Life in the UK

[hoborob]

The term "High Leg" is one with which I am familiar. In a 3 phase system that is 208V between the legs by connecting them in a Wye pattern you get 120V to Neutral form each leg of the Wye. Now if you have a 240V 3 phase system by connecting it in the Delta pattern with pone side center tapped you get 240/120V between those 2 phases. Between the third phase and neutral you would get something like 167V. This type of connection is used on occasion in older factory building that have been feed with a 3 phase 240V system where it is less expensive to keep the 240V feed system than to have the transformers changed out to get to a 208V feed and it is only necessary to have a small feed that needs 120V for a small area of the building. More modern structures use a 480V 3Ph system to feed the building and have 480V to 208/120V transformers to feed the low voltage needs of the facility. Most modern factories use 480V systems for the manufacturing areas and use the 208/120 system in the office areas.

[moonshadow]

The term "High Leg" is one with which I am familiar. In a 3 phase system that is 208V between the legs by connecting them in a Wye pattern you get 120V to Neutral form each leg of the Wye. Now if you have a 240V 3 phase system by connecting it in the Delta pattern with pone side center tapped you get 240/120V between those 2 phases. Between the third phase and neutral you would get something like 167V. This type of connection is used on occasion in older factory building that have been feed with a 3 phase 240V system where it is less expensive to keep the 240V feed system than to have the transformers changed out to get to a 208V feed and it is only necessary to have a small feed that needs 120V for a small area of the building. More modern structures use a 480V 3Ph system to feed the building and have 480V to 208/120V transformers to feed the low voltage needs of the facility. Most modern factories use 480V systems for the manufacturing areas and use the 208/120 system in the office areas.

At the warehouse we're getting a full 208 volts on our high leg.

Okay... so here's a question for the electrical engineers here:

Today I had a look at a bandsaw running a 3 phase duel voltage motor (200-230 / 380-460) strapped for 208 volts. According to the data plate, it should pull 9.3-8.2 amps respectively.

Store calls in and says at one time they smelled something burning and the swore the blade seemed like it was turning slow and was very noisy. I have ruled out a possible single phasing situation. I have inspected everything, the plug looks good, the contactor looks good. The motor has a little bearing noise, but nothing really noticeable. Voltage coming into the contactor is 210/210/212 measured every which way. All phases present. No voltage drop through contactor when operating.

The only thing I found odd was when running, I took an amp reading and the three phases are pulling about 2.4/2.2/2.2 amps. This seems substantially low based on the data plate. This is with the motor running without any real load, only the two pulley's and of course the blade. I had them saw some pork chops and measured the amp readings. When the pork would cross the blade the amps would increase to 5-6 amps then drop again when the cut was complete.

The only thing out of the way here is my very low amp reading, when the motor says it should be pulling three times that. Even the data plate on the saw calls for 8-9 amps. I hadn't really run into this before so I called the boss, we're going to take a "wait and see" and see what it does, if it does it again. I don't like the amp read. Something seems jacked up in the motor. I'm going to another store tomorrow where I want to take an amp reading of a different saw and see what how many amps it pulls.

Thoughts?

[Fred in Skirts]

Ok, We are talking about electrical power to homes. In the USA in the rural areas where I live we have a single phase 14.4 kv line and a transformer that puts out 220/120 volts AC. It is 4 wire in the house. Two hot leads, one neutral and one earth ground. When I talked to the lineman that installed it when I moved it he said it was called phantom phase power. Have any of you here in the States or in Jolly Ole England ever seen this??

Fred

[Taj]

Fred, that sounds like a pretty normal rural distribution system. I haven't heard the term phantom phase, but what you have is one phase of the 14.4kv system, which calculates to 8323 (14.4k / √3). They transform one leg to your center tapped 120/240.

[hoborob]

To answer your question Moon The data plate current information is for the motor running at full load. The no load condition will have a current level that is probably about where you saw it. The fact that the current increased while cutting indicates that everything is functioning normally. All the information you have provided indicates that everything is in correct operating conditions. I would suspect that what caused the burning smell and slow operations mentioned was that some debris had been pulled through and was jamming the pulleys by putting excessive pressure on the tensioning system. The saw was either cleaned really well and the debris cleared or the pulleys pulled the debris through clearing the issue. This is likely a one off incident and may not repeat itself, but if it occurs again have the people look carefully at the machine and make sure that there is no debris in the mechanism and if not to note carefully the conditions that caused the slow down to occur. Finding an intermittent problem is quite difficult until the exact conditions that caused the problem can be repeated and thus the cause to be revealed.

[crfriend]

A six-phase supply would have been a boon to some of the computers I used to work on (KL-10s, <spit>) as a quarter-cycle drop could cause the machine to enter a power-fail sequence (which was usually unrecoverable). KIs would ride those out with aplomb due to the moderate power draw and big fat filter capacitors.

The only stuff I've been exposed to here in the US is residential-grade "single phase" (which is actually split 240V with a centre-tap) and commercial-grade three-phase which has usually been 120 phase-to-neutral and 208 phase-to-phase. I've seen higher voltages (with identical ratios) for internal transmission and I've also encountered 277 for lighting.

