separate conductors that are connected together only near thepower source.

TN-C : A combined PEN conductor fulfils the functions of both a PE and an Nconductor.

TN-C-S : Part of the system uses a combined PEN conductor, which is at some point

split up into separate PE and N lines. The combined PEN conductor typicallyoccurs between the substation and the entry point into the building, whereas

within the building separate PE and N conductors are used. In the UK, this

system is also known asprotective multiple earthing (PME), because of thepractice of connecting the combined neutral-and-earth conductor to real earth

at many locations, to reduce the risk of broken neutrals - with a similar

system in Australia being designated as multiple earthed neutral (MEN).
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TN-S:separate protective earth (PE)

and neutral (N) conductors fromtransformer to consuming device,which are not connected together at

any point after the building

distribution point.

TN-C:combined PE and N conductor

all the way from the transformer to theconsuming device.

TN-C-S earthing system:combi

PEN conductor from transformerbuilding distribution point, butseparate PE and N conductors in

indoor wiring and flexible power

cords.

It is possible to have both TN-S and TN-C-S supplies from the same transformer.

For example, the sheaths on some underground cables corrode and stop

providing good earth connections, and so homes where "bad earths" are found

get converted to TN-C-S.

TT network

In a TTearthing system, the protective earth connection of the consumer is

provided by a local connection to earth, independent of any earth connection at

the generator.


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IT network

In an ITnetwork, the distribution system has no connection to earth at all, or it

has only a high impedanceconnection. In such systems, an insulation monitoring

deviceused to monitor the impedance.

Properties
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Cost

TN networks save the cost of a low-impedance earth connection at the site of each

consumer. Such a connection (a buried metal structure) is required to provide

protective earthin IT and TT systems.

TN-C networks save the cost of an additional conductor needed for separate N

and PE connections. However, to mitigate the risk of broken neutrals, special

cable types and lots of connections to earth are needed.

TT networks require RCDprotection, and often an expensive time-delay type is

needed to provide discrimination with an RCD downstream.

Safety

In TN, an insulation fault is very likely to lead to a high short-circuit current thatwill trigger an overcurrent circuit-breaker or fuse and disconnect the Lconductors. In the majority of TT systems, the earth fault loop impedance will be

too high to do this, and so an RCD must be employed.

In TN-S and TT systems (and in TN-C-S beyond the point of the split), a residual-

current device can be used as an additional protection. In the absence of anyinsulation fault in the consumer device, the equationIL1+IL2+IL3+IN= 0 holds, and

an RCD can disconnect the supply as soon as this sum reaches a threshold

(typically 10-500 mA). An insulation fault between either L or N and PE will

trigger an RCD with high probability.

In IT and TN-C networks, residual current devices are far less likely to detect an

insulation fault. In a TN-C system, they would also be very vulnerable to

unwanted triggering from contact between earth conductors of circuits ondifferent RCDs or with real ground, thus making their use impracticable. Also,

RCDs usually isolate the neutral core, and it is dangerous to do this in a TN-C

system.

In single-ended single-phase systems where the Earth and neutral are combined

(TN-C, and the part of TN-C-S systems which uses a combined neutral and earth

core), if there is a contact problem in the PEN conductor, then all parts of the

earthing system beyond the break will rise to the potential of the L conductor. Inan unbalanced multi-phase system, the potential of the earthing system will move

towards that of the most loaded live conductor. Therefore, TN-C connections

must not go across plug/socket connections or flexible cables, where there is ahigher probability of contact problems than with fixed wiring. There is also a risk

if a cable is damaged, which can be mitigated by the use of concentric cable

construction and/or multiple earth electrodes. Due to the (small) risks of the lost
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neutral, use of TN-C-S supplies is banned for caravans and boats in the UK, and it

is often recommended to make outdoor wiring TT with a separate earth electrode.

In IT systems, a single insulation fault is unlikely to cause dangerous currents to

flow through a human body in contact with earth, because no low-impedance

circuit exists for such a current to flow. However, a first insulation fault caneffectively turn an IT system into a TN system, and then a second insulation faultcan lead to dangerous body currents. Worse, in a multi-phase system, if one of the

live conductors made contact with earth, it would cause the other phase cores to

rise to the phase-phase voltage relative to earth rather than the phase-neutralvoltage. IT systems also experience larger transient overvoltages than other

systems.

In TN-C and TN-C-S systems, any connection between the combined neutral-and-earth core and the body of the earth could end up carrying significant current

under normal conditions, and could carry even more under a broken neutral

situation. Therefore, main equipotential bonding conductors must be sized withthis in mind; use of TN-C-S is inadvisable in situations such as petrol stations,

where there is a combination of lots of buried metalwork and explosive gases.

In TN-C and TN-C-S systems, any break in the combined neutral-and-earth core

which didn't also affect the live conductor could theoretically result in exposed

metalwork rising to near "live" potential!

Electromagnetic compatibility

In TN-S and TT systems, the consumer has a low-noise connection to earth,

which does not suffer from the voltage that appears on the N conductor as a resultof the return currents and the impedance of that conductor. This is of particular

importance with some types of telecommunication and measurement equipment.

In TT systems, each consumer has its own high-quality connection with earth, and

will not notice any currents that may be caused by other consumers on a shared

PE line.

Regulations

In residential and commercial installations in the U. S. and Canada, the feed fromthe distribution transformer uses a combined neutral and grounding conductor

(two phase and one neutral, for three wires total), but within the structure separate

neutral and protective earth conductors are used (TN-C-S). The neutral must beconnected to the earth (ground) conductor only on the supply side of the

customer's disconnecting switch. Additional connections of neutral to ground

within the customer's wiring are prohibited.


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For wiring less than 1000 V, the United StatesNational Electrical Codeand

Canadian electrical code forbid the use of systems that combine the grounding

conductor and neutral beyond the customer's disconnecting switch.

In Argentina, France(TT) and Australia(TN-C-S), the customer must provide

their own ground connection.

Application examples

Most modern homes in Europe have a TN-C-S earthing system. The combined

neutral and earth occurs between the nearest transformer substation and the

service cut out (the fuse before the meter). After this, separate earth and neutral

cores are used in all the internal wiring.

Older urban and suburban homes in the UKtend to have TN-S supplies, with the

earth connection delivered through the lead sheath of the underground lead-and-paper cable.

Some older homes, especially those built before the invention of residual-current

circuit breakers and wired home area networks, use an in-house TN-C

arrangement. This is no longer recommended practice.

