Appendix
System and Protective Earthing
The purpose of this appendix is to describe the system- and protective earthing principles of the Symmetra® MW.
Caution: All wiring to be in accordance with applicable national and/or local electrical wiring rules.
TN Systems
Characteristics
TN systems have one point connected directly to ground. All exposed conductive parts must be connected to that point by protective conductors.
Depending on the way the neutral and protective conductors are fed, there are three types of TN systems:
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Reference to IEC 60364-4-41 413.1.3
All exposed conductive parts of the installation must be connected to the earthed point of the power system by protective conductors which must be earthed at or near to each relevant transformer or generator.
Exposed conductive parts that are accessible at the same time must be connected to the same earthing system, either individually, in groups or collectively.
Normally the earthed point of the power system is the neutral point. If a neutral point is not available or accessible, a phase conductor must be earthed. The phase conductor must not serve as a PEN conductor.
In fixed installations a single conductor may serve both as a protective conductor and a neutral conductor (PEN conductor).
Reference to IEC 60364-5-54 546.2.3
If from any point in the installation the neutral and protective functions are provided by separate conductors, it is inadmissible to connect these conductors to each other from that point. At the point of separation, separate terminals or bars must be provided for the protective and neutral conductors. The PEN conductor must be connected to the terminal or bar intended for the protective conductor.
Symmetra MW II 1200 kW 3 × 400/230 V Installation - | 23 |