Surge test of deltas and wyes

[RUSO]

Hope someone can tell me what to do. How do you hook up a wye or delta wound coil to a surge tester/??? I know how to hipot the coil. Do you do a combination 2 wires at a time? Do 2 wires on one tester lead and the remaing one on the other?? Any help would be good. Thanks...

 

[DougMSOE]

Usually, a surge tester comparies one coil to the other, at least the Baker and PJ electronics equipment does. The surge testers that I have used have a common lead that is the "neutral" for both coils. The other 2 leads go to the other ends of their respective coils. BUT, with a delta winding you need to disconnect all of the coils. Otherwise you will get a cross feed from the coil "not under test". This will destroy the test results.
One more point, if you are doing this test to a machine that has already been wound you are wasting your time as the nature of the iron core will allow the surge to go about 2 turns around the coil before the 'surge' has been attenuated to an extent that the volts /turn is less than the actual line voltage. Take a look at any book on surge attenuation.

 

[electricpete]

I agree 100% with Doug on the subject that most of surge appears across the first few turns.

I don't necessarily agree that this means surge test on a wound machine meaningless. I guess you have to get a little philosophical about the purpose of a surge test:
A - If it is to verify that the motor will stand up to surges during operation, then it is very useful. The coils which are susceptible to damage from surges during operaiton are the same coils that are stressed during testing (the line end coils). Coils in middle of the winding won't be tested but they are not exposed to surges during operation so who cares?
B - If purpose of the test is intended to check the entire winding, then it is very limited. This might apply for instance if we rewedged the machine and wanted to make sure we hadn't caused damage. Or quality control check of new winding. In both cases surge test on the complete winding is limited.

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[edison123]

RUSO

I have used 3 types of Baker surge testers on both delta & wye connected windings. No need to disconnect any coils. If you have 3 leads (say U, V & W)coming out of the winding, here is how it goes:

Type 1 - 2 hot leads (red) 2 cold leads (black)

Two hot leads to U & V, One cold lead to W and other cold lead to stator/rotor frame. Then switch 2 hot leads to V&W, the col lead to U and so on for the last two phases.


Type 2 - Three hot leads (red) 1 cold lead (black) with selector switch (SS)

Simplest - Connect the 3 hot leads to the 3 phases and the cold lead to the frame. Use SS to test two phases at a time.


Type 3 - One hot lead and one cold lead with storage facility.

One hot lead to U and the cold lead to V. Store result and recall it back to the CRO. Switch hot lead to V and the cold lead to W and compare with the earlier waveform. Repeat for W phase.


Finally, I have been using surge testing for nearly a decade and I have found it to be a good PM tool regardless of reservations expressed about its utility. I would strongly recommend it as a PM tool and also as a part of QA program in new motors & rewinds.

 

[jbartos]

Suggestion: Please, post nameplate data of the surge tester.

 

[powerjunx]

i agree to EDZ.., RUS.

BAker tester is also comparable to the test set up or procedure using ELECTROVOM surge comparison tester.

it is only that there is a 4 test probes that is 1, 2, 3 probes are for the so called hot leads, and fourth is the ground lead (for the frame).

simply, hooked up the hot leads (1,2,3) to the motor leads (wye or delta - T1,T2,T3 or U,V,W)in any order provided it's a three leads out (otherwise you configured your connection to obtain three leads out), then proceed to the test equipment's toggle switches and test voltage knobs to test the motor winding.

you might noticed in testing on wye connectecd motor the waveform reflected on the screen is more than as compared to delta connected.since wye connected coils have more resistance as compared to delta.

in the case on using two leads at a time, its also allowable as what EDS cited..

but in testing on the group of coils as in partially rewinded pre-formed coils or it was just formed, you must configure the coil leads to fit to the test leads of the surge tester that is you will combine test leads 3 and ground lead, and 1, 2 leads will then be your hot leads to test the coils or group of coils.

 

[lixc]

Hi guys,
I am new in industry. I din know much about motor.
Can I ask whether I can use surge test for voice coil ?
The voice coil is for speaker. The wire is very thin, like 0.12 or 0.08 mm.

Can I use surge test to test whether there is any short-circuit or open-circuit (even intermittent ones ?

I come across Baker Sidewinder 6000 and WK 6815. They claimed that their tester can detect the defect that I said without damaging the coil.

Hope you guys can help me.

Thank you.

 

[jbartos]

Comment: To be on the safe side, the conductor insulation parameters should be known as well as the tester voltage and voltage type. As far as the conductor test voltage and duration of the test, the conductor or device manufacturer tech support should be contacted first for guidance.

 

[powerjunx]

hi lixc..

evidently, your voice coil has more ohmic resistance as compared to motor windings.when testing, a result would be definitely, you can not view the desired waveform and you might found that it is solidly grounded..as you conclude. id done this upon testing dc motor shunt field coils.. for single coil.

it is better as i practice to insert a parallel resistor - small as your coil - for you will have a small resistance appeared to your surge test leads..so you will view a better result.

when testing, still you have to follow the standard test voltage to your coil rating.. BUT you cannot find a surge tester having a precision test voltage as low as your coil rating since most tester are standardize from minimum of 250 volts per division and above. note: inducing to much test voltage to your coil will damage your coil.

regards.

 

[lixc]

Hi fbjavier:
Thank yuo for replying my question.
The DC resistance of the voicce coil is around 1.x to 4.x .
The Wagne Kerr representative claimed that their tester will not damage the voice coil and still can detect the intermittent cases. He din mention about adding anything to the coil. U think he is lying to me ?
From the spec he gave me, the tester minimum voltage is 500v.
So I have to add a parallel resistor to the voice coil? but how many wattage the resistor should have ?
So actually can I use surge test to test the voice coil ?

Thank you.

 

[powerjunx]

lixc, i think he nver lies.. id give you a better views about your problem but i suggest that the representative knows more about the capabilty of their instrument to test the coil, since instrument manufacturers have different internal circuitry of their products.

important point is:

as long as the test instrument have the conclusive result, absolutely you never add any resistor on it otherwise you have to, as i mentioned before( a resistor that is approximately equal to the coil resistance ).

use test voltage that suits to your coil voltage rating, to protect the coil from damage.

regards.

 

[lixc]

Hi fbjavier[/]:
Thanks for the advice.

 

[jbartos]

Suggestion: Visit

http://www.birclar.com/surge.htm

http://www.plantservices.com/Web_First/ps.nsf/ArticleID/MMHH-4MSE6R/

etc. for surge testing

 

[lixc]

hi jbartos
Thanks for the website.