gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
150925-1349 EDT
Attached is a graph of speed vs torque for a wound-rotor induction motor with rotor resistance being a parameter. From "Alternating-Current Machinery", Bailey and Gault, McGraw-Hill, 1951, p 248. P 242 has a plot of speed-torque vs applied voltage, not shown here.
The curve is monotonic with a sufficiently high rotor circuit resistance. Thus, any speed from 0 to near 100% is obtainable by control of the torque load. Or speed changes with torque load, a lighter load has a higher speed.
A fan blade produces a mechanical load that increases with speed. For a fixed high resistance rotor the RPM of the motor will increase with increasing motor voltage. Load power goes up and input power increases as voltage goes up.
.
Attached is a graph of speed vs torque for a wound-rotor induction motor with rotor resistance being a parameter. From "Alternating-Current Machinery", Bailey and Gault, McGraw-Hill, 1951, p 248. P 242 has a plot of speed-torque vs applied voltage, not shown here.
The curve is monotonic with a sufficiently high rotor circuit resistance. Thus, any speed from 0 to near 100% is obtainable by control of the torque load. Or speed changes with torque load, a lighter load has a higher speed.
A fan blade produces a mechanical load that increases with speed. For a fixed high resistance rotor the RPM of the motor will increase with increasing motor voltage. Load power goes up and input power increases as voltage goes up.
.