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The poles can be varied at a ratio of 1:2 and thus the speed can be varied at 2:1. [7] [8] [9] Normally, the electrical configuration of windings is varied from a delta connection (Δ) to a double star connection (YY) configuration in order to change the speed of the motor for constant torque applications, such as the hoists in cranes.
[2] A DC motor consists of two parts: a rotor and a stator. [3] The stator consists of field windings while the rotor (also called the armature) consists of an armature winding. [4] When both the armature and the field windings are excited by a DC supply, current flows through the windings and a magnetic flux proportional to the current is ...
The rotating magnetic field is the key principle in the operation of induction machines.The induction motor consists of a stator and rotor.In the stator a group of fixed windings are so arranged that a two phase current, for example, produces a magnetic field which rotates at an angular velocity determined by the frequency of the alternating current.
For example; a single-phase motor with 3 north and 3 south poles, having 6 poles per phase, is a 6-pole motor. A three-phase motor with 18 north and 18 south poles, having 6 poles per phase, is also a 6-pole motor. This industry standard method of counting poles results in the same synchronous speed for a given frequency regardless of polarity.
A DC armature of a miniature motor (or generator) An example of a triple-T armature A partially-constructed DC armature, showing the (incomplete) windings In electrical engineering, the armature is the winding (or set of windings) of an electric machine which carries alternating current. [1]
Reactive filtration impedes the high frequency harmonic content but has little effect on the fundamental frequency that determines motor speed. The result is an output to the motor that is closer to an ideal sine wave. In the past, VFDs that have a capacity greater than 3 hp (2.2 kW) were costly, thus making the rotary phase converter (RPC) an ...
A compensation winding in a DC shunt motor is a winding in the field pole face plate that carries armature current to reduce stator field distortion.Its purpose is to reduce brush arcing and erosion in DC motors that are operated with weak fields, variable heavy loads or reversing operation such as steel-mill motors.
To determine the number of coil groups per phase in a 3-phase motor, count the number of coils, divide by the number of phases, which is 3. The coils may span several slots in the stator core, making it tedious to count them. For a 3-phase motor, if you count a total of 12 coil groups, it has 4 magnetic poles.