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DC Machines
Citation preview
Course"EEM 2 DC Machines"
Photo: Siemens AG
SH5002-1B Version 2.1
Author: M.Germeroth
Lucas-Nülle GmbH · Siemensstraße 2 · D-50170 Kerpen (Sindorf) Tel.: +49 2273 567-0
www.lucas-nuelle.de
Some animations require that a Flash player is installed. Should your system not have a Flash player installed,
you can download the latest version at any time from Macromedia.
Copyright © 2005 LUCAS-NÜLLE GmbH. All rights reserved.
LUCAS-NÜLLE Lehr- und Messgeräte GmbH
Siemensstraße 2 D-50170 Kerpen
EEM2 DC machines
Training objectives 1Equipment for 300 W Classic Series 2Information page "Alternative Equipment" 3Safety 5DC shunt-wound motors 7
Connection and starting 9Rotation reversal 17Speed control 23Load characteristic 31
DC shunt-wound generators, separately excited 37Voltage control (field-control range) 39Voltage polarity 45Load characteristic 49
DC shunt-wound generators, self-excited 55Rotation direction and polarity 57Load characteristic 61
DC series-wound motors 67Connection and starting 69Rotation reversal 75Load characteristic 81
DC compound-wound motors 87Load characteristics for various compound ratios 89
Copyright 99
EEM2 DC machines
EEM2 DC machines Training objectives
In this course you will acquire practical knowledge regarding the topic of DC machines. Experiment-based investigations of series-wound, shunt-wound and compound-wound machines are at the focal point of this course and explore such aspects as how the machines function, respond and operate.
Training contents
Motors, generators Series-wound, shunt-wound and compound-wound windings Measurement of armature current, exciter current and voltage Nominal data, rating plate Speed adjustment Rotation reversal Magnetic field weakening Armature and field resistors Power measurement with and without load
Prerequisites
Fundamentals of electrical machines Fundamentals of electrical engineering How to handle measuring instruments
Welcome to the DC machines course. The team from LUCAS-NÜLLE wishes you lots of fun and success in completing the course topics and conducting the experiments. The following pages provide you with an overview of the course contents and the materials and equipment required.
1
EEM2 DC machines Equipment for 300 W Classic Series
*Alternative equipment to the universal load SO3212-6W
SO3636-6V Servo drive/servo brake 0.3 kW 1 SE2662-2A Coupling sleeve 300 W 1 SE2662-2B Coupling guard 300 W 1 SE2672-3D DC multifunction machine 300 W 1 SO3212-6W Universal load for 300 W machines 1 SO3212-6B Starter for DC motor* 1 SO3212-5F Field regulator for DC motor* 1 SO3212-6M Load resistor for generator experiments* 1 SO3212-5H Field regulator for generator experiments* 1 SO3212-5U Power supply for electrical machines 1
SO5127-1ZAnalog/digital multimeter, wattmeter and power factor meter
2
SO5148-1F Set of 47 safety connecting leads 4 mm 1 SO5126-9X Safety connection plugs, 19/4 mm 15SO5126-9Z Safety connection plugs, 19/4 mm, with tap 5
2
EEM2 DC machines Information page "Alternative Equipment"
Universal load (SO3212-6W) for DC motors (connection example: "DC shunt-wound motor")
Starter (SO3212-6B) and field regulator (SO3212-5F) for DC motors (connection example: "DC shunt-wound motor")
3
EEM2 DC machines Information page "Alternative Equipment"
Load resistor (SO3212-6M) and field regulator (SO3212-5H) for DC generators (Connection example: "DC shunt-wound generator")
4
EEM2 DC machines Safety
Basic safety instructions
In all experiments using mains voltages high, life-threatening voltages arise. For that reason use only safety measurement leads and make sure that there are no short-circuits.
It is imperative that all of the devices, which are provided with an earth or where earthing is possible, must be earthed. This is particularly the case for the frequency converter being used.
Always be very careful to check the wiring of the application modules and only switch on the mains voltage after a check has been completed. Whenever possible use a robust current monitoring instrument in the circuit.
Always use shaft-end guards and coupling guards as protection against contact with rotating motor parts
All locally applicable stipulations and standards governing how electrical equipment is handled must be complied with.
5
EEM2 DC machines Safety
General instructions on handling the equipment
Check that the knurled screws at the base of the motor and the coupling sleeves (power grip) on the motor shaft are all securely fastened.
Use shaft and coupling guards. Any prolonged running of the machines when operating under high loads
can subject the machines to excessive heating. The extreme case of the machine being prevented from rotating entirely
may only arise briefly. All of the machines are equipped with a thermal circuit-breaker, which
triggers when the maximum permissible operating temperature is exceeded. These switching contacts are accessible on the terminal board and must always be connected to the corresponding connection sockets of the mains supply and control unit.
All measurements have been recorded using conventional measuring instruments (primarily class 1.5) at the standard mains voltage (230/400V +5% -10% 50Hz) using standard production machines. Experience suggests that measurements will lie within the tolerance range of +/-15% with respect to the specified measurement. For more information on this please refer to VDE0530.
