Skip to main content ↑ ↓
Topic: Phase angles in a 120/240 Volt Supply (Read 779 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Phase angles in a 120/240 Volt Supply

Yahoo Message Number: 67074
Hi Don Bob

WE have an argument here and I see why. All my education in electrical engineering was gained in the UK and Australia. There the terminology is obviously different.
I know this is off topic for many people so I will just get this off my chest and then finish.
We can have a three phase service 120/208V where we have a phase voltage, 120V and a line voltage 208V, and the phase angle between them is 120 degrees. Then why is it difficult to understand the service of 120/240V where 120V is the phase voltage and 240V is the line voltage and the phase angle between them is 180 degrees? The mathematical explanation uses trig and vectors with a possible smattering of complex numbers and I feel not for this forum. If you stick to your terminology it would be difficult to explain when and why the current, amps, tends to not remain in phase with the voltage in an inductive circuit such as an air conditioner where Watts does not equal Volts times Amps, and where the circuit power factor must be incorporated. All vectors and phase angles and very important to understand that volts times amps may not equal watts. If the basics are right the rest will fall into place, usually. Incidentally only in the States is the term Hot use to describe a live wire. Hot it is not Live it definitely is.
I am new to RVing only been doing it for 2 years. In that time I have had two motor homes. Both having a 50A supply from a center tapped transformer. . This type of service is not used in the UK or Australia. There the phase voltage is 240V. and adequate for all purposes unless a 3 phase supply is needed for heavier appliances like domestic air-conditioning.
Last year my wife and I did the Alaska trip and thoroughly enjoyed this great country. This forum is great for the education of all RVers I do hope you don't think I am being too pedantic.
A happy New Year to all.
Regards
Peter J

Re: . Re: Phase angles in a 120/240 Volt Supply

Reply #1 –
Yahoo Message Number: 67080
The word phase has no meaningful value to a discussion of a single phase RV 50 amp connection the current will folow the voltage in the circuit unless we want to confuse the subject with reactive loads BOB 06 Intrigue 12047t

. Re: Phase angles in a 120/240 Volt Supply

Reply #2 –
Yahoo Message Number: 67089
It's simple, draw 2 sinusoidal waves (120 Volts), 180 degrees apart and then add them up, it'll be 240 V. Draw the current wave form (assume a resistive load, for you engineers out there), and look at the current in the neutral, it'll be the difference in the two legs. Note that the values use is to simplify the explanation, the 120 V is an RMS value, and actually the drawn sinusoidal wave is a peak value.

Joe

98 Intrigue 10578

Re: . Re: Phase angles in a 120/240 Volt Supply

Reply #3 –
Yahoo Message Number: 67094
JOSE I think you are wrong a complete cycle is 360 degrees a half cycle is 180 degrees two cycles 180 degrees out of phase adds up to zero a full cycle is made up of 4 segments 90 degrees each 2 positive and 2 negative if you choose to look at it that way BOB 06 Intrigue 12047
 

Re: . Re: Phase angles in a 120/240 Volt Supply

Reply #4 –
Yahoo Message Number: 67097
I agree With Bob.

Forget phase and look at as if you had a 240 volt transformer that is center taped a 120 volts. Thus from each leg to the center tap is 120 volts and across leg to leg is 240 volts.
It is as simple as that.
Marv

Intrigue 11314