Liebert UPS System - Manual (Page 98)

Chapter 8 Parallel System
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8.2.2 Electrical installation
1. Power cables
Wiring of power cables is the same with that of single module UPS system.
Note:
The length and specifications of power source cables including the bypass input
and UPS output cables should be the same, thus the load can be shared evenly in
bypass mode.
2. Signal cables
Wiring of signal cables is the same with that of single module UPS system. Parallel
connection cables should be connected.
You can see the holes for parallel connection cables when opening the front door of
the UPS system. According to the routes, two parallel connection cables are
connected to the P1(P2) and P3(P4) sockets on the ULW2L61M3 parallel board, at
the same time tighten the screws between the connector and sockets. P1/P2 on the
ULW2L61M3 board are two 15-pin sockets with same functions and are used to
transmit parallel logic signal. P3/P4 are two parallel 9-pin sockets with same
functions and are used to transmit the load sharing detection signal. The wiring
method of parallel connection cables of three UPS units are shown in Fig.8-6.
left post
Logic cable
Load sharing detection
UPS 1 parallel
board
Logic cable
left post
Load sharing detection
UPS 2 parallel
board
Logic cable
left post
Load sharing detection
UPS 3 parallel
board
Fig.8-6 Connection of Parallel Operation Cables