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3.4.3 Maintenance Bypass Load Transfers
To manually transfer the load between Maintenance Bypass and the UPS bypass line, carefully follow
these instructions. Do not transfer the load between Maintenance Bypass and the UPS module
(inverter) output. Use the Monitor/Mimic Display screen to verify the UPS bypass line is available.
STEP 1 (Maintenance Bypass Load Transfers - If the Load is on the UPS 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. 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).
STEP 2 (Maintenance Bypass Load Transfers - If the Load is on Maintenance Bypass)
a. Close the Bypass Input Breaker (BIB) or verify BIB is closed. Note that UPS Bypass circuit
breaker (motorized) must also be closed. Refer to 3.4.1 - 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. 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 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.