Laboratory rooms, medical facilities, construction sites, repair workshops, mobile

electrical installations, and other environments that are supplied via engine-

generatorswhere there is an increased risk of insulation faults, often use an IT

earthing arrangement supplied from isolation transformers. To mitigate the two-

fault issues with IT systems, the isolation transformers should supply only a smallnumber of loads each and/or should be protected with an insulation monitoring

device(generally used only by medical or military IT systems, because of cost).

In remote areas, where the cost of an additional PE conductor outweighs the costof a local earth connection, TT networks are commonly used in some countries,

especially in older properties. TT supplies to individual properties are also seen in

mostly TN-C-S systems where an individual property is considered unsuitable forTN-C-S supply (e.g. petrol stations).

In Australia, the TN-C-S system is in use; however, the wiring rules currently

state that, in addition, each customer must provide a separate connection to earthvia both a water pipe bond (if metallic water pipes enter the consumer's premises)and a dedicated earth electrode. In older installations, it is not uncommon to find

only the water pipe bond, and it is allowed to remain as such, but the additional

earth electrode must be installed if any upgrade work is done. The protective earthand neutral conductors are combined until the consumer's neutral link (located on

the customer's side of the electricity meter's neutral connection) - beyond this

point, the protective earth and neutral conductors are separate.
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Definitions :( in alphabetical order)

Accessible- (As applied to wiring methods) Capable of being removed orexposed without damaging the building structure or finish, or not permanentlyclosed in by the structure or finish of the building.

Accessible- (as applied to equipment) Admitting close approach: not guardedby locked doors, elevation, or other effective means. (see Accessible, Readily)

Accessible, Readily- (Readily Accessible) Capable of being reached quickly foroperation, renewal, or inspections, without requiring those to whom ready accessis requisite to climb over or remove obstacles or to resort to portableladders,chairs,etc.

Ambient Temperature- The temperature of the air, water, or surroundingearth. Conductor ampacity is corrected for changes in ambient temperature

including temperatures below 86F. The cooling effect can increase the currentcarrying capacity of the conductor. (Review Section 310-10 of the Electrical Codefor more understanding)

Ammeter- An electric meter used to measure current, calibrated in amperes.

Ampacity- The current-carrying capacity of conductors or equipment,expressed in amperes.

Ampere- The basic SI unit measuring the quantity of electricity.

Bonding Jumper- A bare or insulated conductor used to ensure the requiredelectrical conductivity between metal parts required to be electrically connected.Frequently used from a bonding bushing to the service equipment enclosure toprovide a path around concentric knockouts in an enclosure wall: also used tobond one raceway to another.

Continuity- The state of being whole, unbroken.

Continuos Load - A load where the maximum current is expected to continuefor three hours or more. Rating of the branch circuit protection device shall notbe less tan 125% of the continuos load.

Demand Factor- For an electrical system or feeder circuit, this is a ratio of theamount of connected load (in kva or amperes) that will be operating at the sametime to the total amount of connected load on the circuit. An 80% demand factor,for instance, indicates that only 80% of the connected load on a circuit will everbe operating at the same time. Conductor capacity can be based on that amountof load.


16/92

Dustproof- Constructed or protected so that dust will not interfere with itssuccessful operation.

Dusttight- Constructed so that dust will not enter the enclosing case underspecified test conditions.

Duty, continuos- A service requirement that demands operation at asubstantially constant load for an indefinitely long time.

Duty, intermittent- A service requirement that demands operation foralternate intervals of load and no load, load and rest, or load, no load, and rest.

Duty, periodic- A type of intermittent duty in which the load conditionsregularly reoccur.

Duty, short time- A requirement of service that demands operations at a

substantially constant load for a short and definitely specified time.

Duty, varying- A requirement of of service that demands operation at loads,and for intervals of time, both of which may be subject to wide variation.

Explosionproof- Designed and constructed to withstand and internalexplosion without creating an external explosion or fire.

Feeder- A circuit, such as conductors in conduit or a busway run, which carriesa large block of power from the service equipment to a sub-feeder panel or abranch circuit panel or to some point at which the block power is broken intosmaller circuits.

Ground- A large conducting body (as the earth) used as a common return for anelectric circuit and as an arbitrary zero of potential.

Grounded, effectively- Intentionally connected to earth through a groundconnection or connections of sufficiently low impedance and having sufficientcurrent-carrying capacity to prevent the buildup of voltages that may result inundue hazards to connect equipment or to persons.

Grounded Conductor- A system or circuit conductor that is intentionallygrounded, usually gray or white in color.

Grounding Conductor- A conductor used to connect metal equipmentenclosures and/or the system grounded conductor to a grounding electrode, suchas the ground wire run to the water pipe at a service; also may be a bare orinsulated conductor used to ground motor frames, panel boxes, and other metalequipment enclosures used throughout electrical systems. In most conduitsystems, the conduit is used as the ground conductor.


17/92

Grounding Equipment Conductor- The conductor used to connect thenoncurrent-carrying metal parts of equipment, raceways, and other enclosures tothe system grounded conductor, the grounding electrode conductor, or both, ofthe circuit at the service equipment or at the source of a separately derivedsystem.

Grounding Electrode- The conductor used to connect the groundingelectrode to the equipment grounding conductor, to the grounded conductor, orto both, of the circuit at the service equipment or at the source of a separatelyderived system.

Ground Fault Circuit Interrupter - A device intended for the protection ofpersonal that functions to de-energize a circuit or portion thereof within anestablished period of time when a current to ground exceeds some predeterminedvalue that is less than required to operate the overcurrent protection device of thesupply circuit.

Ground Fault Protection of Equipment- A system intended to provideprotection of equipment from damaging line to ground fault currents byoperating to cause a disconnecting means to open all ungrounded conductors ofthe faulted circuit. This protection is provided at current levels less than thoserequired to protect conductors from damage through the operations of a supplycircuit overcurrent device.

In Sight From- (within sight from, within sight) Where this Code specifies thatone equipment shall be "in sight from", "within sight from" or m"within sight",etc. of another equipment, the specified equipment is to be visible and not morethat 50 distant from the other

Interrupter Rating- The highest current at rated voltage that a device isintended to interrupt under standard test conditions.

Labeled - Items to which a label, trademark, or other identifying mark ofnationally recognized testing labs has been attached to indentify the items ashaving been tested and meeting appropriate standards.

Listed- Equipment or materials included in a list published by an organizationacceptable to the authority having jurisdiction and concerned with productevaluation, that maintains periodic inspection of production of listed equipmentor materials, and whose listing states either that the equipment or material meetsappropriate designated standards or has been tested and found suitable for use inspecified manner.

