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Universal motor can run on
AC
DC
Either AC or DC
None of above
Either AC or DC
A universal motor is a special type of motor designed to operate efficiently on both single-phase AC and DC supply ┬╖ It is essentially a modified DC series motor whose direction of torque remains unidirectional regardless of the polarity of the applied voltage.
A universal motor is a special type of motor designed to operate efficiently on both single-phase AC and DC supply ┬╖ It is essentially a modified DC series motor whose direction of torque remains unidirectional regardless of the polarity of the applied voltage.
TтИЭI2 тАФ Developed torque in terms of current
EbтАЛ=VтИТI(RaтАЛ+RfтАЛ) тАФ Back EMF on DC supply
EbтАЛ=V2тИТ(IX)2тАЛтИТI(RaтАЛ+RfтАЛ) тАФ Back EMF on AC supply
When powered by a DC supply, it operates as a standard DC series motor where torque is proportional to the square of the armature current (TтИЭI2) ┬╖ Under AC supply, both the armature current and main field flux reverse direction simultaneously during every half-cycle, keeping the developed electromagnetic torque positive and unidirectional (TтИЭIrms2тАЛ).
Operates at high speeds (typically 3,000 to 20,000 RPM) on both AC and DC.
The stator core and frame are fully laminated to reduce eddy current losses when operated on AC supply.
Has non-linear high starting torque characteristics typical of series-wound motors.
High power-to-weight ratio and compact size.
High starting torque and high speed operation.
Dual supply versatility (can plug into AC mains or DC power source).
High wear and tear due to mechanical commutator and carbon brushes.
Produces electromagnetic interference (EMI) and radio frequency noise.
Noisy operation at very high speeds.
Domestic appliances like vacuum cleaners, food mixers, and blenders.
Portable power tools like electric drills, portable saws, and angle grinders.
For a given applied voltage, the motor runs at a lower speed on AC than on DC due to reactance voltage drop (IXLтАЛ) in the windings.
Option A and Option B are partially correct, but Option C is the most comprehensive and accurate answer.
C is correct тАФ Universal motor is designed with laminated magnetic circuits to operate on both AC and DC power supplies.
Remember that both field and armature windings are connected in series; modifying the magnetic circuit by laminating the stator allows AC operation without excessive iron losses.