Introduction to IEC/TR 61641 A status update and insides Bas Bouman Hans Meulenbroek Manager Damstra Lab Product Manager LVS Member of NEC 17BD and NEC64 Member of IEC 17D/MT11, MT13, MT15 Member of IEC TC64 and CLC64 September 2009

General information IEC/TR 61641: Enclosed low-voltage switchgear and controlgear assemblies – Guide for testing under conditions of arcing due to internal fault IEC/TR 61641 is: Not a standard, but a technical report Not a part of the IEC 60439/61439 series Not a compulsory test

Update Edition 2 published beginning of 2008 New definitions: Ip arc (permissible current under arcing conditions) t arc (permissible ac duration) Ipc arc (permissible conditional short-circuit current under arcing conditions) Arc free zone Arc proof zone Arc proof assembly New test criteria: 6) and 7) concerning switchgear assembly availability

Important definitions (1) 3.4 Arc Short-circuit arising from a fault between active parts of different potential and/or between active parts and other conductive parts resulting in a free burning arc within an ASSEMBLY 3.5 Personal protection under arcing conditions Ability of an ASSEMBLY to limit the risk of personal injury caused by the mechanical and thermal effects of an internal arcing fault Note 1: This applies to enclosed low-voltage switchgear and controlgear assemblies when doors and covers are closed and correctly secured Note 2: It does not cover all effects which may constitute a risk, such as toxic gases

Important definitions (2) 3.6 ASSEMBLY protection under arcing conditions Ability of an assembly to limit the effects of an internal arcing fault on the operation to a defined area inside the ASSEMBLY 3.7 Arc free zone Part of a circuit within the ASSEMBLY where it is not possible to apply an ignition wire without destroying the insulation material on conductors 3.8 Arc proof zone Part of a circuit where an ignition wire can be applied and fullfilling all relevant criteria for the assessment of the test 3.9 Arc proof ASSEMBLY Assembly consisting of arc free zones and/or arc proof zones

Criteria to assess personal protection Personal protection is achieved when these criteria are fullfilled: Correctly secured doors, covers, etc., do not open Parts (of the ASSEMBLY), which may cause a hazard, do not fly off. (This includes large parts or those with sharp edges, for example inspection windows, pressure relief flaps, cover plates, etc.) Arcing does not cause holes to develop in the freely accessible external parts of the enclosure as a result of burning or other effects The indicators arranged vertically do not ignite (indicators ignited as a result of paint or stickers burning are excluded from this assessment) The protective circuit for accessible parts of the enclosure is still effective

Criteria to assess assembly protection Personnel protection and assembly protection is achieved when criteria 1) to 6) are fullfilled: The ASSEMBLY is capable of confining the arc to the defined area where it ignited, and there is no propagation of the arc to other areas within the ASSEMBLY In addition, if specified by the manufacturer, criterion 7 applies where the ASSEMBLY is to be suitable for limited continued operation: 7) After clearing of the fault or after isolation or disassembly of the affected functional units in the defined area, emergency operation of the remaining ASSEMBLY is possible. This is verified by a dielectric test with a value of 1,5 times the rated operational voltage during 1 min.

Capitole 40 and arc free Incomer Main busbar Vertical busbar Big separators between terminals (arc proof) Epoxy resin insulated busbars between incomer and main busbar (arc free) Main busbar Epoxy resin insulated (arc free) Vertical busbar Fully incapsulated (arc free) Outgoing units Unprotected circuit: arc free Protected circuit: arc proof Units are tested and assessed arc proof in accordance with IEC/TR 61641

Test report Capitole 40 U = 415 V Ip arc = 80 kA t arc = 300 ms