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

How an electroscope charged without contacting charged body, An electroscop...

An electroscope charged WITHOUT contacting a charged body is charged by: a) Induction b) Conduction c) Convection d) Insulation Ans: An electroscope char

Electrical Machines, Design a suitable double –layer lap winding for a 6-po...

Design a suitable double –layer lap winding for a 6-pole dc armature with 18 slots and two coil sides per slot. Give values of front-pitch, brack–pitch and commutator pitch. Draw t

Load stack pointer - stack operations , Load Stack Pointer This  inst...

Load Stack Pointer This  instruction loads the stack  pointer  register with the 16 - bit  data specified in the   instruction. The 16 - bit  data. When  stored in sp  registe

Microprocessor, Memory map of tpa in a personal computer and explain such o...

Memory map of tpa in a personal computer and explain such of the areas in brief

Oscilloscope probe compensation, Q.   what is oscilloscope probe compensati...

Q.   what is oscilloscope probe compensation and how is it adjusted?  What effects are noted when the compensation is not correctly adjustment? Direct Probe: This probe  is

Differentiate between heat transfer and thermodynamics, Briefly Explain ...

Briefly Explain i. Importance of thermal diffusivity. ii. Describe the laws governing Heat Transfer. iii. Differentiate between Heat Transfer and Thermodynamics iv. Des

Semiconductors, Why do potential barriers breaks when a breakdown voltage i...

Why do potential barriers breaks when a breakdown voltage is application to semiconductor

3-phase 180 degree mode vsi , 3-phase 180 0 mode VSI In 1800 mode VSI...

3-phase 180 0 mode VSI In 1800 mode VSI  each thyristor  conduct  for 1800 and two  thyristor  are fired  at 600 interval. For  example  if thyristor  T1  is fired at 00 then

Compute the real power inductive load, Q. A 60-Hz, 440-V, three-phase syste...

Q. A 60-Hz, 440-V, three-phase system feeds two balanced wye-connected loads in parallel. One load has a per-phase impedance of 8 + j3  and the other 4 - j1 . Compute the real po

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