277/480 volt history

[mbrooke]

When did 277/480 come into existence? Or 277 volt lighting?

 

[synchro]

They mention 440 volt delta and 254 volt Y-connected motors in this short piece from 1910:

https://books.google.com/books?id=b...ge&q=254 volts electric journal delta&f=false

At the link below starting on pg. 556 they discuss the types of electric service in Oakland, CA in 1910. It includes 440V and interestingly mentions some residential customers with 220V but no 110V. Also 7-1/2 amp constant current for the series arc lamps in the city . I wonder what the open circuit voltage was on those circuits?

https://books.google.com/books?id=y...conditions at oakland, california 556&f=false

I'm guessing that 440 volts migrated up to 480V in a comparable time frame as 110V moved up to 120V (same percentage increase and maintaining same 4:1 ratio).

 

[mbrooke]

They mention 440 volt delta and 254 volt Y-connected motors in this short piece from 1910:

https://books.google.com/books?id=b...ge&q=254 volts electric journal delta&f=false

At the link below starting on pg. 556 they discuss the types of electric service in Oakland, CA in 1910. It includes 440V and interestingly mentions some residential customers with 220V but no 110V. Also 7-1/2 amp constant current for the series arc lamps in the city . I wonder what the open circuit voltage was on those circuits?

https://books.google.com/books?id=y...conditions at oakland, california 556&f=false

I'm guessing that 440 volts migrated up to 480V in a comparable time frame as 110V moved up to 120V (same percentage increase and maintaining same 4:1 ratio).

My understanding is that 440 was typically ungrounded delta, as there were no 277 volt loads at the time.

 

[electrofelon]

I think Wye in general was not as common back then. I would guess 120/208 also came a bit later just like 277/480?

 

[ActionDave]

Wasn't October 1959? I think it's the seventieth anniversary and we are all missing it because it's football season.

 

[mbrooke]

I think Wye in general was not as common back then. I would guess 120/208 also came a bit later just like 277/480?

Same here, and that is what interests me.

It seems everything other than 120/240 single phase was sealed off from earth and the remnants are its still reflected in code to this day.

 

[electrofelon]

Same here, and that is what interests me.

It seems everything other than 120/240 single phase was sealed off from earth and the remnants are its still reflected in code to this day.

Just assuming from what I have seen, which is certainly limited in scope and geographic area, there were not many Wye systems before the early 70's. Seems three phase was often ungrounded delta without ground detectors hmy:

There was definitely a big push toward grounded systems at some point (both in distribution and premis). Although grounded distribution cuts costs a bit, I still think part of it was myth based, grounded=better=safer

 

[electrofelon]

Wasn't October 1959? I think it's the seventieth anniversary and we are all missing it because it's football season.

Correct. I remember that day well. I showed up to work, and the boss was pissed because we had to pull neutrals to all this stuff we had just installed. He also had just the day prior bought a bunch of fully rated breakers when he could have saved some money on slash rated after that day.:rant:

 

[mbrooke]

Just assuming from what I have seen, which is certainly limited in scope and geographic area, there were not many Wye systems before the early 70's. Seems three phase was often ungrounded delta without ground detectors hmy:

My observations as well.

There was definitely a big push toward grounded systems at some point (both in distribution and premis). Although grounded distribution cuts costs a bit, I still think part of it was myth based, grounded=better=safer

I'd say so, but remember that many ungrounded systems were just operating with a standing ground fault. Those that ran into transients faults sometimes encountered insulation damage.

I can't find it, but many years ago I read a paper toughting that 277/480 came into existence because of the advantages associated with 277 volt lighting circuits.

 

[electrofelon]

I'd say so, but remember that many ungrounded systems were just operating with a standing ground fault. Those that ran into transients faults sometimes encountered insulation damage.

Yeah no doubt. An old building I worked in had a 600V ungrounded service. It had a fault and who knows how long it had been like that, could have been decades. I finally did find it when I was re-routing the elevator circuit into a transformer after upgrading the service to 120/208.

I can't find it, but many years ago I read a paper toughting that 277/480 came into existence because of the advantages associated with 277 volt lighting circuits.

That makes sense. That would make it a lot more efficient for larger buildings to take 277/480 without need to transform most of the lighting. I really hate our low voltages. Hate 208. Even 240 is too low. Like the way Europe does it with 230/400 - except I do like our 60hz

Another question: What happened to 600v? was that a fad that faded out? Lots of the mills in New England were 600. Pretty much never see 600 anymore.

