Re: [MV] 12V - 24V - 36V

SBJohnston@aol.com
Sat, 10 Jul 1999 11:37:29 EDT

Brian wrote:

>Can someone more electricly inclined than I explain why
>some mil equipment some as missile systems and sonar
>systems run at 400HZ / rather than 60HZ?

Applications where weight/size is a concern, such as in a flying machine,
often use 400 Hz AC instead of 60 Hz AC because at a higher frequency the
transformers can be much smaller/lighter for the same power level. I don't
know for certain why this was standardized at 400 Hz.

One drawback to the use of a higher frequency is that any residual "hum" is
going to be a very audible whine instead of the low buzz heard from 60 Hz
systems. Think about the whine often heard on airliner PA announcements and
you'll know what I mean.

Steve Johnston

sbjohnston@aol.com

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