Interlock Application Scheme # 42

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Interlock Application - Precipitator Access

Scheme # 42
To allow operation of dual output transformer rectifiers with one field removed from service and to prevent opening any access doors of an electrostatic precipitator until all power supplies are de-energized and properly grounded.

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All main breakers in ESP control room are closed to supply all transformer rectifiers. All A keys (A-1, A-2, A-3, etc.) are held in L-O interlocks on the breakers (note: one A key is held in a transfer block on each TR). All transformer rectifiers are locked in the ON position. All G keys (G-1, G-2, etc.) are held in L-C interlocks on the ground position of the transformer rectifiers. All access doors are locked closed and all access door keys are held in the transfer panel (key exchange box).

To ground one field of TR1, proceed as follows:

1.
2.

3.

4.

5.

6.

7.

8.

Open breaker A-1.
Turn key A-1 in L-O interlock to lock breaker in open position. Both A-1 keys are now free.
Insert one A-1 key in L-C interlock on HV position of the field to be removed from service. Turn key to unlock. Key A-1 is now held.
Rotate TR1 handle to ground position.
Insert all A keys in the L-C interlocks on the HV position of each TR. Turn A keys to unlock. All A keys are now held.
Turn key G-1 in L-C interlock locking the TR handle in the ground position. Key G-1 is now free.
Insert key G-1 in the transfer block and turn. Key G-1 is now held and key A-1 is free.
Insert key A-1 in L-O interlock on the breaker and turn to unlock. Both A-1 keys are now held.
Close breaker A-1.

Other fields can be removed from service in the same manner. Reverse sequence to restore service.

To open all access doors:

1.
2.

3.

4.

5.
6.

7.

8.

9.

Open breaker A-1.
Turn key A-1 in L-O interlock to lock breaker in open position. Both A-1 keys are now free.
Lock open all other breakers and free all A keys (A-2, A-3, A-4, etc.).
Insert all A keys in the L-C interlocks on the HV position of each TR. Turn A keys to unlock. All A keys are now held.
Rotate all TR handles to the ground position.
Turn all G keys (G-1, G-2, G-3, etc.) in L-C interlocks of each TR to lock all TR handles in the ground position. All G keys are now free.
Insert all G keys in the transfer panel (key exchange box) and turn. All G keys are now held.
Turn and remove the D-1 keys from the transfer panel. Note: D-1 keys are secondary keys and cannot be removed until all primary keys (G
keys) are inserted and turned.
Insert the D-1 keys in each access door interlock and turn to unlock. The D-1 keys will remain held in each access door interlock as long as
the door is open.

To restore service, close and lock all access doors, return all D-1 keys to the transfer panel and reverse the above sequence.

The scheme above represents basic guidelines regarding the proper interlock sequence for an Electro-Static Precipitator. The equipment that comprises an E.S.P., or Baghouse can vary depending upon the manufacturer and age of the equipment. Let us know your specific needs and we will be glad to provide a free proposal without obligation.

Links for more interlock application scheme information:

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