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EARTHING AND GROUDING OF SUBSTATION

Discover overview, principles and grouding products dedicated for substation

Protection of electrical Substations

Equipotential networks on electrical substations

Introduction to permanent grounding of substations

The performance of an equipotential network is linked to the quality of the connections of the constituent elements. Generally speaking, the various metal elements and grounds of a source station must be connected to the general grounding network. It is essential that the connections have high mechanical strength, electrical contact and corrosion resistance.

On the following pictures, some examples of maintenance and installation of a buried grounding network on an electrical transformer station:

Objectives of permanent grounding for substations

In principle, a safe grounding design for substations has the following two objectives:

  • Provide means to carry electrical currents into the earth under normal and fault conditions without exceeding operating and equipment limits or impairing continuity of service
  • Ensure that a person in the vicinity of the grounded facilities is not exposed to the danger of a critical electric shock

A practical approach to safety associated with grounding concerns and aims to control the interaction of two grounding systems, as follows:

  • Intentional grounding, consisting of grounding electrodes buried at a certain depth below the surface of the ground
  • Accidental grounding, temporarily established by a person exposed to a potential difference in the vicinity of a grounded installation

It should never be assumed that any earthed component can be safely touched. A low earth resistance on a transformer station is not, in itself, a guarantee of safety. There is, in fact, no simple relationship between :

  • The resistance of the entire grounding system
  • The maximum shock current to which a person may be exposed

Therefore, a substation with a relatively low ground resistance may be unsafe, while another substation with a very high resistance may be safe or can be made safe by protective measures and/or careful design.

Principle of Protection

The MALTEP range for electrical substations

Schematic diagram for the protection of substations

Earth clamp

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Straight compression lugs with long barrel

Exothermic welding

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C crimp connectors

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Cable holders

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Earth clamps

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Conductors

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Earth braids

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Earth clamps

Discover our range dedicated to sub-stations

Earth clamps for substation

The earth clamp for substations is a set of copper alloy blocks holding the earthing circuit loop

MALTEP / RTE equivalents

Equivalences between MALTEP commercial references and RTE / CNER references
CPAR50-120LSTN-75/116 - A1 mark
CPAR150LSTN-146 - A2 mark
CPAR185LSTN-182 - A3 mark

Copper alloy earth clamps and bolts for metalic structures up to 20mm thick. Icc (A) withstand from 30 to 40 kA/1 s and 63kA/0,5s

CPAR50-120L

Double earth clamps for subsations

Similar to the earth clamp, it includes an additional set of copper alloy block allowing an additionnal earthing circuit loop

MALTEP / RTE equivalences

Equivalences between MALTEP commercial references and RTE / CNER references
2CPAR50-120LSTND-75/116 - C1 mark
2CPAR150LSTND-146 - C2 mark
2CPAR185LSTND-182 - C3 mark

Copper alloy earth clamps and bolts for metalic structures up to 20mm thick. Icc (A) withstand from 30 to 40 kA/1 s and 63kA/0,5s

2CPAR50-120L

Winged earth clamps for substations

Similar to the earth clamp with additional wings for temporary earthing connection during maintenance work on the earthing circuit via earth clamp systems

MALTEP / RTE equivalences

Equivalences between MALTEP commercial references and RTE / CNER references
CLPAR50-120LSTA-2/75/116
CLPAR150LSTA-2/146
CLPAR185LSTA-2/182

Copper alloy earth clamps and bolts for metalic structures up to 20mm thick. Icc (A) withstand from 30 to 40 kA/1 s and 63kA/0,5s

CLPAR50-120L