I would adore a residence with proper three-phase power as it'd allow me to fire up some of my more interesting historical gear.

As an aside, I screwed up a few decades ago and managed to bridge a 208 circuit. It was not pleasant. Thank goodness AC tends to throw one off it. I landed several feet away, much to the horror of those in the room with me.

[Fred in Skirts]

As an aside, I screwed up a few decades ago and managed to bridge a 208 circuit. It was not pleasant. Thank goodness AC tends to throw one off it. I landed several feet away, much to the horror of those in the room with me.

Been there done that and have the scars to show for it!

Fred

[moonshadow]

hoborob,

You were correct. I checked a different saw and it too runs about the same amperage as the one I posted about above.

I would adore a residence with proper three-phase power as it'd allow me to fire up some of my more interesting historical gear.

I'm not aware of any residents of the "common Joe" being equipped with 3 phase. However, maybe you can lease you out a little corner in an industrual warehouse somewhere if you know somebody.

As an aside, I screwed up a few decades ago and managed to bridge a 208 circuit. It was not pleasant. Thank goodness AC tends to throw one off it. I landed several feet away, much to the horror of those in the room with me.

120 of different potentials in each hand? YIKES! You're lucky to be alive! I've never crossed voltage potentials with my body, all of my electrocutions have always been one side of a 120, never to a good ground.

Believe it or not, I get shocked VERY rarely, and it's always been very mild. *knock on wood*

[crfriend]

I'm not aware of any residents of the "common Joe" being equipped with 3 phase. However, maybe you can lease you out a little corner in an industrual warehouse somewhere if you know somebody.

I've never seen a residential area in the USA that's been wired for 3-phase. Even if the 13.8 kV distribution circuits have all three phases atop the poles, the final step-down to 120 is invariably wired to a single phase. Blah.

120 of different potentials in each hand? YIKES! You're lucky to be alive! I've never crossed voltage potentials with my body, all of my electrocutions have always been one side of a 120, never to a good ground.

It definitely got my attention! The "throw-off", however, was completely involuntary and the muscle-reaction was enough to toss me most of the way across a room.

It hasn't happened since -- and I've worked on more potent stuff since then. I think I learned my lesson. Even I am educable. Pain helps sometimes.

[Kirbstone]

Well, most of us here got a single direct current shock when they announced this morning that they're going for Brexit.

There'll be one mighty reshuffle in the coming weeks.

Tom

[crfriend]

There'll be one mighty reshuffle in the coming weeks.

Is this really likely to affect the Republic of Ireland? It'll likely play silly buggers with the Pound Sterling for a bit, but we shall see what happens and it is going to take a while for the dust to settle, but if I'm not mistaken, Eire runs on the Euro now.

[Sinned]

There is trade between Britain and Ireland and, of course there's Northern Ireland which isn't politically part of Eire even though it's on the same island. Naturally, since NI voted to stay in the EU there will be talk of a referendum there and maybe about the reunification of NI with Eire, which has been a thorn in anyone's side for eons. Much bitterness about it and many lives lost in tragic circumstances in which neither the Irish nor us Brits come out with much honour. I am not an expert on the troubles, even though I lived through the sixties, seventies and eighties when there was a lot of trouble, so I won't comment. There's far better than I can do that. There were road blocks for a long while which as far as I know have been dismantled. I wouldn't like to see them reinstated as NI would be possibly out of the EU and Eire in it.

[Ray]

It's a disaster. Little Englanders wrecking the UK. This is going to hurt us badly.

[Kirbstone]

Sure, we use the Euro, but there are untold billions of Irish investments in the UK all of which will have to weather the storm, for that's exactly what's coming. No doubt about it. Also my Sterling pension.
Cameron called the referendum and the protest vote called his bluff, so he cannot survive. Regardless of N.Ireland's 'exit' from the EU, I personally doubt if anyone will be interested in rebuilding fixed border controls, all of which have long been dismantled. For example, travelling by road to Belfast on the M1/A1, the only real visible change is that distances & speed limits become miles, Pump prices are in Sterling and Derry becomes Londonderry on the road signs.

Tom

[Kilty]

It's a disaster. Little Englanders wrecking the UK. This is going to hurt us badly.

There is talk of London becoming an independent city state as they voted Remain, though I can't see that happening. Scotland want out, along with Northern Ireland, Wales want central government to make up the shortfall in European funding, so I can see the country starting to tear like a cheap pencil skirt The Leave campaign didn't really have anything in place and they have been shocked, thinking 'damn, we have to do something now' but they have not thought of financial consequences or how hampered the UK will be with food supply chains, trade, travel etc. It was all done on the lie that it would reduce immigration. EU meet on Wednesday to now discuss how quick UK must leave.

I think they will regret it... they put it to the people, but with a lot who voted to leave now saying they are upset they were lied to, I think they should try and work out how to stay. Everything is on a knife edge. Guess I can pick up some new skirts when the looting starts