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BN-SP-ES07 Inspection Procedure for Metal-Enclosed Low Voltage Draw-OutSwitchgearTable of Contents

Summary1.

General2.

Incoming Feeder and Tie Breakers3.

Bus Bar from Main Switch to Horizontal Bus Bars4.

Horizontal Copper5.

Bus Bar System Vertical Sections6.

Outgoing Units7.

Earthing8.

High Potential Test9.

Insulation Measuring10.

Meters and Protective Relays11.

1. Summary

Before the low voltage switchgear is ready for shipment the vendor shall make suitable tests to establish to the satisfaction of

owners representative that all equipment, devices, protection relays and wiring have been correctly installed and are in

satisfactory working condition and operable as requested.

All tests shall be made in accordance with the nationally recognized standards stated in the requisition.

The entire installation shall be constructed so as to provide maximum safety. Even if more provisions than required by law will

be necessary, it will be vendors responsibility to include these provisions.

Prior to testing, switchgear shall be dust-free and thoroughly cleaned of all waste material.

The switchgear vendor shall take care that all necessary test equipment will be available in the factory or at field.

2. General

The switchgear shall comply with the following requirements:

Is the switchgear of the draw-out or the

nondraw-out type:

draw-out/nondraw-out

Is the incoming feeder a cable connection or a

busduct connection

cable/busduct connection

Is the switchgear for indoor or outdoor use: indoor/outdoor use

Short-circuit current of the installation: KA rms

KA peak

Time short-circuit current of the installation: s.

Maximum nominal current:

1. copper connection incoming feeder A

2. main breaker(s) A

3. horizontal busbar system A

4. tie breaker A

Nominal voltage: V

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Frequency: Hz

Language to be used on the name-plates for

operating instructions and outgoing circuits:

Language to be used for maintenance

instructions:

What is the color of the outer side of the

switchboard:

Dimensions of the installation: length mm width mm height mm

What are Companys numbers of the drawings

according to which the switchgear will beinspected:

1.

2.

3.

4.

5.

Who will take care of the erection at site:

Is the busduct connection between the

transformer and the switchgear finished

and by whom will this connection be installed:

1. busduct connection is not included in the supply.

2. busduct connection

3. installation of the busduct connection by supplier/Company.

4. no busduct connection

The frame which shall be cast-in or connected

to the concrete floor of the substation and will

be supplied by:

1. supplier of switchgear

2. Company

In case the frame will be supplied by the

vendor, have the frames already been shipped:

yes/no

The required height and width of the substation

door(s) are (inclusive of 4 rolls):

height mm

width mm

Take care that everything will be new andunused.

Is a crane necessary for hoisting the

switchgear into the substation:

If yes, contact the Field Engineer for provisions

to hoist the switchgear into the substation.

yes/no

The use of plastic partitions for screening is not

permitted.



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Screening shall be by Pertinax sheets or

equivalent material.

Equivalent material may only be used after

approval by purchaser.

Pay attention to the wiring, relays, terminals

etc.; they must be coded in accordance with

the drawings.

The wiring shall be coded so that after

disconnecting it can be reinstalled without

checking at the right terminals.

What are the colors of the wiring: 1.

What are the colors of the wiring: 2.

3. Incoming Feeder(s) and Tie Breaker

There must be sufficient space for connectionof incoming feeders (check one line for

number).

Check whether the neutral is mounted on the

right side, viewed from the front.

Check the diameters of the holes for the

connection bolts of the busbar with regard to

the width of the busbar. Holes must be too big

(DIN 43673).

flat copper bar, width mm

fastening holes, diameter mm

It must be impossible to touch the incoming

copper when the door is open (pay attention to

the Pertinax sheets).

Check whether the nominal current of the

breaker is sufficient with regard to the

transformer or switchgear rating.

current of breaker A

current of power transformer A

KVA

Incoming feeder and tie breaker shall be

suitable for the dynamic short - circuit

KA peak

current of the transformer and thermal short

current of

KA rms

s.

Check whether the outgoing or incoming

copper is directly mounted above the arcingchutes.

(This is not permitted. The ionized air must be

able to rise freely and may not introduce a

short circuit).

Make sure that there are no obstacles which

can hamper the gas flow on the upper and front

side.

A



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When protective relays are installed on the

breaker, check the current and time settings.

s.

When an inverse current/time relay is used, ask

for relay curve.

inverse

current

setting

time

definite

current

setting

time

Type, number and brand of relay(s):

It shall be possible to operate the main breaker

with the compartment door closed (manually

and electrically)

yes/no

Check whether arcing chutes are undamaged

and uncracked. Try to remove the arcing

chutes from the breakers.

This must be possible without touching any

obstacles.

Wires going from the main busbars to fuses (forexample for closing the main breaker) may not

touch other wiring or steel constructions and

must be short as possible.

