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Re: Electrical Problem

Reply #25 –
Yahoo Message Number: 21174
Hi Folks,

The issue I see is the use of terms.
The shore or generator power is single phase that our coaches connect to. Single phase, 2 phase, 3 phase generation is associated with the generation, transmission and use of electrical energy. Phase is the term for the time delay from one voltage leg to the next.
Shore power comes from a transformer with 2 secondary windings connected such that one winding is reverse connected with respect to the other. The generator has an equivalent connection. The 60 hertz (cycles per second) sine wave voltage (positive magnitude for one half cycle and then negative magnitude for the other half cycle) from each winding is opposite in magnitude (180 degree phase shift). So while one leg is going positive the other leg is going negative. But this is not 2 phase - two phase power generation has a 90 degree phase shift between the 2 voltage legs.

Phase and phase shift have to be used carefully.
It was correctly stated that the two leg currents cancel through the neutral for resistive loads.

For inductive loads (motors) and capacitive loads (some electronics) there is a phase shift between the voltage and current - lags or leads when looking at their respective waveshapes with an oscilloscope.
Then what results is called circulating current through the neutral which is added to the resistive current. Since most loads are inductive, the power company connects high voltage capacitors usually just before the step down transformer to reduce the circulating current. This reduces the amount of energy that must be generated.
Re:Alternating Current Machinery, L.V.Bewley, Macmillan Co, NY, 1949 Fred Kovol

Re: Electrical Problem

Reply #26 –
Yahoo Message Number: 21177
Thanks for the help with the terms You did a good job.
Your right it is single phase.

I thought that folk Also should under stand the relative voltage swing as to NEVER try to parallel the two. Oh yes by the way the arching tha we might experience in relays. switches ect. in 120 and 240 ac circuits including our bodies are subject to the Peak to peak voltage not the average. Again I may not have this right but I think the peak to peak for 240 average goes like this: 240 x 1.414 x 2 = 678 volts P TO P Any way enough of that.
Thank again for the clarification on the subject.

Marv

01 Intrigue 11314

Re: Electrical Problem

Reply #27 –
Yahoo Message Number: 21184
I will change the subject on this one since I am a little off of the original topic. I recently had a 50 amp RV panel installed at my home. How would I check the "phase shift" to make sure it was installed correctly. Is there an easy way to do this?

Thanks

Kevin
05 intrigue
11886

Re: Electrical Problem

Reply #28 –
Yahoo Message Number: 21186
It's 240 x sq root of 2 = 339.41 vac peak to peak or half of the number you quoted.

Re: Electrical Problem

Reply #29 –
Yahoo Message Number: 21187
Hi Kevin,

Measure the voltage between the two circuit breakers at either the line or load side - if it measures 240 vac you are OK, if it measures 0 vac than you have a problem. Electrical contractors should have done it correctly.
Fred Kovol

Re: 50 amp rv panel wiring

Reply #30 –
Yahoo Message Number: 21188
If the circuit breaker is a two pole breaker it will be ok because each hot wire will by design be coming from opposite lugs on the panel.

Just keep it simple...

Jim & Linda
2000 Allure

Re: 50 amp rv panel wiring

Reply #31 –
Yahoo Message Number: 21189
Fred,

Is it possible to check the wiring with a multimeter at the plug on both the 30 amp and the 50amp receptacles without pulling the front of the box off and checking the circuit breakers? Just curious?

Kevin

05 intrigue
11886

Re: 50 amp rv panel wiring

Reply #32 –
Yahoo Message Number: 21190
Hi Kevin,

Yes you can - on the 50 amp socket there are four openings, the two outer most slots should measure 240 vac between them, either outer slot and the center slot should measure 120 vac, the fouth is round (the safety ground) should measure 120 vac to either of the outer slots. If there is 0 vac between the 2 outer slots and 120 vac between an outer slot and the center slot, then there maybe only 50 amps available instead of 100 amps, depending on how it was miswired. On the 30 amp socket, only 120 vac is available, with the right angle slot being the safety ground. So there should be 120 vac from the hot to the return and from the hot to the safety ground - not sure which angled slot is the hot.
Fred Kovol