lab sheet electric machine

8/16/2019 LAB SHEET Electric Machine

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Course"EEM 2 DC Machines"

Photo: Siemens AG

SH5007-1A Version 1.0

Author: M.Germeroth

Lucas-Nülle GmbH · Siemensstraße 2 · D-50170 Kerpen (Sindorf)Tel.: +49 2273 567-0

www.lucas-nuelle.de

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Copyright © 2005 LUCAS-NÜLLE GmbH. All rights reserved.

LUCAS-NÜLLE Lehr- und Messgeräte GmbHSiemensstraße 2 D-50170 Kerpen


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EEM2 DC machines

Training objectives 1Equipment for 300 W Industrial Series 2

Information page "Alternative Equipment" 3Safety 5DC shunt-wound motors 7

Connection and starting 9Rotation reversal 15Speed control 19Load characteristic 27

DC shunt-wound generators, separately excited 31Voltage control (field control range) 33Voltage polarity 37Load characteristic 41

DC shunt-wound generators, self-excited 47Rotation direction and polarity 49Load characteristic 53

DC series-wound motors 57Connection and starting 59Rotation reversal 63Load characteristic 67

DC compound-wound motors 73Load characteristics for various compound ratios 75

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EEM2 DC machines


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EEM2 DC machinesTraining objectives

In this course you will acquire practical knowledge regarding the topic of DCmachines.Experiment-based investigations of series-wound, shunt-wound and compound-wound machines are at the focal point of this course and explore such aspects ashow 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 andconducting the experiments. The following pages provide you with anoverview of the course contents and the materials and equipmentrequired.

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EEM2 DC machinesInformation 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")

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EEM2 DC machinesInformation page "Alternative Equipment"

Starter (SO3212-6M) and field regulator (SO3212-5H) for DC motors(connection example: "DC shunt-wound motor")

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EEM2 DC machinesSafety

Basic safety instructions

In all experiments using mains voltages high, life-threatening voltages arise. For thatreason 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 whereearthing is possible, must be earthed. This is particularly the case for the frequencyconverter being used.

Always be very careful to check the wiring of the application modules and onlyswitch on the mains voltage after a check has been completed. Whenever possibleuse a robust current monitoring instrument in the circuit.

Always use shaft-end guards and coupling guards as protection against contactwith rotating motor parts

All locally applicable stipulations and standards governing how electrical equipmentis handled must be complied with.

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EEM2 DC machinesSafety

General instructions on handling the equipment

Check that the knurled screws at the base of the motor and the couplingsleeves (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 isexceeded. These switching contacts are accessible on the terminalboard 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 tolerancerange of +/-15% with respect to the specified measurement. For moreinformation on this please refer to VDE0530.

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EEM2 DC machinesDC shunt-wound motors

DC shunt-wound motors

Over the next few pages you will perform the following exercisespertaining to "DC shunt-wound motors":

Connection and starting Reversing rotation direction Speed control Load characteristics

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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 themotor 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 __

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Assembly instructions: " Connection and starting"

Note: setting of the DC power supply can only be performed when the motor isconnected.

More detailed information on the brake can be found in the corresponding onlinedocumentation

Circuit diagram for DC shunt-wound motor

"Connection and starting"

Assemble the circuits as specified in the following circuit diagram andset-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

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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

Experiment procedure:

Put the motor into operation and observe its operating response

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The motor demonstrates the following response:

Measure the armature current

Required settings:

Brake mode: "Torque Control"


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?

gfedc The motor rotates at a higher speed than the nominalspeed

gfedc The rotation direction is clockwise

gfedc The rotation direction is anti-clockwise

gfedc The switch-on current is higher than the nominalcurrent

gfedc The motor rotates at nominal speed

gfedc The current increases with increasing speed

More than oneanswer maybe correct

nmlkj The armature current corresponds approximately to

the nominal currentnmlkj The armature current is considerably higher than the

nominal current

nmlkj The armature current is considerably smaller thanthe nominal current

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Record a load characteristic

Required settings: Starter: maximum value ( Note: 0.3 KW class ~ 47Ω; 1 KW class ~ 16 Ω)


The motor should be subjected to the torque loads as set forth in the table Measure the armature current and armature voltage under load Enter the measured values into the table

M/Nm n/(1/min) I/A U/V0.2

0.4

0.6

0.8

1

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 i n ¯ 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

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Which of the following statements apply to the load characteristic?

