Electronics > Beginners
How to wire up a 240VAC receptacle
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Monkeh:
In the majority of european countries (to my knowledge, I am aware some countries have three phase domestically), domestic properties are supplied with one phase and a neutral from a 3-phase 400V supply. So L is 230V to N, there is no L2, and N is nominally 0V to ground. This is what the PDUs you have are designed for.
Spork Schivago:

--- Quote from: james_s on May 19, 2018, 05:47:34 pm ---
--- Quote from: Spork Schivago on May 19, 2018, 06:05:16 am ---
That's what I've been missing.   I wasn't talking about the transformer here, I was talking about 120-0-120 split-phase that comes into the house, and trying to see how it's equivalent to 240VAC over in Europe.   Because over there, they'll have L1 and then Neutral hooked to the heating elements, which would still give the 240VAC.   I think I understand now fully how the AC works.

Now, why would connecting earth ground to a 240VAC source that comes from 120-0-120VAC USA split-phase or whatever you want to call it cause a short there?   It's because L1 and L2 are reciprocals of each other, right?  When one is 120VAC, the other is -120VAC.   When one is 75VAC, the other is -75VAC.   When one is zero, the other is zero.   If we added a ground, when either where anything other than 0VAC, we'd have our direct connection to ground, which would be horrible.   Am I finally understanding this?

--- End quote ---

Look at the schematic of the center tapped transformer winding, you have 3 wires coming out of that transformer, L1 and L2 are the ends and CT from the middle. Now in the North American setup CT is connected to ground, so now what happens when you also connect either L1 or L2 to ground? Draw it on paper if you have to but you should see a direct short across half of the secondary.

--- End quote ---

Yes, with North American setup.   But with the transformer I was going to purchase, I was under the impression if you connect L2 to ground there is no short.   I was under the impression that was the whole reason I needed to purchase that specific transformer that Mr. Crowley originally suggested, because of the single-pole breakers inside of the PDU that I was sold.   So L1 is the only hot wire, with ~240VAC in reference to ground or in reference to L2 (but only with that transformer Mr. Crowley suggested I purchase if I were to continue to keep the current PDU and wanted to maintain safety.)   That way, if one of the breakers tripped, it'd cut the path of L1, but L2 and N would still be active, but wouldn't be a danger.    I think you guys missed the part where I said the transformer that I was going to purchase and think that I'm talking about the transformer on the pole in North America.

With the transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, there shouldn't be an L2 on the secondary side, if I understand everything correctly.   There's only an L1, an N, and an E.   With American transformers, yes, if we connect either L1 or L2 to ground, we get a direct short and the breaker (hopefully!) trips to protect us.   Or, with that transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, on the PRIMARY side, if I connected L1 OR L2 to ground, we'd have a dead short and that'd be horrible and hopefully the double-pole breaker on the mains panel would protect us and trip.   But if we were to be doing that, we shouldn't be playing with electricity until we learned a lot more about it.
Spork Schivago:

--- Quote from: IanB on May 19, 2018, 06:33:47 pm ---
--- Quote from: Spork Schivago on May 19, 2018, 06:26:19 pm ---This was the only reason I was thinking HPE might have been correct, those four pads inside the connector there....but I'm going to try and send the PDU back now and purchase the ones made for 120-0-120 and see how it actually works, see if they're wrong and you guys are right.
--- End quote ---

Please don't say "120-0-120" or "split phase" or anything like that to the sales people. It will cause confusion and get you into trouble.

What you need to say is "200 to 240 V AC single phase for use in the USA". A compatible PDU should be provided with 2-pole breakers for complete isolation of the supply, and the PSUs actually don't care. As long as the PSU is designed for "high-line" 200 to 240 V AC input it will be fine.

--- End quote ---
Good to go!   Now, when you say don't say 120-0-120 or split phase or anything like that to the sales people, is that because it's incorrect or it will just confuse them?   Am I using the wrong terminology here?   I understand the difference between technicians and sales people and I learned a long time ago when I was working on PCs for customers to not get technical.   Keep it simple, no need to confuse them, just say it's fixed, you owe me blah.   Found a bad component or two (something along those lines), rather than saying the capacitors in the VRM circuit blew because of them being directly under the heatsink and not having adequate cooling or the proper heatsink, so I replaced them with high temp Panasonic's and purchased a taller, yet not as wide heatsink with a fan that could push more air per CFM through the heatsink then the previous one.
Monkeh:

--- Quote from: Spork Schivago on May 19, 2018, 07:16:31 pm ---
--- Quote from: IanB on May 19, 2018, 06:33:47 pm ---
--- Quote from: Spork Schivago on May 19, 2018, 06:26:19 pm ---This was the only reason I was thinking HPE might have been correct, those four pads inside the connector there....but I'm going to try and send the PDU back now and purchase the ones made for 120-0-120 and see how it actually works, see if they're wrong and you guys are right.
--- End quote ---

Please don't say "120-0-120" or "split phase" or anything like that to the sales people. It will cause confusion and get you into trouble.

What you need to say is "200 to 240 V AC single phase for use in the USA". A compatible PDU should be provided with 2-pole breakers for complete isolation of the supply, and the PSUs actually don't care. As long as the PSU is designed for "high-line" 200 to 240 V AC input it will be fine.

--- End quote ---
Good to go!   Now, when you say don't say 120-0-120 or split phase or anything like that to the sales people, is that because it's incorrect or it will just confuse them?   Am I using the wrong terminology here?

--- End quote ---

The terminology is fine, but the people on the other end of the phone have absolutely no idea about the concepts of electrical installations. Even the techs you may speak to don't - they leave it all to the electricians and just know how to add simple numbers together for load calculations.

As I said earlier, all you'll get from the people you're able to contact is them reading '240VAC single-phase' off the datasheet and parroting it back. The only people directly involved in any of this hardware who know better are the ones designing the supplies - and they work for Delta and Flextronics, and speak Chinese.
IanB:

--- Quote from: Spork Schivago on May 19, 2018, 07:03:07 pm ---That's what I was asking.   In Europe, are there two power conductors that are hot or just one?   In America, with 240VAC using our 120-0-120 split phase, both conductors, L1 and L2 are hot, each providing 120VAC out of phase from each other by 180°.   Why 180°?   Because 180° + 180° = 360° so when L1 is +120VAC, L2 will be -120VAC, give or take.   L1 and L2 will should always be the same voltage, but opposite signs of each other.   So when L1 is at +20VAC, L2 should be at -20VAC.   That's why they're 180° out of phase from each other.   If they where something like 120° out of phase with each other, L1 might be +120VAC, and L2 wouldn't be -120VAC.

--- End quote ---

Yes, in parts of Europe like the UK you have one live conductor at ~240 V referenced to ground and one neutral conductor at ~0 V.

Therefore in Europe, isolating the single live conductor and leaving the neutral conductor connected is safe (for example with a single pole breaker). Hence the "INTL" or "WW" PDUs have a single pole breaker.

However, using a single pole breaker in the USA where both conductors are hot is not safe. Both conductors have to be isolated (for example with a two pole breaker). Hence the "NA/Japan" PDUs are fitted with two pole breakers.
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