Effect of voltage and frequency on motor performance characteristics

The following table summarises the effect of voltage and frequency on motor characteristics

Parameters	Voltage (%)
	120	110	90
Torque (Starting and Max. running)	Increase 44%	Increase 21%	Decrease 19%
Speed - Synchronous	No change	No change	No change
Speed - Full load	Increase 1.5%	Increase 1%	Increase 1.5%
Percentage slip	Decrease 30%	Decrease 17%	Decrease 23%
Efficiency - Full load	Small increase	Increase 0.5 to 1%	Decrease 2%
Efficiency - 3/4 load	Decrease 0.5-2%	Little change	Little change
Efficiency - Half load	Decrease 7-20%	Decrease 1-2%	Increase 1-2%
Power factor - Full load	Decrease 5-15%	Decrease 3%	Increase 1%
Power factor - 3/4 load	Decrease 10-30%	Decrease 4%	Increase 2-3%
Power factor - Half load	Decrease 15-40%	Decrease 5-6%	Increase 4-5%
Starting current	Increase 25%	Increase 10-12%	Decrease 10-12%
Full load current	Decrease 11%	Decrease 7%	Increase 11%
Temperature rise	Decrease 5-6° C	Decrease 3-4° C	Increase 6-7° C
Max. overload capacity	Increase 44%	Increase 21%	Decrease 19%
Magnetic noise	More significant increase	Slight increase	Slight decrease

Parameters	Frequency (%)
	105	95
Torque (Starting and Max. running)	Decrease 10%	Increase 11%
Speed - Synchronous	Increase 5%	Decrease 5%
Speed - Full load	Increase 5%	Decrease 5%
Percentage slip	Little change	Little change
Efficiency - Full load	Slight increase	Slight increase
Efficiency - 3/4 load	Slight increase	Slight increase
Efficiency - Half load	Slight increase	Slight increase
Power factor - Full load	Slight increase	Slight increase
Power factor - 3/4 load	Slight increase	Slight increase
Power factor - Half load	Slight increase	Slight increase
Starting current	Decrease 5-6%	Increase 5-6%
Full load current	Slight decrease	Slight increase
Temperature rise	Slight decrease	Slight decrease
Max. overload capacity	Slight decrease	Slight decrease
Magnetic noise	Slight decrease	Slight decrease