6
EEM2 DC machines DC shunt-wound motors
DC shunt-wound motors
Over the next few pages you will perform the following exercises pertaining to "DC shunt-wound motors":
Connection and starting Reversing rotation direction Speed control Load characteristics
7
EEM2 DC machines DC shunt-wound motors
8
EEM2 DC machines DC shunt-wound motors
Enter the nominal data for the DC machine
Match the winding designations to the windings
Training content: "Connection and starting"
Identify the terminal connections of the motor and operate the motor as a shunt-wound motor
Read the nominal data of the motor based on the rating plate Connect the motor to the starter Be familiar with how the starter works Operate the motor with the brake Subject the motor to a load Measure armature voltage and current
UA= ____V
IA= ____A
UE= ____V
IE= ____mA
n= ____rpm
A1/A2 __
B1/B2 __
C1/C2 __
E1/E2 __
D1/D2 __
F1/F2 __
9
EEM2 DC machines DC shunt-wound motors
Assembly instructions: "Connection and starting"
Note: setting of the DC power supply can only be performed when the motor is connected.
More detailed information on the brake can be found in the corresponding online documentation
Assemble the circuits as specified in the following circuit diagram and set-up instructions
Include an ammeter and voltmeter in the armature circuit Switch on the brake too. This does not yet subject the motor to any
load
10
EEM2 DC machines DC shunt-wound motors
Circuit diagram for DC shunt-wound motor
"Connection and starting"
11
EEM2 DC machines DC shunt-wound motors
Set-up for DC shunt-wound motor
"Connection and starting"
Put the shunt-wound motor into operation
Required settings:
Starter: minimum value (0 Ω) DC power supply unit: 220V Multimeter measuring method: arithmetic mean
Experiment procedure:
Put the motor into operation and observe its operating response
12
EEM2 DC machines DC shunt-wound motors
The motor demonstrates the following response:
Measure the armature current
Required settings:
Brake mode: "Torque Control"
Experiment procedure:
Apply the brake to slow the motor down to nominal speed In the process of braking measure the armature current
Make sure that the brake is not applied so hard that the motor comes to a halt
What is the magnitude of the armature current?
The motor rotates at a higher speed than the nominal speed
The rotation direction is clockwise
The rotation direction is anti-clockwise
The switch-on current is higher than the nominal current
The motor rotates at nominal speed
The current increases with increasing speed
More than one answer may be correct
The armature current corresponds approximately to the nominal current
The armature current is considerably higher than the nominal current
The armature current is considerably smaller than the nominal current
13
EEM2 DC machines DC shunt-wound motors
Record a load characteristic
Required settings:
Starter: maximum value ( Note: 0.3 kW class ~ 47 Ω; 1 kW class ~ 16 Ω) After starting the motor the starter is set back to 0 Ω.
Experiment procedure:
Gradually increase the motor's load step-by-step until 1.5 times (0.3 kW) or 1x (1 kW) the nominal current and then complete the table
M/Nm n/(1/min) I/A U/V
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5M/Nm
0
500
1000
1500
2000
2500
3000
n/m
in¯¹
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
I/A
0
50
100
150
200
250
300
U/V
14
EEM2 DC machines DC shunt-wound motors
Which of the following statements apply to the load characteristic?
What is the function of the starter?
The armature voltage is considerably reduced when the torque is increased
The armature current increases linearly with the torque
The speed severely drops off once the nominal torque is reached
The armature voltage remains practically constant
The speed remains practically constant (± 3%) in the range of the nominal torque
The speed increases at higher torques
More than one answer may be correct
The starter is primarily used for speed control
The starter restricts the switch-on current
The starter protects the motor from overload during standard operation
15
EEM2 DC machines DC shunt-wound motors
16
EEM2 DC machines DC shunt-wound motors
Definition of rotation direction If you look at the drive shaft end of the DC shunt-wound machine from the perspective of the working machine (in our case the brake), the rotating direction is positive when it is clockwise. If the motor has two workable shaft ends, then it is the shaft end opposite the cooling vents, collector or slip-rings that is the shaft end which defines the rotation direction.
Training content: "Rotation reversal"
Identify the difference between clockwise and anti-clockwise rotation
Put the motor into operation in both rotation directions
17
EEM2 DC machines DC shunt-wound motors
Assembly instructions: "Rotation Reversal"
Circuit diagram for DC shunt-wound motor
"Rotation Reversal"
Assemble the circuit as specified in the following circuit diagram and set-
up instructions. Include an ammeter and voltmeter in the the armature circuit. Switch on the brake. This does not yet subject the motor to any load.
18
EEM2 DC machines DC shunt-wound motors
Set-up for DC shunt-wound motor
"Rotation Reversal"
Rotation reversal
Required settings:
Starter: minimum value (0 Ω) DC power supply: 220V
Experiment procedure:
Switch on the motor and observe how it responds
Note: setting of the DC power supply can only be performed when the motor is connected.
19
EEM2 DC machines DC shunt-wound motors
What is the motor's direction of rotation?
The motor rotates clockwise
The motor rotates anti-clockwise
20
EEM2 DC machines DC shunt-wound motors
Switch the motor off and modify the circuit as shown by changing the polarity of the exciter coil
Turn the motor back on and observe its response
Circuit diagram for DC shunt-wound motor
"Rotation reversal" (reversed rotation direction)
What is the motor's direction of rotation now?
