Performance of dc motors experiment The result getting is not 100% legit

1. THEORY
Electrodynamometer measures torque. Electrodynamometer is an electrical break, in
which the breaking force can be varied electrically. It consists of a stator and a squirrel-cage
rotor. The stator is free to turn; however, its motion is restricted by a spring. A DC current is
applied to the stator winding generating a magnetic field that passes through the stator and
the rotor. The strength of the stator magnetic field can be increased or decreased by the
front panel control. This strength determines the degree at which the revolving rotor can
cause the stator to change position on its axis. As the rotor turns (being belt-coupled to the
driving motor), a voltage is induced in the rotor bars, and the resulting eddy currents react
with the magnetic field causing the stator to turn. The electrodynamometer is calibrated in
Newton-meters (Nm).
Shunt motor. The field coil and the armature windings are connected in shunt or parallel
across the power source. The armature winding consists of relatively few turns of heavy
gauge wire. The voltage across two windings is the same but the armature draws
considerably more current than the field coil. Torque is caused by the interaction of the
current caring armature winding with the magnetic field produced by the field coil. If the DC
line voltage is constant, the armature voltage and the field strength will be constant. The
speed regulation is quite good; the speed is a function of armature current and is not
precisely constant. As the armature rotates within the magnetic field, an EMF is induced in
its wining. This EMF is in the direction opposite to the source EMF and is called the counter
EMF (CEMF), which varies with rotational speed. Finally, the current flow through the
armature winding is a result of the difference between source EMF and CEMF. When the
load increases, the motor tends to slow down and less CEMF is induced, which in turn
increases the armature current providing more torque for the increased load.
Motor speed is increased by inserting resistance into the field coil circuit, which weakens the
magnetic field. Therefore, the speed can be increased from “basic” or full-load, full-field
value to some maximum speed set by the electrical and mechanical limitations of the motor.
The power difference between the motor input and the output is dissipated in form of heat
and constitutes to the losses of the machine. These losses increase with load, since the
motor heats up as it delivers mechanical power.

2. Series motor. The field coil and armature windings are connected in series to the power
source. The field coil is wound with a few turns of heavy gauge wire. In this motor, the
magnetic field is produced by the current flowing through the armature winding; with the
result that the magnetic field is weak when the motor load is light (the armature winding
draws a minimum current). The magnetic field is strong when the load is heavy (the
armature
winding draws a maximum current). The armature voltage is nearly equal to the PS line
voltage (just as in the shunt wound motor if we neglect the small drop in the series field).
Consequently, the speed of the series wound motor is entirely determined by the load
current. The speed is low at heavy loads, and very high at no load. In fact, many series
motors will, if operated at no load, run so fast that they destroy themselves. The high
forces, associated with high speeds, cause the rotor to fly apart, often with disastrous
results to people and property nearby. The torque of any DC motor depends upon the
product of the armature current and the magnetic field. For the series wound motor this
relationship implies that the torque will be very large for high armature currents, such as
occur during start-up. The series wound motor is, therefore, well adapted to start large
heavy-inertia loads, and is particularly useful as a drive motor in electric buses, trains and
heavy duty traction applications. Compared to the shunt motor, the series DC motor has
high starting torque and poor speed regulation

3. Cumulative compound motor combines the operating characteristics of the series and
shunt motors. The high torque capability of the series wound DC motor is some what
compromised by its tendency to overspeed at light loads. This disadvantage can be
overcome by adding a shunt field, connected in such a way as to aid the series field. The
motor then becomes a cumulative compound machine. Again, in special applications where
DC motors are used in conjunction with flywheels, the constant speed characteristic of the
shunt wound motor is not entirely satisfactory since it does not permit the flywheel to give up
its kinetic energy by an appropriate drop in motor speed. This kind of application (which is
found in punch-press work), requires a motor with a "drooping" speed characteristic, that is,
the motor speed should drop significantly with an increase in load. The cumulative
compound wound DC motor is well adapted for this type of work. The series field can also be
connected so that it produces a magnetic field opposing that of the shunt field. This
produces a differential compound motor, which has very limited application, principally
because it tends to be unstable. As the load increases, the armature current increases
increasing the strength of the series field. Since it acts in opposition to the shunt winding, the
total flux is reduced, with the result that the speed increases. An increase in speed will
generally further increase the load, which raises the speed and could cause the motor to run
away. The shunt field winding places a practical limit on maximum no-load speed and it may
be operated at no load. The shunt coil also provides for better speed regulation than a series
motor; while the series coil provides for greater starting torque than a shunt motor. After the
motor is started, the series coil is shorted out for better speed regulation. Cumulative
compound motors are used where fairly constant speed under irregular loading is needed.

