23 Facts About AC motor

An AC motor is an electric motor driven by an alternating current .

The induction AC motor always relies on a small difference in speed between the stator rotating magnetic field and the rotor shaft speed called slip to induce rotor current in the rotor AC winding.

The synchronous AC motor produces its rated torque at exactly synchronous speed.

The brushless wound-rotor doubly fed synchronous AC motor system has an independently excited rotor winding that does not rely on the principles of slip-induction of current.

The brushless wound-rotor doubly fed AC motor is a synchronous AC motor that can function exactly at the supply frequency or sub to super multiple of the supply frequency.

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The first person to conceive of a rotating magnetic field was Walter Baily, who gave a workable demonstration of his battery-operated polyphase AC motor aided by a commutator on 28 June 1879, to the Physical Society of London.

Speed of the AC motor is determined primarily by the frequency of the AC supply and the number of poles in the stator winding, according to the relation:.

Actual RPM for an induction AC motor will be less than this calculated synchronous speed by an amount known as slip, that increases with the torque produced.

The speed in this type of AC motor has traditionally been altered by having additional sets of coils or poles in the AC motor that can be switched on and off to change the speed of magnetic field rotation.

The AC motor takes its name from the shape of its rotor "windings"- a ring at either end of the rotor, with bars connecting the rings running the length of the rotor.

An unloaded squirrel-cage AC motor at rated no-load speed will consume electrical power only to maintain rotor speed against friction and resistance losses.

Furthermore, a stalled squirrel-cage AC motor will consume current limited only by circuit resistance as it attempts to start.

Where a large inrush current and high starting torque can be permitted, the AC motor can be started across the line, by applying full line voltage to the terminals .

Where it is necessary to limit the starting inrush current, the AC motor is started at reduced voltage using either series inductors, an autotransformer, thyristors, or other devices.

Typical two-phase AC servo-AC motor has a squirrel cage rotor and a field consisting of two windings:.

Common single-phase AC motor is the shaded-pole AC motor and is used in devices requiring low starting torque, such as electric fans, small pumps, or small household appliances.

Motor would not start with the terminals open; connecting the common to one other made the AC motor run one way, and connecting common to the other made it run the other way.

An unusual, adjustable-speed, low-torque shaded-pole AC motor could be found in traffic-light and advertising-lighting controllers.

Split-phase AC motor has a secondary startup winding that is 90 electrical degrees to the main winding, always centered directly between the poles of the main winding, and connected to the main winding by a set of electrical contacts.

Resistance start AC motor is a split-phase induction AC motor with a starter inserted in series with the startup winding, creating reactance.

The Hammond organ tone generator used a non-self-starting synchronous AC motor, and had an auxiliary conventional shaded-pole starting AC motor.

Universal AC motor is a design that can operate on either AC or DC power.

High starting torque and low inertia of the conical rotor brake AC motor has proven to be ideal for the demands of high cycle dynamic drives in applications since the AC motor was invented, designed and introduced over 50 years ago.