N O T E: U nder m aintenance m ode, the load is directly fed by the m ains pow er instead of the pure A C
pow er from th e inverter.
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 TOUCHSCREEN does not display any more.
W A RN IN G!
1. If the m aintenance is required, w ait 10 m inutes for the internal D C bus capacitance
disch arging.
2. T h e parts of U PS circuits also have hazardous voltage, though the rectifier input switch ,
bypass input sw itch and battery sw itch are discon nected. Therefore, the U PS m aintenance is
applicab le to q ualified personnel only.
3. If the UPS con tain s only standard Q3 bypass sw itch, all oth er breakers, including an
external maintenance bypass sw itch, m ust be installed for full m aintenance of the UPS and its
cleaning operations.
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 4~6 in Startup Procedures in Normal Mode .
Now the UPS runs in Normal mode.
W A RN IN G! You m ust start the byp ass first, and then disconnect the m aintenance bypass
switch; or it m ay cause output load p ow er failure.
At the m om ent, the load has transferred to UP S norm al m ode.
6 Single UPS Operation Introduction
113
Vertiv™ Liebert® EXM2 UPS User Manual
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