CutTthrough Test for Enameled Copper Wire

Dear Sir,

I have few questions for you regarding cut through test for enameled copper wire.It is about the testing conditions and impact of the same on final outcome. Testing conditions are as given below:-

1) Test voltage -- 80 volts(Standard requires ---100 +/- 10V )

2)Current -- 1mA (Standard requires --- 5mA +/- 1mA )

3) Temperature variation of 7 degrees.(Standard requires --- +/- 3 degrees.

Please help me in this regard.

Best Regards
Prashant

Hello Prashant,

I am not a magnet wire expert but, when it comes to standard tests, it would seem to me that that the standards are what you should be following unless of course, some customer wants the tests done at some other values.

No sense arguing this point. Standards are standards so that results can be properly evaluated and compared.

Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641- 3212

First off any testing that is not done to an accepted standard would therefore be non-standard wire.

If the standard require 100 V +/- 10 then 80 is wrong and your results would probably look better with 80 V then with the standard 100 V.

if the standard requires the current to be 5mA +/- 1mA then if you are using 1mA you are using a current that is only 20% of required. With a lower current again the wire would look better than it actually is when tested like this.

Finally you mention temperature. Thermoplastic flow or cut-thru test are conducted in a heating chamber device where the wires are mounted so that the criss cross, a weight is applied, and the device chamber is heated until the coating become plastic and the applied weight causes the coating to be displaced and when the thickness devreases the coating will be too thin to prevent a short circuit and when it cuts thru, the temperature is noted. It is not unusual for the values to be different. Typically they should be approximately 1.9 to 2.1 times the thermal rating of the wire.

Typically 5 or six samples are tested at the same time and the highest and lowest is discarded and the other 3 or 4 averaged.

I don't ahve a copy of the standard but I'd be less concerned about a 7 degeree variation then I would about testing with low voltage and curent.