Tips for the inspection of low voltage switch gear

Low Voltage Switchgear involves switches like power circuits, relays etc. It is important that a periodic inspection and test carried out at least every 1-2 years and 2-6 months when new equipment is installed. In this section we discuss about some guidelines for inspection and maintenance of low voltage switch gear
1)      On energized equipment
                            Three things you must do
a)      Listen for popping, spitting or cracking sound produced by the electrical discharges-also humming and vibrations produced by the resonance
b)      Look for corona halos
c)      Check for ozone – ozone is produced by corona or overheating of organic materials
2)      On de-energized equipment’s
Three things you must do
a)      Check and confirm that the equipment is free from physical damage
b)      Check the foreign and loose hardware, distorted insulated bus and rusty or bent frameworks
c)      Check the occurrence of carbon tracks, moisture stains, rusts etc.
3)      Heat
The temperature extremes the designed level some of the insulating materials changes its colour and it will affect the dielectric strength of the insulator.
The heating areas can be identified
a)      Cracking or flaking of varnish coats
b)      Damage of tapes and cable insulation
c)      Changes the shape
4)      Moisture
Moisture is usually associated with water, which can readily contact the leakage current
5)      Corona
A corona is an electric discharge brought on the ionization of fluid such as air surrounding a conductor that is electrically charged. Spontaneous corona discharge limits the electric field strength. A corona can be detected without using any instruments.
6)      Electric tracking

It is a leakage of electric current between two points separated by an insulating material caused by dirt, carbon particles, moisture, etc.

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