Introduction:

Voltage fluctuation is a common phenomenon in every part of the country. The industrial units running round the clock, usually face the problem of low and high voltage. 90% of industrial load is of motors. Electric motors draw considerably high current at low & high voltage. This higher current affects the electrical motors (particularly smaller capacity motors upto 7.5 H.P.) in three ways.

• Higher current produces higher losses in electrical motors which causes premature failure of winding.
• These higher losses of electric motors also increase the losses of cables, switches, transformers and other associated equipments.
• For smooth continuous operation of motors, overload relays are usually set at 20% higher setting.

ADVERSE EFFECTS OF SINGLE PHASING

• The line current increases by 1.5 times.
• If the relay setting is at 15-20% higher than actual operating current then the relay will take 4-6 minutes to trip.
• The motor (particularly smaller capacity motors upto 7.5 H.P.) cannot withstand this high current for such a long time and in most of the cases it burns out before the relay trips.
• Heavy short circuit current flows through the relays, contactors, cables etc.
• Under this condition when the relay, contactor trips, they produce sparks and some times bursts..
• This further damages the switchgear and in some of the cases may cause fire also.

Product Details: