That is a “200V” plug, with two phases (lives, hots) on the flat blades, and earth on the pin. In the US, the green conductor color is protective earth, white is neutral, and then black, red, blue are lives/hots/phases.

3-phase devices expect 120 degrees between phases, 2-phase devices must accept either 120 or 180 degrees.

So the cable should not have a white conductor. It will most likely have Black, Red, Green for two phases and protective earth. It should be fine to connect it to L, N, and PE respectively - with a caveat as follows: In the US, the phase-neutral voltage is 120V for such 200V power sources. If there would be some varistors or other overvoltage protection devices between each phase and earth, they might trigger when presented with double than expected voltage.?

So if you plug it in and it blows the fuses, you will want to locate and temporarily remove the input overvoltage protection devices and retry. Or power it up first with an isolation transformer, with the center tap of the secondary connected to earth, and if it works thus but not when plugged directly into the mains, then you’ll know why. It’s not highly likely that such overvoltage protectors would be present but you never know. Murphy’s law tells me that if I mention them, they’ll be absent, but if I gloss over them, you’ll find them there all right :)

I wrote “200V” because in the US this may be either 208V or 240V, and all reasonable devices with such a plug should tolerate either voltage, and most certainly will not be designed to accept only 208V but not 240V.?

In 3-phase supplies, with (R,S,T)-N at 120V and 120 degrees apart, i.e. many commercial locations, the receptacles for those plugs are simply wired between any two phases, so there’s two hots/lives and earth presented to the plug. That’s 208V nominal between phases.

In typical “domestic-style” (plenty commercial locations are that way as well, though) split-phase supplies, the two phases are 180 degrees apart, and there’s 240V between them, and 120V between each and earth.?

I hope that gives you enough information to safely use your supply.

Cheers, Kuba

2 nov. 2018 kl. 19:23 skrev Dr. David Kirkby from Kirkby Microwave Ltd <drkirkby@...>:

Sorry, this is a bit off-topic for the HP/Agilent list, but I'm hoping someone, (probably from the USA), can help me.

I bought a Gamma high-voltage regulated power supply (0-15 kV, 0-12 mA).



from eBay.

The UK seller said it is 120 V, so needs a transformer to run from the UK mains, The mains voltage here is supposed to be 230 -6%/+10%. But I have my suspicions that the UK seller may be wrong, as the US manufacturer sent me a manual on the power supply, which says its 220 VAC. But they wrote it is a 20-year old custom design. (It's entirely possible someone has changed things.)

Am I right in thinking the plug attached to this is not designed for 120 V use, but instead for 240 V? When I look at it, with the earth pin at the top, the live/neutral are horizontal. The live/neutal pins are approximate 1/4" across, with approximately 1/2" between them, so there is approximately 1" between the two furthest edges of the pins.

I know one can always start at a low voltage, and I have a variac. But I'm also aware in some cases that using too low a voltage can damage equipment. So if this thing is supposed to take 220 V, I'd rather not start with 120 V.

The manual has no tolerance for the mains voltage - it just says 220 VAC. My own voltage is typically 235 V.

Some time ago the voltage was logged here for a period of 4 days and peaked at 255 VAC (RMS value), but the transformer taps have since been changed, and the voltage dropped 5%, so I think it might peak at 243 VAC RMS - and that would only be very occasionally.

One other thing. When I cut this mains plug off, what colour cables would I expect to see, and what would be live and neutral?

Here in the UK, neutral is very close in voltage to the earth wire - ideally, it is zero. Would there be an equivalent wire colour on this mains lead?

This thing can produce 15 kV at 12 mA, which I would guess would give someone a nasty burn at the very least, and could even be fatal. But my biggest concern at the minute is how to get power to this.?

Dave

--

Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100

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