Operating System Bypass Switch - Eaton Powerware 9155 UPS20-30kVA User Manual

Operating system bypass switch
The system bypass switch is used to bypass the parallel system during maintenance or
servicing. Using the switch does not cause any break in the output voltage, if the input voltage
and frequency are accepted and the system is synchronised to the input mains.
In the example wiring diagram for parallel systems.The parallel module includes a mechanical
bypass switch S (Make-Before-Break type) and four maintenance switches S1, S2, S3, and S4
for disconnecting the outputs of UPS modules during maintenance or service.
The maintenance bypass switch has the following positions:
'I' or 'UPS' normal position, the load is supplied from the UPS modules.
'I'+'II' or 'UPS+BYPASS' position, the load is supplied from UPS modules (internal bypass
mode) and the system bypass in parallel.
'II' or 'BYPASS' position, the UPS modules are bypassed and the critical load is supplied from
the system bypass power line.
If the system bypass switch needs to be used it is recommended to check that the bypass input
power is connected and present in the SPM cabinet. The swicth is used only on rare occasions
and the procedure is following:
1. Check that the 'bypass not available' alarm is not active in the UPS modules.
(Press menu button, choose UPS status display).
2. Use LCD to turn UPS unit(s) on internal bypass mode.
Select: CONTROL
3. Verify the transfer before proceeding the next step.
4. Turn the maintenance bypass switch to BYPASS position.
Warning
The use of the maintenance bypass switch will cause a break in the output
voltage if the input voltage or frequency is not correct and the UPS system is not
sychronised to mains.
Following procedure does returning to normal online mode:
1. Make sure UPS modules have been started according to chapter 'Start-up procedure',.
2. Check that UPS ON and BYPASS LED's are lit in the front panel.
3. Make sure service switches S1...S4 in the SPM are in 'ON' position.
4. Turn the system bypass switch S to 'UPS' position.
. Use LCD to turn UPS unit(s) to normal mode.
Select: CONTROL
6. Verify the transfer by checking that the yellow bypass LED is turned off.
46
GO TO BYPASS MODE
->
GO TO NORMAL MODE.
->
UPS 20-30 kVA, 230 V 0/60 Hz output
User's Guide
1026743
Revision B