Modifications reserved
Page 60/71
OPM_SGS_USM_M75_M75_2US_V010.doc
User Manual
SG Series 750 UL S2 & SG Series 750 T12 UL S2
7.2.3 From External Maintenance Bypass (option) to normal function VFI
NOTE !
UPS Parallel System
has been turned
OFF
following the
“Maintenance shutdown”
procedure and the
Load
is still powered by
External Maintenance Bypass.
The
Load
must be transferred back to the
UPS Parallel System
.
Open the front door on all UPS units and make sure that:
•
The
safety screens
are fixed in their position.
•
The
UPS Output Switches Q1
,
Input Circuit Breakers CB4
,
Battery Circuit Breakers
are open (Pos.
O)
and the
External Maintenance Bypass Switches
are closed (Pos. I).
LED Alarm
are lit.
1. If not already supplied (separate utility inputs), switch-ON the utility power to the rectifier
input on all UPS units.
2 Close the UPS Output Switch Q1 (Pos. I) on all UPS units.
LED 1 (Utility Rectifier OK)
must be lit.
The
Load
is supplied by the
Utility
through the
UPS
Automatic Bypass
and
External Maintenance Bypass
.
The
Synoptic Diagram
must display the status
“
LOAD
SUPPLIED BY AUTOMATIC BYPASS
”
.
Input Circuit Breaker CB4
closes automatically.
LED 3 (Rectifier ON)
must blink.
The
Rectifier
starts up automatically, supplying the
DC circuit
, and charging the
DC capacitors
.
The
LED 3 (Rectifier ON)
stops blinking and stays ON, indicating that the
DC link
has reached the floating voltage.
3. Transfer the Load from External Maintenance Bypass to Internal Automatic Bypass of all units.
Use the
External Maintenance Bypass panel instructions
to transfer the
Load
from the
External
Maintenance Bypass Breaker (MBB)
to the
UPS Automatic Bypass
of all units.
After this step, the
Load
is supplied by the
Utility
through the
Automatic Bypass
.
MBB Open, MIB(s) Closed, and
“
LOAD SUPPLIED BY AUTOMATIC BYPASS
”
must display on the
Synoptic Diagram
.
WARNING
:
Insure that all
Module Isolation Breakers (MIB)
are closed prior to performing this operation or
power to the critical
Load
will be interrupted.
4. Battery coupling to DC link on all UPS units.
Close the
Battery Bank Circuit Breaker
. The
Battery
is now connected to the
DC Link
.
LED 4b
(Charging Battery)
should be lit indicating
Battery Charge
.
5. Insert the Inverter by pressing the
“
Inverter ON
”
( I ) key on first UPS unit
.
The
Inverter
will start up.
LED 5 (Inverter available)
must be blinking
In a short time, when the
Inverter voltage
is confirmed, the
LED 5 (Inverter available)
will stop blinking and
stay fixed lit.
The
Load
will be automatically transferred from
Utility
to
Inverter
if the
Inverter Power
is sufficient to supply the
Load
.
LED Alarm
turn Off and the
LED Operation
must be lit.
The
Synoptic Diagram
, on first UPS unit, must display the
status
“
LOAD SUPPLIED BY INVERTER
”
.
6. Insert the Inverter by pressing the
“
Inverter ON
”
( I ) key on all other UPS units
Do not start the next
Inverter
until the sequence of the previous ends.
As soon as the output power of the
Inverters
is sufficient to supply the
Load
, the output of the units with
running
Inverter
will transfer to
Inverter
.
LED Alarm
turn Off and the
LED Operation
must be lit.
The
Synoptic Diagram
, on all UPS units, must display the
status
“
LOAD SUPPLIED BY INVERTER
”
.
END OF PROCEDURE