What is the function of the starter?

gfedc The armature voltage is considerably reduced whenthe torque is increased

gfedc The armature current increases linearly with thetorque

gfedc The speed severely drops off once the nominaltorque is reached

gfedc The armature voltage remains practically constant

gfedc The speed remains practically constant (± 3%) in therange of the nominal torque

gfedc The speed increases at higher torques


nmlkj The starter is primarily used for speed control

nmlkj The starter restricts the switch-on current

nmlkj The starter protects the motor from overload during

standard operation

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Definit ion of rotation directionIf you look at the drive shaft end of the DC shunt-wound machine from theperspective of the working machine (in our case the brake), the rotating direction ispositive 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 endwhich defines the rotation direction.

Note: in the "Classic series" (0.3 kW & 1.0 kW) the rotation direction isdetermined by the rotation direction of the brake, i.e. if the asynchronous machinerotates clockwise, i.e. in the positive direction, the control unit of the brake indicatesa negative rotation direction. Thus the rotation direction displayed is always that ofthe brake.

Training content: "Rotation reversal"

Identify the difference between clockwise and anti-clockwiserotation

Put the motor into operation in both rotation directions

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Assembly instructions: "Rotation Reversal"


"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.

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"Rotation Reversal"

Rotation reversal

Required settings:

Starter: minimum value (0 Ω) DC power supply: 220V


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.

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What is the motor's direction of rotation?

Switch the motor off and modify the circuit as shown by changing the polarityof the exciter coil

Turn the motor back on and observe its response


"Rotation reversal" (reversed rotation direction)

What is the motor's direction of rotation now?

nmlkj The motor rotates clockwise

nmlkj The motor rotates anti-clockwise



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Assembly instructions: " Speed Control"

Note: setting of the DC power supply unit can only be performed when the motoris connected.



"Speed control"

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.

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"Speed control"

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Record characteristics " Ia and "n" as a function of "Ua

Required settings: DC power supply 220V Field regulator: minimum value (0 Ω) Brake mode: "Torque Control"


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

Ua/V n/(1/min) Ia/A

220

190

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 i n )

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

I a / A

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Record the characteristic of n" as a function of "M" using the"ActiveDrive/DCMA" software

Required setting:

Brake: Industrial series: "PC Mode" Classic series: "Application Mode" ( Note: when starting the

"ActiveASMA" software you will be prompted to select "Applicationmode")

Field regulator: minimum value (0 Ω) Adjustable DC power supply unit (armature voltage): 220/190/160V DC power supply unit (exciter circuit voltage): 220V


Start the "ActiveDrive/DCMA" software 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:

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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) 220V

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Switch on the DC power supply Vary the Rf value of the field regulator in 3 steps, 0%, 50% and 90% of themaximum value ( Note: 0.3 kW class ~ 2.2 kΩ; 1kW class ~ 680Ω)

At the same time measure the respective variables If and n for each step andenter the measured values into the table

Rf/Ω n/(1/min) If/mA

0 200 400 600 800 1000 1200 1400 1600 1800 2000Rf/Ω

0

300

600

900

1200

1500

1800

2100

2400

2700

3000

3300

n / ( 1 / m i n )

0

20

40

60

80

100

120

140

160

180

200

I f / m A

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Record the characteristic " n" as a function of "M" using the"ActiveDrive/DCMA" software

Required setting:



Field regulator: minimum value (0 Ω) DC power supply unit: (armature & exciter circuit) 220V


Start the "ActiveDrive/DCMA" software The motor should be subjected to a load up to its nominal torque Label the diagram as appropriate in the placeholder below Record three characteristics are recorded in sequence for 3 different field

regulator values (Rf ), one each at 0%, 50% and 90% of the maximum setting( Note: 0.3 kW class ~ 2,2 kΩ; 1 kW class ~ 680 Ω)

After completing the measurement export the graph with all 3 characteristicsand copy it into the placeholder below

Placeholder for characteristics n(M), Rf = 0%/50%/90% of the maximum setting

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Which statements are true of the speed variation?

gfedc A reduction of the armature voltage leads to a drop in

speedgfedc A reduction of the exciter current leads to a drop in

speed

gfedc An increase of the armature voltage leads to a dropin speed

gfedc A decrease of exciter current leads to an increase inspeed


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Setup diagram: "Load Characteristic"

Note: setting of the DC power supply can only be carried out when the motor isconnected

More detailed information on the brake and the software used can be found in theappropriate online documentation


"Load characteristic"

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

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"Load characteristic"

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Record the motor's load characteristics with the aid of the"ActiveDrive/DCMA" software

Required setting:



DC power supply unit: (armature & exciter circuit) 220V


Start the "ActiveDrive/DCMA" software The motor should be subjected to a load up to 1.5 times 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 inthe "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

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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.