Location, damp- A location subject to moderate amount of moisture such assome basements, barns, cold storage, warehouse and the like.


18/92

Location, dry- A location not normally subject to dampness or wetness: alocation classified as dry may be temporarily subject to dampness or wetness, asin case of a building under construction.

Location, wet- A location subject to saturation with water or other liquids.

Megger- A test instrument fpr measuring the insulation resistance ofconductors and other electrical equipment; specifically, a megaohm (millionohms) meter; this is a regiestered trade mark of the James Biddle Co.

Megaohm- A unit of electrical resistamce equal to one million ohms.

Megaohmmeter- An instrument for measuring extremely high resistance.

Noninductive Circuit- A circuit in which the magnetic effect of the currentflowing has been reduced by one several methods to a minimum or to zero.

Nonlinear Load - A load where the wave shape of the steady state current doesnot follow the wave shape of the applied voltage.

Ohm - The derived SI unit for electrical resistance or impedance; one ohmequals one volt per am-pere.

Ohmmeter- an instrument for measuring resistance in ohms. Take a look atthis diagram to see how an ohmeter is used to check a small control transformer.The ohmmeter's pointer deflection is controlled by the amount of battery currentpassing through the moving coil. Before measuring the resistance of an unknownresistor or electrical circuit, the ohmmeter must first be calibrated. If the value ofresistance to be measured can be estimated within reasonable limits, a rangeselected that will give approximately half-scale deflection when the resistance isinserted between the probes. If the resistance is unknown, the selector switch isset on the highest scale. Whatever range is selected, the meter must be calibratedto read zero before the unknown resistance is measured.

Overcurrent- Any current in excess of the rated current of equipment or theampacity of a conductor. It may result from overload, short circuit or groundfault.

Overload- Load greater than the load for which the system or mechanism wasintended. A fault, such as a short circuit or ground fault,is not an overload.

Panelboard- A single panel or group of panel units designed for assembly inthe form of a single panel: includes buses and may come with or without switchesand/or automatic overcurrent protective devices for the control of light, heat, orpower circuits of individual as well as aggregate capacity. It is designed to beplaced in a cabinet or cutout box that is in or against a wall or partition and isaccessible only from the front.


19/92

Plenum- Chamber or space forming a part of an air conditioning system

Rainproof- So constructed, projected, or treated as to prevent rain frominterfering with the successful operation of the apparatus under specified testconditions.

Raintight- So constructed or protected that exposure to a beating rain will notresult in the entrance of water.

Separately Derived System- A premises wiring system whose power isderived from a battery, a solar photovoltaic system, or from a generator,transformer, or converter windings, and that has no direct electrical connection,including solidly connected grounded circuit conductor, to supply conductorsoriginating in another system.

Service Drop- Run of cables from the power company's aerial power lines to

the point of connection to a customer's premises.

Service Conductors- The supply conductors that extend from the street mainor transformers to the service equipment of the premises being supplied

Service Entrance Conductors- (Overhead) The service conductors betweenthe terminals of the service equipment and a point usually outside the building,clear of building walls, where joined by tap or splice to the service drop.

Service Entrance Conductors- (Underground) The service conductorsbetween the terminals of the service equipment and the point of connection tothe service lateral.

Service Equipment- The necessary equipment, usually consisting of a circuitbreaker or switch and fuses and their accessories, located near the point entranceof supply conductors to a building and intended to constitute the main controland cutoff means for the supply to the building.

Service Lateral- The underground service conductors between the street main,including any risers at a pole or other structure or from transformers, and thefirst point of connection to the service-entrance conductors in a terminal box,meter, or other enclosure with adequate space, inside or outside the buildingwall. Where there is no terminal box, meter, or other enclosure with adequatespace, the point of connection is the entrance point of the service conductors intothe building.

Service Point- The point of connection between the facilities of the servingutility and the premises wiring.

Switchboard- A large single panel, frame, or assembly of panels havingswitches, overcurrent, and other protective devices, buses, and usually


20/92

instruments mounted on the face or back or both. Switchboards are generallyaccessible from the rear and from the front and are not intended to be installed incabinets.

Switch, general use- A switch intended for use in general distribution and

branch circuits. It is rated in amperes and is capable of interrupting its ratedvoltage.

Switch, general-use snap- A type of general-use switch so constructed that itcan be installed in flush device boxes or on outlet covers, or otherwise used inconjunction with wiring systems recognized by the National Electric Code.

Switch, isolating- A switch intended for isolating an electrical circuit from thesource of power. It has no interrupting rating and is intended to be operated onlyafter the circuit has been opened by some other means.

Switch, knife- A switch in which the circuit is closed by a moving bladeengaging contact clips.

Switch, motor-circuit- A switch, rated in horsepower, capable of interruptingthe maximum operating overload current of a motor of the same horsepowerrating as the switch at the rated voltage.

Switch, transfer- A transfer switch is an automatic or nonautomatic device fortransferring one or more load conductor connections from one power source toanother.

Switch-Leg- That part of a circuit run from a lighting outlet box where aluminaire or lampholder is installed down to an outlet box that contains the wallswitch that turns the light or other load on or off: it is a control leg of the branchcircuit.

Voltage Drop- The loss of voltage between the input to a device and the outputfrom a device due to the internal impedance or resistance of the device. In allelectrical systems, the conductors should be sized so that the voltage drop neverexceeds 3% for power, heating, and lighting loads or combinations of these.Furthermore, the maximum total voltage drop for conductors for feeders andbranch circuits combined should never exceed 5%.

Watertight- So constructed that water/moisture will not enter the enclosureunder specified test conditions.

Weatherproof - So constructed or protected that exposure to the weather willnot interfere with successful operation.


21/92

FromIndustrial Text and Video Co.

The Leader in Electrical, Motor

Control and PLCsVideo Training Programs(www.industrialtext.com 1-800-752-8398)

Electrical Relay Diagramand

P&ID Symbols


22/92

2

Electrical RelayDiagram Symbols

www.industrialtext.com 1-800-752-8398

ELECTRICALRELAYD IAGRAMSYMBOLS

SWITCHES

Disconnect Circuit

Interrupter

Limit

Neutral PositionCircuit

Breaker NormallyOpen

NormallyClosed

HeldClosed

HeldOpen

Actuated

Maintained

Position Closed Open

Proximity Switch

Limit (cont.)

