AC motor doc

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 Reversal of rotation Prerequ

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SH5007-1D Version 1.0 Author: M.Germeroth Lucas-Nülle GmbH · Siemensstraße 2 · D-50170 Kerpen (Sindorf)

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 Reversal of rotation

Prerequisites

z Basic knowledge of electrical engineering

Welcome to the Three-phase Asynchronous Machine course The

team from LUCAS-NÜLLE 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

SO3636-6U Active machine test stand 300 W 1 each

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

{ 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

can subject the machines to excessive heating

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

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

Asynchronous motors

z Connection and starting

z Rotation reversal

z Load characteristics

z Dynamic load experiments (Classic series only )

On the subsequent pages you will be performing the following exercises

on the "asynchronous motor":

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 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

UN star circuit connection V

UN delta circuit connection V

IN delta circuit connection A

Uphase= V

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

Putting the asynchronous motor into operation in star configuration

Required settings:

z Brake mode: "Torque Control"

z Put the motor into operation and observe its response

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= V

Iphase= A

Circuit diagram "Connection & starting" (delta connection)

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

z Put the motor into operation and observe its response

z At the same time measure the phase variables Uphase and Iphase

Make sure that the ammeter and voltmeters have been connected correctly

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"

Experiment procedure:

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

Table1 (star connection)

Table2 (delta connection)

200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000

200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000

Which of the statements below are true?

g The maximum torque of the motor is identical for

both circuit types

g In star configuration the phase current is lower

g A delta connection offers the better speed/torque

ratio as compared to a star circuit

g The starting current is generally lower for the star

connection than delta configuration

g The star/delta switch has practically no significance

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

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

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

Rotation reversal

Experiment procedure:

What is the motor's direction of rotation?

diagram

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

What is the motor's direction of rotation

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

n Only by exchanging phase lines L2 & L3

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 highest degree of efficiency

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

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

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

{ Industrial series: "PC mode"

{ Classic series: "Application mode" ( Note: when starting the

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

mode")

Experiment procedure:

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 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:

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

Placeholder for load graph (star connection);

P2(n); cosφ(n) ;η(n) (η => "eta")

Placeholder for load graph (delta connection);

P2(n);cos φ(n); η(n) (η => "eta")

What is the efficiency of the asynchronous machine in star configuration at

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 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

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

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

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

Recording a load characteristic for the motor in star configuration with compensation (0.5/1.0 µF) 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")

Experiment procedure:

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 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 φ(n)

and copied into the appropriate placeholders below

Placeholder for load graph; compensation 0.5 µF

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

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

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

Recording a load characteristic for the motor in delta configuration with

compensation (0.5/1.0 µF) using the "ActiveDrive/ActiveASMA" software

Required settings:

{ Industrial series: "PC mode"

{ Classic series: "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 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 µF

z For each compensation level a separate graph is to be plotted

{ Apparent power S(n)

{ Active power P1(n)

{ Reactive power Q(n)

{ Power factor cos φ(n)

z After completing the plots export the graphs and copy them into the

corresponding placeholders below

Placeholder for load graph; compensation 0.5 µF

Placeholder for load graphs; compensation 1.0 µF

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

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

g When the capacitors are too large the capacitive

reactive power is tapped from the mains

on the mains and for that reason tends to be

desirable

g 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

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:

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 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

Circuit diagram "Connection and starting" (Steinmetz circuit)

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

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

Required settings:

z Brake mode: "Torque control"

Experiment procedure:

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

current variables Uphase, Iphase and the required braking torque MBrake

Make sure that the ammeter and voltmeter are connected correctly