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EEM2 DC machinesDC 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 followingexercises on a "separately excited DC shunt-wound generator":

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Assembly instructions: " Voltage Control"

Note: setting of the DC power supply can only be carried out when the exciter

circuit is connected


Circuit diagram for DC shunt-wound generator, separately excited

"Voltage Control"

Training contents: "Voltage Control"

Connect up the machine as a separately excited DC shunt-wound generator

Recognise which variables affect the output voltage of thegenerator

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

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Set-up for DC shunt-wound generator, separately excited

"Voltage control"

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Record the characteristic of " UG" as a function of " n" for different excitercurrents

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


Put the generator into operation First run the drive motor up to a speed of 3000 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.=90mA

n/(1/min) Ug/V Ug/V Ug/V Ug/V

30002800

2600

2400

2200

2000 2200 2400 2600 2800 3000 3200n/(1/min)

0

50

100

150

200

250

300

350

U g ( I e r r = 0 ) / V

0

50

100

150

200

250

300

350

U g ( I e r r

. = 5 0 m

A ) / V

0

50

100

150

200

250

300

350

U g ( I e r r

. = 7 0 m

A ) / V

0

50

100

150

200

250

300

350

U g ( I e r r

. = 9 0 m

A ) / V

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Why does the generator produce a low voltage at an exciter current of I = 0mA?

Which of the following variables have an immediate impact on the generatorvoltage?

nmlkj The voltage results from the inaccuracy of themeasuring instruments being used

nmlkj The generator charges up statically due to therotating motion of the rotor. This surge in charge ismeasurable as a low voltage

nmlkj This voltage is caused by the residual magnetisation(remanence) of the exciter field

nmlkj The exciter winding's coercive field strength is notsufficient to generate a low voltage when it is off

gfedc Exciter field voltage

gfedc Speed

gfedc No-load torque

gfedc Exciter current

gfedc Polarity of the armature winding


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Assembly instructions: " Voltage Polarity"

Note: setting of the DC power supply unit can only be performed when the excitercircuit is connected

More detailed information on the brake can be found in the corresponding online

documentation

Circuit diagram for DC shunt-wound generator, separately excited

"Voltage polarity"

Training contents: "Voltage Polarity"

Recognise the relationship between the polarity of the connection ofthe exciter winding, the rotation direction of the generator and howthey relate to the resulting generator voltage

Assemble the circuits as specified in the circuit diagram and set-upinstructions 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

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"Voltage polarity"

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Properties of a generator when the polarity of the exciter winding is reversedand 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


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?

nmlkjThe polarity of the generator voltage is independentof the generator's rotation direction

nmlkj The polarity of the exciter winding and the rotationdirection of the generator are determined by thepolarity of the generator voltage

nmlkj The polarity of the generator voltage cannot bechanged as it is fixed to the same polarity by themanufacturer

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Training contents: "Load Characteristics"

Record and interpret the load characteristics of a DC shunt-woundgenerator

Understand the relationship between the generator voltage,armature current, exciter current and speed

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Assembly instructions: " Load Characteristics"

Note: setting of the DC power supply unit can only be performed when the excitercircuit is connected


Circuit diagram for shunt-wound generator, separately excited

"Load Characteristics"

Assemble the circuit as specified in the circuit diagram and set-upinstructions

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

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"Load characteristics"

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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)


The drive motor is to be run up to a speed of 3000 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 thenominal exciter current)

Measure the variables UG (generator voltage) and P2 (power output) when thearmature 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]

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100% of nominal exciter current

50% of nominal exci ter current

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

U g / V

0

50

100

150

200

250

300

350

P 2 / W

Ig/A 0.3 0.6 0.8 1 1.2 1.4

Ug/V

P2/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

U g / V

0

50

100

150

200

250

300

350

P 2 / W

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EEM2 DC machinesDC 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":

