Curso de Maquina asincrona

Course "EEM 41 Three-phase asynchronous machines"

Photo: ABB Group

SH5007-1D Version 1.0

Author: M.Germeroth

Lucas-Nlle GmbH Siemensstrae 2 D-50170 Kerpen (Sindorf) Tel.: +49 2273 567-0

www.lucas-nuelle.de

Copyright 2006 LUCAS-NLLE GmbH.

All rights reserved.

LUCAS-NLLE Lehr- und Messgerte GmbH

Siemensstrae 2 D-50170 Kerpen

EEM41 Three-phase asynchronous machines

Training objectives 1Equipment: 300 W Industrial Series 2Safety 3Asynchronous motor 5

Connection and starting 7Rotation reversal 17Load characteristics 23Reactive compensation 31

Asynchronous motor, Steinmetz circuit 43Connection and starting 45Load characteristics 51

Copyright 57

EEM41 Three-phase asynchronous machines

EEM41 Three-phase asynchronous machines Training objectives

This course is designed to convey practical know-how on the topic of three-phase asynchronous machines. Experiment-based investigations of the asynchronous motor are the focus and cover the functioning of the machine, its response and how it operates.

Training contents

z Motor operation z Nominal data, rating plate z Star cnnection, delta connnection z Star/delta switches z Steinmetz circuit (300W series) z Reactive power compensation z Measurement of phase-to-phase and line-to-line values z Reversal of rotation z Measurement of power output with and without oad

Prerequisites

z Basic knowledge of electrical machines z Basic knowledge of electrical engineering z Knowledge of using measuring instruments

Welcome to the Three-phase Asynchronous Machine course. The team from LUCAS-NLLE wishes you lots of fun and success while working through the course topics and performing the experiments. The following pages provide you with an overview of the course content and the required materials.

1

EEM41 Three-phase asynchronous machinesEquipment: 300 W Industrial Series

SO3636-6U Active machine test stand 300 W 1 each SE2662-2A Coupling sleeve 300 W 1 each SE2662-7B Coupling guard 300 W 1 each

SE2672-3G Three-phase motor with squirrel-cage rotor 300 W 1 each

SO3212-1W On/off switch 4-pole 1 each SO3212-2D Star-delta switch 1 each SO3212-5U Power supply for electrical machines 1 each

SO5127-1Z Analog/digital multimeter, power meter and power factor meter 1 each

SO3212-6E Compensation unit 1 each

SO5148-1F Set of safety connecting leads 4 mm (47 each) 1 each

SO5126-9X Set of safety connection plugs 19/4 mm (15 each) 15 x

SO5126-9Z Set of safety connection plugs 19/4 mm with tap (5 each) 5 x

2

EEM41 Three-phase asynchronous 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.

3

EEM41 Three-phase asynchronous machinesSafety

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.

4

EEM41 Three-phase asynchronous machines Asynchronous motor

Asynchronous motors

z Connection and starting z Rotation reversal z Load characteristics z Dynamic load experiments (Classic series only ) z Reactive power compensation

On the subsequent pages you will be performing the following exercises on the "asynchronous motor":

5

EEM41 Three-phase asynchronous machinesAsynchronous motor

6


Enter the nominal data for the asynchronous machine

What is the maximum permissible voltage of the motor winding (phase voltage)?

Training content: Connection and starting

z Identify the terminal connections of the motor and operate the motor as a three-phase asynchronous motor on a three-phase mains network

z Utilise the nominal data of the motor based on the rating plate z Measure the phase voltage and phase current z Put the motor into operation in star and delta configurations z Identify the differences between star and delta connections z Understand the function of adelta switch z Put the motor into operation with the brake z Subject the motor to load

Nominal power ____WUN star circuit connection ____VUN delta circuit connection ____VIN star circuit connection ____AIN delta circuit connection ____Acos ____Speed ____rpmFrequency ____Hz

Uphase= ____V

7


Assembly instructions: "Connection and starting"

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

Circuit diagram "connection & starting" (star configuration)

z Assemble the circuits as specified in the following circuit diagram and

set-up instructions z Switch on the brake too. This does not yet subject the motor to any load

8


Set-up "Connection & starting" (star configuration)

Putting the asynchronous motor into operation in star configuration

Required settings:

z Brake mode: "Torque Control"

9


Experiment procedure:

z Put the motor into operation and observe its response z Brake the motor down to its nominal speed z At the same time measure the phase variables Uphase and Iphase

Make sure that the ammeter and voltmeters have been connected properly

What do you measure the phase variables Uphase and Iphase to be?

Uphase= ____VIphase= ____A

10


Circuit diagram "Connection & starting" (delta connection)

11


Set-up "Connection & starting" (delta connection)

Putting the asynchronous motor into operation in delta configuration

Required settings:

z Brake mode: "Torque Control"


z Put the motor into operation and observe its response z Brake the motor down to its nominal speed z At the same time measure the phase variables Uphase and Iphase

Make sure that the ammeter and voltmeters have been connected correctly

12


What do you measure the phase variables Uphase and Iphase to be?

Circuit diagram "Connection & starting" (star and delta switch)

Uphase= ____VIphase= ____A

13


Set-up "Connection and starting" (star and delta switch)

Putting the asynchronous motor into operation with a star/delta switch and recording the load characteristics

Required setting:

z Brake mode: "Torque mode"


z One load characteristic each is to be recorded for the star and delta circuits z Subject the motor to the load torques as given in the table z Enter the measured values (M, n, Uphase, Iphase) into the tables

14


Table1 (star connection)

Table2 (delta connection)

M/Nm 0 0.1 0.3 0.5 0.7 0.9n/(1/min)

Ustr/VIstr/A

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2M/Nm

0200400600800

10001200140016001800200022002400260028003000

n/(1

/min

)

0

50

100

150

200

250

Ust

r

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5

Istr

M/Nm 0 0.5 1 1.5 2 2.5n/(1/min)

Ustr/VIstr/A

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0M/Nm

0200400600800

10001200140016001800200022002400260028003000

n/(1

/min

)

0

50

100

150

200

250

300

350

400

Ust

r

0.0

0.3

0.6

0.9

1.2

1.5

1.8

2.1

2.4

2.7

3.0

Istr

15


Which of the statements below are true?

gfedc The maximum torque of the motor is identical for both circuit types gfedc In star configuration the phase current is lower gfedc A delta connection offers the better speed/torque

ratio as compared to a star circuit gfedc The starting current is generally lower for the star

connection than delta configuration gfedc The star/delta switch has practically no significance

at all gfedc The star/delta switch permits the motor to start "more

smoothly" gfedc In practice asynchronous motors are operated only in

star configuration

16


Definition of rotation direction If you look at the drive shaft end of the asynchronous 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.

Note: in the "Classic series" (0.3 KW & 1.0 KW) the rotation direction is determined by the rotation direction of the brake, i.e. if the asynchronous machine rotates clockwise, i.e. in the positive direction, the control unit of the brake indicates a negative rotation direction. Thus the rotation direction displayed is always that of the brake.

Training content: "Rotation reversal"

z Identify the difference between clockwise and anti-clockwise rotation

z Put the motor into operation in both rotation directions

17


Assembly instructions: "Rotation reversal"

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

Circuit diagram "Rotation reversal" (star/delta switch)

z Assemble the circuits as specified in the circuit diagrams and set-up

instructions below. z Switch on the brake too. This does not yet subject the motor to any load.

18


Set-up for "rotation reversal" (star/delta switch)

Rotation reversal


z Switch on the motor and observe how it responds

What is the motor's direction of rotation?

nmlkj The motor rotates clockwise nmlkj The motor rotates anti-clockwise

19


z Switch the motor off and modify the circuit according to the following circuit diagram

z Turn the motor back on and observe its response again

Circuit diagram "Rotation Reversal" (star-delta switch)

20


What is the motor's direction of rotation

How can the rotation direction of the three-phase asynchronous machine be reversed?

nmlkj The motor rotates clockwise nmlkj The motor rotates anti-clockwise

nmlkj Interchanging any two phase lines nmlkj Only by exchanging phase lines L2 & L3

21


22


Assembly instructions: "Load characteristics"

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

Training contents: "Load characteristics"

z Record the load characteristics of the motor z Determine the nominal torque z Determine the highest degree of efficiency z Study how the motor responds to loads

z Assemble the circuits as specified in the following circuit diagram and

set-up instructions. z Switch the brake on too. This does not yet subject the motor to any load.

23


Circuit diagram "Load characteristics" (star-delta switch)

24


Set-up "Load characteristics" (star-delta switch)

Recording the motor's load characteristics with the aid of the "ActiveDrive/ ActiveASMA" software

Required settings:

z Brake: { Industrial series: "PC mode" { Classic series: "Application mode" ( Note: when starting the

"ActiveASMA" software you will be prompted to select "Application mode")

25



z Start the "ActiveDrive/ActiveASMA" software z Select the operating mode "automatic speed control" z Apply the brake to the motor in 20 discrete steps until the motor ceases

to turn ( Note: in the "ActiveDrive / ActiveASMA" software enter the corresponding number of steps before this occurs under "Settings" -> "Presets" -> "Ramp")

z The load characteristics of the asynchronous motor are to be recorded for both star as well as delta connection

z Begin with a star connection z For each operating mode two graphs are plotted z Label and scale the graphs as shown in the place holders below z The following parameters are to be recorded:

