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

Image retreval and face recognization technique, block diagram of eigen fac...

block diagram of eigen face,Viola & Jones Method,Bio-ID,RWTH-i6 Groups of People Database

Solar steam power generator, This project is about another particular appli...

This project is about another particular application of a particular embodiment of the patent: A Long Stroke Steam Engine using Solar Generated Steam. The machine elements such as

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?

Generation and control of electron beam, Illustration the basic working pri...

Illustration the basic working principle, process parameters, economics, safety precautions and applications of plasma Arc Machining process(PAM) Discuss Electron Beam Machining

Explain the fixed bias circuit, Q. Explain the fixed bias circuit?     ...

Q. Explain the fixed bias circuit?           The Fig refers to the common emitter collector characteristics and the ac and dc load lines.The Fig shows the points Q 1 and Q 2

Find the total current and total resistance, For the circuit in figure, fin...

For the circuit in figure, find: a)  Total resistance b)  Total current c)  Current flow through resistor 6Ω and 4Ω

Calculate the starting torque, A squirrel-cage inductionmotor operates at a...

A squirrel-cage inductionmotor operates at a slip of 0.05 at full load. The rotor current at starting is five times the rotor current at full load. Neglecting stator resistance and

Explain analog communication system, Q. Explain Analog communication system...

Q. Explain Analog communication system? Analog signals in an analog communication system can be transmitted directly via carrier modulation over the communication channel and d

Field effect and bipolar junction transistor, Q. What is the difference bet...

Q. What is the difference between field effect transistor and the bipolar junction transistor? The important points of the comparison between the field effect transistor ands t

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