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Switch gear applications

 

Electrical Switchgear Interlocking

mGard mechanical trapped key systems are used to prevent the paralleling of power supplies

In this application example the two incoming supply isolators are fitted with BM1 bolt interlocks.

When the key is free, the bolt is extended, locking the isolator open. Inserting and turning the key withdraws the bolt and allows the isolator to be closed.

Only one key is supplied, ensuring that only one isolator can be closed at any one time.

 

Capacitor bank access scheme

To prevent closing earth/ground switch under load and to enable access to the capacitor bank enclosure only after the capacitor bank has been earthed/grounded and discharged.

To gain access to capacitor bank enclosure, proceed as follows:
  1. Open the circuit breaker, turn and remove key “A” from the BM1-CLIN bolt interlock. This locks the breaker in the open position.
  2. Insert Key "A" in the second BM1-CLIN and turn. The earth/ground switch can now be closed
  3. Turn and remove key “B” from the BM1-CLIN bolt interlock, this locks the earth/ground switch closed.
  4. Key "B" can now be used to unlock access door 1 of the capacitor bank. By inserting this key into the DM2-CLIN-F double door lock, a second key "C" is released to open the DM1-CLIN-F single door lock of door 2.

 

Capacitor bank access scheme with multiple access points

To prevent closing earth/ground switch under load and to enable access to the capacitor bank enclosure only after the capacitor bank has been grounded and discharged.

To gain access to capacitor bank enclosure, proceed as follows:
  1. Upon receipt of a signal following the opening of the circuit breaker, the solenoid of the SS1-CLIN-A02022D024B is energized releasing key "A".
  2. By inserting key "A" in the BM1-CLIN bolt interlock, the isolator can be opened, removing key “B” locks the isolator open.
  3. Key "B" can now be inserted in the second BM1-CLIN bolt interlock allowing the earth/ground switch to be closed, removing key “C” from the BM1-CLIN bolt interlock, locks the earth/ground switch closed.
  4. Key "C" can now be inserted into the XM5-CLIN key exchange box releasing four access keys "D".
  5. The doors of the capacitor bank can now safely be opened by inserting keys "D" in the DM1-CLIN-F door locks.
 

Capacitor bank access scheme with time delay

To prevent closing earth/ground switch under load and to enable access to the capacitor bank enclosure only after the capacitor bank has been earthed/grounded and discharged.

  1. Open the circuit breaker and turn and remove key “A” from the BM1-CLIN bolt interlock. This locks the circuit breaker open.
  2. Inserting key "A” in the TD-CLIN-024 time delay unit releases key "B” when the rundown time has elapsed (signalled by the LED status indicator on the unit).
  3. Key “B” can now be inserted in the second BM1-CLIN bolt interlock allowing the earth/ground switch to be closed, removing key “C” from the BM1-CLIN bolt interlock, locks the earth/ground switch closed.
  4. Key "C” can now be used to unlock access door 1 of the capacitor bank. By inserting this key into the DM2-CLIN-F double door lock, a safety key "C” is released, that can be taken inside the capacitor bank to prevent the operator being locked in or the system re-energized.