The electricity feeding a separate sub-panel in a separate part of an old warehouse we’re turning into artists’ studios is wired with three wires, all reading hot. In other words, three-wire three-phase instead of four-wire three-phase. If it were a four-wire system (with a neutral) I wouldn’t need to be asking this question but there isn’t a neutral coming out of the meter box.
The transformer is an old Delta Transformer. Is there any way that you can get a neutral line (for 110 usage) from this system? Can one of the three terminals on the transformer somehow be converted to a neutral?
Are there any other options?
2006-09-26 16:47:42 · 5 answers · asked by Doc Watson 7 in Science & Mathematics ➔ Engineering
rhsaunder, thank you.
I'm printing out your instructions. Of course, I'll be careful.
2006-09-26 17:06:46 · update #1
Are you an electrician? I don't think so from the way you asked the question. Does your area allow non-licensed people to do electrical work? You wouldn't be allowed to do this here. I think you are way beyond your capability and should get an electrician. If you want a 3 phase panel with a neutral, it still won't be a "220 panel" as your question says. If you have 220 or 240V delta now, you cannot simply connect it up as a wye and get 120V, you will have that 220 or 240V phase to neutral.
2006-09-27 03:34:44 · answer #1 · answered by An electrical engineer 5 · 0⤊ 0⤋
Who up there! You've only talked about the transformer, not the panel, and you haven't said anything about voltage. Open up the panel (carefully) and see if it has a neutral bus bar. Also see if you have any single-pole breakers in it (assuming a breaker panel and not a fuse panel). Measure (even more carefully) the line-to-line voltage. If it is 208 V. and you have single-pole breakers, you're home free, so to speak. You have a 120/208V 3P-4W system with a floating neutral. Not good, but workable. If it's 480 V you're stuck with having to buy a transformer.
Another remote possibility is that your transformer could have 240V center-tapped secondary windings, in which case you already have what you need.
2006-09-26 18:05:59 · answer #2 · answered by Helmut 7 · 0⤊ 0⤋
If you can get at the ends of the windings, you can convert the delta configuration to a Y configuration. Just remove one of the two wires at each terminal and connect the three wires together. (Gotcha: make sure that you have each terminal left connected to a separate winding!) Now power the thing up and use your handy dandy voltmeter to see what you've got. If you have 120 volts from each phase to the newly constructed common terminal, you have got as good as it gets. Which is not as good as you would like: anything that wants 240 volts is going to have to settle for 208. Some appliances don't care; some do.
2006-09-26 16:55:37 · answer #3 · answered by Anonymous · 0⤊ 0⤋
You have two options:
OPTION #1.
You plan to use only single phase (0 - 110V) for your artist's studio.
In this case use/buy an isolation transformer as under:
a) Primary winding of 220V phase to phase
b) Secondary winding 0 - 110V.
c) KVA Rating - depends on the load you plan to connect
Connect any two hot wires to the primary winding. Secondary winding will have 0 - 110V. You can connect your load to the secondary. You have the additional advantage of isolation.
OPTION #2.
Your application requires three phases (three phase motors etc.)
Buy a new transformer having:
a) Primary winding - Three Phase Delta connection (3 terminals - R, Y, B - Phase to phase voltage 220V)
b) Secondary winding - Three Phase Star connection (4 terminals - R, Y, B, N - Phase to phase voltage 220V, Phase to Neutral Voltage 110V)
c) KVA Rating - depends on the load you plan to use.
For both of the above applications, youvwill have to calculate the load that you will be connecting to the transformer and derive the KVA rating.
2006-09-26 19:03:01 · answer #4 · answered by kkonline 3 · 0⤊ 0⤋
buy a new larger panel
2006-09-26 16:49:22 · answer #5 · answered by wizard 4 · 0⤊ 0⤋