Low Voltage Effects on Ac Motors Essay Example
Low Voltage Effects on AC Motors
A drop in voltage will result in a proportionate increase in current. If the current exceeds the nameplate rating and is not corrected, this can result in damage to the motor from overheating
Nameplate Rating
An electric motor will have a nameplate rating for both voltage and amperage. When a load is on a motor, the motor must draw a fixed amount of power. The required power is about equal to volts times amps. Should the voltage fall below the nameplate rating, the amperage will increase. This can result in increased heat that will shorten the motor's life, according to Motorsanddrives.com. Torque
The motor is subject to several kinds of torque. The starting or start-up torque is the amount present when the motor is stationary and power is applied. The pull-up torque is the minimum amount necessary for the motor during the starting sequence.
Effects of Low Voltage on Torque
A reduced amount of voltage will reduce the amount of torque. This can result in difficulty for start loads. A reduction of voltage to 80 percent would result in a torque value of only 64 percent. In light loads, a reduction in voltage may actually be preferable because it will result in increased efficiency.
Even a small voltage unbalance will result in large current unbalance during the running of motor by a factor of 6 times.
• Negative phase sequence components will lead to heating of motor
• Negative phase sequence currents leads to reduction in motor output torque.
• Motor is forced to run at higher slip leading to increased rotor loss and reduced efficiency.
• Electricity boards should look in to this phenomenon seriously where irrigation pump sets suffer the voltage imbalance, even 1% loss of efficiency for the country like India would mean a great loss. 5 HP irrigation pump sets with a quantity of 6 Lakh approximate, the loss of power would be 22MW and annual wastage of Rs.47.5 millions (At 3 Rs/unit,
A drop in voltage will result in a proportionate increase in current. If the current exceeds the nameplate rating and is not corrected, this can result in damage to the motor from overheating
Nameplate Rating
An electric motor will have a nameplate rating for both voltage and amperage. When a load is on a motor, the motor must draw a fixed amount of power. The required power is about equal to volts times amps. Should the voltage fall below the nameplate rating, the amperage will increase. This can result in increased heat that will shorten the motor's life, according to Motorsanddrives.com. Torque
The motor is subject to several kinds of torque. The starting or start-up torque is the amount present when the motor is stationary and power is applied. The pull-up torque is the minimum amount necessary for the motor during the starting sequence.
Effects of Low Voltage on Torque
A reduced amount of voltage will reduce the amount of torque. This can result in difficulty for start loads. A reduction of voltage to 80 percent would result in a torque value of only 64 percent. In light loads, a reduction in voltage may actually be preferable because it will result in increased efficiency.
Even a small voltage unbalance will result in large current unbalance during the running of motor by a factor of 6 times.
• Negative phase sequence components will lead to heating of motor
• Negative phase sequence currents leads to reduction in motor output torque.
• Motor is forced to run at higher slip leading to increased rotor loss and reduced efficiency.
• Electricity boards should look in to this phenomenon seriously where irrigation pump sets suffer the voltage imbalance, even 1% loss of efficiency for the country like India would mean a great loss. 5 HP irrigation pump sets with a quantity of 6 Lakh approximate, the loss of power would be 22MW and annual wastage of Rs.47.5 millions (At 3 Rs/unit,