I'm studying from Wildi's textbook on electrical machines and I came across the following on starting a synchronous motor:
"To limit the voltage induced in the rotor windings during the starting of the machine and to improve the starting torque , we either short-circut the slip-rings or connect them to an auxiliary resistor during the starting period".
I get the part about limiting the voltage but since the current will be less how is the torque greater than before?
Best Answer
This information is not related to synchronous motor but rather to an induction motor with wound rotor and slip rings.
Adding a resistance in rotor circuit affects the torque vs. speed characteristics, so you can get higher starting torque. Note that this doesn't increase the available torque, it only shifts the max. torque point to the zero speed.