Chapter 2 Installation Of UPS Rack System And Parallel System 25
LIEBERT APM UPS Module And Parallel System 30kVA~150kVA User Manual
3.2.2 External Protective Devices
Refer to
Chapter 1 par.
1.6
3.2.3 Power Cables
The power cable connection of the parallel system is similar to that of the single UPS rack system. If the bypass input
and rectifier input share the same neutral terminal and if an RCD protective device is installed at the input, then the
RCD device must be installed before the input cables are connected to the neutral terminal.
Note: The length and specification of the power cables of each UPS module should be the same, including the
bypass input cables and UPS output cables, so that the load sharing effect can be achieved in bypass mode.
3.2.4 Control Cables
Refer to
Chapter 1
1.7
Parallel control cable
The parallel control cable has THREE types in terms of length: 5m, 10m, and 15m. All the parallel cables are
designed to be shielded and double insulated, and are intended to be connected between the UPS racks to form a
loop as shown below. The parallel signal board X2 is installed at the front of the static switch power module. This
close loop connection ensures the reliability of the parallel system control. Refer to Fig.
3-2 and to Fig.
3-3
Fig.
3-2:
Connection of parallel control cables of 2 UPS rack systems
Fig.
3-3:
Connection of parallel control cables of 4 UPS rack systems