Normally

Open

Normally

Closed

Liquid Level Vacuum & Pressure

Normally

Open

Normally

Closed

Normally

Open

Normally

Closed

Temperature

Flow (Air, Water)

NormallyOpen

NormallyClosed

NormallyOpen

NormallyClosed

Foot Toggle CableOperated(Emerg.)Switch

Plugging Nonplug

Pluggingw/Lockout

Coil 2-Position

Selector

3-Position NonbridgingContacts

Rotary Selector

BridgingContacts

OR OR

Total Contacts To Suit Needs

ThermocoupleSwitch

Push Buttons

SingleCircuit

Normally

Open

NormallyClosed

Double Circuit

MushroomHead

Connections, Etc.

MaintainedContact

Conductors

NotConnected

Connected

DISC C1CB

LS LS

LS LS

LS

NP

NP

LS

LS PRS PRS FS FS PS PS TS TS

FLS FLS FTS FTS TGS

COS

PLSF

PLS

R

F FPLS

R

FPLS

1LO

SS

1 2

SS

1 2 3 RSS RSS

RSSRSS

TCS

+OFF

1

2

+

+

PB

PB PB

PBPB

PB

PB


23/92

3

Electrical RelayDiagram Symbols


Connections, Etc. (cont.)

GroundChassis

Or FrameNot Necessarily

Grounded

PlugandRecp.

Contacts

Time Delay After Coil

NormallyOpen

NormallyClosed

NormallyOpen

NormallyClosed

Relay, Etc.

NormallyOpen

NormallyClosed

ThermalOver-Load

GRD CH

RECP

PL TR TR TR TR CR M

CON

CR M

CON

OL

IDL

Coils

Relays,Timers,

Etc.

Solenoids, Brakes, Etc.

General2-Position

Hydraulic3-PositionPneumatic

CR

M

TR

CON

SOL SOL

2-PositionLubrication

ThermalOverloadElement

ControlCircuit

Transformer

2-H

SOL

3-P 2-L

SOL OL

IOL

H1 H3 H2 H4

X1 X2

Coils (cont.)

Reactors (cont.)

AdjustableIron Core

Air Core Magnetic AmplifierWinding

Motors

3-PhaseMotor

DC MotorArmature

X

X

MAX MTR MTR

A

Pilot Lights Horns, Siren, Etc. Buzzer Bell

PL PL

Push to TestAH ABU ABE

T


24/92

4

P&IDSymbols


P&ID SYMBOLS

INSTRUMENT L I NE SYMBOLS

SYMBOLS FOR TRANSDUCERS AND ELEMENTS

Orifice plate

Control valve

RotameterMagnetic

Venturi or nozzle

FE

10

FE104

EE

4

FI5

Capillary tube

Electric signal

EM, sonic, radioactive

Hydraulic

Pneumatic

Process

FV

101


25/92

5

P&IDSymbols


INSTRUMENT IDENT IF ICAT ION LETTER ING

First Letter Second Letter

A Analysis AlarmB Burner, combustion Users choice*C Users choice ControlD Users choiceE Voltage Sensory (primary element)F Flow rateG User's choice Glass (sight tube)H Hand (manually initiated)I Current (electric) Indicate

J PowerK Time or time schedule Control stationL Level Light (pilot)M Users choiceN Users choice Users choiceO Users choice Orifice, restrictionP Pressure, vacuum Point (test connection)Q QuantityR Radiation Record or printS Speed or frequency SwitchT Temperature TransmitU Multivariable Multifunction

V Vibration, mechanical analysis Valve, damper, louverW Weight, force WellX Unclassified** UnclassifiedY Event, state, or presence Relay, computeZ Position, dimension Driver, actuator, unclassified

* Users choice may be used to denote a particular meaning, having onemeaning as a first letter and another meaning as a second letter. The usermust describe the particular meaning(s) in the legend. This letter can be usedrepetitively in a particular project.

** Unclassified letters may be used only once or to a limited extent. If used, theletter may have one meaning as a first letter and another meaning as a second

letter. The user must specify the meaning(s) in the legend.

Reference: ANSI/ISA-S5.1-1984,Instrumentation Symbols and Identification, ISBN 0-87664-844-8


26/92

Sentry 10/20/30 Hipot Tester

Sentry CE 15/25/35 Hipot TesterInstruction Manual

Form 150460/A8

QuadTech, Inc., 2000

5 Clock Tower Place, 210 EastMaynard, Massachusetts, U.S.A. 01754

August 2003

Telephone 978-461-2100

Sales 800-253-1230

Facsimile 978-461-4295Website www.quadtech.com

The material in this manual is for informational purposes only and is subject to change, without

notice. QuadTech assumes no responsibility for any error or for consequential damages that may

result from the misinterpretation of any procedures in this publication.

WARNINGPotentially dangerous voltages may be present on front and rear panel terminals. Follow all

warnings in this manual when operating or servicing this instrument. Dangerous levels of energy

may be stored in capacitive devices tested by this unit. Always make sure the high voltage

indicator is noton when connecting or disconnecting the device under test.

!

Product will be marked with this symbol (ISO#3684) when it is necessary for the user torefer to the instruction manual in order to prevent injury or equipment damage.

Product marked with this symbol (IEC417) indicates presence of direct current.

Product will be marked with this symbol (ISO#3684) when voltages in excess of 1000Vare present.


27/92

Page 2 of 57


28/92

Page 3 of 57

Contents

Warranty .........................................................................................................................................5

Specifications ...................................................................................................................................7

Accessories ....................................................................................................................................9

Safety Precautions ...........................................................................................................................11

Condensed Operating Instructions ...............................................................................................12

Introduction - Section 1

1.1 Unpacking and Inspection .....................................................................................................15

1.2 Product Overview .................................................................................................................15

1.3 Controls and Indicators ..........................................................................................................151.3.1 Front Panel Controls and Indicators ..........................................................................15

1.3.2 Rear Panel Controls and Connectors ........................................................................17

1.4 Installation .............................................................................................................................18

1.4.1 Dimensions ...............................................................................................................18

1.4.2 Instrument Positioning ..............................................................................................18

1.4.3 Power Requirements .................................................................................................18

1.4.4 Safety Inspection .......................................................................................................19

Operation - Section 2

2.1 Terms and Conventions ........................................................................................................21

2.2 Start-Up .................................................................................................................................232.3 Programming Hipot Tests .....................................................................................................24

2.3.1 Programming an AC Hipot Test ...............................................................................26

2.3.2 Programming a DC Hipot Test .................................................................................27

2.4 Programming Insulation Resistance (IR) Tests .....................................................................28

2.5 Instrument Zeroing/Offset .....................................................................................................29

