What happens when a synchronous motor is connected to an infinite bus while operating on a leading power factor?
Right Answer is:
Excitation voltage will be more than the supply voltage.
Synchronous Motor Connected to Infinite Busbar
The bus bars whose frequency and the phase magnitude of potential differences are not affected by changes in the condition of anyone machine connected to it are called infinite bus bars.
A network having zero impedance and infinite rotational inertia is also termed as Infinite bus-bars.
An overexcited synchronous motor draws current at the leading power factor. If d.c. field excitation of a synchronous motor is such that the back emf Eb is greater than applied voltage V, then the motor is said to be over excited.
An overexcited synchronous motor acts as a power factor correction device and is also known as a synchronous condenser. The variation of armature current and power factor as a function of field current is plotted to give a better insight.
We can state that an over-excited synchronous motor draws a leading power factor current from the mains. The synchronous motor, therefore, when over-excited, in addition to driving some load, will work as a capacitor or condenser. A capacitor draws a leading power factor current. An over-excited synchronous motor draws the leading power factor current from the mains.
An over-excited synchronous motor is also called a synchronous condenser. Synchronous motors are used as constant-speed drive motors. Over-excited synchronous motors are used to improve the power factor of electrical loads in industries. Generally, the motor is run on load, and by overexcitation, the system power factor is also improved.