Split-phase induction motor is used in most of fractional horsepower technique. Two stator windings one-to begin with, and one to run. Running windings are made in two or four rolls in the series, depending on the desired speed of the engine. These coil voltage (there is a current flowing in them) in the period of work of the motor.
Everything winding have the same number of turns. They, as a rule, turns a few degrees from under the windings. Smaller caliber wires used in the starting winding than in the running winding. However, it has more turns than the running winding. Counter EMF (electromotive force) in a larger number of revolutions of the causes of the current build more slowly in the winding. Thus, the magnetic effect will be more electric degrees behind the running winding. This creates a torque on the rotor, to do his will start to rotate in the right direction. Starting winding switched off when the engine is about 75% of its running speed.
No windings on the rotor, but the magnetism builds up around the rotor bars.
Some rotors have heavy copper tyres fitted into slots in laminated iron. The ends of these copper bars braze-welding of heavy copper rings at each end. This completes the induced (magnetism) of the circuit. Such a mechanism is often called sqinrrel-cage. (The term electrical degrees means that the maximum influence of magnetic field on the rotor of a few degrees away from the (back) influence of the magnetic field in the stator.)
The most common reasons for the failure of the motor are overload and overheating. An overload condition may result in a molten conductors or burned motor insulation of conductors. Considerable damage can also occur if the compressor and/or " engine overheating". This overheating can happen without the current becomes excessive.
It is important to protect the motor from both current overload and overheating. Therefore, you must use both current and temperature-sensitive devices. This will be an open scheme before there is damage to the engine. The following devices are used to protect the engine:
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