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Topic Title: Polarization Test Of Motor.
Topic Summary:
Created On: 29 September 2017 12:57 PM
Status: Read Only
Linear : Threading : Single : Branch
 Polarization Test Of Motor.   - Zoomup - 29 September 2017 12:57 PM  
 Polarization Test Of Motor.   - davezawadi - 29 September 2017 01:09 PM  
 Polarization Test Of Motor.   - Fm - 29 September 2017 04:05 PM  
 Polarization Test Of Motor.   - ToniSM - 30 September 2017 02:02 PM  
 Polarization Test Of Motor.   - AncientMariner - 30 September 2017 10:03 PM  
 Polarization Test Of Motor.   - ToniSM - 01 October 2017 02:55 PM  
 Polarization Test Of Motor.   - rocknroll - 01 October 2017 03:34 PM  
 Polarization Test Of Motor.   - mapj1 - 01 October 2017 09:36 PM  
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 29 September 2017 12:57 PM
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Zoomup

Posts: 3266
Joined: 20 February 2014

Does anybody actually do this test?

http://www.youtube.com/watch?v=FUjZwMMoltQ

Z.
 29 September 2017 01:09 PM
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davezawadi

Posts: 3845
Joined: 26 June 2002

If you refurbish a motor one would, but it only needs to be done once. The IR test would follow normal maintenance procedures.

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk
 29 September 2017 04:05 PM
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Fm

Posts: 1710
Joined: 24 August 2011

We used to do it as part of our commissioning checks

Equipment could be ordered, sit in a yard, delivery to site, site on site for a long time, so this was down prior to mechanical installation.
Info recorded on commissioning sheet for the particular asset
 30 September 2017 02:02 PM
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ToniSM

Posts: 329
Joined: 21 November 2006

I'd like to know how he knew he had got the finish U2 V2 W2 one of them could be the start.

-------------------------
Could there be a better way?

In theory yes, but in practice?
 30 September 2017 10:03 PM
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AncientMariner

Posts: 709
Joined: 14 December 2004

Just over 25 years ago I went on a Ship's Electrical course at South Shields Tech.

One of the tasks was to correctly identify the U1/2, V1/2 & W1/2 connections of the 3-phase motor. The six ends had been brought out to a test board, each terminated in a 4mm socket, but not marked up. Once we had identified the three windings, it was a case of trying each combination in turn using 4mm plug terminated test leads. The 415v supply was brought to rewireable fuses, so it was a case of make a guess, try it and replace the blown fuse wire until we had a running motor. I was horrified when I first saw it, but no easy way without specialised test equipment to do it. And on a merchant navy ship we certainly did not have specialised test equipment!

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Clive S Carver GCGI IEng MIET MITP
 01 October 2017 02:55 PM
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ToniSM

Posts: 329
Joined: 21 November 2006

There is a test for locating the start and end of the winding using a low voltage AC supply. For some reason I can't upload pictures.

-------------------------
Could there be a better way?

In theory yes, but in practice?
 01 October 2017 03:34 PM
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rocknroll

Posts: 9541
Joined: 03 October 2005

Originally posted by: ToniSM

There is a test for locating the start and end of the winding using a low voltage AC supply. For some reason I can't upload pictures.


Your talking about the simple polarisation test that we were taught on the C course and also featured in the exam.
First you identified the coils using a mulitmeter and marked them A, B and C, then you connected two of the coils in series and applied 240V and if the voltage reading was lower than the applied voltage then you marked them A1, A2, B1, B2 respectively, you did the same to the C pair with one of the other windings.

Regards

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"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 01 October 2017 09:36 PM
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mapj1

Posts: 9348
Joined: 22 July 2004

I have used a variant of the fuse blowing method with three lamps as current limiters, one in series each line, and the option to switch in some low resistance loads.
I reused that visible over current indicator idea with a piece of wood and two forks wired across the mains and a quartz halogen flood lamp in series, as a mains fired pickle or sausage 'cooker' to demonstrate the dangers of electricity. (Scouts again, yes a push button and a key switch too.)

-------------------------
regards Mike
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