Re: Mylar sheeting

• To: tesla-at-pupman-dot-com
• Subject: Re: Mylar sheeting
• From: Teslaman-at-aol-dot-com (by way of Terry Fritz <twf-at-verinet-dot-com>)
• Date: Sun, 18 Apr 1999 20:10:15 -0600
• Approved: twf-at-verinet-dot-com

In a message dated 4/18/99 5:48:44 AM Central Daylight Time, tesla-at-pupman-dot-com 
writes:

> Can anyone tell me what the dielectric strength of mylar is per mil of
>  thickness? I am building a custom made transformer and I want to use mylar 
> as
>  an interlayer insulation.
>   
  Max

  Mylar (polyester)  has several different grades.  The perfect type for 
transformers would be type MO and EL but any will work as I have used it in 
high voltage transformers without failure.  For insulation  between a high 
voltage winding and the core I would use polyethylene if they are close 
together.  

  Short term dielectric strength for 1 mil  D.C. 25 deg. C. 14 kV, for 60 HZ, 
7500 volts, and at 150 deg. C 5000 volts.  Dissipation factor is .0025 -at- 
60HZ.  Corona resistance for 3 mil. is 30 hours at 3000 volt 60 HZ 25 deg. C. 
 Melting point for type A is 250 deg. C. Service temp. 150 deg. C.  Does 
deteriorate over time slightly in hydrocarbon based oil.

  Mylar is getting hard to find at our local Regal Plastic outlet, I used to 
buy 20" x 50" x 0.007" sheets for $2.00.  They replaced it with lexan 
(polycarbonate) film.

Hope this helps.

Kevin E.

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