LONG shunt + SHORT shunt = COMPOUND motor

1. “
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DC Compound Motor
Presentation Topic
Group Member
Sahib ullah BEE F14 207
Zain Aslam BEE F14 270
M Faisal Khan BEE F14 291

2. Layout
• Introduction
• Circuit Diagram
• Working
• Speed Control Methodology
• Applications
• Limitations
• References
• Q/A

3. Introduction
• Electrical Motor: it is machine which convert Electrical energy into Mechanical energy
• AC Motor: Motor that run on alternating current (AC)
• DC Motor: Motor that run on Direct current (DC)

4. DC Compound Motor
• Dc compound motor is the combination of series motor and shunt motor
• It has a series field winding that is connected in series with the armature and
shunt field winding that is in parallel with the armature
• The combination of series and shunt winding
Allow motor to have a torque characteristics of the series motor
 And the regulated speed characteristics of shunt motor

5. Circuit Diagram

6. Types Of DC Compound Motor
• The compound wound DC motor can further be subdivided into 2 major
types on the basis of its field winding connection with respect to the
armature winding and they are:
Long Shunt Compound Wound DC Motor
Short Shunt Compound Wound DC Motor

7. Long Shunt Compound Wound DC Motor
In long shunt compound wound DC motor:
• The shunt field winding is connected in parallel across the series
combination of both the armature and series field coil
• Current Equation
I 𝑡𝑜𝑡𝑎𝑙 = 𝐼𝑠ℎ + 𝐼𝑠𝑒
• Voltage Equation
E= 𝐸 𝑏 + 𝐼 𝑎(𝑅 𝑎 + 𝑅 𝑠𝑒)

8. Short Shunt Compound Wound DC Motor
• The shunt field winding is connected in parallel across the armature winding only.
And series field coil is exposed to the entire supply current, before being split up
into armature and shunt field current
• Current equation
𝐼𝑡𝑜𝑡𝑎𝑙 = 𝐼 𝑎 + 𝐼𝑠ℎ
• Voltage equation:
E=𝐸 𝑏 + 𝐼 𝑎 𝑅 𝑎 + 𝐼𝑠𝑒 𝑅 𝑠𝑒 ∴ 𝐼𝑠𝑒 = 𝐼𝑡𝑜𝑡𝑎𝑙
E=𝐸 𝑏 + 𝐼 𝑎 𝑅 𝑎 + 𝐼𝑡𝑜𝑡𝑎𝑙 𝑅 𝑠𝑒

9. Sub classification
• Depending on the polarity of the connection of shunt field winding, series
field winding, and armature:
Cumulative Compound Motor
Differential Compound Motor

10. Cumulative Compounding of DC Motor
• A compound wound DC motor is said to be cumulatively compounded
when the shunt field flux produced by the shunt winding assists or enhances
the effect of main field flux, produced by the series winding.
∅ 𝑡𝑜𝑡𝑎𝑙 = ∅ 𝑠𝑒𝑟𝑖𝑒𝑠 + ∅ 𝑠ℎ𝑢𝑛𝑡

11. Differential Compounding of DC Motor
• A compound wound DC motor is said to be differentially compounded
when the flux due to the shunt field winding diminishes the effect of the
main series winding.
∅ 𝑡𝑜𝑡𝑎𝑙 = ∅ 𝑠𝑒𝑟𝑖𝑒𝑠 − ∅ 𝑠ℎ𝑢𝑛𝑡
• This particular trait is not really desirable, and hence does not find much of a
practical application.

12. Working Of Cumulative Compound Motor
• Most common DC motor:
Provides high starting torque and good speed regulation at high speed
Can start even with large load and then operate smoothly when the load varies
slightly
• Recall that:
Shunt motor can provide smooth operation at full speed, but can't start with large
load attached
Series motor can start with heavy load, but it speed can’t be controlled

13. Working Of Differential Compound Motor
• Connection in slightly different manner
Two magnetic field oppose each other in this case
The motor will tend to over speed when the load is reduced just like series
motor
Speed also drop more then the cumulative compound motor when the load
increases at full RPM

14. Speed Controlled Methodology
1. Terminal voltage of the armature V.
2. External resistance in armature circuit R.
3. Flux per pole φ.
• The first two cases involve change that affects armature circuit and the third
one involves change in magnetic field Therefore speed control of DC motor
is classified as
1. Armature control method
2. Field control method

15. Applications Cumulative Compound Motor
• These motor have high starting torque
• They can be operated even at no loads as they run at a moderately high speed at no
load
• Hence cumulative compound motor are used for following applications
1. Elevators 6. Business Machine
2. Rolling mills 7. Machine tools
3. Punches 8. Agitators
4. Shears 9. Mixers
5. planers 10. Presses

16. Applications Differential Compound Motor
• The speed of these motor increases with the increases in the load which lead
to an unstable operation
• Therefore we can’t use this motor for any practical applications

17. Summary
• The dc compound motor is used where a compromise is needed between the
series and the shunt motor.
• The compound motor has better speed characteristic than the series motor
and better torque characteristics than the shunt motor.
• The motor can be connected so that the shunt field and the series fields are
in the same direction. This is the cumulative connection.

18. Limitations
The speed of a DC compound motor can be easily controlled. It is enough
if we change just the voltage supplied to it.
The differential type is not use in any event.
Protected from any physical damage at starting.

19. Comparison B/w Shunt, Series and Compound
• Shunt Motors: Constant speed” motor (speed regulation is very good). Adjustable speed,
medium starting torque.
• Applications: centrifugal pump, machine tools, blowers fans, reciprocating pumps, etc.
• Series Motors: Variable speed motor which changes speed drastically from one load
condition to another. It has a high starting torque.
• Applications: hoists, electric trains, conveyors, elevators, electric cars.
• Compound motors: Variable speed motors. It has a high starting torque and the no-load
speed is controllable unlike in series motors.
• Applications: Rolling mills, sudden temporary loads, heavy machine tools, punches, e t c

20. Video adding

21. References
• Google
• Wikipedia
• Slideshare.net
• Electric machines fundamental by champion