Check especially the bolt connections of the

copper bars to the main breaker, even if

something shall be removed. Check the

number of bolts and the bolt diameters with

regard to the mounting busbar. Check also the

tensile strength of bolts.

Check the distance of the busbars with regard

to each other and with regard to earth (neutral).

The distance shall be at least 2 cm.

Check whether there is a link in the neutral of

the incoming feeders.

The presence of a link shall be clearly indicated

with a nameplate.

Check especially that the air circulation along

the breaker is not obstructed. This is for cooling

of the breaker. (Wrong positioning of the

Pertinax plates.)

How is the incoming breaker controlled: automatically/manually

Is the transfer from one feeder to another

automatic or manual:

1. manual

2. automatic

3. no automatic

4. one feeder

Are both feeders in parallel while transferring: 1. manual transfer yes/no



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2. automatic transfer: yes/no

What is the position of the tie breaker in normal

operation:

1. open

2. closed

3. no tie breaker

Are feeder breakers and tie breaker of the draw

-out type:

Check especially the draw-out contacts when

the breakers are of the draw-out type.

yes/no

Are feeder breakers and tie breaker

interchangeable:

yes/no

Can one feeder handle the total load: % continuous

% h

Are protective relays installed on the tie

breaker:

yes/no

Is the coupler a breaker, link or a load switch: breaker/link/load switch

When a link is installed, an ampere meter shall

be installed:

Ampere meter: yes/no

Close the feeder breaker and try to withdraw

the switch in the closed position.

Also try in the opposite sequence.

Take the feeder breaker out of the switchgear,

close the breaker and try to insert the breaker.

Before the main contacts touch each other the

breaker will be switched off.

Even when it is not possible to insert thebreaker in the closed position, this will be an

acceptable construction.

When the feeder breaker is inserted, but is in

the off-position with charged springs for fast

closing, the breaker must be able to unload

automatically, or further movement of breaker

must be prevented.

4. Busbars from Main Switch to Horizontal Busbars

Vertical busbars from main switch to horizontal

busbars must have the same cross-section as

the copper of the incoming feeders. Is this so?

yes/no

It shall be impossible to touch this copper, even

with an open door (screening with Pertinax

plates).

If there are lids instead of doors, screening of

the busbar is not necessary. The lids must be



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fastened with captive screws. Fastening the

lids with toggles is not permitted.

Check the voltage distances with regard to

each other and with regard to earth. Take into

account where these distance are found.

Take care of the bolt connections in the busbar.

Check the bolt connections with a torquewrench.

This is applicable to the entire busbar system.

Check whether all bolts are easily accessible.

If current transformers are applied, take care of

the current direction (current goes always from

K to L).

Check the following characteristics of the

current transformers:

1. ratio:

2. class:

3. output: VA

4. excess current: N =

5. suitably for short-circuit current or during a

time of:

KA peak

KA rms

1 s.

The wiring connected to the secondary side of

the current transformer inclusive of earthing

shall be at least 4 mm2.

The busbar shall be marked with painted dots

in the color specified in the requisition. This

shall be done at different places in the

switchgear.

Check whether there is a partition plate

between the vertical copper and the horizontal

copper. If there is no partition plate, check

whether the horizontal copper has partition

plates on both sides of the incoming feeder

panel.

If parallel buses are used, check whether there

are copper pieces and check how they are

fastened; bolts screwed in the copper of the

busbar are not acceptable.

Spring washers shall be placed under the nuts

of the fastening bolts of the buses.



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5. Horizontal Copper

The horizontal copper must have the same

cross-section through the entire switchboard.

What is the cross-section of the horizontal

copper with regard to the incoming feeder

panel?

Check also the cross-section of the neutral.

Is the horizontal busbar compartment

separated from the vertical compartments?

(Partition plates between horizontal copper and

outgoing vertical copper)

Check especially the distance of the busbars

with regard to earth where the angle iron of the

vertical sections have been mounted.

Insulation tape or Pertinax to improve the

situation at certain spots is not acceptable. Thisis applicable to the entire switchgear.

Check especially the bolt connections. The bolt

has to come just through the nuts. This applies

to the entire busbar system. Check whether all

bolts are easily accessible.

Check whether the supporting of the busbars is

sufficient. A strip of insulation material mounted

on the top of the insulators to improve the

maximum allowed force in acceptable.

The busbars at the ends of the switchgear shall

be finished in such a way that an extension ofthe switchgear is possible without any further

mechanical handling.

Check the bolt connections of the horizontal

copper with the downgoing vertical copper.

Take care of possible torques. This occurs on

those places where an angle is in the copper

and no support is placed in the angle, because

torques reduce the short-circuit capacity. This

applies to the entire busbar system.

