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

Compute the fourier transform, Compute the Fourier Transform of the followi...

Compute the Fourier Transform of the following function: f(x) = exp( - x 2 /(2σ 2 )) cos (2πx/k) where σ and k are constants. What is the minimum sampling rate required

Determine the equivalent resistance of circuit, Determine the equivalent re...

Determine the equivalent resistance of circuit: Determine the equivalent resistance of network across the source terminals and find the current drawn from the source.

Uses of fet, Uses of FET IGBTs (Insulated-gate bipolar transistor) se...

Uses of FET IGBTs (Insulated-gate bipolar transistor) see application in switching internal combustion engine ignition coils, in which fast switching and voltage blocking cap

Calculate the pu voltage and line to line voltage, The one line diagram of ...

The one line diagram of a simple power system is shown below. The data of the system are given in the table below. (a) Draw the impedance diagram of the system and mark all impe

Automatic irrigation system on running solar power b, how to upload the pro...

how to upload the program on proteus soft ware by using personal computer?

Calculate the amplitude of the dc component, A periodic voltage consists of...

A periodic voltage consists of sinusoidal pulses having an amplitude of 150 V (SEE DIAGRAM BELOW). Use Fourier Series Expansion to calculate: 1.       the amplitude of the DC co

Show the familiar electric sources, Q. Show the familiar electric sources? ...

Q. Show the familiar electric sources? Batteries and ac outlets are the familiar electric sources. These are voltage sources.An ideal voltage source is one whose terminal volta

Consequent effects on the real and reactive power losses, Q. Consider an up...

Q. Consider an upgrade of a three-phase transmission system in which the operating line-to-line voltage is doubled, and the phase or line currents are reduced to one-half the previ

Explain common emitter configuration, Q. Explain Common emitter configurati...

Q. Explain Common emitter configuration? Common emitter configuration: In this circuit the emitter is common to both input and the output.Such a configuration is also known as

Motor., if load is removed so which motor will run fast? series or shunt?

if load is removed so which motor will run fast? series or shunt?

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