- المجال: Electrical equipment
- Number of terms: 4774
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A load (flywheel, fan, etc.) which tends to cause the motor shaft to continue to rotate after the power has been removed (stored kinetic energy). If this continued rotation cannot be tolerated, some mechanical or electrical braking means must normally be applied .
Industry:Electrical equipment
A material which tends to resist the flow of electric current (paper, glass, etc.) In a motor the insulation serves two basic functions:
1. Separates the various electrical components from one another.
2. It protects itself and the electrical components from attack of contaminants and other destructive forces.
Industry:Electrical equipment
Five specialised elements are used, which together constitute the motor's INSULATION SYSTEM. The following are typical in an AC motor:
1. TURN-TO-TURN INSULATION between separate wires in each coil. (Usually enamel on random wound coils of smaller motors - tape on "form wound" coils of larger motors.
2. PHASE-TO-PHASE INSULATION between adjacent coils in different phase groups. (A separate sheet material on smaller motors - not required on form wound coils because the tape also performs this function.
3. PHASE-TO-GROUND INSULATION between windings as a whole and the "ground" or metal part of the motor. (A sheet material, such as the liner used in stator slots, provides both di-electric and mechanical protection.
4. SLOT WEDGE to hold conductors firmly in the slot.
5. IMPREGNATION to bind all the other components together and fill in the air spaces. (A total impregnation, applied in a fluid form and hardened, provides protection against contaminants.
Industry:Electrical equipment
Since there are various ambient temperature conditions a motor might see and different temperature ranges within which motors run and insulation is sensitive to temperature; motor insulation is classified by the temperature ranges at which it can operate for a sustained period of time.
When a motor insulation class is labelled on the nameplate the total insulation system is capable of sustained operation at the above temperature.
Industry:Electrical equipment
A requirement of service that demands operation for alternate intervals of (1 ) load and no load; or (2) load and rest; or (3) load, no load and rest; such alternate intervals being definitely specified.
Industry:Electrical equipment
An auxiliary set of field poles carrying armature current to reduce the field flux caused by armature reaction in a DC motor.
Industry:Electrical equipment
An electronic device that converts fixed frequency and fixed voltages to variable frequency and voltage. Enables the user to electrically vary the speed of an AC motor.
Industry:Electrical equipment
A device used for levelling the positioning of a motor. These devices are adjustable screws fitting on the base or motor frame. Also a device for removing endshields from a motor assembly.
Industry:Electrical equipment
Since the watt is a relatively small unit of power, the kilowatt (kw), 1,000 watts, is used where larger units of power measurements are desirable.
Industry:Electrical equipment
The steel portion of the rotor and stator cores made up of a series of thin laminations (sheets) which are stacked and fastened together by cleats, rivets or welds. Laminations are used instead of a solid piece in order to reduce eddy-current losses.
Industry:Electrical equipment
