Author Topic: Copper Magnet Wire Breakdown Voltage  (Read 6465 times)

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Offline ZeroResistanceTopic starter

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Copper Magnet Wire Breakdown Voltage
« on: September 21, 2018, 08:24:55 am »
I intend to use round enamelled copper wire for voltages upto 500V.

I see that as per https://en.wikipedia.org/wiki/Magnet_wire.

Quote
Breakdown voltage depends on the thickness of the covering, which can be of 3 types: Grade 1, Grade 2 and Grade 3. Higher grades have thicker insulation and thus higher breakdown voltages.

In the 500V application that I have is of a capacitor discharge magnetizer, the magnet wire would be subjected to current pulses not more than 10A. Capacitor would be charged to upto 500V.

My questions are do I really need to used Grade III wire for this application.
what kind of enamel coating is suitable for this voltage range, I see that threre are a range of single and dual coat insulation coatings for magnet wire. Polyester, Polyesteramide, Polyamide-Imide.
Is thare an insualtion coating well suited for this voltage range.

There is also thermal class. But currently I'am more concerned for the voltage breakdown rating of the wire.

Thanks in Advance.
 

Offline IanB

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Re: Copper Magnet Wire Breakdown Voltage
« Reply #1 on: September 21, 2018, 09:38:31 am »
You care about the voltage difference between the wire and anything it is touching. Commonly this would be adjacent turns in a coil, so that voltage per turn becomes important.

A higher voltage could exist between one layer of a coil and the next outer/inner layer. This can be mitigated by including a wrap of insulation between each layer on the coil former.

Given these considerations, the source voltage of 500 V is almost irrelevant. You need to consider the worst case insulation stress based on the design of your system and where maximum voltage differences will appear.
 
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Offline ZeroResistanceTopic starter

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Re: Copper Magnet Wire Breakdown Voltage
« Reply #2 on: September 21, 2018, 12:20:02 pm »
A higher voltage could exist between one layer of a coil and the next outer/inner layer. This can be mitigated by including a wrap of insulation between each layer on the coil former.
I am actually trying to avoid putting in the extra insulation and for this going in for either Grade II or Grade III magnet wire which has a thicker insulation than Grade I.
I have found a table of insulation thicknesses for various grades and various AWG / SWG sizes of conductors. However to add to this I need a method to calculate the breakdown voltage for a particular conductor dia and particular enamel thickness, maybe enamel material also comes into play here.
That would enable me to select either Grade I , II or III.
 

Offline tpowell1830

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Re: Copper Magnet Wire Breakdown Voltage
« Reply #3 on: September 21, 2018, 12:31:38 pm »
I see you are focusing on the wire, although the only determining factor is the actual coating breakdown voltage parameters. Any insulating materials have a breakdown voltage rating and this is also determined per thickness (i.e. per mm). You would then have to know how many mm the coating is and then determine whether it suits your needs. For instance PTFE breakdown voltage is 19.7 KV/mm. This is also know as the dielectric strength. Magnet wire is coated with different types of material and this is your determining factor.

Hope this helps...
PEACE===>T
 
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