Tuesday, November 9, 2010

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

No comments:

Post a Comment