The motor rotates clockwise
The motor rotates anti-clockwise
21
EEM2 DC machines DC shunt-wound motors
22
EEM2 DC machines DC shunt-wound motors
Assembly instructions: "Speed Control"
Note: setting of the DC power supply unit can only be performed when the motor is connected.
More detailed information on the brake can be found in the corresponding online documentation
Training content: "Speed Control"
Put the DC motor into operation using the field regulator Investigate speed control by modifying the armature current power Investigate operation in the field weakening range
Assemble the circuits as specified in the circuit diagram and set-up
instructions below. Include an ammeter and voltmeter in the armature circuit . Include an ammeter in the exciter circuit. Switch on the brake. This does not yet subject the motor to any load.
23
EEM2 DC machines DC shunt-wound motors
Circuit diagram for DC shunt-wound motor
"Speed control"
24
EEM2 DC machines DC shunt-wound motors
Set-up for DC shunt-wound motor "Speed control"
Record characteristics "Ia and "n" as a function of "Ua
Required settings:
Adjustable DC power supply (armature circuit voltage): 220V DC power supply unit (exciter circuit voltage): 210V Field regulator: minimum value (0 Ω) Brake mode: "Torque Control"
Experiment procedure:
Reduce the armature voltage in 3 stages via the adjustable DC power supply (220/190/160V)
At the same time measure the variables Iaand n and enter the measured values into the table
25
EEM2 DC machines DC shunt-wound motors
Record the characteristic of n" as a function of "M" using the "ActiveDrive/ActiveServo" software
Required setting:
Brake: Industrial series: "PC Mode" Classic series: "PC Mode"
Field regulator: minimum value (0 Ω) Adjustable DC power supply unit (armature voltage): 220/190/160V DC power supply unit (exciter circuit voltage): 210V
Ua/V n/(1/min) Ia/A220 2188.0190
160
150 160 170 180 190 200 210 220 230 240Ua/V
0
300
600
900
1200
1500
1800
2100
2400
2700
3000
n/(
1/m
in)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
Ia/A
26
EEM2 DC machines DC shunt-wound motors
Experiment procedure:
Start the "ActiveDrive/ActiveServo" software In the menu select Setting -> Operating mode -> Torque control The motor should be subjected to a load equivalent to its nominal torque Label the diagram as given in the placeholder Record a total of three load characteristics for the three specified armature
circuit voltages After completing the measurement export the completed diagram with all three
characteristics and copy it into the appropriate space below Compute the nominal torque of the motor as given by the following equation:
Placeholder for characteristics n(M), Ua=220/190/160V
Record the characteristics of "If" and "n" as a function of Rf
Required settings:
Brake mode: "Torque Control" Field regulator: minimum value (0 Ω) DC power supply unit: (armature & exciter circuit) 220/210V
27
EEM2 DC machines DC shunt-wound motors
Experiment procedure:
Switch on the DC power supply Vary the value Rf of the field regulator in 3 steps to reach the speed specified
in the table ( Note: 0.3 KW class ~ 2,2 kΩ; 1 KW class ~ 680 Ω) For each setting measure If and transfer the measured values into the table
Record the characteristic "n" as a function of "M" using the "ActiveDrive/ÁctiveServo" software
Required setting:
Brake: Industrial series: "PC Mode" Classic series: "PC Mode"
Field regulator: minimum value (0 Ω) DC power supply unit: (armature & exciter circuit) 220/210V
n(1/min) If/mA2300.02600.03000.0
2300 2400 2500 2600 2700 2800 2900 3000n/(1/min)
0
30
60
90
120
150
180
210
240
270
300
If/m
A
28
EEM2 DC machines DC shunt-wound motors
Experiment procedure:
Start the "ActiveDrive/ActiveServo" software The motor should be subjected to a load up to its nominal torque Label the diagram as appropriate in the placeholder below One after another 3 characteristic curves are recorded for 3 field regulator
settings (Rf), each one at the respective speeds 2.300 min-1, 2.600 min-1 and 3000 min-1 (rpm) ( Note: 0.3 KW class ~ 2.2 kΩ; 1 KW class ~ 680 Ω)
After completing the measurement export the graph with all 3 characteristics and copy it into the placeholder below
Placeholder for the graph n(M), 2300 min-1/2600 min-1/3000 min-1
Which statements are true of the speed variation?
