Comparative photos of a 40,000 Amp bolted short circuit inside of a 15 kV 2-high switchgear with PACSafe Arc Resistant Switchgear construction, compared to switchgear in which an explosive arc invaded personnel space. PACSafe Arc Resistant Switchgear was tested successfully at the KEMA Laboratory in Chalfont, PA., in accordance with IEEE Standard C37.20.07 which is intended to protect personnel in front of, at the sides, and behind the switchgear in case of an electrical explosive fault. In addition to reinforced cubicle construction in which doors stay closed, and there is no burnthrough in the front, rear, or sides, PACSafe switchgear also includes a top reinforced steel full length plenum that collects all of the explosive flames, smoke, and residue, enabling these dangerous byproducts to be ducted to a safe area, safeguarding the switchgear room.
This photo illustrates a 3 cubicle, 2 high switchgear of PACSafe Arc Resistant Switchgear construction, prepared for the test. A bolted 40 kA short circuit is precipitated in each of the front top and bottom cubicles, each of the rear top and bottom cable cubicles, and the interior main bus section. The front cubicles include a separate test for a circuit breaker cubicle, and a PT or CPT cubicle. Racks are placed around the perimeter of the switchgear, containing cotton heat detecting flags. If any flag is singed during an event, or if there is burnthrough, or flying parts, the test is a “fail”. The PACSafe test switchgear endured 7 short circuit events all of which cleared through the top plenum, which survived admirably.
This photograph demonstrates the tremendous explosive force that can be caused by an electrical arc explosion. Without proper Arc Resistant construction, the front door can be blown open and the explosive force will invade the personnel operating area. Any personnel standing in the switchgear area could be injured.
It is for this reason that Arc Resistant Switchgear construction requirements have become prevalent in the USA, Canada, and elsewhere. In addition to creating a much safer electrical environment, insurance rates could be lowered.
This is one of a series of PACSafe “passed” shots. The flame and smoke have been blown upwards into the steel reinforced plenum. Ductwork is not required or used for these tests, but notice how all of the doors remained closed; energy is exiting the plenum, which in a real application would be ducted away from the switchgear. Personnel standing anywhere in the perimeter of the switchgear would not have been injured by the blast.
There was no burnthrough to any adjacent cubicles, or through the front or rear doors, or side panels, or flying parts. |
