# Find rotor stator loss in a three-phase delta-connected induction motor

I'm trying to work out stator input power of a three-phase delta-connected induction motor.

I have the equation Stator Input Power (P1), where P1 = Pm + rotor copper loss + rotor stator loss.

I have Pm and rotor copper loss but I don't know how to find the equation for rotor stator loss. If anyone could help out it would be greatly appreciated.

• The "electrical" and "engineering" tags are pretty much useless. If you want people who are interested in induction motors to notice your question, use the "induction-motor" tag.
– user80875
Jun 4, 2019 at 2:01
• Thanks very much for the tip! Jun 4, 2019 at 14:50

For an induction motor, the motor input power is equal to the mechanical power developed in the rotor plus the stator copper loss plus the rotor copper loss plus the iron loss.

The rotor copper loss is the mechanical power developed in the rotor multiplied by per-unit slip. Per-unit slip is (synchronous speed minus rotor speed) divided by synchronous speed.

• I don't have iron loss given in my equation I have rotor copper loss and Pm. My equation is for Output power with friction losses. Where Pm= 2 x pi x nr and then did Pm-mechanical losses. Jun 4, 2019 at 14:48
• For rotor copper loss I first worked out Ir, then loss per phase and finally total copper loss. Jun 4, 2019 at 14:49
• How would I work out rotor stator loss? Jun 4, 2019 at 14:50
• I have never seen the term "rotor stator loss." The only losses in my books are the ones I listed plus mechanical losses and "stray losses." Stray losses are essentially losses that can not be determined.
– user80875
Jun 5, 2019 at 3:04
• How would you then work out input power then because I'm trying to work out input and output power so I can calculate the mechanical efficiency of my motor at full load running speed? would input power be mechanical power + mechanical losses. Mechanical losses was the only value I was given. Jun 5, 2019 at 17:37