2.6 Connection To Device Under Test ........................................................................................30

2.7 Measurement Procedure ........................................................................................................31

2.8 Programming A Two-Step Test ............................................................................................33

2.9 Special Function Key Lock ...................................................................................................34

2.10 Software Version Display .....................................................................................................34

2.11 Clear Setup Memory .............................................................................................................34

2.12 Continuity Check ..................................................................................................................35

2.13 Fail Continuous Mode ...........................................................................................................35

2.14 Beeper Setup Mode ...............................................................................................................36

2.15 Auto Range Mode .................................................................................................................36

2.16 Software Automatic Gain Control ........................................................................................37


29/92

Page 4 of 57

Contents (Continued)

Operation Section 2 (Continued)

2.17 Pass/Fail Modes ....................................................................................................................37

2.17.1 High Limit Failure ....................................................................................................382.17.2 Low Limit Failure .....................................................................................................38

2.17.3 ARC Limit Failure ....................................................................................................39

2.17.4 CONt Ck Failure .......................................................................................................39

2.17.5 Exceed Upper Measurement Range ..........................................................................40

2.18 Remote Control .....................................................................................................................41

2.19 G16 International Power Strip ..............................................................................................43

2.20 S03 Corded Product Adaptor ................................................................................................44

2.21 S05 Foot Switch ....................................................................................................................45

2.22 S06 High Voltage Probe .......................................................................................................46

2.23 S07 Power Entry Adaptor Cable ...........................................................................................47

2.24 S08 Gun Probe ......................................................................................................................482.25 Connection to Sentry 50 Ground Bond Tester ......................................................................49

Service & Maintenance - Section 3

3.1 General ..................................................................................................................................51

3.2 Instrument Return .................................................................................................................51

3.3 Calibration .............................................................................................................................51

3.3.1 Sentry 10/20/30 ........................................................................................................51

3.3.1.1 Equipment ....................................................................................................51

3.3.1.2 Procedure .....................................................................................................52

3.3.1.2.1 Voltage Calibration ........................................................................52

3.3.1.2.2 Current Calibration ........................................................................533.3.2 Sentry 15/25/35 ........................................................................................................54

3.3.2.1 Equipment .....................................................................................................54

3.3.2.2 Procedure ......................................................................................................55

3.3.2.2.1 Voltage Calibration ........................................................................55

3.3.2.2.2 Current Calibration ........................................................................56


30/92

Page 5 of 57

Warranty

QuadTech warrants that Products are free from defects in material and workmanship and, when

properly used, will perform in accordance with QuadTech's applicable published specifications.

If within one (1) year after original shipment it is found not to meet this standard, it will be

repaired, or at the option of QuadTech, replaced at no charge when returned to a QuadTech

service facility.

Changes in the Product not approved by QuadTech shall void this warranty.

QuadTech shall not be liable for any indirect, special or consequential damages, even if

notice has been given of the possibility of such damages.

This warranty is in lieu of all other warranties, expressed or implied, including, but not

limited to any implied warranty or merchantability or fitness for a particular purpose.

SERVICE POLICY

QuadTechs service policy is to maintain product repair capability for a period of at least five (5)

years after original shipment and to make this capability available at the then prevailing schedule

of charges.


31/92

Page 6 of 57


32/92

Page 7 of 57

Specifications

Sentry 10/15, 20/25 and 30/35

AC Output Voltage: Range: 0.1to 5kV AC, in 10V/steps, 50/60 Hz

Accuracy Display: 1% of reading +5VRegulation: 1% +5V

Sentry 20/25 and 30/35 Only

DC Output Voltage:Range: 0.1 to 6kV DC, in 10V/steps

Accuracy Display: 1% of reading +5VRegulation: 1% +5V

Sentry 30/35 Only

Insulation Resistance: Range: 10M- 10GAccuracy: 10% of reading + 10 cts, 500V,


33/92

Page 8 of 57

Specifications (continued)

Features Standard On All Sentry Units

Leakage Current: Range:0.001 to 15mA AC0.001 to 5.0mA DC (15/25/35)

0.001 to 7.5mA DC (10/20/30)

Accuracy: (1.5% + 5 counts)

Breakdown: Detection: Imax: 0.001 to 15mA AC, 5.0mA DC (15/25/35)

Imax: 0.001 to 15mA AC, 7.5mA DC (10/20/30)

Accuracy: (1% of limit + 5counts) I: 10sec, 1mA to 15mA

Indication: Pass/fail light, audible sound

Minimum Threshold: 0.001mA to Imax limit

Test Time: Ramp: 0.1 to 99.9sec (20ms), Hold: 0.1 to 999sec (20ms)

Remote Control: Remote Start, Stop, Pass/Fail Output, Interlock

Continuity Check: Current: 0.1A DC, Max Gnd Resistance: 10.1

Mechanical: Bench Mount with Carry Handle

Dimensions: (w x h x d):11x4x14in (270x100x350mm)

Weight: 21 lbs (10kg) net, 28 lbs (13kg) shipping

Environmental: Meets MIL-T-28800E, Type 3, Class 5

Operating: 0C to +40oCHumidity:


34/92

Page 9 of 57

Accessories

Accessories Included

Item Quantity QuadTech P/NU.S. AC Power Cable (3-prong) 1 4200-0300International AC Power Cable (2-prong), 15/25/35 only 1 630031High Voltage Lead Set 1m (1 Blk, 1 Red with clips) 1 S02Continuity Check Clip Lead (White cable terminated byblack banana plug and black alligator clip)

1 700100

3.15A 250V Line Fuse: 115V Operation 1 5200721.6A 250V Line Fuse: 230V Operation 1 520074Instruction Manual 1 150460Calibration Certificate 1 N/A

Accessories/Options Available

Item Quantity QuadTech P/NHV Lead Set High & Low, 1m (std with unit) 1 S02HV Lead Set High & Low, 2m 1 S04HV Lead, 1 meter unterminated 1 S09HV Lead, 2 meters unterminated 1 S10Corded Product Adaptor, 115V 1 S03Corded Product Adaptor, 115V, use for GB test 1 G13Corded Product Adaptor, 240V, use for GB test 1 G25Foot Switch 1 S05Power Entry Adaptor Cable 1 S07High Voltage Probe 1 S06Gun Probe 1 S08Gun Probe with Remote Start 1 S11Load Box, Resistive 1 S12Load Box, Custom Resistors 1 S14Interconnect Cable (To Sentry 50) 1 S15Rack Mount Assembly 1 S16International Power Strip 1 G16


35/92

Page 10 of 57


36/92

Page 11 of 57

Safety Precautions

WARNING

The Sentry Series Hipot Tester can provide an output voltage as high as 6000VDC (5000VAC) to

the external device under test (DUT).Although the Sentry unit is designed with full attention to operator safety, serious hazards could

occur if the instrument is used improperly and these safety instructions are not followed.

