[R-390] Another xfmr question

[Scott, Barry (Clyde B)]

Roy,

Yes, I plan to do all three of your "end notes".

I may drop the guys at Signal a note and see what they say.

Thanks again,

Barry(III) - N4BUQ

-----Original Message-----
From: Roy Morgan [mailto:roy.morgan@nist.gov]
Sent: Wednesday, November 05, 2003 11:22 AM
To: Scott, Barry (Clyde B); R390 (E-mail)
Subject: Re: [R-390] Another xfmr question


At 10:50 AM 11/5/03 -0600, Scott, Barry (Clyde B) wrote:
>At the risk of being chased off the list...
>
>http://www.belfuse.com/Data/DBObject/pgs28_29.pdf
>The same transformer in question 1 has a primary tap at 110VAC.  Is it
>unadvisable to run the primary at this tap given a line voltage of 123VAC?

I predict it will work fine, for two reasons:
1) these are "industrial grade" transformers. That means continuous duty.
2) They are meant for 50 cycles to 400 cycles.. That means it has a larger 
core than would be needed for 60 cycle minimum operation.

>Using the 120VAC primary, the 110VAC tap is a bit too low.  I was thinking
>if I run the primary at the 110VAC tap and use the 104VAC secondary tap, I
>might get closer to 115VAC on the output.

You will get (roughly) 104/110 of the input voltage, or about 95 
percent.  So if your input (line) voltage is 122 like it is at my house, 
you'll get about 115 volts out.

>   Is it simply an effeciency thing that
>won't harm the transformer or is there more smoke risk?

I predict no smoke.  You could always send the folks at Signal Transformer 
company a short note asking if this is ok (say it's intermittent duty and 
you expect to not be drawing full rated load.)

Here is your link to their "Contact Signal" page. In about two minutes 
you'll be done:
<http://www.belfuse.com/signaltransformer/ContactSignal.asp>

Last notes:

1) Fuse at least the input of the thing.
2) Use three wire grounded line cord and ouput outlets.
3) House the thing in a case that protects you, the cat, and the kids from 
contacting the open terminals on the thing!




- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
roy.morgan@nist.gov --