PARALLEL SYSTEM AND LBS SYSTEM
User Manual 10H52246UM60 - Rev. 1 - 01/2017
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Pressing the ALARM CLEAR key silences the audible alarm but the alarm message is displayed until the alarm condition is
rectified.
2. Close all the UPS external maintenance bypass switches, but do not close the UPS internal maintenance bypass
switches Q3.
3. At this point, the external maintenance bypass should be connected in parallel with the static switch on each
individual UPS.
4. At this point, the message 'Maint. sw. closed' appears on the LCD on each UPS.
5. Open the output switch Q5 and neutral line switch Q6 on each UPS in turn, so that the load power is supplied by
the maintenance bypass line.
Caution
When the system is in maintenance bypass, the load is not protected against abnormal mains supply conditions.
6. Pressing the EPO button on each UPS module de-energizes the corresponding rectifier, inverter, static switch and
battery, but does not affect the maintenance bypass, which continues to power the load normally.
Note
When the system is in maintenance bypass, the load is fed directly by the mains power instead of the pure AC power from the
inverter.
7. If the UPS has internal battery, use the special tool to open the battery compartment door, then disconnect the
three terminals 'BAT+', 'BAT-' and 'BAT N' (see Figure 5-3 for details). If the UPS has external battery, open the
corresponding external battery switch. All UPS modules should be disconnected from the batteries.
8. Open the rectifier input switch Q1 and bypass input switch Q2 on each UPS in turn.
At this point, all the internal UPS power supplies are disconnected and the LCD does not display any more.
Warning
1. If UPS maintenance is required, wait 10 minutes for the internal DC bus capacitors to discharge completely.
2. Hazardous voltages are present at some points on the UPS circuits, even when the rectifier input switch, bypass input
switch and battery switch are open. Therefore, UPS maintenance must be carried out by qualified personnel only .
7.3.3
Procedures for Isolating One UPS Module in a Parallel System
Important
These procedures may only be carried out Vertiv service personnel or under their guidance.
Warning
Before carrying out the following operation, confirm that the system redundancy capacity is sufficient to avoid system
shutdown 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. Press the EPO button on the UPS module to be isolated in order to de-energize the rectifier, inverter, static switch
and battery; this action will not affect the other UPS in the parallel system, which will continue to supply power to
the load normally.
2. If the UPS has an internal battery, use the special tool to open the battery compartment, then disconnect the
three terminals 'BAT+', 'BAT-' and 'BAT N' (see Figure 5-3 for details). If the UPS has external battery, open the
corresponding external battery switch.
3. Open the rectifier input switch Q1, bypass input switch Q2, output switch Q5 and neutral line switch Q6.
At this point, all the internal UPS power supplies are disconnected and the LCD does not display any more.
Warning
1. Position a label at the AC input distribution (normally located at a distance from the UPS) alerting personnel that
maintenance is being carried out on the UPS.
2. Wait 10 minutes for the internal DC bus capacitors to discharge completely. At this point the UPS is completely shut down.