1. 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

2. 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 is:
Not a standard, but a technical report
Not a part of the IEC 60439/61439 series
Not a compulsory test

3. 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

4. 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

5. 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

6. 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

7. 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.

8. 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

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