what's the difference between single phase ac power and three phase?

Answer 1

Single phase has one hot line whereas 3 phase has three hot lines

Answer 2

The main difference between single phase and 3 phase power, apart from the obvious, is the fact that when the same amount of active power is being delivered to the load resistance/s , the power loss in 3 phase due to line resistances / inductances is halved . This is the main advantage , theoretically speaking . The reactive power components in a 3 phase balanced system also cancel out , thus providing better efficiency.

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Harish.S

Answer 3

Single Phase power is delivered on one hot wire (with a ground of some type). Three phase power is delivered through three hot conductors (which share a single ground of some type)..With both types of power, 1 phase and 3 phase, it is understood that we are talking about alternating current. With 3 phase power the voltage peaks are staggered at equal intervals across the 3 conductors. That means that, after one conductor reaches a voltage peak, another peaks a third of a cycle late, and the third one peaks 2/3 of a cycle later. This staggered voltage on the 3 phases is very useful in making motors turn. It is a simple thing to have coils spaced around a rotor, each fed by a different phase, resulting in the voltage peak in the coils and thus the current and magnetic field in the coils moving around the motor and causing the rotor to turn. With a single phase motor, the motor doesn't know which way to go because there is only one rising and falling field. Such a motor needs to have an artificial second phase created by using a capacitor to delay the voltage rise on a starting coil. Once the motor gets going, the start up coil is turned off and momentum causes the motor to keep going in one direction. On such a motor, if the start up capacitor is removed, you can apply power to the motor and spin it in either direction to get is started, and then it will continue to run in the direction you spun it.

Answer 4

see single phase have power transfer thru one wire and it is used when we require low load (ie in houses where 230 v is req.)
but in industries as 11kv power is req so a single wire can't handle such load so 2 more wire r joined so they can transfer power effectively without much power loss

Answer 5

See graph at source

Answer 6

One sinusoidal wave and three sinusoidal waves