1. The Sentry unit is designed to be operated with its chassis connected to earth ground.

The Sentry instrument is shipped with a three-prong power cord to provide this

connection to ground. The power cord should only be plugged in to a receptacle that

provides earth ground. Serious injury can result if the Sentry unit is not connected to

earth ground.

2. Tightly connect cable(s) to the (black) GND terminal. If this is not done, the DUTs

casing can be charged to the high voltage test level and serious injury or electrical shock

hazards could result if the DUT is touched.

3. Never touch the metal of the High Voltage probe directly. Touch only the

insulated parts of the lead(s).

4. Never touch the test leads, test fixture or DUT in any manner (this includes insulation on

all wires and clips) when the high voltage is applied and the red DANGERLED is lit.

5. Before turning on the Sentry unit, make sure the AC power cord is plugged

into the proper voltage source and that there is no device (DUT) or fixture

connected to the test leads.

6. After each test, press the [STOP](red) button for safety. This terminates the high voltage

being applied to the output terminals.

7. When the DANGERLEDis lit NEVER touch the device under test, the lead wires or theoutput terminals.

8. Before touching the test lead wires or output terminals make sure:

a) The red [STOP]button has been pressed.

b) The DANGERLEDis OFF.

c) The output voltage display is 0 (zero).

9. In the case of an emergency, turn OFF the [POWER] switch using ahot stick and

disconnect the AC power cord from the wall. DO NOT TOUCH THE Sentry

INSTRUMENT.

10. If the DANGERLEDdoes not go off when the [STOP]button is pressed, immediately

stop using the tester. It is possible that the output voltage is still being delivered

regardless of the TEST ON/OFF control signal.11. Be extremely careful when the Sentry instrument is used in remote control mode. The

High Voltage Output is being turned on and off with an external signal.


37/92

Page 12 of 57

Condensed Operating Instructions

WARNINGHigh Voltage is applied to the white H.V. output terminal anytime the red DANGERLED is litor flashing. Always make sure the DANGERLED is OFF when connecting or disconnecting

the Device under Test (DUT).

General Information

The Sentry Series AC/DC/IR testers are measuring instruments for direct readout of Hipot outputvoltage, leakage current and insulation resistance. The voltage applied to the device under test isadjustable from 0.1 to 5kVAC and 0.1 to 6kVDC. The current range is adjustable from 0.001 to15mA AC and 0.001 to 5.0mA DC (15/25/35). The (10/20/30) units have a DC current rangefrom 0.001 to 7.5mA. PASS and FAIL LEDs provide a visual display of test results based onpreset limits. In FAIL mode, a buzzer gives an audible indication of test result based on presetlimit.

Start-Up

The Sentry unit can be operated from a power source between 90 and 250VAC at a power linefrequency of 50 or 60Hz. The Sentry (15/25/35) unit is shipped from QuadTech with a 3.15Afuse in place for AC 100-240V operation. The Sentry (10/20/30) unit contains a 4A fuse in placefor AC 100-240V operation. The Sentry unit is shipped with the line voltage selector set for108-132V. Refer to paragraph 1.4.3 to change a fuse and to change the line voltage selector.

Connect the Sentry instrument AC power cord to the source of proper voltage.

Press the [POWER] button on the front panel to apply power. To switch the power off press the[POWER] button again or if measurements are to be made proceed with Test Parameter Set-Upbelow. Note: the Sentry instrument should warm-up for 15 minutes prior to use.

Test Parameter Set-Up

Press [PROG] and enter the Test Parameters according to your test specification.

Test Test

Voltage

(kV)

Line

Frequency

(50 or 60Hz)

Current

HI Limit

(mA)

IRTest = HI R M

Current

LO Limit

(mA)

IRTest = LO R M

ARC

Detect

Test

Time

(sec)

Ramp

Time

(sec)

AC

Hipot

SET SET SET SET SET SET SET

DC

Hipot

SET SET SET SET SET SET

Insulation

Resistance

SET SET SET SET SET

Refer to paragraph 2.3 for full description of programming test parameters and instruction onhow to store the test setup. Note: Test parameters must be set before the Sentry unit can bezeroed.


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Page 13 of 57

Condensed Operating Instructions

Zeroing/Offset

After setting the test parameters, zero the Sentry unit by using the automatic offset (continuity

check must be set to OFF or continuity leads shorted together if set to ON, refer toparagraph 2.12). Make sure the black ground cable is connected to the Sentry GND terminaland the red high voltage test cable is connected to the Sentry H.V output terminal and the clipsare not touching. Press [ENTER] key twice then press [UP] key once. Display reads OFStoFF. Press [UP] key once. Display reads OFSt GEt. Press [START] key once. Displayshows the offset. Offset has to be recalculated each time the test parameters, test cables or testfixture are changed.

Figure COI-1: Cable Connection for Offset Function

Measurement Mode

1 Turn [POWER] ON.2 Let Sentry unit warm-up 15 minutes.

3 Connect Black ground cable to Sentry GND terminal.4 Connect Red high voltage cable to Sentry H.V. terminal.5 Press [PROG] and enter your Test Parameters Press [PROG] again to accept it.6 [STORE] Test set-up (If desired).7 Zero the Sentry unit (OFFSET).8 Select Continuity Check OFF ( 2.12).9 Connect Device Under Test (DUT).10 Press [START].11 Record Readings.12 Press [STOP] .

Figure COI-2: Cable Connection To Device Under Test

P O W E R

Q uadTech Sentry 35 AC/DC/IR Hipot Tester

1

0

STOP START CAL ENABLE

TEST

RAMP

PASS

FAIL

HI

SECARC

LO M

mA

50Hz

60Hz

IR k V

DC

AC

BUZZER

GND H.V.

DANGERHIGH VOLTAGE

MAX: 5k VAC6k VDC

!

RECALLUPSTORE

ENTERDOWNPROG!

P O W E R


1

0

STO P START CAL ENABLE

TEST

RAMP

PASS

FAIL

HI

SECARC

LO M

mA

50Hz

60Hz

IR kV

DC

AC

BUZZER

G ND H.V.

DANGER

HIGH VOLTAGE

MAX: 5kVAC

6kVDC

!

