UPS Multi-Module Installation

3.3.3Power Cables

The wiring of power cables is similar to that of single module system except that the output of the upstream UPS is fed into the bypass input of the downstream UPS, and the load is fed by the down- stream UPS through its inverter or bypass. The bypass and the main input sources must be refer- enced to the same neutral potential and input earth leakage monitoring devices, if installed, must be located upstream of the common neutral sinking point. Refer to the instructions in 1.0 - Single Mod- ule UPS Installation.

No control wires other than those specified for the single module configuration are required.

Figure 17 Hot standby configuration

INPUT DISTRIBUTION

UPSTREAM

Mains L1,

Bypass L1,

Mains L1,

L2, L3, N

L2, L3, N

L2, L3, N

DOWNSTREAM

Bypass L1,

L2, L3, N

CB1

RECTIFIER

STATIC

SWITCH

INVERTER

L1, L2, L3, N

UPS1

OUTPUT

CB1

L1, L2, L3, N

TO LOAD

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Liebert NX UPS System user manual Input Distribution Upstream