4. PART A : DC SHUNT MOTOR LOAD CHARACTERISTICS
OBJECTIVE
1. To construct the direct current (dc) shunt motor circuit.
2. To determine the load characteristics of dc shunt motor.
3. To interpret the load characteristics of a dc shunt motor.
LIST OF REQUIREMENTS
Equipment
(Experimental panel system unit 1000 W)
1. Variable dc power supply
2. Brake unit
3. Control unit servo brake
4. Display panel
5. Coupling collar
6. Shaft and cover
7. DC shunt motor
8. Connection mask (3125111)
9. Voltmeter (1 unit)
10. Ammeter (2 units)

5. PROCEDURE
1) The connection was performed according to the Figure 2.3.
2) The ammeter 1 connect to 10A, ammeter2 connect to 1A and voltmeter connect to
1000V.
3) Before this experiment started, the operating elements of the control unit servo
brake was adjusted as in below table 2.1 :
Table 2.1
Operating switch on position M const/T
Switch “Torque range” position 10Nm
Switch “Speed range” position 6000
4) The power supply was switched on.The Dc voltage was adjusted to 220V.A constant
voltage of 220V was maintained throught the experiment.The direction of the motor
was checked and turn in clockwise direction.
5) The “store/start” button was pressed twice. The torque load was adjusted from 0Nm
to 2Nm. The data was recorded in the Table2.2.
6) Then the calculation had be made and the result also recorded in Table 2.2.

6. I) Total output power,P2=(Torque X Speed)/9.55
II) Power input,P1=Voltage X Total Current
III) Efficiency =P2/P1
IV) Total Current=Current A + Current E
7) N,IA,P2 and Ƞ was graphically as a function in Figure 2.4
PART B: DC SERIES MOTOR LOAD CHARACTERISTICS
OBJECTIVES
1. To construct the DC series motor circuit.
2. To determine the load characteristics of a DC series motor.
3. To interpret the load characteristics of a DC series motor
LIST OF REQUIREMENTS
Equipment
(Experimental panel system 1000W)
1. Voltage supply
2. Brake unit
3. Control unit servo brake
4. Display panel
5. Coupling collar
6. Shaft and cover
7. DC series motor
8. Connection mask(3125113)

7. 9. Voltmeter(1unit)
10. Ammeter(1unit)
PROCEDURES
1) Firstly, connect all the wire according to the diagram that shown in Figure 2.7
Note the maximum range: ammeter1:10A, and voltmeter:1000V
2) After that, adjust the operating elements of the control unit servo brake was adjusted
as in table 2.3 and then,the control unit was switched on

8. Operating Switch on Position M const/T const
Switch “Torque range” position 10 Nm
Switch “Speed range” position 6000
Table 2.3
3) The power supply was switched on.The Dc voltage was adjusted to 110V.A constant
voltage of 110V was maintained throught the experiment.The direction of the motor
was checked and turn in clockwise direction.
4) The “store/start” button was pressed twice. The torque load was adjusted from 0Nm
to 1Nm. The data was recorded in the Table 2.4.
5) Then the calculation had be made and the result also recorded in table 2.4
i) Total output power,P2=(Torque X Speed)/9.55
ii) Power input,P1=Voltage X Current
iii) Efficiency =P2/P1
6) N,IA,P2 and Ƞ was graphically as a function in Figure 2.8
PART C: DC COMPOUND MOTOR LOAD CHARACTERISTICS
OBJECTIVES
1. To construct the DC series motor circuit.
2. To determine the load characteristics of a DC compound motor.
3. To interpret the load characteristics of a DC compound motor
LIST OF REQUIREMENTS
Equipment
(Experimental panel system 1000W)
1. Voltage supply
2. Brake unit
3. Control unit servo brake

