Chapter 7 Parallel System & Dual Bus System 73
NX UPS Single Module And Parallel System 250kVA ~ 800kVA User Manual
2. The open circuit voltage provided is 12Vdc, <10mA.
3. The external EPO device can be composed of another control system which can disconnect the UPS mains supply or the
bypass input.
4. Pins 1 and 2 of the remote EPO input port J24 on the front panel of the control module in the bypass cabinet are factory-linked.
J24:3
J24:4
Control module of
bypass cabinet
J24:3
J24:4
Control module of
bypass cabinet
EPO
J24:1
J24:2
Control module of
bypass cabinet
J24:1
J24:2
Control module of
bypass cabinet
UPS1
EPO
UPS 2
UPS1
UPS 2
Bypass control
module
Bypass control
module
Bypass control
module
Bypass control
module
Figure 7-5 EPO circuit diagram
7.3 Operating Procedures Of Parallel System
Warning
If UPS input uses RCD, differential switch is only used in the system’s bypass mains supply. At the moment of electrical
connection, current may not be immediately separated, which may result in the tripping of RCCB respectively.
Only one step is needed for once, and only after finishing this operation step of each UPS module, the next step can
be carried on.
7.3.1 Start-Up Procedures (Into Normal Mode)
These procedures are applicable to start the UPS under total power-down state, which means the UPS or the
maintenance bypass has not supplied the load before. Make sure UPS has been completely installed and
commissioned by the engineer, and external power supply switch has been closed.
Warning
These procedures will make the output terminals of UPS have dangerous voltage. If any load equipment is connected to the UPS
output terminals, please check with the load user and ascertain whether it is safe to apply power to the load. If the load is not
ready to receive power, please disconnect downstream load connection switches and attach warning label to the connection
points of the load.
Refer to
5.2 UPS Start-Up Procedure
s for the operating procedures.
