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From: Robert Baer
X-Mailer: Mozilla 4.75 [en] (Win98; U)
Subject: Re: TRIAC "wears out" on dimmer circuit
References: <3DB89391.E73EF17E@earthlink.net> <3DBA2E08.19B9E242@earthlink.net> <firstname.lastname@example.org>
Date: Mon, 28 Oct 2002 03:55:02 GMT
NNTP-Posting-Date: Sun, 27 Oct 2002 19:55:02 PST
Organization: EarthLink Inc. -- http://www.EarthLink.net
Phil Allison wrote:
> "Robert Baer" wrote in message
> > Phil Allison wrote:
> > >
> > > "Robert Baer" wrote in message
> > > news:3DB89391.E73EF17E@earthlink.net...
> > >
> > > (snip)
> > >
> > > > Also please note the surge or turn-on current is much larger than
> > > > think.
> > >
> > > ** Are you a mind reader ?? The OP did not give any size for the
> > > surge.
> > >
> > > It would be about 16 amps peak for the first cycle or so -
> > > within the 12 amp triac's surge limits.
> > >
> > > . . . . . ............... Phil
> > But *NOT* within the unpublished I*I*T rating (spoken as "eye squared
> > tee")!
> ** So you are a double mind reader. First you read the OP's mind
> now you inform us that an unpublished I*I*t spec is unbelievably poor.
> The ITSM figure for the TIC 236 D is given as 100 amps and this
> is typical for a 12 amp triac which have I*I*t figures of about 40. Have
> you any reason, that does not involve ESP, to say that a 240 watt lamp load
> will do it in.
> ..................... Phil
By your own statement, the lamp takes 16 amp peak and the rating is 12
So by that alone, the rating is exceeded.
I have worked with Ignitrons, SCRs, Triacs and other solid state
devices in the daze (long ago) when I*I*T ratings were published or
otherwise reasonably available.
No current published data sheets by manufacturers give I*I*T ratings;
that info seems to have gone by way of the metaphorical dinosaur,
roughly 30 years ago.
The so-called info via ISTM looks as flaky as using a 2N2222 chip
mounted in a TO-3 package for 1 amp switching (do not laugh; this has
been done; prolly by execs that moved on to Enron).
And i can categorically state that one can be within current, power
and voltage ratings (even within SOAR ratings) and *still* be way
outside I*I*T ratings of these devices.
I do not have to be a mind reader to know that the resistance of any
incandescent lamp (or tube filament for that matter) is far lower than
the steady state resistance.
All one needs a little simple knowledge and the rest is a logical
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