A reduction of the armature voltage leads to a drop in speed
A reduction of the exciter current leads to a drop in speed
An increase of the armature voltage leads to a drop in speed
A decrease of exciter current leads to an increase in speed
More than one answer may be correct
29
EEM2 DC machines DC shunt-wound motors
30
EEM2 DC machines DC shunt-wound motors
Setup diagram: "Load Characteristic"
Note: setting of the DC power supply can only be carried out when the motor is connected More detailed information on the brake and the software used can be found in the appropriate online documentation
Training content: "Load characteristic"
Record the motor's load characteristic Calculate the nominal torque Determine the highest degree of efficiency Recognise how the motor responds to loads
Assemble the circuit as specified in the following circuit diagram and set-
up instructions Include an ammeter and voltmeter in the armature/exciter circuit Switch the brake on too. This does not yet subject the motor to any load
31
EEM2 DC machines DC shunt-wound motors
Circuit diagram for DC shunt-wound motor
"Load characteristic"
32
EEM2 DC machines DC shunt-wound motors
Set-up for DC shunt-wound motor
"Load characteristic"
33
EEM2 DC machines DC shunt-wound motors
Record the motor's load characteristics with the aid of the "ActiveDrive/ActiveServo" software
Required setting:
Brake: Industrial series: "PC Mode" Classic series: "PC Mode"
DC power supply unit: (armature & exciter circuit) 220V
Experiment procedure:
Start the "ActiveDrive/ActiveServo" software The motor is to be loaded up to its nominal torque Label the diagram as given in the placeholder The following parameters should be recorded: The degree of efficiency η(M) (η
=> "Eta"), of the armature current IA, the power output P2 and the speed n(M) Before starting the measurement you must have answered the question
concerning the nominal torque, which you should have determined in the "speed control" experiment
After completing the measurement export the generated graph and copy it into the corresponding placeholder below
Determine from the diagram the highest degree of efficiency obtainable
34
EEM2 DC machines DC shunt-wound motors
What is the nominal torque?
Placeholder for graph η(M) (η => „Eta“), IA(M), P2(M), n(M)
What is the maximum efficiency "η" for the shunt-wound motor?
MN= ____Nm
η= ____% approx.
35
EEM2 DC machines DC shunt-wound motors
36
EEM2 DC machines DC shunt-wound generators, separately excited
Separately excited DC shunt-wound generator
Voltage control (field regulating range) Voltage polarity Load characteristics
Over the next few pages you will be conducting the following exercises on a "separately excited DC shunt-wound generator":
37
EEM2 DC machines DC shunt-wound generators, separately excited
38
EEM2 DC machines DC shunt-wound generators, separately excited
Assembly instructions: "Voltage Control"
Note: setting of the DC power supply can only be carried out when the exciter circuit is connected
More detailed information on the brake can be found in the corresponding online documentation
Training contents: "Voltage Control"
Connect up the machine as a separately excited DC shunt-wound generator
Recognise which variables affect the output voltage of the generator
Determine the output voltage as a function of the speed Understand the purpose of the field regulator and how it works
Assemble the circuit as specified in the following circuit diagram and set-up instructions
Include an ammeter and voltmeter in the exciter circuit Set the field regulator to the value 0 Ω Set the DC power supply to a voltage of 220 V In this experiment the brake is used as a drive motor
39
EEM2 DC machines DC shunt-wound generators, separately excited
Circuit diagram for DC shunt-wound generator, separately excited
"Voltage Control"
40
EEM2 DC machines DC shunt-wound generators, separately excited
Set-up for DC shunt-wound generator, separately excited
"Voltage control"
41
EEM2 DC machines DC shunt-wound generators, separately excited
Record the characteristic of "UG" as a function of "n" for different exciter currents
Required settings:
Brake mode: "Speed Control" Field regulator: maximum value ( Note: 0.3 kW class ~ 2.2 kΩ; 1 kW
class ~ 680 Ω) DC power supply unit: (exciter circuit) 220 V Multimeter measurement method: arithmetic mean
Experiment procedure:
Put the generator into operation First run the drive motor up to a speed of 2000 rpm Use the field regulator to set the exciter currents specified in the table Begin at Ierr.= 0 mA Measure the generator voltage UG produced at each speed as you lower the
speed step by step (see table)
Ierr.=0mA Ierr.=50mA Ierr.=70mA Ierr.=90mAn/(1/min) Ug/V Ug/V Ug/V Ug/V
20001800160014001200
1200 1300 1400 1500 1600 1700 1800 1900 2000n/(1/min)
0
25
50
75
100
125
150
175
200
225
Ug
(Ier
r=0)
/V
0
25
50
75
100
125
150
175
200
225
Ug
(Ier
r.=
50m
A)/
V
0
25
50
75
100
125
150
175
200
225
Ug
(Ier
r.=
70m
A)/
V
0
25
50
75
100
125
150
175
200
225
Ug
(Ier
r.=
90m
A)/
V
42
EEM2 DC machines DC shunt-wound generators, separately excited
Why does the generator produce a low voltage at an exciter current of I = 0 mA?
Which of the following variables have an immediate impact on the generator voltage?
