Automatic Voltage Controller Voltage Stabilization Range 390/400 Volts Relay Setting Reduction 15-20% Lower Setting Current Draw Reduction 15-20% Lesser

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 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 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, contractors, cable etc.
• Under this condition when the relay, contractor trips, they produce sparks and some times burst.
• This further damages the switch gear and in some of the cases may cause fire also.

with the installation of the stabilizer and maintaining 390/400 volts, the motor will operate smoothly drawing 15-20% lesser current and correspondingly the relay setting can be reduced by 15-20% In case single phasing occurs, the relay will trip in 40-50 seconds. The motor can withstand the high current fot this period and will be safe. Also, the relays, contractors, switchgears, etc. incorporated with the motor will be safe.