RECALLUPSTORE

ENTERD O W NPROG!

DUT

Rx +

Rx -


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Introduction Page 15 of 57

Section 1: Introduction

1.1 Unpacking and Inspection

Inspect the shipping carton before opening. If the carton is damaged, contact the carrier agentimmediately. Inspect the Sentry instrument for any damage. If the instrument appears damaged

or fails to meet specifications notify QuadTech (refer to instruction manual front cover) or its

local representative. Retain the shipping carton and packing materials for future use such as

returning for recalibration or service.

1.2 Product Overview

The Sentry is available in six models, all of which provide AC Hipot testing capability.

Additionally, the Sentry 20/25 provide DC Hipot testing, and the Sentry 30/35 provide DC Hipot

testing and Insulation Resistance testing. The hipot test can be programmed over a voltage range

of 0.1 to 5kV AC and 0.1 to 6kV DC with a min/max leakage current detection range of 10A to15mA AC and 5.0mA DC (15/25/35), 7.5mA DC (10/20/30). Insulation resistance

measurements are possible to 10Gat programmable DC test voltages between 50 and 1000V.Each instrument comes standard with ground continuity check, internal storage of 10 test setups,

and interface with remote start/stop inputs and pass/fail outputs.

1.3 Controls and Indicators

1.3.1 Front Panel Controls and Indicators

Figure 1-1 illustrates the controls and indicators on the front panel of the Sentry 35 AC/DC/IRHipot Tester. Table 1-1 identifies them with description and function.

Figure 1-1: Sentry Series Front Panel Controls and Indicators

P O W E R


1

0

STOP START CAL ENABLE

TESTRAMP

PASSFAIL

HI

SE CAR C

LO M

mA

50Hz60Hz

IR kV

DCAC

BUZZER

GND H.V.

DANGER

High Voltage

MAX: 5kVAC

6kVDC

!

RECALLUPSTORE

ENTERD O W NPROG!

1 42 3 765

10

98

11121316 15 1418 17


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Page 16 of 57 Introduction

Table 1-1: Sentry Series Front Panel Controls and Indicators

Reference

Number

Figure 1-1

Name Type Function

1 AC/DC/IR Green

LED

When lit indicates that tester is in AC Hipot, DC Hipot or Insulation

Resistance Mode2 Voltage 4 Digit

Display

Green LEDs

Indicates voltage setting when test is not in process. Indicates output voltage

when test is in process. AC 0.1-5kV, DC 0.1-6kV, IR 0.05-1kVDC

3 Frequency Green LED Indicates output frequency (50/60Hz) when an AC Hipot Test is selected

4 Limit Indicator Green LED Indicates the function of the limit shown on the Limit Display

(HI, LO or ARC)

5 Limit/Measure

Display

4 Digit

Display

Green LEDs

Indicates Limit Setting when test is not in process. Indicates Testing Value

when test is in process.

WAC: HI (0-15mA)

LO (0-5.0mA: 15/25/35), (0-7.5mA: 10/20/30)

ARC (1-15mA)

WDC: HI (0-5mA)

LO (0-3.75mA)ARC (1-5mA: 15/25/35), (1-7.5mA: 10/20/30)

IR: HI (1-9999M), LO 1-9999M)6 Display Units Green LED Indicates the units for the Limit Display (mA: AC/DC Hipot , M: IR)7 Timer Indicator Green LED Indicates the Timer Display (Test or Ramp Time)

8 Timer Display 3 Digit

Display

Green LED

Indicates the time countdown. Ramp is the rising time of the Voltage

(0-99.9sec) and Test is the measure time (0-999sec). Setting the Test time

equal to 0 places the unit in continuous measure mode.

9 PASS/FAIL Grn/Red

LEDs

Indicates a pass or fail based on the preset limits.

10 H.V. White

4-point

Receptacle

High Voltage output terminal

11 DANGER Red LED When lit, high voltage is present on the output terminals

12 GND Blk Female

receptacle

Ground Terminal. Low potential terminal for high voltage output.

13 BUZZER Hole Audible output indicates test complete. Remains on until STOP pressed on

FAIL condition.

14 CAL ENABLE Hole For Qualified Service Personnel to use during instrument calibration.

15 Data Entry Keys

STORE

UP

RECALL

ENTER

DOWN

PROG

White Push

Button

Switches

6 keys to enter test conditions

PROGPress to enter Test Condition Change mode, Press again to exit

ENTERPress to confirm the entered Test Condition

and Select step 1 or step 2 with unit in standby status (Refer to 2.5)and Increase/decrease selected parameter when programming test cond.STOREPress to initiate storage of 1 to 40 2-Step or 80 1-Step test set-ups

RECALLPress to initiate recall of 1 to 40 2-Step or 80 1-Step test set-ups

16 START Green P-B

Switch

It starts a test and applies High Voltage to the Test Terminals

17 STOP Red P-B

Switch

It stops the test in progress. Must be pressed before a test is started (reset)

18 POWER Grey P-B

Switch

To Turn Power On (push button IN) or OFF (push button OUT)


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1.3.2 Rear Panel Controls and Connectors

Figure 1-2 illustrates the controls and connectors on the rear panel of the Sentry Series unit.

Table 1-2 identifies them with description and function.

Figure 1-2: Sentry Series Rear Panel Controls & Connectors

Table 1-2: Sentry Series Rear Panel Controls & Connectors

Reference

Number

Figure 1-2

Name Type Function

1 VOLTAGE

SELECTOR

2 Red slide switches To select range of AC power source

Set to 100V position for 90-100VAC




2 REMOTE 11 Slot Screw Panel Terminals for remote control connections ( 2.17)

3 1CAL Black Screw Calibration for Continuity4 AC Line Output 3-wire AC Receptacle

and Fuse Drawer

Connection for AC power source and Replace Fuse

3.15A, 250V SB for 115V Operation (15/25/35)

1.6A, 250V SB for 230V Operation (15/25/35)

4A, 250V SB for 115V Operation (10/20/30)

2A, 250V SB for 230V Operation (10/20/30)

5 CONT. CHECKOPTION

Black Banana PlugReceptacle

Connection for Continuity Check

6 FAN 115V 50-60Hz 0.1A fan Temperature controlled fan

ON >50COFF


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Page 18 of 57 Introduction

1.4 Installation

1.4.1 Dimensions

The Sentry unit is supplied in a bench configuration, i.e., in a cabinet with resilient feet or

placement on a table. Flip feet are provided under the front feet so that the Sentry instrumentcan be tilted up for convenient operator viewing.

Figure 1-3: Sentry Instrument Dimensions

1.4.2 Instrument Positioning

The Sentry unit contains three (3) digital meters for direct readout of measured parameters. The

optimum angle for viewing is slightly down and about 10 degrees either side of center. For

bench operation the front flip feet should always be used to angle the instrument up. In bench or

rack mount applications the instrument should be positioned with consideration for ample air

flow around the rear panel fan ventilation hole. An open space of at least 3 inches (75mm) is

recommended behind the rear panel.

1.4.3 Power Requirements

The Sentry can be operated from a power source of 90 to 130 VAC or 200 to 250 VAC. Power

connection is via the rear panel through a standard receptacle. Before connecting the 3-wire

power cord between the unit and AC power source, make sure the voltage selection switches on

the rear panel (as indicated) are in accordance with the power source being used. 4A or 3.15A,

250V, 5x20mm, for 90-130V source and 2A or 1.6A, 250V, 5x20mm, for 200-250V source.Always use an outlet that has a properly connected protection ground.

4.00"

100.00mm

10.50"

262.50mm

13.75"

343.75mm

P O W E R

QuadTech Sentry 35 AC/DC/IR Hipot Tester

1

0

S TO P ST ART CAL ENABLE

TEST

RAMP

PASS

FAIL

HI

SECARC

LO M

mA

50Hz

60Hz

IR kV

DC

AC

BUZZER

G ND H.V.

DANGERHIGH VOLTAGE

MAX: 5kVAC

6kVDC

!

RECALLUPSTORE

ENTERDOWNPROG!


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WARNING

MAKE SURE THE UNIT HAS BEEN DISCONNECTED FROM ITS AC POWER

SOURCE FOR AT LEAST FIVE MINUTES BEFORE PROCEEDING.

Procedure For Changing A Sentry Fuse

Remove the fuse drawer, by inserting a flat head screwdriver behind the small tab located just

below the 3-prong receptacle, and force outward.

Once the fuse drawer has been removed from the instrument snap the fuse from the holder and

replace. Make sure the new fuse is of the proper rating. Note that the fuse drawer can also be

used to store a spare fuse.

Install the fuse drawer back in the inlet module (fuse down) by pushing in until it locks securely

in place.

Figure 1-4: Fuse Replacement Rear Panel Sentry Unit

1.4.4 Safety Inspection

Before operating the instrument inspect the power inlet module on the rear of the Sentry to

ensure that the properly rated fuse is in place, otherwise damage to the unit is possible. Refer to

paragraph 1.4.3.

The Sentry instrument is shipped with a standard U.S. power cord, QuadTech P/N 4200-0300

(with Belden SPH-386 socket or equivalent, and a 3-wire plug conforming to IEC 320). CE units

are shipped with an approved international cord set. Make sure the instrument is only used with

these cables (or other approved international cord set) to ensure that the instrument is provided

with connection to protective earth ground.

The surrounding environment should be free from excessive dust to prevent contamination of

electronic circuits. The surrounding environment should also be free from excessive vibration.

Do not expose the Sentry instrument to direct sunlight, extreme temperature or humidity

variations, or corrosive chemicals.

3-Prong Receptacle

Fuse Drawer

Fuse Rat ing 115V

3.15A 250V (15/25/35)

4A 250V (10/20/30)

Fuse Rat ing 230V

1.6A 250V (15/25/35)

2A 250V (10/20/30)


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Operation Page 21 of 57

Section 2: Operation

2.1 Terms and Conventions

Table 2-1: Measurement Unit Prefixes

Multiple Scientific Engineering Symbol

1000000000000000 1015 Peta P

1000000000000 1012 Tera T

1000000000 109 Giga G

1000000 106 Mega M

1000 103 Kilo k

.001 10-3 milli m

.000001 10-6 micro u

.000000001 10-9 nano n

.000000000001 10-12 pico p

.000000000000001 10-15 femto f

Dielectric Strength: The ratio between the voltage at which breakdown of the

insulating material occurs and the distance between the two

points subject to the applied voltage.

Dielectric Absorption: The physical phenomenon in which insulation appears to absorb

and retain an electrical charge slowly over time. Apply a voltage to

a capacitor for an extended period of time, and then quicklydischarge it to zero voltage. Leave the capacitor open circuited for

a period of time then connect a voltmeter to it and measure the

residual voltage. The residual voltage is caused by the dielectric

absorption of the capacitor.

Charging Current: An insulated product exhibits the basic characteristics of a

capacitor. Application of a voltage across the insulation causes a

current to flow as the capacitor charges. This current

instantaneously rises to a high value as voltage is applied then

exponentially decays to zero as the DUT becomes fully charged.

Charging current decays to zero much faster than dielectricabsorption.

Leakage Current: The steady state current that flows through the insulation. Leakage

current is equal to the applied voltage divided by the insulation

resistance.


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Page 22 of 57 Operation

Discharge: The act of draining off an electrical charge to ground. Devices that

retain charge should be discharged after an IR or DC Hipot test.

Insulation Resistance: Measures the total resistance between any two points separated by

electrical insulation. The IR test determines how effective the

dielectric (insulation) is in resisting the flow of electrical current.

ARCing: Sparking or flashing over caused by a breakdown of electrical

insulation.

RAMPing: The gradual increase or decrease of voltage or current over a

period of time (step).

Frequency: The rate at which current or voltage reverses polarity and then

back again completing a full cycle, measured in Hertz (Hz) or

cycles/second. AC Line Frequency = 50 or 60 Hz.

Ground: The base reference from which voltages are measured, nominally

the same potential as the earth. Also the side of a circuit that is

at the same potential as the base reference.

Ground Continuity Test: Test to verify that all conductive parts of a product that are

exposed to user contact are connected to the power line ground.

GC test is normally performed with a low current DC signal that

checks to ensure the ground connection has a resistance of


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Operation Page 23 of 57

2.2 Start-Up

Check to make sure the Voltage Selector Switch on the rear panel agrees with the power source

available (Depending on the power source the switch positions should be in the up or down

positions as shown on the instrument rear panel).

WARNING

When the high voltage is applied and red DANGERlight ON

Never touch the test leads in any manner (this includes insulation on all wires and clips).

Use all precautions necessary to avoid touching the device under test when the red DANGER

light is ON or flashing.

Before connecting the instrument to its power source the interlock function on the rear panel

remote connector must be properly utilized. This is an important safety feature for the

protection of the operator. Turn on of the instrument's high voltage is inhibited wi

basic of electrical

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