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Assembly instructions: " Rotation Direction and Polarity"

Note: setting of the DC power supply unit can only be carried out when theexciter circuit is connected

More detailed information regarding the brake can be found in the correspondingonline documentation

Circuit diagram for DC shunt-wound generator, self-excited

"Rotation direction and polarity"

Training content: "Rotation Direction and Polarity"

Recognise how the generator voltage results from the polarity of theexciter winding and the generator's rotation direction


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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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)

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Put the generator into operation by running the drive motor up to a speed ofapprox. 3000 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

nmlkj The amplitude of the generator voltage is the samefor both rotation directions

nmlkj When rotating clockwise the ampltiude of thegenerator voltage is the highest

nmlkj For both rotation directions the generator voltageis zero

nmlkj During clockwise rotation the amplitude of the

generator voltage is somewhat lower than for anti-clockwise rotation

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Circuit diagram for DC shunt-wound generator, self-excited

"Load characteristics"

Training content: "Load Characteristics"

Record and interpret the load characteristics for a self-excited DCshunt-wound generator

Understand the relationship between the generator voltage, excitercurrent 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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Set-up for DC shunt-wound generator, self-excited

"Load Characteristic"

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Record the load characteristic o f 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)


Put the generator into operation First run the drive motor up to a speed of 3000 rpm Make sure that you have the correct rotation direction of the motor, as

determined in the experiment "rotation direction and polarity" In no-load operation the nominal exciter current must be set with the aid of the

field regulator The the load resistance should be lowered in several steps (see table),

thereby increasing the load 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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Select those statements that are true about the load characteristic

Ra/Ω Ug/V Ig/A P2/W

1000

500250

150

100

50

22

0 100 200 300 400 500 600 700 800 900 1000Belastungswiderstand R/Ohm

0.0

0.3

0.6

0.9

1.2

1.5

I g / A

0

50

100

150

200

250

300

U g / V

0

50

100

150

200

250

300

P 2 / W

gfedc P2 is dependent on the load resistor

gfedc As R A rises P2 also increases continuously

gfedc The characteristics for P2 & IG have the same pattern

in terms of their curvegfedc The generator voltage UG drops with increasing load

gfedc The armature current is constant

More than one

answer maybe correct

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EEM2 DC machinesDC 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 exerciseson "DC series-wound motors":

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Assembly instructions: " Connection and Starting"

Note: setting of the DC power supply unit can only be carried out when the motor

is connected


Circuit diagram for DC series-wound motor

Training content: "Connection and Starting"

Identify the terminal connections of the motor and operate themotor 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 andset-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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"Connection and Starting"

Set-up for of the DC series-wound motor

"Connection and Starting"

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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


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 themotor 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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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


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

Ra/Ω n/(1/min) I/A U/V

0 5 10 15 20 25 30 35 40 45 50Belastungswiderstand R/Ω

0

500

1000

1500

2000

2500

3000

n / ( 1 / m i n )

0

50

100

150

200

250

300

U / V

0.0

0.3

0.6

0.9

1.2

1.5 I / A

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Definit ion of rotation directionIf you look at the drive shaft end of the DC shunt-wound machine from theperspective of the working machine (in our case the brake), the rotating direction ispositive 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 endwhich defines the rotation direction.

Note: in the "Classic series" (0.3 kW & 1.0 kW) the rotation direction isdetermined by the rotation direction of the brake, i.e. if the asynchronous machinerotates clockwise, i.e. in the positive direction, the control unit of the brake indicatesa negative rotation direction. Thus the rotation direction displayed is always that ofthe brake.

Training content: "Rotation Reversal"

Recognise the difference between clockwise and anti-clockwiserotation

Put the motor into operation in both directions

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Assembly instructions: "Rotation Reversal"

Note: setting of the DC power supply unit can only be performed with the motorconnected

More detailed information can be found in the corresponding onlinedocumentation


"Rotation Reversal"

Assemble the circuits as specified in the circuit diagram and set-upinstructions 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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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


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"

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What is the motor's rotation direction?

