Answer / pravesh

the bsic difference between a.c. and d.c. motor is that in
a.c. motor there is no commutator while in d.c. motor there
is commutator in d.c. motor .

Answer / sath

DC machines can be classified as self-excited, separately
excited, permanent magnet (PM), and brushless.
AC machines can be classified as induction, wound rotor,
and synchronous.
Self-excited machines can be further classified as shunt,
series, and compound. Compound machines can be further
classified as cumulative and differential. Cumulative and
differential machines can be further classified as long
shunt and short shunt. As you can see, there are a variety
of electrical configurations for a DC machine.
Induction motors can be further classified as 3-phase and
single-phase. A 3-phase induction motor can be further
classified as delta wound or wye wound. Single-phase
motors can be further classified as split phase (Fig. 3),
capacitor start, capacitor start/capacitor run, shaded
pole, repulsion start, and universal. As you can see, there
are several varieties of AC motors.
Common terms you will hear discussed with DC motors include
commutator, brushes, counter electromotive force (EMF),
torque, speed regulation, and speed-torque characteristic
curves.
Common terms you will hear discussed with AC motors include
frequency, synchronous speed, and slip.
In d.c. motor speed is depended on field strength of the
machine.
In a.c. motor speed is depended on frequency of the machine.
In d.c. motor torque is depended on armature current and
field flex.
In a.c. motor torque is depended on slip.

Answer / sivasamy k

DC motor :

This is working in conduction principle...

But...Ac Motor :

This is working in induction principle....

Answer / bharath

The basic and important difference b/w the AC & DC MOTORS:
The DC motor operates on the conduction principle.
The AC motor operates on the induction principle.

Answer / buddhadev dewasi (imps college

AC stands for alternate current, DC stands for direct
current. Alternate current alternates between positive and
negative and the number of times it does per minute is
called cycles. Depending on the number of poles in the
motor, the speed is constant. Where as in a DC drive, the
speed control is simple, by introducing a resistance.

Answer / nikhil

I think they would be asking to differentiate physically AC
and DC motor. Same question was asked to me also.

Answer:- DC motor have brushes so heat is generated in them
hence in a dc motor slots will be provided for the
ventilation and better cooling purpose.
Also on a AC motor there will be three wires going in
(either single or three phase) for electrical connection
whereas it is not the case with the DC motors.

Answer / amir

Ac motor have less torque than dc motor. in other word says
that ac motor speed is less than dc motor.

Answer / r.sharma

in the dc moror field as well as armature winding is
provided but in ac motor short circuited armature is
placed. we give the supply to the field and armature in dc
motor but in ac we provide supply only to the field or
armature.depends upon the supply giving to the ac motor it
is classified into 2 types one is rotating field system
with stationary armatue another one is rotating armature
with stationary field system.

Answer / venkatesh k g

1.DC motors are direct current motors while ac motors are alternating current
motors.
2.DC motors generally characterize a continual and standard current flow
while AC motors are used in variant situations irrespective of the quality of the
current flow.
3. DC motors are single phase motors whereas AC motors are both 1 and 3
phase.
4.DC motors are self starting whereas AC motors require effective starting
equipment.
5.Direct current or DC electric motors work for situations where speed needs to
be controlled.

Answer / rama krishna

Direct current or DC electric motors work for situations
where speed needs to be controlled. DC motors have a stable
and continuous current. DC motors were the first and
earliest motors used. They were found, however, to not be as
good at producing power over long lengths. Electric
companies found using DC motors to generate electric did not
work because the power was lost as the electric was
transmitted. Brush DC motors use rings that conduct the
current and form the magnetic drive that powers the rotor.
Brushless DC motors use a switch to produce the magnetic
drive that powers the rotor. Direct current motors are often
found in appliances around the home.

Alternating current or AC electric motors are used
differently based on what type of AC motor it is. Single
phase AC motors are known as general purpose motors. They
work well in many different situations. These AC motors work
great for systems that are hard to start because they need a
lot of power up front. Three phase, also called polyphase,
AC motors are usually found in industrial settings. These
motors also have high starting power built transmit lower
levels of overall power. AC power gets its name from the
fact that it alternates in power. The amount of power given
off by an AC motor is determined by the amount of power
needed to operate the system.

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