Has AC had its day?

My most infamous event occurred when I was getting cute with load line shaping on switching power supplies for GenRad. With clever snubbing I literally had the load lines following the V and I axes.

So I had the technician take off the heat-sinks from the TO-220's and we ran it for a while.

Then I said, "Let's see how hot these devices are getting."

Then I took hold of the TO-220 flag... forgetting that there was 340V P-P there ;-)

Produced all most as much laughter from the technicians as when an car ignition circuit knocked me over the seat-back of a lab stool without knocking it over :-)

...Jim Thompson

Ultra lame 'Obama Day' joke! Off with your Teleprompter!

The real problem with 50/60 Hz mains is the requirement for huge transformer cores.

The other problem is the low 3000/3600 rpm synchronous motor speed.

For this reason, simple induction motors are quite heavy and hence, unreliable universal motors with commutators has to be used in hand tools in order to have some reasonable weight/power ratio.

Yeah. Who re-animated Edison and Westinghouse?

-- Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com

------------------------------------------------------------------ I had a dog that would chase anyone riding a bicycle. In the end I had to take his bicycle away.

Increase the frequency significantly and transmission losses skyrocket. The decision was a matter of trade-offs.

His claim is stupid.

They have it even better then as most outlying areas only see about 90V out of that 100V.

Pain in the ass to design the lower limit of a power supply that has to work on the world standard, yet still has to run on the worst Japanese standard, which means we had to operate down to a drop out point of about

It lasted more than a day.

Now we know why you are the way you are.

No.

Hope This Helps! Rich

Yeah - that's another benefit - the Darwin effect. ;-)

Cheers! Rich

You are an idiot.

The world touched you on the backside of your brain (obviously).

The damned shame is that we cannot pull away from you and your stupidity.

Stop expounding on things which you are utterly clueless about.

Note that when you state bullshit, you will be called on it. When you state bullshit that relates to electrical safety, you should get your ass kicked.

Depends on whether delta or wye is chosen. That floating no-ground crap they use here is lame.

Tesla is rolling over in his grave.

The use of 25 Hz in some early US installations was dictated by the available motors and generators.

The use of 16.7 Hz in some railroad systems in Europe was dictated by the use of universal AC/DC motors that worked quite well at DC and frequncies up to 20 Hz.

Universal hand tools motors work quite well also with 50/60 Hz AC.

Anyway feeding something like 400 Hz in to the local power distiribution network, especialy if the US power pig ransformer is replaced with something generation 110/220 AC at 400 Hz might be sensible.

I thought the big argument was between Edison and Tesla.

Westinghouse just ended up with the manufacturing contract after Tesla won the battle.

He, in fact, manufactured from Tesla's patent.

Generators, in particular the RPM required, more than the motors, I suspect.

Universal motors that large? In the US these sorts of frequencies were used, too, but I suspect it was a generation issue.

"Well" is relative.

Power isn't "local". That's the problem with 400Hz.

Most of Europe is 230/400 V wye/delta.

Norway and some parts of Russia did some times use something like 220 (230 V) delta.

Unless you can prove that you have a very low grounding resistance from wye neutral to actual ground, there is not much point in declaring your system as IEC TN-C/TN-C-S/TN-S.

In practice, we would be discussing various variants of the IEC IT systems :-).

On a sunny day (Sun, 03 Apr 2011 19:00:30 +0300) it happened snipped-for-privacy@downunder.com wrote in :

There are about 400 Hz railway systems. I had the opportunity to do some measurements next to such a system, as to check for interference to inductive loop hearing aid systems. We got the 400 Hz everywhere, it is right in the audio band. So I would suspect 400 Hz house wiring to cause a few problems with some audio and radio equipment.

So? He has nothing better to do, what with his being dead and all.