Mounting instruction 21/08/14

Test & measurement terminal blocks type ST…Operational & mounting instructions for the short circuit bridges

The following SC-JB8… short circuit bridges allow the safe Current Transformer shortcircuiting before making any operation on the user side

Series Type Part numberSNK series SC-JB8-2 1SNK900652R0000

SC-JB8-3 1SNK900653R0000SC-JB8-4 1SNK900654R0000SC-JB8-5 1SNK900655R0000

SNA series PCS 2 IP20 1SNA199871R2100PCS 3 IP20 1SNA199872R2200PCS 4 IP20 1SNA199870R0400

These short circuit bridges are compatible with the following test and measurement blocks:

Series Terminal blocks familySNA series M6/8.ST…SNK series ZS10-ST…

Short circuiting bridges Number of poles Test sockets needed

PCS 2 IP20SC-JB8-2

2 consecutive 2 x AJS9

PCS 3 IP20SC-JB8-3

3 consecutive 3 x AJS9

PCS 4 IP20SC-JB8-4

4 consecutive 4 X AJS9

SC-JB8-5 5 alternated 3 X AJS9

Short circuit bridges mounting procedure:

� Loosen (4 screwdriver complete rotations max.) the test sockets AJS9… of the terminalblocks with a Dia. 3.5mm screwdriver

� Unscrew the end stop to clear the blocks sideways and leave a space between blocks (1-2mm)

�a- Position the short circuiting bridge across the two blocksb- Engage the screwdriver into the slot provided for this purposec,d,e- Slide until it engages the hook around the test socket.

a b c d e

� Reposition the terminal blocks side by side. The short-circuiting bridge is now in place andcaptive. The next step is to choose a position (short-circuited or not) depending on the requiredoperation. To do this, follow the procedure described later in this document.

1 to 2mm

Important

- By construction, the secondary of a current transformer must continuously feed ratheron a low impedance or be shorted.

- In no case the secondary of a current transformer must be empty when the primary isfed under penalty of a sudden rise in the voltage across the secondary and a significantrisk of injury to operators and destruction of the transformer.

- Thus any test or equipment replacement operation requiring the maneuver on ourterminal blocks must be done exclusively by an authorized personnel trained forthis type of operations

- The test procedure described in this document is provided for information purposes onlyand can in no way substitute the internal procedures of our customers or be regarded aslegal document.

1) Continuous operation: CT online, equipment (meter or relay) supplyeffective

1-1 AJS9 test sockets are tightened to the recommendedtorque; they allow locking of short circuit bridge in notconnected position. The colored sliding links are in closedposition and tightened to the recommended torque.

Note: The sliding links are yellow on the M6/8.ST terminalblocks from SNA range and orange on terminal blocksZS10.ST ... from SNK range.

Note: To reduce handling errors, when the short circuit bridge is indisconnected position, it just prevent access to the cursor of slidinglink, thus avoiding the opening by mistake of the live circuit. Photobelow shows how SC-JB8 short circuit bridge is positioned above thecursor.

SNA range SNK rangeyellow sliding link closed Orange sliding link closed

Measuring Device

(Protection relays, meters..)

2

1

3

Closed slidinglink

symbol

12

3

3

2

2

2) Test or replacement phase of equipmentThe short circuit bridge is in short-circuiting position

OpenedSliding link

symbol

2

Measuring Device

(Protection relays, meters..)

2

2-1 Loosen (4 screwdriver complete rotations max.) the AJS9 testsockets using suitable screwdriver (isolated Dia. 3.5mmscrewdriver recommended).

Engage the screwdriver into the slot provided for this purpose andslide until the hook is engaged around the test sockets AJS9. Tightenthe test sockets to the recommended torque.

2-3 Once AJS9 test sockets and the short circuit bridge aretightened and clamped in place (the current transformer isshorted), open the disconnect sliding link to isolate thesource (current transformer) from the measuring apparatus

.

Important Reminder: Operation not permitted.When the transformer is in short-circuited mode ( SCJB8 short circuit bridge in place , AJS9test socket tightened) and downstream and upstream isolated (disconnect sliding link opened).

It is forbidden to remove the two AJS9 test sockets and remove the short circuit bridge SCJB8under penalty of a sudden rise in the voltage across the disconnected parts (current transformersecondary opened) and a risk of electric shock for operator.

4

5

2-4 Once the measuring or replacement operation of theequipment is done, the below procedure must be followed :

2-4-1 Unscrew the sliding links on both terminal blocks.

2-4-2 Slide them into closed position.

2-4-3 Tighten the disconnect sliding link to therecommended torque

2-4-4 Unscrew the AJS9 test sockets2-4-5 Engage the screwdriver in the slot provided for this

purpose and slide it until it stops.2-4-6 Tighten the AJS9 test sockets to maintain the short

circuit bridge in the opened position

2

2-4-1 & 2-4-2 2-4-3

2-4-4 2-4-5 2-4-6

2

54

Contact us

ABB FranceLow Voltage Products Division3, rue Jean PerrinF-69687 Chassieu cedex / France

NoteWe reserve the right to make technical changes ormodify the contents of this document without priornotice.ABB does not accept any responsibility whatsoeverfor potential errors or possible lack of information inthis document.

We reserve all rights in this document and in thesubject matter and illustrations contained therein.Any reproduction, disclosure to third parties orutilization of its contents – in whole or in parts – isforbidden without prior written consent of ABB.

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