The voltage results from the inaccuracy of the measuring instruments being used
The generator charges up statically due to the rotating motion of the rotor. This surge in charge is measurable as a low voltage
This voltage is caused by the residual magnetisation (remanence) of the exciter field
The exciter winding's coercive field strength is not sufficient to generate a low voltage when it is off
Exciter field voltage
Speed
No-load torque
Exciter current
Polarity of the armature winding
More than one answer may be correct
43
EEM2 DC machines DC shunt-wound generators, separately excited
44
EEM2 DC machines DC shunt-wound generators, separately excited
Assembly instructions: "Voltage Polarity"
Note: setting of the DC power supply unit can only be performed when the exciter circuit is connected
More detailed information on the brake can be found in the corresponding online documentation
Training contents: "Voltage Polarity"
Recognise the relationship between the polarity of the connection of the exciter winding, the rotation direction of the generator and how they relate to the resulting generator voltage
Assemble the circuits as specified in the circuit diagram and set-up
instructions below Include an ammeter and voltmeter in the exciter circuit. Set the field regulator to the value 0 Ω Set a voltage of 220 V on the DC power supply In this experiment the brake is used as a drive motor
45
EEM2 DC machines DC shunt-wound generators, separately excited
Circuit diagram for DC shunt-wound generator, separately excited
"Voltage polarity"
46
EEM2 DC machines DC shunt-wound generators, separately excited
Set-up for DC shunt-wound generator, separately excited
"Voltage polarity"
47
EEM2 DC machines DC shunt-wound generators, separately excited
Properties of a generator when the polarity of the exciter winding is reversed and when the rotation direction is reversed
Required settings:
Brake mode: "Speed Control" Field regulator: minimum value (0 Ω) DC power supply unit: (exciter circuit) 220 V
Experiment procedure:
Put the generator into operation First run the drive motor up to a speed of 2000 rpm Measure the generator voltage UG Now change the polarity of the exciter winding and then the rotation direction
of the drive motor Measure the generator voltage UG after each modification
Which of the following statements is true?
The polarity of the generator voltage is independent of the generator's rotation direction
The polarity of the exciter winding and the rotation direction of the generator are determined by the polarity of the generator voltage
The polarity of the generator voltage cannot be changed as it is fixed to the same polarity by the manufacturer
48
EEM2 DC machines DC shunt-wound generators, separately excited
Training contents: "Load Characteristics"
Record and interpret the load characteristics of a DC shunt-wound generator
Understand the relationship between the generator voltage, armature current, exciter current and speed
49
EEM2 DC machines DC shunt-wound generators, separately excited
Assembly instructions: "Load Characteristics"
Note: setting of the DC power supply unit can only be performed when the exciter circuit is connected
More detailed information on the brake can be found in the corresponding online documentation
Assemble the circuit as specified in the circuit diagram and set-up
instructions Include an ammeter and voltmeter in the exciter/armature circuit The armature circuit is to be ted to the load resistor In this experiment the brake is used as a drive motor
50
EEM2 DC machines DC shunt-wound generators, separately excited
Circuit diagram for shunt-wound generator, separately excited
"Load Characteristics"
51
EEM2 DC machines DC shunt-wound generators, separately excited
Set-up for DC shunt-wound generator, separately excited
"Load characteristics"
52
EEM2 DC machines DC shunt-wound generators, separately excited
Record the load characteristics of the generator with various exciter currents
Required settings:
Brake mode: "Speed Control" DC power supply unit: (exciter circuit) 220V Field regulator: minimum setting (0 Ω) Load resistor: maximum ( Note: 0.3 kW class ~ approx. 1 kΩ; 1 kW class ~
approx. 440 Ω)
Experiment procedure:
The drive motor is to be run up to a speed of 2000 rpm with the generator operating without a load (load resistor set to maximum)
Record the load characteristics based on the armature currents specified in the table with 2 different nominal exciter currents (50% and 100% of the nominal exciter current)
Measure the variables UG (generator voltage) and P2 (power output) when the armature current IG is increased step by step
Increase the armature current by reducing the load resistance Calculate the power output and enter all the measured values into the tables
The electrical power output is computed as follows:
P2=UG*IG; UG[V], IG[A], P2[W]
53
EEM2 DC machines DC shunt-wound generators, separately excited
100% of nominal exciter current
50% of nominal exciter current
Ig/A 0.30 0.60 0.80 1.00 1.20 1.40Ug/VP2/W
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5Ig/A
0
50
100
150
200
250
300
350
Ug
/V
0
50
100
150
200
250
300
350
P2
/W
Ig/A 0.30 0.60 0.80 1.00 1.20 1.40Ug/VP2/W
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5Ig/A
0
50
100
150
200
250
300
350
Ug
/V
0
50
100
150
200
250
300
350
P2
/W
54
EEM2 DC machines DC shunt-wound generators, self-excited
DC shunt-wound generator, self-excited
Rotation direction and polarity Load characteristics
Over the next few pages you will be conducting exercises on a "self-excited DC shunt-wound generator":
55
EEM2 DC machines DC shunt-wound generators, self-excited
56
EEM2 DC machines DC shunt-wound generators, self-excited
Assembly instructions: "Rotation Direction and Polarity"
More detailed information regarding the brake can be found in the corresponding online documentation
Training content: "Rotation Direction and Polarity"
Recognise how the generator voltage results from the polarity of the exciter winding and the generator's rotation direction
Assemble the circuits as specified in the circuit diagram and set-up
instructions below Include an ammeter and voltmeter in the armature circuit Include an ammeter in the exciter circuit Connect the armature circuit to the load resistor In this experiment the brake is used as a drive motor
57
EEM2 DC machines DC shunt-wound generators, self-excited
Circuit diagram for DC shunt-wound generator, self-excited
"Rotation direction and polarity"
58
EEM2 DC machines DC shunt-wound generators, self-excited
Set-up for DC shunt-wound generator, self-excited
"Rotation direction and polarity"
Properties of the generator when rotation direction is reversed
Required settings:
Brake mode: "Speed Control" Field regulator: minimum setting (0 Ω) Load resistor: maximum ( Note: 0.3 kW class ~ 1 k Ω; 1 kW class ~ 440 Ω) Multimeter measurement method: arithmetic mean
59
EEM2 DC machines DC shunt-wound generators, self-excited
Experiment procedure:
Put the generator into operation by running the drive motor up to a speed of approx. 2000 rpm
Measure the generator voltage UG and enter this into the box corresponding to the rotation direction
Now reverse the rotation direction of the drive motor Finally measure the generator voltage UG again and enter this value again into
the corresponding box
The generator voltage for anti-clockwise rotation of the generator is:
The generator voltage for clockwise rotation of the generator is:
Which of the following statements is true of the generator voltage?
