- #1
fonz
- 151
- 5
One of the characteristics of full voltage starting (DOL) of an asynchronous induction motor is that full load current is exceeded quite significantly when the motor is started in this way.
So what is happening is that when line voltage is applied, the difference in synchronous and rotor speed (slip) is maximum causing the motor to produce torque equal to the voltage * current (assuming no losses).
If you take away the rotor and consider just one of the motors windings as a pure inductor. Applying line voltage to the inductor will cause no current to flow initially because it is behaving as a pure inductor i.e. resisting the change in current and shifting the current and voltage out of phase.
So in the motor application, something is happening that is causing a current to flow initially. Can somebody explain this?
Thanks
So what is happening is that when line voltage is applied, the difference in synchronous and rotor speed (slip) is maximum causing the motor to produce torque equal to the voltage * current (assuming no losses).
If you take away the rotor and consider just one of the motors windings as a pure inductor. Applying line voltage to the inductor will cause no current to flow initially because it is behaving as a pure inductor i.e. resisting the change in current and shifting the current and voltage out of phase.
So in the motor application, something is happening that is causing a current to flow initially. Can somebody explain this?
Thanks