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3.9.2 Parallel cable installation
Shielded and double insulated control cables available must be interconnected in a ring
configuration between UPS modules as shown below. The parallel control board is
mounted on each UPS module. The ring configuration ensures high reliability of the
control.
3.9.3 Requirement for the parallel system
A group of paralleled modules behave as one large UPS system but with the advantage of
presenting higher reliability. In order to assure that all modules are equally utilized and
comply with relevant wiring rules, please follow the requirements below:
1) All UPS must be of the same rating and be connected to the same bypass source.
2) The Bypass and the Main input sources must be referenced to the same neutral potential.
3) The outputs of all the UPS modules must be connected to a common output bus.
4) The length and specification of power cables including the bypass input cables and the UPS
output cables should be the same. This facilitates load sharing when operating in bypass
mode.
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