Liebert UPS System user manual Signal cable, Earthing Method, Routing the signal cable

Chapter 3 Electrical Assemble

4. Earthing Method

The UPS rectifier source has no neutral cable. The bypass and output source have neutral cables and the input and output neutral cables are short circuited.

The lightning protection earth PE and the protection earth of the cabinet are connected as shown in Figure 3-5. The user can decide whether to use a connection cable according to his earthing requirement.

PE for lightning protection

PE inside cabinet

Protective earth

Fig. 3-5 Wiring inside cabinet

Generally, the separated neutral mode is better for human safety. The united connection mode is better for the UPS system. If there is C-level lightning protection unit inside the UPS, the cabinet protection earth and the lightning protection earth should be connected together.

In the bottom cable entry mode, the protection earth cable should be connected with a copper terminal on the beam inside the cabinet or connected to the copper busbar marked with PE. User board M8x12 to fix the cable.

Note

The leakage current of the UPS should be less than 1 ampere.

The earthing resistance of the UPS cabinet should be less than 1 ohm.

3.2.2 Signal cable

The Signal cable includes serial communication cables, control cables of input/output contacts, logic and load sharing cables.

1. Routing the signal cable

The signal cables should be routed according to Figure 3-6

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