{ In the first graph: Torque M(n) Slip s(n) ( Note: in the "ActiveDrive / ActiveASMA" software

enter the corresponding number of steps before this occurs under "Settings" -> "Presets" -> "Machine")

{ In the second graph: Mechanical power P2(n) Power factor cos(n) Efficiency (n)

z After completing the measurement, export the plotted graph and copy it in place of the placeholder below

z Determine the the highest possible efficiency (n) for each operating mode based on the second graph

26


Placeholder for the load graph (star connection); M(n); s(n)

Placeholder for load graph (star connection);

P2(n); cos(n) ;(n) ( => "eta")

27


Placeholder for load graph (delta connection); M(n); s(n)

Placeholder for load graph (delta connection); P2(n);cos (n); (n) ( => "eta")

28


What is the efficiency of the asynchronous machine in star configuration at nominal speed?

What is the torque of the asynchronous machine at nominal speed in star configuration?

What is the efficiency of the asynchronous machine in delta configuration at nominal speed?

What is the torque of the asynchronous machine at nominal speed in delta configuration?

= ____%

MN = ____Nm

= ____%

MN = ____Nm

29


30


Assembly instructions: "Reactive power compensation"

More detailed information regarding the brake can be found in the corresponding

online documentation

Training content: "Reactive power compensation"

z Understand the purpose of reactive power compensation z Recognise the influence of the connection configuration (Y- or

configuration) and the effect of the capacitance on reactive power compensation

z Assemble the circuits as specified in the following circuit diagrams and

set-up instructions. z Switch on the brake too. This does not yet subject the motor to any load.

31


Circuit diagram "Reactive power compensation" (star connection with compensation)

32


Set-up "Reactive power compensation" (star connection with compensation 0.5 F)

33


Set-up "Reactive power compensation" (star connection with compensation 1.0 F)

Recording a load characteristic for the motor in star configuration with compensation (0.5/1.0 F) using the "ActiveDrive/ActiveASMA" software

Required settings:

z Industrial series: "PC mode" z Classic series: "Application mode" ( Note: when starting the software

"ActiveASMA" you will be prompted to select "Application mode")

34



z Start the "ActiveDrive/ActiveASMA" software z Select "Automatic speed control" operating mode z The brake should be applied to the motor in 20 steps until the motor can no

longer rotate ( Note: enter the corresponding number of steps in the "ActiveDrive/ActiveASMA" software under the "Settings" -> "Presets" -> "Ramp")

z Record a load characteristic for the asynchronous motor in star configuration with various reactive power compensation levels

z Begin with a compensation of 0.5 F z A separate graph is to be plotted for each compensation z Label the graphs as in the placeholders below z The following parameters are to be recorded:

{ Apparent power S(n) { Active power P1(n) { Reactive power Q(n) { Power factor cos (n)

z After completing the measurements the graphs plotted should be exported and copied into the appropriate placeholders below

Placeholder for load graph; compensation 0.5 F

35



36


Circuit diagram "Reactive power compensation" (delta connection with compensation)

37


Set-up "Reactive compensation" (Delta connection with compensation 0.5 F)

38


Set-up "Reactive power compensation" (delta connection with compensation 1.0 F)

Recording a load characteristic for the motor in delta configuration with compensation (0.5/1.0 F) using the "ActiveDrive/ActiveASMA" software

Required settings:

z Brake: { Industrial series: "PC mode" { Classic series: "Application mode" ( Note: when starting the

"ActiveASMA" software you will be prompted to select "Application mode")

39



z Start the "ActiveDrive/ActiveASMA" software z Select "Automatic speed control" operating mode z The brake is to be applied to the motor in 20 discrete steps until the motor is

no longer able to rotate ( Note: enter the corresponding number of steps it takes for this to occur into "ActiveDrive/ActiveASMA" under "Settings" -> "Presets" -> "Ramp")

z Record a load characteristic for the asynchronous motor in delta configuration with various reactive power compensation levels

z Begin with a compensation level of 0.5 F z For each compensation level a separate graph is to be plotted z Label the graphs as shown in the placeholders below z The following parameters should be recorded:

{ Apparent power S(n) { Active power P1(n) { Reactive power Q(n) { Power factor cos (n)

z After completing the plots export the graphs and copy them into the corresponding placeholders below


40


Placeholder for load graphs; compensation 1.0 F

For which connection type is a higher reactive power compensation achieved?