9. 4. Display panel
5. Coupling collar
6. Shaft and cover
7. DC series motor
8. Connection mask(3125113)
9. Voltmeter(1unit)
10. Ammeter(1unit)

10. PROCEDURES
1) The connection was performed according to the Figure 2.11.
2) The ammeter 1 connect to 10A, ammeter2 connect to 1A and voltmeter connect to
1000V.
3) Before this experiment started, the operating elements of the control unit servo
brake was adjusted as in below table 2.5 :
Table 2.5
Operating switch on position M const/T
Switch “Torque range” position 10Nm
Switch “Speed range” position 6000
4) The power supply was switched on.The Dc voltage was adjusted to 220V.A constant
voltage of 220V was maintained throught the experiment.The direction of the motor
was checked and turn in clockwise direction.
5) The “store/start” button was pressed twice. The torque load was adjusted from 0Nm
to 2Nm. The data was recorded in the Table2.2.
6) Then the calculation had be made and the result also recorded in Table 2.6.
V) Total output power,P2=(Torque X Speed)/9.55
VI) Power input,P1=Voltage X Total Current
VII) Efficiency =P2/P1

11. VIII) Total Current=Current A + Current E
7) N,IA,P2 and Ƞ was graphically as a function in Figure 2.12.
RESULT
Part A
Table 2.2
Measured Value
Torque ζ(Nm) 0.0 0.5 1.0 1.5 2.0
Current IA(A) 0.8 1.2 1.8 2.4 3.0
Current IE(A) 0.44 0.44 0.44 0.44 0.44
Speed N(rpm) 2907 2867 2815 2765 2698
Calculated Value
Power P! (W) 272.8 360.8 492.8 624.8 756.8
Power P2 (W) 0.0 150.1 294.8 434.3 553.7
Efficiency η(%) 0.0 0.41 0.60 0.70 0.73
Total currentIcct(A) 1.24 1.64 2.24 2.84 3.44
Part B
Measured Value
Torque Nm 0.0 0.2 0.4 0.6 0.8 1.0
Current, IA (A) 2.4 2.7 3.0 3.4 3.7 3.9
Speed, N (rpm) 4100 3670 3050 2660 2290 2110
Calculated Value
Power,P1 (W) 264 297 330 374 407 429
Power,P2 (W) 0.0 76.86 63.87 55.71 47.96 44.19
Efficiency (%) 0.0 0.26 0.20 0.15 0.12 0.10
Part C
Measured Value
Torque ζ(Nm) 0.0 0.5 1.0 1.5 2.0
Current IA(A) 0.7 1.2 1.7 2.3 2.8
Current IE(A) 0.43 0.43 0.43 0.43 0.42
Speed N(rpm) 2810 2750 2660 2570 2478
Calculated Value
Power P! (W) 268.6 358.6 468.6 600.6 710.6
Power P2 (W) 0.0 144.0 278.5 403.7 519.0

12. Efficiency η(%) 0.0 0.40 0.59 0.67 0.73

13. REFERENCES
Matthew N.O sadiku, Charles K. Alexander(2009), Fundamental Of Electric Circuit 4(ed),
Singapore:Mc Graw Hill.
Rusnani Ariffin, Mohd Aminuddin Murad(2009), Laboratory Manual : Electrical Engineering
Laboratory 1 EEE230, Shah Alam: University Publication Centre (UPENA) Universiti
Teknologi Mara.
http://www.engineersedge.com/motors/dc
http://www.micromotcontrols.com/htmls/Motor%20characteristics.html
http://electriciantraining.tpub.com/14177/css/14177_59.htm

14. FACULTY OF ELETRICAL ENGINEERING
UNIVERSITY TEKNOLOGI MARA
ELECTRICAL ENGINEERING LABORATORY 1
(EEE230)
EXPERIMENT 2
PERFORMANCE OF DC MOTORS

15. TABLE OF CONTENT
CONTENT PAGE
ABSTRACT
Theory
OBJECTIVES
LIST OF REQUIREMENTS
EXPERIMENT PROCEDURE
EXPERIMENT RESULT
DISCUSSION
CONCLUSION
REFERENCE
APPENDICES