N O T E: Under m aintenance m ode, the load is directly fed by the m ains pow er instead of the pure AC
pow er from the in verter.
6. Disconnect the rectifier input switch Q1, bypass input switch Q2, and output switch Q5.
At the moment, all the internal power supply is off, and the TOUCH SCREEN does not display any more.
W ARN ING ! If the m aintenance is requ ired, wait 10 m inutes for the internal DC bu s capacitance
to discharge.
W ARN ING ! T he p arts of U P S circuits also have hazardous voltage, though the rectifier input
sw itch, bypass in pu t sw itch and battery sw itch are disconnected. Therefore, the UP S
m aintenance is applicable to q ualified personn el only.
W ARN ING ! F or m odels w ithout Q 1, Q 2 and Q5, w hen the external inpu t sw itch is not
disconnected , there is a hazard ous voltage inside the UP S.
6.3.5 Transfer from Maintenance Mode to Normal Mode
The following procedures will transfer the maintenance bypass supply mode of the UPS to the normal mode.
1. Close the output switch Q5, external power bypass switch, bypass input switch Q2, external power main switch
and rectifier input switch Q1 in turn.
Confirm that the TOUCHSCREEN is on and the UPS runs in Bypass mode.
2. Disconnect the maintenance bypass switch Q3.
3. Start the system according to steps 4 to 6 in Startup Procedures in Normal Mode.
Now the UPS runs in Normal mode.
W ARN ING ! Y ou must start the b ypass first, an d then disconnect the maintenan ce bypass
sw itch; or it m ay cause ou tput load pow er failure.
At the moment, the load has transferred to UPS normal mode.
6 Single UPS Operation Introduction
104
Vertiv™ Liebert® APM Plus User Manual
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