Now modify the circuit diagram as shown below:


"Rotation Reversal"

(reversed rotation direction)

What is the motor's rotation direction now?




nmlkj The motor rotates counterclockwise

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Note: setting of the DC power supply unit can only be performed when the motoris connected


Circuit diagram for DC series-wound motor"Load Characteristics"

Training content: "Load Characteristics"

Analyse and understand the relationship between the load of theseries-wound motor and its speed and armature current


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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Set-up for DC series-wound motor

"Load Characteristics"

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Record the load characteristics of the motor using the "ActiveDrive/DCMA"software

Required setting:


"ActiveASMA" software you will be prompted to select "Applicationmode"

DC power supply unit: (motor circuit) 220 V


Start the "ActiveDrive/DCMA" software The motor should be subjected to a load up to 1.5 times its nominal torque Label the graph as given in the placeholder below 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 are to be plotted: the consumed

electical power and the mechanical output power (P1(M), P2(M)) as well as theresulting 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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Placeholder for graph U(M), I(M), n(M)

Placeholder for graph η(M) (η => "Eta"), P1(M), P2(M)

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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.

gfedc The exciter field and the armature current are lowwhen the loads are also low

gfedc The armature current increases linearly with the load

gfedc The efficiency "η" is constant

gfedc The speed is inversely proportional to the torque

gfedc Under low load the speed and armature currentlevels increase

gfedc The rotation speed drops off severely with increasingload


nmlkj Without a load the speed drops off at a rapid rate

nmlkj Without a load the motor can start to "race"

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EEM2 DC machinesDC 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 DCcompound-wound motor:

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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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Note: setting of the DC power supply unit can only be performed when the motoris connected


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 andset-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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Set-up for compound wound machine

"Load characteristic for different compound winding ratios"

(100% series-wound component – " over-compounded“)

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Record the load characteristics of the motor wi th various compoundratios using the software "Act iveDrive/DCMA"

Required settings:

Brake: Industrial series: "PC Mode" Classic series: "Application Mode" ( Note: when starting the "DSMA"

software you will be prompted to select "Application mode") DC power supply unit: (motor circuit) 220 V


Start the "ActiveDrive/DCMA" 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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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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(70% series-wound component – "normal compounded“)

Placeholder for graph U(M), I(M), n(M)

(70% series-wound component – "normally compounded“)

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Placeholder for graph η(M) (η => "Eta"), P1(M), P2(M) (70% series-wound component – "normally compounded“)



(30% series-wound component – "under-compounded“)

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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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Which compound winding ratio produces the highest efficiency "η"?

What is the optimum efficiency "η" of the compound-wound motor at theappropriate compound winding ratio?

Based on the graphs, which statements are true of the compound wound motor?

nmlkj 100% shunt-wound/70% series-wound



η= ____

% approx.

gfedc The speed of the compound-wound motor under loaddrops more severely than for the shunt-wound motorregardless of the compound winding ratios

gfedc The compound-wound motor can start to "race" in

the no-load state just like the series-wound motorgfedc The higher the series-wound component, the lower

the speed drop under load

gfedc The smaller the series-wound component, the lowerthe speed drop under load

gfedc If the polarity of the series-wound winding isreversed, the speed increases, due to the fact thatthe shunt-wound winding is weakened

gfedc When the polarity is reversed in the series-wound

winding, the speed increases because the field of theshunt wound winding is amplified


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EEM2 DC machinesCopyright

Copyr ight © 2004-2006 LUCAS-NÜLLE GmbH.

This course "EEM 2 DC machines" is protected by copyright. All rightspertaining thereto are reserved. Any reproduction of the document as a file or inwritten form be it photocopy, microfilm or any other method or conversion into amachine-compatible language, in particular for data processing systems, without theexpressed written approval of the LUCAS-NÜLLE GmbH is strictly forbidden.

The software as described above is made available on the basis of a generallicensing agreement or in the form of a single license. The use or reproduction of thesoftware is only permitted in strict compliance with the contractual terms statedtherein.

If changes have been performed in a manner which was not strictly authorised bythe LUCAS-NÜLLE GmbH, any product liability or warranty claims pertaining theretoare null and void.

Congratulations!

This is the last page. You have completed the course "EEM 2 DCmachines".

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16

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Siemensstraße 2 · D-50170 Kerpen-Sindorf

Telefon +492273567-0 · Fax +49 2273567-30

www.lucas-nuelle.de

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