Two Main and One Transfer Bus System Explained

fsdf

Transferring a Feeder from Main Bus to Transfer Bus without Interruption of Power:

Transferring:

1. Check if the TBC Breaker is in OFF Condition.
2. Close the Transfer Bus Isolator of the Concerned Feeder and check for correct Isolator Status.
3. Close the Bus Isolator and the Transfer Bus Isolator of the Transfer Bus Coupler (TBC). Note that, if the Concerned Feeder is on Main Bus 1, Main Bus 1 Isolator of the TBC shall be closed). And check for the correctness of the Isolator Logic in Control Room.
4. Place the “NIT Switch” from “N” to “I” position.
5. Switch ON the TBC Breaker. Now, a parallel path will be created for the concerned Feeder through the Transfer Bus and TBC.
6. Switch “OFF” the Own Breaker.
7. Open the Bus and the Line Isolator of the Own Breaker and check for the correctness of the Isolator Logic in the Control Room.
8. Place the “NIT Switch” from “I” to “T” position.
9. Now, the Work Permit can be taken on the Own Breaker for Maintaince/replacement.

Restoration:

1. Cancel the Work Permit, if any on the Own Breaker.
2. Close the Bus and the Line Isolator of the Own Breaker and check for the correctness of the Isolator Logic in the Control Room.
3. Change the position of  the “NIT Switch” from “T” to “I”.
4. Switch “ON” the Own Breaker. Now, a parallel path will be created for the concerned Feeder through the Main Bus and the Own Breaker.
5. Switch “OFF” the TBC Breaker.
6. Change the position of  the “NIT Switch” from “I” to “N”.
7. Open the Transfer Bus Isolator of the Concerned Feeder and check for correct Isolator Status.
8. Open the Bus Isolator and the Transfer Bus Isolator of the Transfer Bus Coupler (TBC).
9. The Feeder is now being restored to its Own Bus and Own Breaker.