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

What do you understand by breakdown diodes, (a) Draw and illustrate the V-I...

(a) Draw and illustrate the V-I characteristics of PN junction diode. How the characteristics reflected with change in temperature? (b) Describe physically why a PN junction dio

Define hysteresis, Define Hysteresis Hysteresis is the 'lagging' effect...

Define Hysteresis Hysteresis is the 'lagging' effect of flux density B whenever there are changes in the magnetic field strength H. When an initially unmagnetized ferromagnetic

Data rates in pstns, Data rates in PSTNs: A voice channel in a PSTN is ...

Data rates in PSTNs: A voice channel in a PSTN is band limited with a nominal bandwidth of 3.1 kHz. A first-cut estimate of this can be attained from Nyquist's theorem that app

Illustratecommon base configuration, Q. IllustrateCommon base configuration...

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

Show the frequency response of rc coupled amplifier, Q. Show the Frequency ...

Q. Show the Frequency response of Rc Coupled Amplifier? 1. At low frequency i.e,less than 50 Hz reactance of Cc is going high hence same part of the signal will pass from one s

Calculate the magnetic flux in the core, Q. A toroid with a circular cross ...

Q. A toroid with a circular cross section is shown in Figure. It is made from cast steel with a relative permeability of 2500. The magnetic flux density in the core is 1.25 Tmeasur

Energy meter, Energy Meter 1. The energy meter is the cash register of...

Energy Meter 1. The energy meter is the cash register of the utility. Energy meters form a vital instrument of revenue realization for the Supply Utilities. Based on the meter

Basic definition of electromagnetism, Q. Basic definition of electromagneti...

Q. Basic definition of electromagnetism? A basic understanding of electromagnetism is essential to the study of electrical engineering because it is the key to the operation of

Sparking with electrical equipment, Sparking : In ordinary domestic situat...

Sparking : In ordinary domestic situations, small electrical sparks are usually not hazardous. In certain conditions which are frequently encountered in science labs, even the sma

Explain the different types of polarizations, Explain the different types o...

Explain the different types of polarizations. Polarizations are of three types. i. Electric polarization ii. Ionic polarization. iii. Dipolar polarization.

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