In AC series motor, power factor is low because of __________.

AC series motor

AC series motors are also known as the modified DC series motors as their construction is very similar to that of the DC series motor.

After making some modifications to its construction, the AC series motor can be made to work on both AC and DC. 

However, a series motor that is mainly designed for DC operation, and works on single-phase AC supply suffers from the following drawbacks. The efficiency becomes low because of hysteresis and eddy current losses. The power factor is low due to the large reactance of the field and the armature windings.

Construction of AC series Motor

The construction of the AC series motor is identical to the DC series motor except for some changes as given follows:

• The magnetic circuit must be laminated.
• The field circuit must be designed for much lower reactance than the DC motor field in order to reduce the reactance voltage drop of the field and improve the power factor.
• Distributed compensation winding is required to minimize the reactance of armature winding.
• The compensating winding may be connected in series with the field and armature winding called conductively compensated and conductively compensation required armature which is designed to operate on AC and DC voltage.
• If compensation winding short-circuited to itself and received excitation voltage by transformer action called inductively coupled.