Maintenance Bypass - Liebert 7400 Series User Manual

7400 Series UPS User Manual
Single Module and One plus One Systems
How to turn off the system but continue to provide load power through the
This procedure should be followed if the UPS is to be powered-down while continuing to supply the load through the
maintenance bypass line. Note that during this procedure the load will be unprotected against mains supply disturbances once
the inverter(s) has been switched off.
Step
1. Ensure that LS3 is illuminated on the mimic panels
(indicating that the static bypass supply is healthy).
2. Press the Inverter OFF switch (S6) (on both modules
in the one plus one system)
3.
Close the Maintenance Bypass Isolator (on both
modules in the one plus one system).
4.
Open the Output Isolator (on both modules in the
one plus one system).
5.
(On each module in the one plus one system)
Open the battery circuit breaker followed by the
Input Isolator and Static Bypass Isolator.
On 80 - 120 - 200 kVA: open auxiliary fuses F1... F6
WAIT AT LEAST 5 MINUTES

maintenance bypass

Action
WARNING
Wait at least 2 minutes for the d.c. capacitors to discharge.
The following points will be live within the UPS:
- Bypass supply input terminals -
- Maintenance Bypass Isolator switch -
- Static Bypass Isolator Switch (if fitted) -
- UPS output terminals -
6310018a.02.doc
Mimic panel leds
LS4 and LS6 should extinguish (on both modules in
the one plus one system) and LS5 should illuminate
to show that the load has been transferred to the
static bypass line.
Note: On a one plus one redundant system both
Inverter OFF switches (S6) must be operated before
LS5 illuminates but in a non-redundant system the
Inverter OFF switch must be pressed on one
module only before LS5 illuminates. However, as
the load is transferred to the static bypass, the
second module should be turned OFF also.
Mimic panel leds
No change.
Mimic panel leds
LS5 should extinguish (on both modules in the one
plus one system).
All the operator panel led indications and messages
should extinguish as the mains driven internal
power supplies decay.
Chapter 2 - Operating Instructions
One plus One
Response
.
2-5
Issue 2
(02/98)