UG= ____V
UG= ____V
The amplitude of the generator voltage is the same for both rotation directions
When rotating clockwise the ampltiude of the generator voltage is the highest
For both rotation directions the generator voltage is zero
During clockwise rotation the amplitude of the generator voltage is somewhat lower than for anti-clockwise rotation
60
EEM2 DC machines DC shunt-wound generators, self-excited
Assembly instructions: "Load Characteristics"
More detailed information on the brake can be found in the corresponding online
documentation
Training content: "Load Characteristics"
Record and interpret the load characteristics for a self-excited DC shunt-wound generator
Understand the relationship between the generator voltage, exciter current and speed
Assemble the circuits as specified in the circuit diagram and set-up
instructions below Include an ammeter and voltmeter in the armature circuit Include an ammeter in the exciter circuit Connect the armature circuit to the load resistor In this experiment the brake is used as a drive motor
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EEM2 DC machines DC shunt-wound generators, self-excited
Circuit diagram for DC shunt-wound generator, self-excited
"Load characteristics"
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EEM2 DC machines DC shunt-wound generators, self-excited
Set-up for DC shunt-wound generator, self-excited
"Load Characteristic"
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EEM2 DC machines DC shunt-wound generators, self-excited
Record the load characteristic of the generator
Required settings:
Brake mode: "Speed Control" Field regulator: minimum setting (0 Ω) Load resistor: maximum ( Note: 0.3 kW class ~ approx. 1 kΩ; 1 kW class ~
approx. 440 Ω)
Experiment procedure:
Put the generator into operation First run the drive motor up to a speed of 2000 rpm Make sure that you have the correct rotation direction of the motor, as
determined in the experiment "rotation direction and polarity" Now the nominal exciter current must be set using the field regulator Reduce the resistance in consistent intervals In the process measure the generator voltage UG, the armature current IG and
use these measurements to compute the power output P2 Transfer all of these values into the table
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EEM2 DC machines DC shunt-wound generators, self-excited
Select those statements that are true about the load characteristic
Ug/V Ig/A P2/W
0 20 40 60 80 100 120 140 160 180 200U/V
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Ig/A
0
10
20
30
40
50
60
70
80
90
100
P2
/W
P2 is dependent on the load resistor
As R(A) rises P2 also increases continuously
The characteristics for P2 & IG have the same pattern in terms of their curve
The generator voltage UG drops with increasing load
The armature current is constant
More than one answer may be correct
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EEM2 DC machines DC shunt-wound generators, self-excited
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EEM2 DC machines DC series-wound motors
DC series-wound motors
Connection and starting Reversing rotation direction Load characteristics for various voltages
Over the next few pages you will be conducting the following exercises on "DC series-wound motors":
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EEM2 DC machines DC series-wound motors
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EEM2 DC machines DC series-wound motors
Assembly instructions: "Connection and Starting"
Note: setting of the DC power supply unit can only be carried out when the motor
is connected
More detailed information on the brake can be found in the corresponding online documentation
Training content: "Connection and Starting"
Identify the terminal connections of the motor and operate the motor as a shunt-wound motor
Put the motor into operation with the brake Connect the motor to the starter Be familiar with how the starter works Measure the motor voltage and the motor current Determine the degree of efficiency
Assemble the circuit as specified in the following circuit diagram and
set-up instructions Include an ammeter and voltmeter in the motor circuit Switch on the brake too. This does not yet subject the motor to any load
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EEM2 DC machines DC series-wound motors
Circuit diagram for DC series-wound motor
"Connection and Starting"
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EEM2 DC machines DC series-wound motors
Set-up for of the DC series-wound motor
"Connection and Starting"
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EEM2 DC machines DC series-wound motors
Determine the nominal efficiency
Required settings:
Brake mode: "Torque Control" ( Note: The brake should definitely be active) Starter: minimum value (0 Ω) DC power supply unit: 220 V Multimeter measurement method: arithmetic mean
Experiment procedure:
Brake the motor down to its nominal torque In the process measure the motor current Use the provided equation to compute the efficiency of the motor based on the
rated data and the measured variables
Make sure that the motor is not operated without any load, as otherwise the motor could start to "race"
The efficiency is defined as:
P2=Mn*ω, P1=UM*IM, ω=2*π*n
What is the efficiency "η" of the series-wound motor with a nominal load?
η=P2/P1
η= ____% approx.
