IEEE C37.20.7-2017 pdf download
IEEE C37.20.7-2017 pdf download.IEEE Guide for Testing Switchgear Rated Up to 52 kV for Internal Arcing Faults.
3) All ventilation openings used for equipment cooling and designed to close during an overpressure event shall be open and functional before starting the test.
4) If the equipment is intended for use with specific control devices, such as relays and meters, mounted on exposed doors or covers that are not for isolated compartments designated for low- voltage control or instrumentation, a representative sample or mockup of these devices should be present on the test specimen and the method of mounting any mockups should match the standard mounting method for the actual device.
If the design of the equipment is intended for use with a variety of control devices mounted on exposed doors or covers that are not for isolated compartments designated for low-voltage control or instrumentation, the conditions experienced during the tests on the exposed doors or covers shall be measured (pressure, and deflection) for use in evaluating the suitability of devices to be located on those doors or covers.
See Annex C (suffix B) for an alternative test method for isolated compartments designated for instrumentation and control. For compartments tested to the requirements of suffix B or suffix C (refer to Annex C) and having no primary circuit components in the compartment, there are no further restrictions for components mounted on covers or doors of such compartments.
The equipment-specific annexes may also contain guidance on special treatment of isolated compartments designated for instrument and control devices.
5) Any openings created in the equipment as a result of manufacturing, assembly, or modification that have an intentional covering, plug, or similar device may have that device installed. Openings that do not have intentional coverings may not be blocked in any way for this test.
6) Surfaces of components and the enclosure that are exposed to the arc should be finished using the surface-finishing methods (paint, plating, insulating materials, etc.) intended for service.
d) The normal ground point(s) of the test specimen shall be connected to the test supply neutral through an adequate conductor. Also refer to 5.3.2.
e) The arc should be initiated in a way that is representative of faults that could occur under service conditions and normal activities associated with the equipment. See 7.2 and the appropriate annex for typical locations for arc initiation.
For the purpose of this guide, normal operating conditions means the conditions of metal-enclosed switchgear required to carry out operations, such as opening or closing switching devices, connecting and disconnecting withdrawable parts, reading of measuring instruments and monitoring equipment, and so on. Therefore, when normal operations require that any cover be removed and/or any door be opened in a compartment containing a primary circuit component, the test shall be carried out with the cover and/or door removed so it does not interfere with placement of burn indicators.
Removing or replacing active components (e.g., fuses or any other removable primary component) and activities required to carry out maintenance work are not considered to be normal operations.
f) Whether the equipment is for indoor or outdoor installation, the test arrangement should simulate room or surrounding conditions in a manner that enables the manufacturer to provide application guidelines that consider the following:
1) Distance to adjacent walls
2) Ceiling height
3) Any obstruction located near the equipment that may deflect hot gas into an area defined by the accessibility type
4) Any openings beneath the equipment (e.g., for a cable vault) that may allow hot gas to escape into an area defined by the accessibility type
If the design incorporates an exhaust system that will vent pressure directly out of the room, no room simulation is necessary.
The minimum extension past the perimeter of the enclosure for the test sample exhaust system shall be 2 rn. When the duct is intended to have a cover, for weatherproof designs or segregation, this cover shall be present for the test. The duct cover is not considered part of the unit under test, hut is required to verify the equipment functionality as the duct and cover may create venting restrictions that will influence the performance of the equipment.
