Emerson 250-400kVA - Manual (Page 33)

Operation
27
NOTICE
Risk of equipment damage. The UPS system must be on internal bypass before performing
the following procedures and operating MIB or MBB, or damage to the UPS may occur and
the critical load may be lost.
Maintenance Bypass Load Transfers—If Load is on UPS Bypass
1. If the maintenance bypass cabinet or switchboard has an optional two-key interlock system, press
the button on the maintenance bypass cabinet to remove the key from the solenoid.
2. If using a key interlock system, insert the key into the lock for the Maintenance Bypass Breaker
(MBB) to enable it to be closed.
3. Close the Maintenance Bypass Breaker (MBB).
4. Open the Maintenance Isolation Breaker (MIB). The UPS system is now isolated from the critical
load, and the load is now on Maintenance Bypass.
5. If using a key interlock system, remove the key from the lock for the Maintenance Isolation
Breaker (MIB) to lock it open.
6. If the maintenance bypass cabinet or switchboard has an optional 2-key interlock system, replace
the key into the solenoid.
7. If UPS bypass shutdown is required, open the Bypass Input Breaker (BIB).
Maintenance Bypass Load Transfers—If Load is on Maintenance Bypass
1. Close the Bypass Input Breaker (BIB) or verify BIB is closed. Note that UPS Bypass circuit
breaker (motorized) must also be closed. Refer to 2.4.1 - Startup Procedure.
2. If the maintenance bypass cabinet or switchboard has an optional two-key interlock system, press
the button on the maintenance bypass cabinet to remove the key from the solenoid.
3. If using a key interlock system, insert the key into the lock for the Maintenance Isolation Breaker
(MIB) to enable it to be closed.
4. Close the Maintenance Isolation Breaker (MIB).
5. Open the Maintenance Bypass Breaker (MBB). Load is now on UPS Internal Bypass.
6. If using a key interlock system, remove the key from the lock for the Maintenance Bypass Breaker
(MBB) to lock it open.
7. If the maintenance bypass cabinet or switchboard has an optional 2-key interlock system, replace
the key into the solenoid.
NOTE
If the maintenance bypass cabinet or switchboard has any other type of custom interlock, follow
the specific instructions for that interlock system to remove the key.
NOTE
If the maintenance bypass cabinet or switchboard has any other type of custom interlock, follow
the specific instructions for that interlock system to remove the key.