Table of Contents
- 1 When we run the overexcited synchronous motor with no load it is known as?
- 2 What happens when synchronous motor is over excited?
- 3 When load on an over excited or under excited synchronous motor is increased rate of change of its armature current as compared with that of power factor is?
- 4 How a synchronous motor can be operated as a synchronous condenser?
When we run the overexcited synchronous motor with no load it is known as?
A synchronous motor running with no load will lead the current i.e. leading power factor like a capacitor. This synchronous motor running without load i.e. over-excited is synchronous condenser.
What happens when synchronous motor is over excited?
An over-excited synchronous motor draws leading current. Therefore, if the field of the synchronous motor is overexcited then its power factor will be leading. An over-excited synchronous motor running at no load is known as the synchronous capacitor or synchronous condenser.
When a synchronous motor is excited it behaves like a synchronous condenser?
Under excitation causes it to operate at a lagging power factor. When the motor is operated at no load with over-excitation, it takes a current that leads the voltage by nearly 90 degrees. Thus, it behaves like a capacitor and under such operating conditions, the synchronous motor is called a synchronous capacitor.
When load on an over excited or under excited synchronous motor is increased rate of change of its armature current as compared with that of power factor is?
V curve of synchronous motor: When the load on an over-excited or under excited synchronous motor is increased, the rate of change of its armature current as compared with that of the power factor is less and the same can be observed by using v curves as shown below.
How a synchronous motor can be operated as a synchronous condenser?
A synchronous condenser is operated in a borderline condition between a motor and a generator with no mechanical load to fulfill this function. It can compensate either a leading or lagging power factor, by absorbing or supplying reactive power to the line. This enhances the power line voltage regulation.
When the motor runs on no load then back emf is almost equal to applied voltage?
The back EMF can not be equal to the applied DC voltage. The motor draws armature current when it drives the mechanical load or even at no load operation. The back EMF (eb) can’t be equal to the applied voltage (V). If Ia is zero, the torue (T= flux*Ia) will be zero and the motor will not produce the torque.