synchronous machine lab book

8/10/2019 Synchronous Machine Lab Book

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Synchronous Machine Lab Book

Danijel Matejevi

Jrme Clavel

Marko Petkovi


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Tests to perform:

- Rs measurement

- No-load test

-

Short-circuit test- Synchronisation test

- Negative excitation test

Rs measurement

Wiring scheme:

Procedure:

Connect a Multimeter and set to resistance measurement, plug in between U1 and u1,

V1 and v1 or W1 and w1 and measure the resistance

Result:

Rs = 3

No-load test

The test is done using a DC machine coupled with synchronous machine. Nameplate

values of both machines will be presented in equipment used section.

Wiring scheme:


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Procedure:

- Increase the DC machine excitation current to 0.8A on table 7. First switch on

the table 7 and turn the switch for setting excitation current to 1.- Increase the voltage on DC machine on table 5 until reaching nominal speed of1500rpm

- Switch on the excitation of SM on table 1 and set the excitation current to 0A

- Record values of excitation current and the voltage at 0A excitation current

- Increase the voltage, thus increasing the excitation current and monitor thefrequency of the stator

- Increase the voltage until reaching 220V on the machine- After finished, decrease the excitation voltage until reaching zero excitation

current and disconnect the excitation, switch off- Decrease the armature voltage of the DC machine until the machine stops-

Decrease the armature current of the DC machine until it reaches 0. Switch to

0.

Equipment used:

DC Machine GL100 28W2F2A: M545Synchronous machine, nameplate values

- Pn = 1840W- cos = 0.8- Un = 220V/380V

-

In = 6.1A/3.5A- S = 2300VA- n = 1500 rpm

Tachometer Reo 444 R1 F909 (more accurate than the one build in the bench)MultimeterMX54C, lab designation AV1004

Wattmeter: Yokogawa WT230 W110

Results:

See annexe with Excel graph and values

At 0A excitation current we see that there are 3.74V on the machine on the stator. Thisis due to the remanence effect. We see that the voltage is linear up to some point, thenit loses linearity due to the saturation. All calculations will be done using linear part ofthe voltage characteristics!

During the test we obtained the constant speed, which is required during the test, by

monitoring the frequency as a more precise way than if we would have measured thespeed. We also measured the speed with tachometer just to be sure and to make a

comparison.


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Short-circuit test

Wiring scheme:

Procedure:

- Connect SM stator into a short-circuit

- Set excitation of DC machine to 0.8A, its nominal value

-

Increase speed of DC machine to 1500rpm, its nominal value- Observe the current and voltage on the SM and notice that there is some

current circulating and some voltage due to the remnant field.- Switch from 0 to 1 on table 1 switch and increase the excitation current of SM

in steps of 0.2A until reaching 3.5A stator current, nominal value of stator

current

Equipment used:DC Machine GL100 28W2F2A: M545Synchronous machine, nameplate values

- Pn = 1840W- cos = 0.8- Un = 220V/380V- In = 6.1A/3.5A- S = 2300VA- n = 1500 rpm

Tachometer Reo 444 R1 F909 (more accurate than the one build in the bench)MultimeterMX54C, lab designation AV1004


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Wattmeter: Yokogawa WT230 W110

Most basic lab switch

Results:

See annexe.

Now, form the no-load and short-circuit test we can determine the Xd reactance, the

saturated one. This is done by choosing the nominal voltage of the no-load test and

reading the value of the excitation current. Then, this excitation current is used to findthe value of the stator short-circuit current and the result is obtained by the formula:

=0

= 77.1

Where Un0 is nominal voltage and Icc is the stator current corresponding to

excitation current for which Un0 is obtained.

What is interesting to see is that even we have a short circuit on the stator there is some

voltage on the stator side. Theoretically, there should be no voltage because of the shortcircuit. This might be because the voltage is not purely symmetrical.

Synchronisation with the grid

Wiring scheme:

Procedure:

- Increase the DC machine excitation current to 0.8A on table 7. First switch on

the table 7 and turn the switch for setting excitation current to 1.

- Increase the voltage on DC machine on table 5 until almost 1500rpm.1500rpm should never be set as the SM would not be able to synchronise

properly- Increase the SM voltage to 220V- Check the rotation direction of the grid and order of phases- Check the rotation direction of the machine and order of the phases- Recheck the phases between the machine and the table to be sure- Observe the synchroscope and watch if the frequencies and voltages match

-

Wait until the turning hand on the synchroscope matches the red hand, thenturn the switch on

- To disconnect the machine do everything above in reverse order

Equipment used:

Results and observations:

synchronous machine lab book

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