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EEM2 DC machines DC series-wound motors
Record a load characteristic (with starter)
Required settings:
Brake mode: "Torque Control" (the brake should definitely be active) Starter: minimum value (0 Ω) DC power supply unit: 220 V
Experiment procedure:
Brake the motor down to 0.5 times its nominal torque Now adjust the starter in 5 steps from 0 up to 100% of its maximum value (
Note: 0.3 kW class ~ 47 Ω; 1 kW class ~ 16 Ω) At the same time measure the motor current and voltage Transfer the measurement values into the table
U/V n/(1/min) I/A
150 160 170 180 190 200 210 220 230 240 250U/V
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
n /(
1/m
in)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
I/A
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EEM2 DC machines DC series-wound motors
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EEM2 DC machines DC series-wound motors
Definition of rotation direction If you look at the drive shaft end of the DC shunt-wound machine from the perspective of the working machine (in our case the brake), the rotating direction is positive when it is clockwise. If the motor has two workable shaft ends, then it is the shaft end opposite the cooling vents, collector or slip-rings that is the shaft end which defines the rotation direction.
Training content: "Rotation Reversal"
Recognise the difference between clockwise and anti-clockwise rotation
Put the motor into operation in both directions
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EEM2 DC machines DC series-wound motors
Assembly instructions: "Rotation Reversal"
Note: setting of the DC power supply unit can only be performed with the motor connected
More detailed information can be found in the corresponding online documentation
Assemble the circuits as specified in the circuit diagram and set-up
instructions below Include an ammeter and voltmeter in the motor circuit Switch on the brake too. This does not yet subject the motor to any
load Set the starter to a setting of 0 Ω Set a voltage of 220 V on the DC power supply unit
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EEM2 DC machines DC series-wound motors
Circuit diagram for DC series-wound motor
"Rotation Reversal"
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EEM2 DC machines DC series-wound motors
Set-up for DC series-wound motor
"Rotation Reversal"
Determining the respective rotation direction
Required settings:
Brake mode: "Torque Control" (the brake should definitely be active) Starter: maximum setting ( Note: 0.3 kW class ~ 47 Ω; 1 kW class ~ 16 Ω) DC power supply unit: 220V
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EEM2 DC machines DC series-wound motors
Experiment procedure:
Put the motor into operation and observe the following
Make sure that the motor is not operated without any load, as otherwise it could "race"
What is the motor's rotation direction?
Now modify the circuit diagram as shown on the next page:
The motor rotates anti-clockwise
The motor rotates clockwise
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EEM2 DC machines DC series-wound motors
Circuit diagram for DC series-wound motor
"Rotation Reversal"
(reversed rotation direction)
What is the motor's rotation direction now?
The motor rotates clockwise
The motor rotates counterclockwise
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EEM2 DC machines DC series-wound motors
Assembly instructions: "Load Characteristics"
Note: setting of the DC power supply unit can only be performed when the motor is connected
More detailed information regarding the brake can be found in the corresponding online documentation
Training content: "Load Characteristics"
Analyse and understand the relationship between the load of the series-wound motor and its speed and armature current
Assemble the circuits as specified in the circuit diagram and set-up
instructions below Include an ammeter and voltmeter in the motor circuit Switch on the brake too. This does not yet subject the motor to any load
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EEM2 DC machines DC series-wound motors
Circuit diagram for DC series-wound motor
"Load Characteristics"
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EEM2 DC machines DC series-wound motors
Set-up for DC series-wound motor
"Load Characteristics"
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EEM2 DC machines DC series-wound motors
Record the load characteristics of the motor using the "ActiveDrive/ActiveServo" software
Required setting:
Brake: Industrial series: "PC Mode" Classic series: "PC Mode" ActiveDrive / ActiveServo: Setting -> Operating mode -> Speed control
DC power supply unit: (motor circuit) 220 V
Experiment procedure:
Start the "ActiveDrive / ActiveServo" software Make sure that you start the brake at 3000 min-1 prior to switching on the
motor, as otherwise the motor might "race" The motor should be braked from 3000 min-1 to 1600 min-1 in 20 discrete
steps using the ramp function Label the graph as given in the placeholder below In the first graph the following parameters should be plotted: the motor current
I(M), the motor voltage U(M) and the torque M(M) In the second graph the following parameters are to be plotted: the consumed
electical power and the mechanical output power (P1(M), P2(M)) as well as the resulting efficiency η(M) (η => "Eta")
After completing the measurements export the generated graphs and copy them into the placeholders below
Determine the highest possible efficiency from the second graph
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EEM2 DC machines DC series-wound motors
Placeholder for graph U(M), I(M), M(M)
Placeholder for graph η(M) (η => "Eta"), P1(M), P2(M)
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EEM2 DC machines DC series-wound motors
What is the maximum efficiency "η" for the series-wound motor?
Which of the following statements regarding the load graphs are true?
Why is it imperative that a series-wound motor is never operated without load?
η= ____% approx.
