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An arc-fault is a phase-to-phase or phase-to-ground short circuit through air which is caused by a reduction in the insulating clearances to such an extent that the potential different applied can no longer be withstood by the system. Such reductions can be as a result of; dropped tools, or other elements that may be accidentally left behind that could compromise the distance between energized components. Often incidents occur when a worker mistakenly fails to insure that the equipment has been properly de-energized.
An Arc-fault condition results in an Arc-flash. An Arc-flash consists of a plasma arc between shorted components which, once established has a virtually unlimited current carrying capacity. In addition to the plasma-arc itself, an explosion occurs which results in a huge amount of radiated energy, a high pressure blast wave and noise levels which can deafen.
Arc Flash incidents typically occur in applications above 120V and can occur when electrical equipment is being serviced or inspected. In fact, some incidents occur when a worker is removing a cover or trim from a piece equipment.
Today, many medium voltage (MV) electrical systems are designed to withstand an arc-fault condition. These systems are known as "Arc Resistant" and have been subjected to a series of Type Tests in accordance with the relevant local standard. Tests are typically performed by a third party testing organization in order to ensure impartial and thorough testing for the good of the end user.
Hawk IR Sightglasses have been tested to both IEEE and IEC arc-resistant switchgear standards by third part bodies in Australia and Canada respectively, for more information on the Arc-flash and other tests performed by Hawk IR click here
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