# Electrical

Discussion in 'General Electronics Chat' started by harman16, Apr 26, 2006.

1. ### harman16 Thread Starter New Member

Apr 26, 2006
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why a 2 Φ circuit does not exist?

2. ### Grant Member

Mar 5, 2006
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We can use 2 phases together of a 3 phase supply to act as a single phase if it gives us the desired voltage we require for the equipment we want to power. This equipment is single phase- meaning the heating element or coil or lamp is run off just one phase, singular- "single phase".
Cheers,
Grant

3. ### kubeek AAC Fanatic!

Sep 20, 2005
4,691
806
In short because the two phases add up and act like a single phase.

When you have a center-tapped supply transformer and take the center as a common point, then you have two phases, shifted by 180deg, on the opposite sides of the secondary. But when you take one end of the secondary as a common point, than you have just a single phase supply with two voltages.

4. ### Papabravo Expert

Feb 24, 2006
10,340
1,850
In brushless DC motors you want the phase with the current to be at 90 degrees or less away from the rotor, so that maximum torque can be applied while it is energized. In a two phase machine there is just no good way to satisfy this criteria.

5. ### alim Senior Member

Dec 27, 2005
113
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Hi 2 phase circuits were in existence before the advent of 3phase,in 2ph. the voltages are 90deg .out of phase .Kubeek refers to a centre tapped transformer as 2 ph. but that should be called a bi phase transformer.