 

[mbrooke]

Yeah no doubt. An old building I worked in had a 600V ungrounded service. It had a fault and who knows how long it had been like that, could have been decades. I finally did find it when I was re-routing the elevator circuit into a transformer after upgrading the service to 120/208.



That makes sense. That would make it a lot more efficient for larger buildings to take 277/480 without need to transform most of the lighting. I really hate our low voltages. Hate 208. Even 240 is too low. Like the way Europe does it with 230/400 - except I do like our 60hz

Another question: What happened to 600v? was that a fad that faded out? Lots of the mills in New England were 600. Pretty much never see 600 anymore.

I have that same question. 600 took off in Canada, but why not the US?

230/400 is vastly superior as its a descent compromise between 120/208 and 277/480.

Personally I like 138/240 and not having a neutral to worry about.

 

[jim dungar]

Just assuming from what I have seen, which is certainly limited in scope and geographic area, there were not many Wye systems before the early 70's. Seems three phase was often ungrounded delta without ground detectors hmy:

At least as far back as the 1950's, Square D was selling ML-2 and NY1B circuit breakers for use on 277V. In 1958, the Square D QO line was listed as suitable on 120/208VAC 3PH 4W.

 

[electrofelon]

At least as far back as the 1950's, Square D was selling ML-2 and NY1B circuit breakers for use on 277V. In 1958, the Square D QO line was listed as suitable on 120/208VAC 3PH 4W.

Do you know when the QO line came out?

 

[Tony S]

1

 

[jim dungar]

Do you know when the QO line came out?

Sometime in the last part of the 50's.

 

[broadgage]

I suspect that 277 volt lighting circuits only became popular with the introduction of fluorescent lighting.
A simple fluorescent lamp circuit consists of a choke in series with the lamp and a glow or thermal starter. For such a circuit to work, the supply voltage has to be at least one and a half times the lamp voltage.
With a 120 volt supply this only allowed lamps up to about 24 inches in length on a simple series choke circuit. Longer lamps required a step up transformer in the fixture which added to costs, complication and losses.
With a 277 volt supply, longer lamps up to the largest manufactured could be used with a simple series choke circuit.
Whilst a single small fluorescent lamp COULD be used on a 277 volt circuit, this was not optimum since the cost/weight/bulk of the choke and the losses therein increased. Most fixtures for 277 volts used either longer lams, or two shorter lamps in series.

These days, most any size fluorescent lamp can be used on any voltage with a suitable electronic ballast, but this is a relatively recent development.

277 volts is too high for optimum operation of incandescent lamps. 277 volt incandescent lamps do exist but are expensive and less efficient than 120 volt lamps. Here in the UK, 240 volts has been more or less standard for 50 years, and was very widespread even before becoming the standard.
240 volt incandescent lamps are inferior to 120 volt lamps especially in the smaller wattages. On strictly economic grounds there would have been a case for use of series pairs of 120 volt lamps on 240 volts. This was sometimes done, but in general the complication and risk of mistakes outweighed the small saving in money.

 

[mbrooke]

Talking of odd voltages and this is one I never did find the reason for. We used either 433V or 550V, the plant this was on had all German equipment which at that time normally would be 415V.

A 440V transformer would be a special order, I don’t know why?

I'm guessing a rounding error or a transformer ratio preference ie 90% of 440 is 396 volts and 90% of 12,000 (highest IEC rating of 11kv equipment) is 10,800. So an 11,000 volt input yields about 400 volts output.

 

[mbrooke]

At least as far back as the 1950's, Square D was selling ML-2 and NY1B circuit breakers for use on 277V. In 1958, the Square D QO line was listed as suitable on 120/208VAC 3PH 4W.

Any idea before that?

 

[broadgage]

Utility transformers often have a slightly odd voltage. They are often designed to supply not the nominal utilisation voltage, but a voltage at the upper end of the permitted tolerance band, so as to allow for voltage drop between the transformer and the load.
The standard utilisation voltage in the UK was 240 volts phase to neutral and 415 volts between phases. The transformers to supply this voltage usually have a 433 volt output. That should achieve an average of 415 volts at the load.

The declared or nominal voltage in the UK is now 230/400 volts. This however is a political measure to harmonize with Europe. The actual measured voltage still tends to average about 240/415 volts in most places.

 

[electrofelon]

Utility transformers often have a slightly odd voltage. They are often designed to supply not the nominal utilisation voltage, but a voltage at the upper end of the permitted tolerance band, so as to allow for voltage drop between the transformer and the load..

This might be an example of that. This is a Seattle City Light transformer. I dont know what their "official" distribution voltage is, but it is often called 25.5KV. You can see the transformer doesnt say that.