According to William Noble :
But also check space around the heat sink, to make sure that there is room for the stud and nut in place of the press-fit. You may have to stick with the press-fit to keep the form factor reasonable.
Right -- make sure of everything which was connected to it.
Enjoy, DoN.
According to Ted Samuels :
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I've never seen one of those, and I would think that one for such a low frequency would have enough iron so it would have no troubles with 60 Hz. Are you sure that wasn't "360 cycles per second"? That would be close to the 400 Hz ones which I have used -- and *those* just plain won't work with 60 Hz at normal voltage. :-)
also -- was it a genuine Variac (made by General Radio), or another brand of variable autotransformer? The 400 Hz ones above were genuine Variacs.
Enjoy, DoN.
Oh yes. Google 6 HZ and you'll get more hits then you would ever imagine. Believe me I had to do a double take when I read the "per minute".
I think the deal is that that there just are not enough turns to produce enough CEMF, so at 60 hz and 110 volts the windings that are there, did not short circuit, but really there was just to much amperage for the breaker.
T talking as if he knew something about the subject.
I have no doubt. The variac is a genuine Variac.
top posted again to annoy everyone.
I would speculate that you wired it incorrectly - did you try looking up the specific variac on the superior electric (I think that's right) web site? can you explain exactly how you wired it? does it trip the breaker if you disconnect the bridge?
Got to correct a couple of statements I made:
1st. While this unit carries the registered "Variac (R)" name, it was made by Technipower of Davis instruments and calibration2nd. I initially read 350 cycles per minute but when I was on the computer I automatically assumed that I must have read 360 CPM , (Makes more sense to me.) On a re read I find that it actually says "350 Cycles Min."
God I hate making mistakes.
T
I was wrong about the 6HZ but not by much. I assumed that I was in error when I read
350 CPM and wrote 360 CPM but it was in fact 350 CPM (5.83 HZ)As I mentioned to Don : this unit carries the registered Variac(R) trademark but was not made by superior, it was made by Technipower of Davis instruments and calibration, type M 10, CDC part number 23253800.
Not at all in doubt about wiring as I removed that Variac and replaced it with another and it's working just fine. The only question I have is that the motor I am running is rated as 60 volts at 11.2 amps and the Variac is rated as 120 Volt at
6.0 amps.I would assume I'm OK with a 672 watt load through a 720 watt transformer but maybe there is something I am missing.
I ran continuously (no load) for 15 min and found no heating of the Variac the bridge rectifier or the motor.
T
The tradename for Superior's variable transformers was Powerstat. GenRad (the successor to General Radio) sold the "Variac" licence to Technipower, who then sold the license to Power Designs Inc. That firm subsequently went belly up.
Kevin Gallimore
well, I agree something is odd about the first variac, but without either looking at it, or a bunch of photos or something I can't tell you what. I can tell you that I had a variac with brass holders for carbon brushes (it had two), and one carbon brush had broken or worn off so the brass holder contacted the windings - this caused a significant increas in current and heating (because some windings were shorted by the brass) - there may be an effect like this. the 350Cycles per minute nomenclature suggests that it is a duty cycle spec not an input power spec but that's speculation on my part. I can tell you for sure that you will NOT see a transformer rated at 350CPM for input power frequency, so either it isnt' a transformer, or the spec is for some other attribute other than input power.
??????
Well the brush looks fine so I do not know what to say. If I had an ammeter shunt I might dare see what current is flowing across the Variac windings.
Send me your address privately and I'll send you a close up front, side and top view of it.
Simply replace the "." in my posted address and replace it with a "1"
T
Look at the windings. I have seen them so oxidized that the brush couldn't make contact.
I think I figured out the problem. The actual wording on the front of the Variac is "350 CYCLES Min" I took it to mean "350 CYCLES Minute" but what it probably means is
350 CYCLES Minimum.In either case it's just not suitable for 60 Hz.
T
No, that is a 400 Hz Variac, and definitely not usable on 60 Hz, but it makes a nice volume control for a PA system with 70 or 100 volt line transformers.
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That would have simply made the thing unable to deliver current to the load -- no chance for that making it pop fuses or circuit breakers.
O.K. Then it is most likely a 400 Hz one, which is what I thought. There, there is not sufficient iron, so 60 Hz saturates it and draws a ton of current.
Agreed. Nice to have around aircraft power systems, however.
Enjoy, DoN.
I bought three of them all ganged on a common shaft in the late 90s . Took a quick look and assumed I was getting 3, 10 amp Variacs for $8.
A fool and his money are soon parted. In any case I am told that 400Hz Variacs go for about $10 ea so nothing's lost yet, except my expectations.
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