What effect does the capacitance of the capacitors have on the performance?

nmlkj Star connection nmlkj Delta connection

gfedc None gfedc When the capacitors are too large the capacitive

reactive power is tapped from the mains gfedc An oversized capacitor reduces the capacitive load

on the mains and for that reason tends to be desirable gfedc In general the following holds true: the lower the

capacitance of the capacitors, the worse the reactive power compensation

More than one answer may be correct

41


42

EEM41 Three-phase asynchronous machines Asynchronous motor, Steinmetz circuit

Asynchronous motor, Steinmetz circuit

z Connection and starting z Load characteristics

On the subsequent pages you will be performing the following exercises on the asynchronous motor with a Steinmetz circuit:

43

EEM41 Three-phase asynchronous machinesAsynchronous motor, Steinmetz circuit

44


Assembly instructions: "Connection and starting"

More detailed information regarding the brake and the software can be found in

the appropriate online documentation

Training contents: "Connection and starting"

z Identify the motor terminals and operate the three-phase asynchronous motor using the Steinmetz circuit from a single-conductor mains (AC power mains)

z Measure the phase voltage and the phase current z Examine the attributes of the Steinmetz circuit with various

operating capacitors (capacitances) z Put the motor into operation with the brake z Subject the motor to loads

z Assemble the circuits as specified in the following circuit diagrams and

set-up instructions. z Switch on the brake too. This does not yet subject the motor to any load.

45


Circuit diagram "Connection and starting" (Steinmetz circuit)

46


Set-up "Connection and starting" (Steinmetz circuit, CB = 6F)

Putting the three-phase asynchronous motor into operation on the AC mains with the aid of an operating capacitor (CB=6F)

Required settings:

z Brake mode: "Torque control"


z Put the motor into operation and observe how it responds z Apply the brake to the motor until the motor reaches the nominal speed z At the same time measure the phase winding voltage and

current variables Uphase, Iphase and the required braking torque MBrake

Make sure that the ammeter and voltmeter are connected correctly

47


Enter your measurements

Set-up "Connection and starting" (Steinmetz circuit, CB = 3F)

Uphase = ____VIphase = ____AMBrake = ____Nm

z Now reduce the capacitance of the operating capacitor by modifying the

set-up as shown below.

48



z Put the motor back into operation and observe how it responds

How does the motor respond?

Which of the following statements are true?

nmlkj There is a severe delay before the motor starts to rotate nmlkj The motor does not start

gfedc Due to the lower capacitance of the operating capacitor, sufficient current cannot be induced and for that reason the motor does not start gfedc The size of the operating capacitor is irrelevant to the

starting response of the motor gfedc The greater the capacitance the higher the starting

torque gfedc Of course the size of the capacitor determines the

rotation direction of the asynchronous motor gfedc The torque of the three-phase motor connected to an

AC mains is considerably lower than one connected to a three-phase mains

More than one answer may be correct

49


50


Assembly instructions: "Load characteristics"

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

Training contents: "Load characteristics"

z Record the load characteristics of the motor z Compute the nominal torque z Determine the highest degree of efficiency z Study how the motor responds to loads

z Assemble the circuits according to the following circuit diagram and set-

up instructions. z Switch on the brake too. This does not yet subject the motor to any load.

51


Circuit diagram "Load characteristics" (Steinmetz circuit)

52


Set-up "Load characteristics " (Steinmetz circuit, CB = 6F)

53


Required settings:

z Brake: "PC mode" or "Application mode" ( Note: when starting the "ActiveASMA" software you will be prompted to select "Application mode")


z Start the "ActiveDrive/ActiveASMA" software z Select "Automatic speed control" operating mode z The brake is applied to the motor in 20 discrete steps until a speed of 1200

rpms is reached ( Note: enter the corresponding number of steps it takes to achieve this in the "ActiveDrive/ActiveASMA" software under "Settings" -> "Presets" -> "Ramp".)

z Record load characteristics for the asynchronous motor on an AC mains z A total of two graphs are to be recorded z Label and scale the graphs as in the appropriate placeholders shown below z The following parameters are to be recorded:

{ In the first graph: Torque M(n) Degree of efficiency (n)

{ In the second graph: Mechanical power P2(n) Apparent power S(n) Active power P1(n) Reactive power Q(n)

z After completing the measurement export the plotted graphs and copy them into the appropriate placeholders below

54


Placeholder for load graph; M(n); (n) ( => "eta")

Placeholder for load graph; P2(n); S(n); P1(n); Q(n)

55


Based on the first graph determine the efficiency for the nominal speed

= ____%

56

EEM41 Three-phase asynchronous machines Copyright

Copyright 2004-2006 LUCAS-NLLE GmbH.

This course "EEM 41 Three-phase asynchronous 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-NLLE 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-NLLE GmbH, any product liability or warranty claims pertaining thereto are null and void.

Congratulations! This is the last page. You have completed the course "EEM41 Three-phase asynchronous machines".

57

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Lucas-Nlle Lehr- und Megerte GmbHSiemensstrae 2 D-50170 Kerpen-Sindorf

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

www.lucas-nuelle.de

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