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G8MNY > TECH 16.03.08 03:00l 50 Lines 2440 Bytes #999 (0) @ WW
BID : 50256_GB7CIP
Read: GUEST
Subj: Variacs
Path: IZ3LSV<IW2OHX<OE6XPE<DB0RES<ON0AR<ON4HU<ON0BEL<GB7CIP
Sent: 080315/2356Z @:GB7CIP.#32.GBR.EU #:50256 [Caterham] $:50256_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (New Dec 07)
(8 Bit ASCII Graphics use code page 437 or 850)
Varaic is a traded name of The General Radio Co for a variable tapped toroid
mains transformer usually with up to 17% overvoltage.
260 o___ Ratings are normally in amps. But this can be
240 o_||) fuse confusing as the laminate core will have a power
LÄo-oÄÄÄo___||)<ÄoÄoÄL rating as a 50% step down auto transformer which is
fuse 220 ||) when the core has the maximum work to do of half the
||) output rating, as half the output current flows
||) through the top section & half comes up from the
0o_||) lower. However using a few % from the top or bottom
NÄÄÄÄÄÄÄÄÄo_||)______N you can easily cook the winding as the core can put
-10 ³ out huge currents. So an input & output fuse is needed
EÄÄÄÄÄÄÄÄÄoÄÄÁÄÄÄÄÄÄÄE to protect it! e.g. 250VA one needs a 1.5A slow blow
mains fuse & a 3A fast blow on the output should do.
Wiper _ Turns
ÜÜÜ======³ ³ Bared _.úÂÂÂú._
Ú---------------------¿ .ú~ /~\ ~ú.
³²²²²²²²²²²²²²²²²²²²²²³ .' \ ³ Û ³ / '.
³²²²²²²²²²²²²²²²²²²²²²³ / .ú' ³ ³ 'ú. \
³²²²²²²²²²²²²²²²²²²²²²³One layer Þ . ³ ³ . Ý
³²²²²²²²²²²²²²²²²²²²²²³of winding |___ / \ ___|
³²²²²²²²²²²²²²²²²²²²²²³ ÝÄÄ: ³ 0 ³ :ÄÄÞ
³²²²²²²²²²²²²²²²²²²²²²³ |~~~ \ / ~~~|
³²²²²²²²²²²²²²²²²²²²²²³ Þ ' ~---~ ' Ý
³²²²²²²²²²²²²²²²²²²²²²³ \ 'ú. .ú' /
³²²²²²²²²²²²²²²²²²²²²²³ '. / ' úúú ' \ .'
~~~~~~~~~³ ³~~~~~~~~~ 'ú._ ³³³ _.ú'
³ ³Shaft ~~ÁÁÁ~~
ÀÄÙfor
knob
Bad arcing can damage the brush & windings. Do check the brush & spring out if
you have arcing. Insulation damage can cause fires as a shorted turn has almost
infinite current available.
With toroidals the winding are exposed on the outside & variacs even more so if
the bare windings are not fully encased,
Why Don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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