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3.4.4 Maintenance Bypass Load Transfers
To manually transfer the load between Maintenance Bypass and the UPS system bypass line, care-
fully follow these instructions. Do not transfer the load between Maintenance Bypass and the UPS
system (module inverters) output. Use the SCC Monitor/Mimic Display screen to verify the UPS sys-
tem bypass line is available.
If the load is on the UPS System Bypass:
a. If the maintenance bypass cabinet or switchboard has an optional 2-key interlock system,
press the button on the maintenance bypass cabinet to remove the key from the solenoid.
b. If using a key interlock system, insert the key into the lock for the Maintenance Bypass
Breaker (MBB) to enable it to be closed.
c. Close the Maintenance Bypass Breaker (MBB).
d. Verify closure of the MBB. Then open the Maintenance Isolation Breaker (MIB). The UPS
system is now isolated from the critical load and the load is now on Maintenance
Bypass.
e. If using a key interlock system, remove the key from the lock for the Maintenance Isolation
Breaker (MIB) to lock it open.
f. If the maintenance bypass cabinet or switchboard has an optional 2-key interlock system,
replace the key into the solenoid.
g. If UPS bypass shutdown is required, open the Bypass Input Breaker (BIB).
If the load is on Maintenance Bypass:
a. Close the Bypass Input Breaker (BIB) or verify BIB is closed. Note that UPS System Bypass
circuit breaker (motorized) must also be closed. Refer to 3.4.1 - SCC Start-Up Procedure.
b. If the maintenance bypass cabinet or switchboard has an optional 2-key interlock system,
press the button on the maintenance bypass cabinet to remove the key from the solenoid.
c. If using a key interlock system, insert the key into the lock for the Maintenance Isolation
Breaker (MIB) to enable it to be closed.
d. Close the Maintenance Isolation Breaker (MIB).
e. Verify closure of the MIB. Then open the Maintenance Bypass Breaker (MBB). Load is now
on UPS Internal Bypass.
f. If using a key interlock system, remove the key from the lock for the Maintenance Bypass
Breaker (MBB) to lock it open.
g. If the maintenance bypass cabinet or switchboard has an optional 2-key interlock system,
replace the key into the solenoid.
!
CAUTION
Make sure you understand the proper sequence before operating any circuit breaker.
Operating a Maintenance Bypass circuit breaker out of sequence could cut off power to the
critical load.
!
CAUTION
The UPS system (SCC) 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.
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.