Smart Guy question! - Electrical related (3 phase)...(let's see how good you are!)

a reply to: Thenail

Not to just jump in here, but I'm actually a bridge builder.
Maybe I could help you to get over yourself?
:

Did anyone solve the problem yet?

a reply to: randomtangentsrme

Honestly bud , let’s be done with this . You have less knowledge than almost every first year apprentice I’ve ever met . A dryer is 240 volt 30 amp circuit in the USA . 1800 amps is the main breaker for the whole damn huge building. Considering a 15 amp space heater is typically 1400 watts . So should I have everyone rip it out tomorrow and we’ll just do a 120 volt 20 amp circuit for the school . wire a whole school on 1440 watts . Jesus Christ you don’t know the difference between a watt and amp or a volt . You are the most ignorant fool ever. You must be a troll . You’re own god damn link disputes your vast knowledge in the first picture . I’m not qualified and need to remove myself from this thread ? Lmao . You don’t have an electrical job . You’re dads not even an electrician. You might of met an electrician but that’s as far as that goes . I make a boatload of money just on my electrical knowledge and I know you’re a fool . First year apprentices are way smarter. Sorry for blowing up but my god. Do you show up to job sites and argue with the head plumber because you don’t have a clue what you’re talking about ?

originally posted by: Thenail
a reply to: randomtangentsrme

Honestly bud , let’s be done with this . You have less knowledge than almost every first year apprentice I’ve ever met . A dryer isen.wikipedia.org... whole school on 1440 watts . Jesus Christ you don’t know the difference between a watt and amp or a volt . You are the most ignorant fool ever. You must be a troll . You’re own god damn link disputes your vast knowledge in the first picture . I’m not qualified and need to remove myself from this thread ? Lmao . You don’t have an electrical job . You’re dads not even an electrician. You might of met an electrician but that’s as far as that goes . I make a boatload of money just on my electrical knowledge and I know you’re a fool . First year apprentices are way smarter

originally posted by: randomtangentsrme
a reply to: caterpillage

Please explain it to me?

208y/120 three phase power in a commercial build has 3 120 volt black lines coming in, there is also a neutral wire and a ground.

The neutral is connected to a bus in the panel allowing the service to supply standard 120 volt circuits with any one of the 3 hot lines and a white back to the neutral bus.

The 3 hot lines form 208 between any 2 legs, normally used for wiring lots of lighting,
Some applications even use all 3 legs to run electric motors.

It's a good system for commercial applications as it allows an easy access to 120 volt without need for a transformer. While still giving the ability for higher voltages for long runs of lighting.


Wher I work, we have a 3 phase 480 drop into our electrical room, powering lots of large conveyor systems, motors up to 350 horse power.
There is a transformer converting the 3 phase 480 into 3 phase 208y/120 to supply lighting in the facility, as well as 120 power to another building.


What you describe as being 2 hot legs doubling the power, is typical 120 volt single phase. 2 hot 120 lines powering something like a range or dryer double the power to 240 volt. Sometimes called 220.

I'm not an electrician, nor an engineer, nor an instructor, so I dont know how to explain it much better than that.


If you read the wiki you posted, it describes it pretty well actually.

a reply to: caterpillage

Thanks bud , that explains it pretty well .it’s usually color coded black red and blue to differentiate between what hot is what . You don’t need to step down 277/480 to do lighting . 277 runs it pretty good . A big building usually has 277/480 feeding it and they step it down for things in the building . That’s brown orange and yellow , getting zapped by that pains the bones a little good grief lol . I’m glad they put a no hot work in place policy in recently

originally posted by: Thenail
a reply to: caterpillage

Thanks bud , that explains it pretty well .it’s usually color coded black red and blue to differentiate between what hot is what . You don’t need to step down 277/480 to do lighting . 277 runs it pretty good . A big building usually has 277/480 feeding it and they step it down for things in the building . That’s brown orange and yellow , getting zapped by that pains the bones a little good grief lol . I’m glad they put a no hot work in place policy in recently

Now that you say that, I think the main lighting in the big building is on 277, the stepped down 208 is going into the second building solely.
Not sure why that was done, other that to get the 120? As nothing in that building is running the 3 phase except for a ventilation fan that has a pretty small motor that could have easily been done on 120 in my opinion.

I work with the stuff, and have only been fairly recently trying to educate myself on how it all works. As to be able to be a first round check when something goes awry.

At this point, I think I know just enough to be dangerous lol

a reply to: caterpillage
Yeah right . Me too lol . Yeah I think you’re right man . Well you must have 277/480 stepped down to 120/208 In your building to run receptacle outlets and stuff like that .

originally posted by: Flyingclaydisk
Messages we were getting was the inverter was about ready to blow, and the battery stack was getting hot.

Total time pressure!

What's the solution?

(Narcoleptic Buddah, Munnin...you have the answers, right? I'm a liar, fiction writer, right...what's the gawd dammed solution, smart guys???) How would I know this, if I didn't live it every day??? So, what is the solution...smart guys????

