APC Symmetra MW Installation Guide download pdf (Page 41)

Appendix: TN Systems

Symmetra MW 800 kW 3 × 400/230 V Installation Guide - 990-1510B 35

Additional requirements for generating sets (IEC 60364-5-55 551.4.2)

To be used when the generating set provides a switched alternative to the public supply.

Protection by automatic disconnection of supply must not rely on the connection to the earthed points

of the public supply system when the generator is operating as a switched alternative to a TN system.

A suitable earth electrode must be provided.

Protective devices in TN systems

The following protective devices are recognized in TN systems:

• Overcurrent protective devices

• Residual current protective devices (not to be used in TN-C systems)

When a residual current protective device is used in a TN-C-S system, a PEN conductor must not be

used on the load side. The connection of the protective conductor to the PEN conductor must be made

on the source side of the residual current protective device (see below illustration):

L1 L1

PEN N

SOURCE SOURCE

Residual Current Sense

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APC Symmetra MW Installation Guide Page 41