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ECN Bø or Cø Meter Stinger/Red/Orange/Purple/Power/Wild/Bastard/High Leg? #128106 05/25/02 04:04 PM
Joined: Apr 2002
Posts: 2,527
Bjarney Offline OP
Pardon me, but this was getting (a bit) OT in the "theorists" thread. About 12 years ago, Pacific Gas and Electric {and a few other EUSERC member utilities here out west} modified their service-entrance ¡°Green Book¡± to allow for landing the odd phase of 240∆ on any position in a CT section {as long as clearly identified}, but still required righthand mounting in self-contained [¡Ü200-amp] sockets. The reason for holding out on the RH requirement in the meter was evident if you closely examined the meter internals. The two 120V phases had to be grouped together for lack of room for busbar crossover under the glass to do otherwise.

Nowadays, where a universal, solid state, wide-voltage-range, don¡¯t-even-care-of-it¡¯s-delta-or-wye meter is installed, some utilities have caved in and allow the anarchistic 208V leg on the center jaws of a self-contained meter, because it finally won¡¯t affect accuracy or become bar-b-qed on heatup. This wasn¡¯t the case with electromechanical meters. {Even more proof of the entrenchment of 4w∆ over here, paul¡­}

Tools for Electricians:
Re: ECN Bø or Cø Meter Stinger/Red/Orange/Purple/Power/Wild/Bastard/High Leg? #128107 05/25/02 04:31 PM
Joined: Apr 2002
Posts: 2,527
Bjarney Offline OP
paul-- ASR33 teletype linked to a PDP-11? Man I had it good. After being weaned on keypunch cards for Algol-W programming on a Burroughs mainframe, we could use DEC BASIC on a PDP-11 via a remote, time-shared KSR33 <OR!> a Hazeltine terminal. I'm sure the campus paid a mint {monthly, even} for the specially conditioned telco 50-baud/20-miiliamp current-loop 'Data' lines between buildings.

Re: ECN Bø or Cø Meter Stinger/Red/Orange/Purple/Power/Wild/Bastard/High Leg? #128108 05/26/02 04:05 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline
The PDP-11/40 I used was at the local college and we had a TTY stuck in an old store cupboard at my school. This would have been about 1978. I was only 12, but as my mom was a teacher and good friends with the head of the math dept., I got access whenever I wanted. [Linked Image] It was a real luxury to go down to the college and use their Cifer VDT's. They also had a huge room with about 25 ASR33s, and boy was it noisy when they were all in use. But I digress again....

The acceptance of 4-wire deltas in the U.S. is fascinating. It would be interesting to know how widely such systems (and other "oddball" systems like corner-grounded delta) are used elsewhere, whether they were once used and discarded, and so on. Are they so prevalent in Canada, or other parts of the Americas which generally follow U.S. practice in other respects?

I'm assuming that 120/208 Y dates back to the very early days of 3-phase distribution. But if 240 delta, 480 delta, and the 4-w delta were once very common, when did the 277/480 Y system make it's debut? And why did Canada end up with 347/600 volts?

Sorry about all the questions folks, but I'd really like to get an idea of the historical development of all these systems.

Re: ECN Bø or Cø Meter Stinger/Red/Orange/Purple/Power/Wild/Bastard/High Leg? #128109 05/26/02 08:16 PM
Joined: Apr 2002
Posts: 2,527
Bjarney Offline OP
Paul-- Slightly related...the 5+volt several-hundred-amp power supplies on PDPs made sort of a welder, and over here they were rated 208V 3ø.

Ok, here is one of a million possibilities. An early mention of 480Y and 208Y was published in Donald Beeman's 1955 Industrial Power Systems Handbook. I worked in a plant built in 1957 that was Textbook Beeman...almost scary.

I first came across 480Y in small-town baseball field lighting. A state architect had called for Y-service to power about a ¼ megawatt of quartz-halogen lamps that was being built by the local one-man shop, and the janitor who could drive a tractor to set 60-foot wood poles and feed wire to the electrician on the other end. The little irrigation-district utility was flabbergasted when they hooked the “H-frame” bank up in delta, and floored by the 277V ø-ø readings, coupled with the fact that the transformers had only two [not 4] secondary bushings/spades/eyebolt connections, and they still had to sag a fourth lead to the switchboard. I’m sure that the utility’s meterman was foaming at the mouth wondering how in the heck his CTs and meter was ever going to work with this terrible new system. All they had ever done was &#8710;-&#8710; for a million irrigation pumps and a few “giant” plants. Wye service started showing up in school plans from the state architect’s office, probably because that was their cookie-cutter/boilerplate way that had worked so far and little rural utilities had to get in line with these “really weird” 120 and 277V “wye” transformer configurations. I think some linemen wanted to get a preacher to absolve this evil thing crammed down their throats by stupid guys in some distant office building.

My guess is that the delta-secondary transformers was so well entranced because of the influx of dual-secondary/split transformers and motors. Every region seems to have a little different take on it. With solidly-grounded 480Y, it was not yet realized that the arcing burndown potential of a sustained arc at roughly the 150-250V level could be sustained until, in some cases, large-city office-building basement switchboards many sections wide could burn until there was no “fuel” left. It took introduction of reliable, field-testable Ground Fault protection in ’71 for 480&#8710; to drop out of favor, even though Beeman had been warning of its perils since 1955.

As for Canada, there was probably an similar evolution from 600V&#8710; to 600Y/346V (or 347V?) It seems like they use a fair amount of 208Y/120 like the southland. 600&#8710;-208Y/120V “dry-types” up north—480&#8710;-208Y/120V “dry-types” in the south. A lot of discharge-lighting ballasts are available in 277V and 347V.

For anal retentives:
600/1.73205 = 346.41 &#8776; 346
600/1.73000 = 346.82 &#8776; 347

Re: ECN Bø or Cø Meter Stinger/Red/Orange/Purple/Power/Wild/Bastard/High Leg? #128110 05/27/02 05:22 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline
Interesting.... I think I'm beginning to see this a little more clearly now.

With 120V already established as a common utilization voltage in 120/240V 3-wire set-ups, I was assuming (bad thing to do, I know) that the 120/208-Y system would have been the natural progression when 3-phase started to become common.

You seem to be suggesting that wye systems didn't catch on until the latter half of the century. I think I see my mistake, in that the wye system became common in England so that the same xfmr banks could feed 3-ph commercial with 350-440V and 1-ph 2-wire tapped off of it for residential 200-250V. But with residential service in the U.S. being mostly from smaller 1-ph xfmrs, I see that this wouldn't necessarily have been a factor in favor of adopting wye over delta.

With the preference for 2:1 ratios you mentioned earlier, I suppose it was inevitable that 240V and 480V would become standard, with the 4-w delta being a useful "trick" for the convenience of providing 120V as well. Am I getting near the crux of the matter now?

You mentioned solidly grounded 277/480Y systems with reference to GFI protection, which brings me to another point that occurred to me while pondering this subject.

How do you arrange proper grounding on simple 240 or 480 delta services? If the NEC requires the building ground to be bonded to the neutral on wye or 1-ph 3-w, what happens on a delta service where there is no neutral to bond to?

Obviously 4-w delta and corner-grounded delta wouldn't be a problem, so was corner-grounded delta very common?

Or were many of the straight delta systems floating???


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