The exciter field and the armature current are low when the loads are also low
The armature current increases linearly with the load
The efficiency "η" is constant
The speed is inversely proportional to the torque
Under low load the speed and armature current levels increase
The rotation speed drops off severely with increasing load
More than one answer may be correct
Without a load the speed drops off at a rapid rate
Without a load the motor can start to "race"
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EEM2 DC machines DC compound-wound motors
DC compound wound motor
Load characteristics for different compound ratios
On the next page the following exercise will be conducted on the DC compound-wound motor:
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EEM2 DC machines DC compound-wound motors
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EEM2 DC machines DC compound-wound motors
Training content: "Load Characteristics for Different Compound Winding Ratios"
Identify the terminal connections of the motor and operate the motor as a DC compound-wound motor
Put the motor into operation with the brake Record the load characteristics for different series-wound
components Identify the difference between over-compounded, normal and
under-compounded motors Compare the response of acompound-wound machine with
series and shunt-wound machines
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EEM2 DC machines DC compound-wound motors
Assembly instructions: "Load Characteristics"
Note: setting of the DC power supply unit can only be performed when the motor is connected
More detailed information regarding the brake can be found in the corresponding online documentation
Circuit diagram for compound-wound machine
"Load characteristics for different compound winding ratios"
(100% series-wound component – "over-compounded“)
Assemble the circuit as specified in the following circuit diagram and
set-up instructions Include an ammeter and voltmeter in the motor circuit Switch on the brake too. This does not yet subject the motor to any
load
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EEM2 DC machines DC compound-wound motors
Set-up for compound wound machine
"Load characteristic for different compound winding ratios"
(100% series-wound component – " over-compounded“)
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EEM2 DC machines DC compound-wound motors
Record the load characteristics of the motor with various compound ratios using the software "ActiveDrive/ActiveServo"
Required settings:
Brake: Industrial series: "PC Mode" Classic series: "PC Mode"
DC power supply unit: (motor circuit) 220 V Multimeter measurement method: arithmetic mean
Experiment procedure:
Start the "ActiveDrive/ActiveServo" software The motor should be subjected to a load up to 1.5 times its nominal torque Label the graph as specified in the placeholder below You should perform three measurements for different compound winding
ratios (100%, 70%, 30% series-wound component) recording two graphs, each with different parameters
In the first graph the following parameters are to be plotted: the motor current I
(M), the motor voltage U(M) and the speed n(M) In the second graph the following parameters should be plotted: consumed
electrical power and the mechanical power output (P1(M), P2(M)), as well as the resulting degree of efficiency η(M) (η => „Eta“)
Export the plotted graph and copy it into the placeholder below Determine the optimum efficiency in each case from the second graph
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EEM2 DC machines DC compound-wound motors
Placeholder for graph U(M), I(M), n(M) (100% series-wound component – "over-compounded“)
Placeholder for graph η(M) (η => „Eta“), P1(M), P2(M)
(100% series-wound component – "over-compounded“)
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EEM2 DC machines DC compound-wound motors
Circuit diagram for compound-wound machine
"Load characteristics for different compound winding ratios"
(70% series-wound component – "normal compounded“)
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EEM2 DC machines DC compound-wound motors
Placeholder for graph U(M), I(M), n(M) (70% series-wound component – "normally compounded“)
Placeholder for graph η(M) (η => "Eta"), P1(M), P2(M)
(70% series-wound component – "normally compounded“)
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EEM2 DC machines DC compound-wound motors
Circuit diagram for compound-wound machine
"Load characteristics for different compound winding ratios"
(30% series-wound component – "under-compounded“)
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EEM2 DC machines DC compound-wound motors
Placeholder for graph U(M), I(M), n(M) (30% series-wound component – "under-compounded“)
Placeholder for the graph η(M) (η => „Eta“), P1(M), P2(M)
(30% series-wound component – "under-compounded“)
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EEM2 DC machines DC compound-wound motors
Which compound winding ratio produces the highest efficiency "η"?
What is the optimum efficiency "η" of the compound-wound motor at the appropriate compound winding ratio?
Based on the graphs, which statements are true of the compound wound motor?
100% shunt-wound/70% series-wound
100% shunt-wound/100% series-wound
100% shunt-wound/30% series-wound
η= ____% approx.
The speed of the compound-wound motor under load drops more severely than for the shunt-wound motor regardless of the compound winding ratios
The compound-wound motor can start to "race" in the no-load state just like the series-wound motor
The higher the series-wound component, the lower the speed drop under load
The smaller the series-wound component, the lower the speed drop under load
If the polarity of the series-wound winding is reversed, the speed increases, due to the fact that the shunt-wound winding is weakened
When the polarity is reversed in the series-wound winding, the speed increases because the field of the shunt wound winding is amplified
More than one answer may be correct
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EEM2 DC machines Copyright
Copyright © 2004-2006 LUCAS-NÜLLE GmbH.
This course "EEM 2 DC machines" is protected by copyright. All rights pertaining thereto are reserved. Any reproduction of the document as a file or in written form be it photocopy, microfilm or any other method or conversion into a machine-compatible language, in particular for data processing systems, without the expressed written approval of the LUCAS-NÜLLE GmbH is strictly forbidden.
The software as described above is made available on the basis of a general licensing agreement or in the form of a single license. The use or reproduction of the software is only permitted in strict compliance with the contractual terms stated therein.
If changes have been performed in a manner which was not strictly authorised by the LUCAS-NÜLLE GmbH, any product liability or warranty claims pertaining thereto are null and void.
Congratulations! This is the last page. You have completed the course "EEM 2 DC
machines".
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