All high-tensile strength steel bolts, nuts andrings shall be corrosion-proof.

Check the interconnections of the horizontal

busbars. With how may bolts are they

connected? What are the sizes of the bolts?

What are the dimensions of the copper

overlapping?

Threading in the main rail system is not

acceptable.



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Top of insulators may not be used for

interconnections of the busbar system.

The insulators on the supporting iron shall be

installed so that also the outer rim of the

insulator bottom is supported and the insulator

is supported completely on its bottom surface.

When insulators are fastened with a bolt, it isnot permitted that the insulator is turned to be

fastened, but the bolt shall be screwed into the

insulator. Pay attention to welded tap ends;

these are places where such things happen.

The insulators shall be free of paint, dust and

damage.

When partitions are used to support the

busbar, check whether the copper is firmly

enclosed by the supports and check whether

the partitions are fabricated of nonhygroscopic

material.

Check whether the bolts of the steel top cover

do not come too close to the busbars.

6. Busbar System Vertical Sections

Check the dimensions of the vertical copper

and the supporting of the vertical copper:

dimensions copper

x mm

distance between two insulators in the length and width

It shall be impossible to touch the vertical

copper (even not from an adjacent panel orwhen the units are drawn-out).

Check especially the lower part of the copper.

This must be protected so that ionized air

cannot flow into adjacent panels.

Check the connections between the vertical

copper and the various units.

Check especially the distances, supports and

bolt connections.

If there is a copper connections between

vertical copper and a unit, it must be screened

with an insulating material, which is fireproof

(no tape or similar).

When working in an outgoing panel, it must be

absolutely impossible to touch any live parts,

even not the live parts of an adjacent unit.

It shall always be possible to insert the

outgoing cables without touching the busbar

system.



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Installation of the cables will be done energized

busbar system.

The maximum fuse rating of the back-up fuse

may not be more than 200 A.

It is allowed to provide the units behind that

back-up fuse with fuse holders and fuses of the

screw type.

Check whether the vertical sections are totally

enclosed:

Check also the bottom.

totally enclosed: yes/no

Check whether soft packing rims are used

between the vertical sections to avoid

openings.

7. Outgoing Units

A short circuit in a unit may never cause acomplete busbar short circuit. This shall be

checked carefully. The most dangerous place

is the connection between unit and busbar

system.

Before the main and auxiliary contacts touch

each other, there must be a good earth

connection between unit and enclosure, so that

there can never be a voltage difference

between unit and earth, not even under the

most unfavorable circumstances. Earthing of

the unit must be checked carefully.

Check especially the draw-out contacts andconnections to the circuit part. Wrong insertion

may never cause a short circuit or a damage to

the contacts and/or pins.

If electrical components are mounted on the

doors, a flexible connection between door and

fixed part shall be installed.

All units of the same type shall be

interchangeable. Some units shall be drawn out

to check the wiring at the units.

Unit compartment shall be totally enclosed and

preferably be made of metal.

The connection of the primary side of the fuses

and the contacts at the back of the draw-out

unit shall be at least 25 mm and shall run free

of other wiring and steelwork.

Partitions of insulating material shall be placed

between the fuses, sticking out above the

fuses. This is also applicable to the draw-out



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units to prevent a short circuit at the primary

side of the fuses. Partitions must continue at

the upper side.

The air distances between the live parts at the

primary side of the fuses shall be made as long

as possible. A short circuit at the primary side

of the fuses means a short circuit at the main

busbar system (full-circuit capacity).

Check the fuse holder rating with the fuse

concerned. This shall be an internationally

standardized fuse holder and fuse of the knife-

type.

Check type of fuse (gL preferred):

am/gL

In connection with the short-circuit capacity of

the transformer pay attention to the highest

permissible short circuit of the fuse.

Screw-type fuses may only be used behind

back-up fuses of maximum 200 A.

For screw fuses only the E27 type is

acceptable.

The location of the components in the unit shall

be so that ionized air around a contactor or a

short circuit within the unit can never cause a

short circuit at the primary side of the fuse. The

fuse must always interrupt the short circuit of

flash-over.

This is very important!

Try to make a short circuit with the fuse

remover.

Check the relation between the fuse rating and

the thermal relay rating. This is to prevent

damage of the thermal relays in case of short

circuiting. This should only be done

according to leaflets of thermal relay

manufacturer and not according to any

Company or vendors drawing!

Check the adjusting devices of the thermal

relays.

Check whether the rating of the smallestcontactor is 20 A. It is not allowed to use relays

or auxiliary relay in the primary wiring of the

motor circuit.

The connections in the unit shall be made with

flexible wires. Cable lugs shall be of the crimpit

type. Soldering connections are not acceptable.

