Shunt dc motor, Electrical Engineering

Assignment Help:

Shunt DC motor

In this arrangement, the armature and field coils are connected in parallel (the motor is called 'shunt connected').

 

1845_shunt DC motor.png

 

Analysis

With reference to the diagram above,

1226_shunt DC motor  1.png

Normally If is a approxmetely constant and Ra is very small (so V>>Ia.Ra).Therefore the motor speed is approximately constant for a given supply voltage, V. The speed may be controlled by reducing the field If  by increasing the field resistor Rf   is reduced and the so Φ speed  increases.

 

  • If  is approximately constant in this motor configuration, determined by the supply voltage and the resistance of the field coils. 
  • Since Ra is very small, V>>Ia.Ra.Hence, although Ichanges significantly with change in motor speed, (and hence also the torque), the motor speed need only change very slightly to cause a large change of armature current and torque produced. This means that the torque can overcome any imposed mechanical load  with very little change of motor speed (so shunt motor has approximately  onstant speed vs load characteristics)
  • Since the armature winding resistance is small, measures must be taken to limit the surge of armature current when it is first
    switched on (i.e. increase the supply slowly to allow the motor to gain speed before full supply voltage is applied). 
  • Methods for controlling the speed are:

    i)    vary the resistance of the field circuit, Rf . Increasing Rf  a increases the speed.

    ii)   change the applied voltage. Increasing V increases the speed.

    iii)  change Ra by means of an extra (small) resistance in the armature circuit. Increasing Ra  reduces the speed.

    iv)  increasing the mechanical load reduces the speed only slightly. (Approx. constant speed vs load characteristics)

    The preferred method of speed control atconstant supply voltage is method (i)because the field current is low compared to the armature current, and a resistance added in series with the field windings results in less power being wasted.

 


Related Discussions:- Shunt dc motor

How is segmentation implemented in typical microprocessors, How is segmenta...

How is segmentation implemented in typical microprocessors? The first advantage is as memory segmentation has is that only 16 bit registers are needed both to store segment bas

Electric discharge machining process, Describe the following in Electric di...

Describe the following in Electric discharge Machining Process(EDM). a) Dielectric fluids & their characteristic b) Electrodo feed Control c) Flushing System

Calculation of receiving end voltage, Calculation of Receiving End Voltage ...

Calculation of Receiving End Voltage Consider the simple circuit shown in Figure. To find the voltage V 2 using analytical method:   P = I V 2 = 0.5      ..... (1)

Commercial losses in electrical systems, Commercial Losses in Electrical Sy...

Commercial Losses in Electrical Systems Commercial losses are caused by pilferage, theft, defective meters, and errors in meter reading and in estimating un-metered supply of

#titleclipper diode.., Ask quedisadvantages stion #Minimum 100 words accept...

Ask quedisadvantages stion #Minimum 100 words accepted#

EDC, why biasing of bjt transistor is essential?

why biasing of bjt transistor is essential?

Show process of power transmission and distribution, Q. Show Process of Pow...

Q. Show Process of Power transmission and distribution? The structure of a power system can be divided into generation (G), transmission, (T), and distribution (D) facilities,

Subtract registers and borrow from accumulator, Subtract Registers and Borr...

Subtract Registers and Borrow from Accumulator The  contents of the  register  and borrow  flag  are subtracted from   the contents of the accumulator and the  result is  store

Inverter, single phase voltage source inverter complete circuit

single phase voltage source inverter complete circuit

Cpu based exchange, CPU Based Exchange:   In centralized control, all contr...

CPU Based Exchange:   In centralized control, all control equipment is replaced by a single processor which should be quite powerful. It should be capable of processing 10 to 100 c

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd