Search Results for: motor

Types of Motor Enclosures: In order to protect machines against the ingress of dirt and dust or larger foreign bodies like spanners, vermin etc. into it, it is desirable that some suitable enclosure be provided. But the enclosure provided for this protection will interfere with the free entry of cool air into the machine with […]

Electrical Braking of Polyphase Induction Motors: Electrical Braking of Polyphase Induction Motors which consists of different types, namely, Plugging (or Counter-Current Braking) Dynamic (or Rheostatic) Braking Regenerative Braking 1. Plugging (or Counter-Current Braking) Plugging can be achieved in an induction motor merely by reversing two of the three phases which causes a reversal of the

Speed Control of AC Commutator Motors: Speed control of ac commutator motors can be had either by varying the applied voltage or by movement of the brushes round the commutator. The former method makes use of tappings on a transformer or, occasionally, a series resistor or inductor so as to provide variation of voltage in

Speed Control of Single Phase Induction Motor: The stator winding of a speed control of single phase induction motor can easily be arranged to give two synchronous speeds, one double the other. In Fig. 1.88 (a) the connections for two pole motors are shown in which two coils A and B have been connected in

Speed Control of Three Phase Induction Motor: The problem of speed control of three phase induction motor in particular is of great practical importance. In a number of industries motors must satisfy very strict speed characteristic requirements, both with respect to the range and smoothness of control and also with respect to economical operation. From

Constant Current System for Speed Control of DC Motor: For certain services, where there is a possibility of the motors being stalled such as with excavators, ship’s windlasses etc. the constant current system is advantageous and is used. In this system a dc generator delivering a constant current by means of a special exciter under

Booster Speed Control of DC Motor: A booster in series with the armature of the main motor may be employed for varying the voltage across the driving motor. The booster speed control is a sepa­rately excited dc generator, which adds or subtracts the volt­age in the motor feeder. The adding (boosting) or subtracting (bucking) depends

Armature Resistance Control Method of DC Motor: In this armature resistance control method of speed control, reduced speeds are obtained by inserting resistance in the armature circuit. It may be employed with series, shunt and compound wound motors. For the last two types, the series resistance is connected between the shunt field and armature, not

Paralleling Field Coils for DC Series Motor: In this Paralleling Field Coils method, used in fan motors, several speeds can be obtained by regrouping of field coils, as illustrated in Fig. 1.72 (c). In case of dc shunt motors the flux can be varied by inserting a variable resistance in series with the field winding

Tapped Field Control for DC Series Motors: Tapped field control for dc series motors is another method of increasing the speed by reducing the flux and it is accomplished by reducing the number of turns of the field winding through which the current flows. In this method of speed control of dc series motors a