Fault And Fault Process Methods - Liebert UPS System User Manual

This figure only shows the connection method of control cables of parallel operation
system with 3 UPS units. The others can be done according to the same methods.
Where, "1"-Normally closed contacts for emergency shutdown

8.5.6 Fault and Fault Process Methods

The faults of single module UPS system is given in Chapter 7. The faults that
specially belong to the parallel operation system are given in Table 8-3. If some
UPS unit has fault, it can exit the system and other units can maintain the normal
operation mode. But redundancy is not available, so the faulty UPS unit must be
repaired as soon as possible.
Chapter 8 Parallel System
1 2 3 4
1 2 3 4
1 2 3 4
Fig. 8-6 Emergency shutdown button
"2"- Central contacts for emergency shutdown
"3"- Normally open contacts for emergency shutdown
"4"- Normally closed contacts for common alarm
99
Emergency stop button