RATING AND HEATING OF MOTORS

Periodic Intermittent Duty

Periodic Intermittent Duty: The class of duty making use of the ability of electric motors to operate with overload is called Periodic Intermittent Duty. The load on the motor is a sequence of identical duty cycles as shown in Fig. 5.17. The drive motor is loaded at constant load for a period ton. At the […]

Short Time Intermittent Duty

Short Time Intermittent Duty: Another class of duty for normally occurring loads is Short Time Intermittent Duty in which the load requires a constant power for a short interval of time and rests for sufficiently longer time. When a motor is used for this purpose, duration of the load on the motor is less than […]

Continuous Duty Motor

Continuous Duty Motor: There are two types of Continuous Duty Motor — continuous duty at constant load and continuous duty with variable load cycle. In the former the load torque remains constant for a sufficiently longer period corresponding normally to a multiple of time constant of the drive motor. The drive motor is therefore loaded for […]

Electric Motor Cooling and Heating

Electric Motor Cooling and Heating: The geometry of an Electric Motor Cooling is too complex to predict accurately the heat flow and temperature distribution. This is a difficult task. A portion of the conductors of armature winding are embedded in slots and some portion is outside the iron material as overhang. The heating calculations are […]

Electric Motor Power Loss and Heating

Electric Motor Power Loss and Heating: An Electric Motor Power Loss and Heating occurring in its various parts such as copper losses occurring in armature and field and eddy currents in the magnetic material used as a core, and mechanical losses due to friction and windage. These unavoidable Electric Motor Power Loss cause localized heating […]

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