Ok this is one for the old timers. I was working on old grain handling facility and came a crossed one I can?t figure out. The contractor that did the initial wiring in the 70?s has gone to the great code forum in the sky so I am unable to find out from him how he did it. Anyhow. The site is a 480-volt system and some how they pulled two legs from that system, ?created? a low voltage source for lighting, and convince outlets with out a transformer. When I measure between the ?grounded? and hot I get 216 volts but my power tools and site lighting seem to work at that voltage with out any adverse effects can any one explain this to me?
help me!!!
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Ed MacLaren
Senior Member
Re: help me!!!
I would qualify as an old-timer, but your numbers still don't add up.
Are you sure there isn't a transformer hidden somewhere?
On a 4-wire (wye connected) 480 volt system, hot to neutral should be approximately 277 volts.
On a corner-grounded 480 volt system, hot to ground should be 480 volts.
Checked your voltmeter lately?
Ed
I would qualify as an old-timer, but your numbers still don't add up.
Are you sure there isn't a transformer hidden somewhere?
On a 4-wire (wye connected) 480 volt system, hot to neutral should be approximately 277 volts.
On a corner-grounded 480 volt system, hot to ground should be 480 volts.
Checked your voltmeter lately?
Ed
charlie
Senior Member
- Location
- Indianapolis
Re: help me!!!
This could be a 480 volt delta system with three separate transformers. Wired with a center tap on one transformer to make a 240/480 volt three phase, 4 wire system, with the center tap grounded.
I have also seen the center taps from all three transformers taken out to create a 240 delta from a 480 delta configuration. This here is sum old nasty stuf. LOL
This could be a 480 volt delta system with three separate transformers. Wired with a center tap on one transformer to make a 240/480 volt three phase, 4 wire system, with the center tap grounded.
I have also seen the center taps from all three transformers taken out to create a 240 delta from a 480 delta configuration. This here is sum old nasty stuf. LOL
Re: help me!!!
This appears to be a Y-YG Scott TG connected bank.
The teaser leg to ground is unstable when measurement is made on an open circuit status.
The voltage will stabilize when the circuit is closed. Measure the voltage when under load.
[ May 03, 2003, 08:42 PM: Message edited by: bennie ]
This appears to be a Y-YG Scott TG connected bank.
The teaser leg to ground is unstable when measurement is made on an open circuit status.
The voltage will stabilize when the circuit is closed. Measure the voltage when under load.
[ May 03, 2003, 08:42 PM: Message edited by: bennie ]
charlie
Senior Member
- Location
- Indianapolis
Re: help me!!!
Wow Bennie, I have not seen a Scott connected bank since the late 60's. It has been so long that I had forgotten about the 87% tap (OK 86 2/3%) but I don't know what configuration you are talking about to get a voltage even close to 216 volts.
Wow Bennie, I have not seen a Scott connected bank since the late 60's. It has been so long that I had forgotten about the 87% tap (OK 86 2/3%) but I don't know what configuration you are talking about to get a voltage even close to 216 volts.
Re: help me!!!
Charlie: I am only making a wild_ _ _ guess. The voltage does not compute. An off center neutral tap could produce a strange voltage. I have a problem with it being 120 though.
I have some old engineering books and will do some more research. The farming community was very innovative in electrical applications.
Charlie: I am only making a wild_ _ _ guess. The voltage does not compute. An off center neutral tap could produce a strange voltage. I have a problem with it being 120 though.
I have some old engineering books and will do some more research. The farming community was very innovative in electrical applications.
jmc
Member
- Location
- Massachusetts
Re: help me!!!
Sounds like a European voltage system. 3-phase 380 volts, wye connected. The voltage to the neutral (grounded conductor) is 380/1.73 = 219V.
Sounds like a European voltage system. 3-phase 380 volts, wye connected. The voltage to the neutral (grounded conductor) is 380/1.73 = 219V.
jtb
Senior Member
- Location
- Pennsylvania
Re: help me!!!
Hey! Don't stop this thread until y'all figger it out, ok?
Hey! Don't stop this thread until y'all figger it out, ok?
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