Plug and light indicate full voltage form multi meter, and plug tester shows everything works, but when I try to plug anything into it, there is no power. Is it an unbalanced phase problem or ???
2007-07-26 08:38:33 · 6 answers · asked by Darren I 2 in Science & Mathematics ➔ Engineering
If its a 480 volt system it could be a delta with a phase out.
There are 2 ways 3 phase transformer systems are connected, Delta and/or Wye "Y". On a three phase Delta system, being that its a "closed loop", if one line feeding the transformer is dead, you will still read 480 across all phases. Check the transformer fuses on the high or input side. (ONLY someone qualified on High Voltage should accomplish this without question!).
These factors also apply to 240v delta as well. But is experience with 480 more commonly.
On a "Y" system, you can check "phase" to neutral or ground. If the phase is good you will get either 120/208 on a high leg delta or 277 on a 480 delta (No neutral on 480 delta...or rarely) on a 240vac delta, there will be a stinger leg, usually phase "B" will read 208 phase to neutral.
Above all be very careful.
2007-07-26 09:17:01 · answer #1 · answered by The prophet of DOOM 5 · 0⤊ 0⤋
Today I was using one of my 3-phase widebelt sanders and ran through something too thick and the machine shut down. So I tried starting the machine up again and there was very little power going to it and the machine would not operate. I went to another one of 3-phase machines and it would not work either. All my 3-phase machines didn't work. There was a little power going to them, when the 3-phase machines were started it would make a buzz sound All my other 1-phase machines would work. Do you think this is a case where the problem is a blown fuse or a open circuit?
2007-07-28 13:02:26 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The balance is not important if your neutral is connected right.From any phase to the neutral is 120 volts. If u show that and it will not work some how someone has connected to ground and not neutral. The ground may not be a good ground if the ground id too dry ,it will not carry a load. In the high mountains of Ecuador it rained a lot. It had washed all the salts out of the soil and from one ground at the generator to the equipment was 2 meg ohm as again there was nothing to conduct electricity. Rain water does not conduct electricity. We had to run a neutral cable with it grounded at each end.
2007-07-26 09:28:31 · answer #3 · answered by JOHNNIE B 7 · 0⤊ 0⤋
More than likely you have a blown fuse or open circuit on one phase, and a high impedance load (like a control circuit transformer) connected between that phase and another phase. Open the disconnect, remove the fuses, and check each fuse separately.
2007-07-26 12:30:11 · answer #4 · answered by Helmut 7 · 0⤊ 0⤋
Probably that line has open circuit but due to the lines which having power they are inducing voltage to the open circuit wire. You can measure a voltage into this line because your multimeter has very high input resistance and cannot able to dissipate the induced power.
2007-07-26 08:47:33 · answer #5 · answered by dongskie mcmelenccx 3 · 0⤊ 1⤋
You have lost two phases. Always measure phase to phase. Not phase to neutral.
2007-07-27 15:18:50 · answer #6 · answered by david m 3 · 0⤊ 1⤋