Liebert UPS System - Manual (Page 92)

Chapter 7 Troubleshooting
86
No.1 Fault description Reason Actions to be taken
49
Transfer to bypass
due to surge
The system transfers to bypass
mode due to surge current and back
to inverter mode after load is
decreased
Avoid applying load abruptly and the UPS
can recover automatically
50
User’s wrong
operation
Wrong operation such as start the
UPS with the maintenance bypass
switched on
Operate with reference to User’s Manual
51
The actual transfer
times exceed the
permissible transfer
times per hour Transfer times exceed the times set
by background. The system will stay
in bypass mode until next hour.
Avoid frequent overload
Table 7-2 Fault of parallel operation system
No. Fault description Reasons Fault processing
1
Overload of parallel
operation system Overload occurs and the
redundancy is not available Disconnect the load of low priority, maintain the
power supply to important load
2
Neighbouring UPS
module requires to
transfer to bypass
mode
In parallel operation system,
some UPS module may
require to transfer to bypass
due to surge or overload,
other modules will transfer to
bypass after receiving the
signal sent by this UPS
module that requires to
transfer to bypass mode
If the parallel operation system transfers to
bypass mode, and the operation condition
enables, all the UPS modules can recover to
normal mode synchronously.
3 Load sharing fault
The load current of each UPS
module is noticeably
unbalanced, thus the system
loading ability is affected.
Notify the service dept for repairing
4
Parallel operation
board fails
The board is damaged. Notify the service dept for repairing