Lol, I love living rent free in your head.
🤣

What a tough cowboy you are.

sounds like the c phase is not in phase for some reason it is the same as the A. the cycles are off and AC is combining which means it is only 208 volt...the cycle should be off and it isn't.

I have toyed with three phase inverters but not the three phase from the power company. This is just my guess, how that could happen is not anything I know, and I could be wrong, I did mostly single phase wiring but did do some wiring after an inverter.

I don't know much about the new technology controllers for three phase, what I worked on the one time was about thirty years ago and it had been put in about ten years earlier. Basically, I know just enough about three phase to get myself in trouble, but I used to know who to ask, my cousin was a master electrician and worked with three phase at the mine. I worked under him for about seven jobs and when a friend of mine had his inverter go out, I called him to help me try to fix it. It was simple for him to fix and he taught me some stuff on how three phase works that day and then on the jobs we worked on together.

Maybe a shorted motor which is backfeeding into the system?

As far as the original topic of the thread,
First off, its stated that the readings on the 208 panel were reading 208 for each leg to ground, shouldnt that be 120?

Then were off to reading leg to legs being 480, so, I guess from my level of understanding nothing in the OP makes any sense.

a reply to: rickymouse
I’m a master electrician who answered if you care to read my posts . Most of the problem is flying clay dick posted a thread 8 hours ago and hasn’t come back to answer follow up questions . What’s the point of making a thread ?

a reply to: caterpillage

Well yes if it’s 120/208 it would read 120 hot to ground and not the 208 to ground op has . There’s a lot missing to this story and a lot of hoopla of wasting all our time . Thanks clay

a reply to: Thenail

As far as 208 goes, I recently bought an inverter tig welder that the manufacturer says will run on either 120 or 240, and seems to list it as a variance of voltage. It's not a dual wiring setup like they used to be,

My question is, and after lengthy reading online and lots of study, (I think I'm ok)

Can I run 2 of the legs of my 208 as well as a ground to a welder outlet? as measured I'm getting 215. It seems to be working fine. I understand my amperage draw will be higher, and machine performance will be reduced.

My ultimate question I guess is due to phasing. Is it ok to use 2 legs of three phase to approximate 2 feeds of single?

a reply to: caterpillage

Yes if I know what you’re asking . Some things just use two hots . You probably should use a 2 pole breaker and not a three . Two pole is good for dryer or range or some welders . If it only needs two hot wires then that’s what it needs . I wouldn’t do my own electrical work if 8 wasn’t qualified.

When do we get the answer to this problem? I am curious even though I avoided using 208v.

I had four 277/480 entrances, 3 were 2000A and the other 1200A. The office equipment, exit lights and a couple dozen service recepticles scattered around the plant were fed by a single phase transformer, 120/240v that was fed by one of the three phase systems. Both systems were easier to work with then anything I have been involved with that had 208v.

a reply to: Thenail

My apologies for the delay in responding! Got pulled away on something else, then life.

Somethings loose ... Check your c phase tightness ... Do you want me to come there and fix it for you lol .

BINGO!! We have a winner!

Electrician who made up the Distribution panel back in an electrical room about 400 yards away didn't get the C phase let torqued down properly. Conductor came loose from the lug and sprang over and made contact with the A phase, hence the readings.

I never would have believed it unless I saw it.

As it turned out it was another Master Electrician (such as yourself) who deduced the same thing. "Only way this could even be possible is if...". At the same time, one of the lugs in the service panel serving the transformer was also loose, hence the heat issue. The heat issue likely contributed to the fault back at the Distribution Panel also.

That electrician is no longer with the electrical firm who did the work.

Very good! Excellent deduction!

ETA - So you really are "that good"!

a reply to: beyondknowledge

See answer above. Thenail figured it out.

I don't know why the UPS was designed like that. Required and extra transformer which could have been eliminated. Maybe they got them at a discount, I dunno.

a reply to: Thenail

Exactly! You are correct.

120/240 is still single phase, just "split single phase" typically used for residential.

208/120 is 3 phase (as is 480/277).

Big difference!

ETA - Anyone need proof? What do you get when you multiply 120 times the sq. root of 3? Yep, 208. What do you get when you multiply 120 times 2? Yep, 240. Therein lies the difference.

a reply to: Flyingclaydisk

As I suspected, you had an open leg. Whenever all of your legs read hot to ground and one combination of the leg to leg reads half the amount of the other two, one leg is dead.
Any three phase components in the circuit after that will be single phasing. Motors will hum, not turn and overheat.

a reply to: Flyingclaydisk

Conductor came loose from the lug and sprang over and made contact with the A phase, hence the readings.

Are you 100% sure of this?

Any time that I have seen phase to phase shorts.... they are not pretty. Big arcs, melted conductors and blown fuses or tripped breakers.