Speed control of dc shunt motor - motor control , Electrical Engineering

Speed Control of DC Shunt Motor

Vdc  the output of rectifying circuit which is  applied to the motor field  as shown  in figure  for armature voltage Vdc  is controlled by SCR  which  is series connected to armature winding of dc motor. FD  is freewheeling diode connected across the armature winding . Daic is  used  as firing  circuit  of SCR  which is  trigged  through  capacitor C.

Initially this  discharging capacitor C state charging  through  armature winding diode  D6 and variable  resistance R1  for each half cycle. When  this  capacitor voltage  is more  than the forward  break over  voltage  of diac VBO it gives  triggering  pulse  to the SCR  and SCR  gets  turned on which  completes  the armature  circuit.

At the end of the half  cycle capacitor C discharges through  diode D5 resistance R2  and field windings. At  this time  SCR  turns  off and FD provides a discharge path for  the energy stored in the inductance of the are armature winding. The  output  waveform  across armature of dc  shunt motor is  shown in figure  where  α is firing  angle and β is conducting angle.

When load is  fluctuating  the speed of  motor  fluctuates accordingly. For example  if the load  is increased motor  speed  goes  slow  down  which  will be  responsible to reduce the back emf Eb. this reduced back  emf increase the  voltage  across SCR  hence capacitor  charges more rapidly to turn on the SCR on somewhat earlier than the increase in load takes place. As a result the average dc voltage across the armature will change and speed of motor can control  accordingly. The controlled output  voltage is given by.

 

 

Posted Date: 4/3/2013 2:18:51 AM | Location : United States







Related Discussions:- Speed control of dc shunt motor - motor control , Assignment Help, Ask Question on Speed control of dc shunt motor - motor control , Get Answer, Expert's Help, Speed control of dc shunt motor - motor control Discussions

Write discussion on Speed control of dc shunt motor - motor control
Your posts are moderated
Related Questions
DC Load line

Describe the three main sources of power dissipation in CMOS logic. Hence calculate the power dissipated in a CMOS ASIC of 40,000 gates operating at a frequency of 133MHz with a s

if a resistor is present between 2 branches in such way that its polarities are different to compare with one another so how we choose polarity of that resistor

With the help of neat diagrams illustrate the construction and working of various elements used in hydro-electric power plant. Compare hydro-electric power plant with other type

ELECTRICAL STARTER MOTOR This usually consists of a heavy duty, compound wound, DC motor, which draws its electrical supply from an external source. The motor works in conjunc

Q. Consider the circuit shown in Figure in the time domain aswell as in the s-domain. Its transfer function V 2 (s)/V 1 (s) can be shown to be  which is a second-order bandpass tra

Q. For the circuit shown in Figure(a), determine the diode current and voltage and the power delivered by the voltage source. The diode characteristic is given in Figure.

Consider the circuit of Figure (a) with v S (t) = 10 cos ωt. Use the piecewise-linear model of the diode with a threshold voltage of 0.6 V and a forward resistance of 0.5  to dete

Q. What is meant by biasing transistor? The purpose of dc biasing of transistor is to obtain a certain dc collector current at a certain dc collector voltage. These values of c

how to compute the fourier series expansion of a rectangular pulse train