GE Industrial Solutions SG Series 750 T12 UL S2 User Manual - Manual (Page 60)

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