Series connected motor, Electrical Engineering

Assignment Help:

In this case, the armature is connected in series with the field coils. Thus
Ia  = If = I

 

1627_Series connected motor.png

 

 

911_Series connected motor 1.png

 

NB. At starting, the back emf is zero (because the motor is initially stationary) and hence the current is very large (limited only by the field and armature resistances). Hence the starting torque will be extremely large and if no load is applied (so that the torque requirement is small) the motor will accelerate rapidly to dangerously high speeds. A series connected motor must be started with a mechanical load attached to prevent the speed at start up rising to damaging speeds.

Note that saturation of the magnetic material in the motor can occur at high currents and then the flux generated by the field coils becomes independent of current. This causes the characteristics to become similar to that of a shunt wound motor that also has an approximately constant field flux.

336_Series connected motor 2.png

 

The series motor gives a high starting torque (proportional to 1/I2 ), 2.5 to 3 times the full load (rated) torque) but it falls rapidly as the speed increases. Applications: heavy duty, with intermittent starting under conditions where a mechanical load is always present - e.g. traction, cranes, hoists. etc


The speed of a series wound motor may be controlled by the addition of a resistor in parallel with the field coil. This diverts
some of the current away from the field coil, reducing the field strength and hence the back emf at a given speed. The additional resistor is called a 'diverter'. The speed must increase to compensate this reduction in back emf. . Hence a reduction in the diverter resistance reduces the field strength and increases the speed of the motor.


Related Discussions:- Series connected motor

Estimate the network resistance, When three resistors R1, R2 and R3 are con...

When three resistors R1, R2 and R3 are connected in parallel as shown in the diagram. For these resistors the equivalent resistance is given by: a. Derive a rule to

DECISIEN FEEDBACK, Do you provide me matlab code for comparison the perfor...

Do you provide me matlab code for comparison the performance of decision feedback equalizer over MLSE

How linear sweep voltage is generated, Q. With a suitable block circuit, sh...

Q. With a suitable block circuit, show how linear sweep voltage is generated ? The above figure shows a basic sweep waveform generator. The switching action of the switch

Compute number of electrons and find their average velocity, Q. A wire with...

Q. A wire with n = 10 30 electrons/m 3 has an area of cross section A = 1mm 2 and carries a current i = 50 mA. Compute the number of electrons that pass a given point in 1 s, an

D.c machine, What are the advantages of distributing windings in an alterna...

What are the advantages of distributing windings in an alternator?

Gate source cut off voltage, Q. Gate source cut off voltage? It is the ...

Q. Gate source cut off voltage? It is the gate source voltage where the channel is completely cut off and the drain current becomes zero.It is interesting to note that the valu

Determine the voltages, Question: a) For the circuit shown in figure ...

Question: a) For the circuit shown in figure (i) Determine the voltages across R1 and R2 and (ii) Determine the current which flows across R1 and R2. Both D1 and D2 a

Determine the output voltage, Q. In a differentiating circuit, R=10 kW,and ...

Q. In a differentiating circuit, R=10 kW,and C=2.2μF.If the input voltage goes from 0V to 10 V at a constant rate in 0.4s, determine the output voltage. Solution: e 0 =

Explain how ccitt standards help in building the base band, Q. Discuss FDM ...

Q. Discuss FDM and illustrate how CCITT stndards help in building the base band? Ans: Frequency Division Multiplexing: It is the process of combining numerous informatio

Flexible manufacturing systems, (a) What are the elements of Flexible Manuf...

(a) What are the elements of Flexible Manufacturing Systems? (b) What are the basic types of workstations typically found in an FMS. Describe them briefly?

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