Wiring for protection and transfer circuits shall

be numbered at both sides. Wiring, mounted in

the units, must be numbered at the terminal

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blocks so that it is not required to measure the

wiring before reconnecting the wires to the

terminals.

Control fuses may be of the E27 type, if placed

behind main fuses. If MCBs are used, check

characteristic (L).

It shall always be possible to check the current

of the unit with a hook-on ampere meter in

order to adjust the thermal relay. The wiring

must allow space for that.

A number of units of different types shall be

checked on their proper electrical working. If

any defects are found all units shall be

checked.

It shall be possible to reset the thermal relay

from the outside of the unit.

The lamp holder shall be made of copper to

prevent sticking of the lamp at high

temperature.

The terminals shall be of a good quality and

preferably be made of thermosetting material

and not of porcelain.

Check the quality of the short-circuit connection

at the terminals. This in connection with short-

circuiting of the current transformers.

The outgoing cables of the various units shall

be supported. The supporting saddles shall be

supplied by the manufacturer of the switchgear.

Check whether fuse ratings, contactor rating,

thermal relays, etc. comply with the drawings.

Dont forget the spare units. These shall be

installed completely as marked on the

drawings. Check also the space units.

It shall not be necessary to switch off the

switchgear while equipping the space unit.

Terminals carrying different voltages shall be

separated by means of partitions, which totally

stick out of the terminal.

Take a draw-out unit of the fuse-switch type

from the switchgear and try to draw-in the unit

in the switchgear again with the switch in the

on position.

Also try in the other way around. The unit is

installed in the switchgear. Switch on and try

to take it out of the switchgear.



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8. Earthing

There shall be an earth bar over the entire

length of the switchgear. It shall have a

dimension of at least 25 x 5 mm.

The copper shall be as long as possible to

minimize the number of connections.

The earth bar shall be mounted directly to the

steel structure and so that each vertical part

has at least one connection with the main earth

bar.

At the end of the horizontal earth bar two holes

shall be drilled for connection to the external

earth system ( 13 mm).

If there are terminals below the outgoing

groups, the main earth bar shall have earth

screws: for each cable at least one.

The connection shall be so that it is possible toearth the lead sheath as well as the earth

conductor of the cable.

When the cables are connected directly to the

units, there will also be an earth bar mounted

along the units.

It is not acceptable that the cables are stripped

all over the height of the installation for earthing

the cable at the bottom at the main earth bar.

The main breakers shall have a direct copper

connection with the main earth bar.

When the switchgear has a bus duct, there will

also be an earth bar inside the bus duct.

All parts of the bus duct will be connected to

the earth bar. There will also be an earth bar

between switchgear and bus duct.

The secondary side of the current transformers

shall also be earthed. Looping of an earth wire

is not acceptable. The connection will be at

least 4 mm.

9. High Potential Test

Check whether the installation is ready to be

put into operation; so all units, fuses, switches,

etc. shall be present and the switches shall be

in the off position.

High potential tests shall be 2500 V for 1

minute and applied between:



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phase to phase1.

phase to neutral2.

phase and neutral to earth3.

If certain components such as coils of

contactors, motors of breakers, current

transformers, voltage transformers, etc. lookstrange the components shall be tested in the

following way:

coils

small motors of breakers

current transformers

small transformers

The control fuses of the meters and relays shall

be removed.

The high voltage test set shall have a minimum

capacity of 3 KVA.

1000 V 1 minute

1000 V 1 minute

3000 V 1 minute

1500 V 1 minute

10. Insulation Measuring

Insulation resistance will be measured after the

high potential test. The resistance will be

measured:

phase to phase1.

phase to neutral2.

phase and neutral to earth3.

If possible, test the meter with a calibration

resistance.

The resistance shall be at least 10 M if the

installation is in dry condition.

If the humidity is very high the switchgear must

be dried before measuring.

Make a connection between one phase and

earth and check whether the megger is

indicating zero.

This is to be sure that the entire switchgear is

tested.

The insulation shall be measured with a 500 V

megger (or higher).

11. Meters and Protective Relays

The working of directional relays shall be

checked very carefully.



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The final test shall be performed in the field.

Check whether the wiring complies with

vendors data: directional relays testing yes/no

The same is applicable to the Kwh KWh meters tested: yes/no

meters and the power factor meters: power factor meters tested: yes/no

These are directional instruments and the

correct working depends upon the

KWA meters tested: yes/no

right polarity of the connections. KW meters tested: yes/no

Check whether the voltage on the meters and

relays is correct. The same is applicable to the

current. It may be possible that the current coils

need be switched in parallel or in series.

This is indicated on the relays.

Are the relays of the draw-out or nondraw-out

type.

draw-out/non draw-out

In how many phases are the directional relays

placed:

phases

How are the Kwh meters connected: phases


159 Bn Sp Es07 Inspe

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