Vertiv Liebert EXM2 - Procedures for Isolating One UPS Module from Parallel System

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 which m u st be d isconnected. Therefore, the UP S
m aintenance is applicable to qualified personnel only.
8.3.3 Procedures for Isolating One UPS Module from Parallel System
These procedures shall only be carried out by service personnel of Vertiv or under their guidance.
W A RN IN G! Please check if the parallel U PS system is configured in redundancy m ode or not.
If so, proceed w ith steps given below . If not, please ab ort the operation to avoid system
shutdow n due to overload.
The following procedures apply when one UPS module must be isolated from the parallel system for repair due to serious
fault:
1. Pressing the EPO button on the GHMI stops the operation of rectifier, inverter, static switch and battery, but this
action will not affect other UPSs in parallel system to power the load normally.
2. Disconnect the external power mains switch, rectifier input switch Q1, external power bypass switch, bypass
input switch Q2, output switch Q5, BCB and single module external output switch.
W A RN IN G!
1. Post a lab el at the AC input distribution (generally far aw ay from the U P S) to alert that the
UP S is under m aintenance.
2. W ait 10 m inutes for the internal D C bus capacitance discharg ing . Then the U PS is
com pletely shut down.
8 Parallel System and LBS System
146
Vertiv™ Liebert® EXM2 UPS User Manual