Disconnecting switch
The disconnecting switch is a electromechanical apparatus making it possible to separate, in a mechanical way, a Electrical circuit and its food, while ensuring a satisfactory distance from cutting physically electrically. The objective perhaps to ensure the safety of the people working on the part isolated from the Electrical communication, to eliminate part of the network in disfonctionnement to be able to use the other parts of them.
The disconnecting switch, unlike the Circuit breaker or of the Interruptory , does not have capacity breaking, nor of closing. It is imperative to stop the equipment downstream to avoid an opening in load. In the contrary case of serious burns could be caused, related to a Electric arc caused by the opening.
The disconnecting switch to satisfy the Norme S in force must be able to be condemned in open position.
Categories
Disconnecting switch low tension
This apparatus is often provided with fusible S, it is then called disconnecting switch fuse holders . Certain disconnecting switches comprise also contacts with précoupure making it possible to cut the order of the bodies of power in order to avoid an operation in load.Roles of the various bodies:
- principal Contacts: to cut an electrical circuit by isolating the source from the consumer;
- auxiliary Contacts: to cut the control circuit;
- the handle of order: it can be locked by a Cadenas in open position;
- Of the fuse holders (optional).
Disconnecting switch high voltage
The principal function of a disconnecting switch High voltage is to be able to isolate an element from an electrical communication (Ligne with high voltage, transformer, portion of electric Poste,…) in order to allow an operator to carry out a maintenance action on this element without risk of electric shock. The disconnecting switch must:
- To indicate without ambiguity its position: one speaks sometimes about " cut visible" ;
- To be able to be padlocked to guarantee to the operator whom a isolated circuit will not be closed again by inadvertency;
- To have an insulation between the terminals, which guarantees to the operator that a Surtension cannot put at fault this insulation and give the live circuit inopportunely.
Disconnecting switch of earthing
One often combines the disconnecting switches high voltage and BT of strong power with a put at the ground (or MALT or disconnecting switch of ground ). This MALT is visible above on the photograph (on the left, yellow and black striped pole). It is a question of a concerned with safety unit, of which the goal is to fix the potential of an installation put beforehand not under tension, to in full safety allow the human intervention on an installation.
Performances of a disconnecting switch
The performances of the disconnecting switches with high voltage are defined in the international standards, such as CEI.The principal performance which characterizes a disconnecting switch is its behavior with the Courant of short-circuit, i.e. the maximum current which it is able to support when it is closed. The values of behavior to the current of short-circuit lie typically between 25 kA and 63 kA. The dielectric behavior is another important parameter, characterizing the capacity to be isolated from the disconnecting switch, even in the presence of Surtension S.
These performances are checked by tests carried out full-scale, following standards such as CEI 62271 in specialized laboratories.
Notes & References
See too
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