Everything David Simmons said is 100% correct.
I forgto to note- the grounded B service is NOT used in residential wiring. Commercial or industrial only.
I forgot to note- the grounded B service is NOT used in residential wiring. Commercial or industrial only.
Thankyou, Crafterman, for your delightfull responses.
Ummm, the “delta” system you describe is called that because the vector diagram of the phase voltages looks like a Greek delta and the phase voltages are 120[sup]o[/sup] apart. The system Joey described had two voltages 180[sup]o[/sup] apart with the center grounded.
Quote:
“Unless you’re in Wisconsin (in the WEPCO service area)…We have a grouded second phase. If you pop open the cover on a 3 phase breaker box, the center phase goes directly to ground, and phase one and phase 3 are 180 degrees apart.”
In the delta three phase system, if the voltage on each each phase is 120 v., for example, the voltage between the two “hot” lines would be 120*sqrt(3) = 208 v. and not 240.
Not at all the same thing.
Actually the voltage between the two “hot” 120 v. wires in the delta configuration would be 120 v. Is there any graceful way that I can pretend my 208 v. figure cited above doesn’t exist? That I never wrote it?
Maybe I should mention that this is at a commercial bussiness. Also I just checked out everything to make sure that I remembered correctly. The box says 3 Phase 240 Volts. I popped the lid and it has two wires running through the switch (and the time delay fuses) and the third wire goes directly to ground.
My parents’ house in Houston has 208V 3 phase service, so it isn’t completely unknown for 3ph to be used for residential.
The only appliance that is wired for 3ph is the A/C unit. I haven’t seen how other things are wired, but I know that the incoming service is 3 insulated hot wires and one bare neutrals.
How do we know the voltages are 180 degrees apart as JOEY stated?
Simmons, are you disputing my knowlegde of the existence of 240 or 480 grounded systems?
Maybe Joey is describing and open delta system.
In any case the physical configuration of the windings is DELTA, or WYE, not just the phase vector diagrams. Take apart a XFMR, and trace the windings to thier sources and you will actually see DELTA or WYE configuration. In a common XFMR the core is grounded. In a grounded B system the tap between A and B is grounded. In a High leg system the B winding is grounded in the center.
120 - 208 is an example of a WYE output
277 - 480 is an example of a WYE output
In a High leg system the A-C winding is tapped in the center.
Beg pardon
We can only answer the question as it is stated in the OP.
Quoth StPaul:
Are the balls bright orange? Those are put there in regions where there might be low-flying aircraft, to make the lines more visible.