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WG B3.37 Internal arc effects in Medium Voltage switchgear (1-52kV)-mitigation techniques

The WG has been officially set-up in July 2013, after some preparatory work. It will prepare a Brochure expected to be available in 2017.

Background:

Several switchgear assemblies in the market place incorporate internal arc fault limiting devices. These devices generally operate by short-circuiting and hence diverting the fault arc using very fast detection and a fast making switch, generally to earth. The international MV switchgear standard IEC 62271-200 (valid for air-insulated and gas-insulated assemblies) acknowledges such devices as supplementary protective measures, but with little information. This standard also states that in general, arc limiting devices are out of its scope. They are not described or specified and no guidance is given for the related name plating of the switchgear. The IEC sub-committee SC17C requested CIGRÉ to carry out a technical review to give recommendations to support an extension of the current standard to cover such a function and to provide assessment of the same.

Scope:

1)       Review of methods for arc effect mitigation under internal arc fault conditions of medium voltage switchgear assemblies.

2)       Mapping of existing technical solutions related to arc effects mitigation: parameters for detection, means for actuation, power supply issues, etc.

3)       Review the status of current Standards and existing specifications.

4)       Consideration of the benefits and consequences resulting from arc effect mitigation including: limitation of pressure rise in switchgear and switch-rooms (digital simulations are already used for such purpose), limitation of fire risk and other damages, possible reduction of outage duration, transients on the network, etc.

5)       Analysis of the possible methods for verification of performance, assessment and the definition of general requirements for standardized type and routine testing.

6)       Guidance for the user on relevant selection parameters: personnel safety, downtime, maintainability, environmental impact, investment costs, life time, immunity to EMI etc.