Phase applies only to AC current and not DC current. Reactive components - inductors and capacitors - in a system will result in the system output either lagging or leading (capacitance lags and inductance leads).
If we apply an AC signal to the input of a system, we can observe the input and the output on an oscilloscope. If the system lags then the output signal will appear to be shifted to the right relative to the input singal, and vice versa for a system that leads. Since AC signals are periodic we think of one period as being 360 degrees (or 2*pi radians). The phase of output signal relative to the input signal is thus measured in degrees.
For example:
An AC signal of period of 10 seconds and a peak current of 2A is applied to the input of a system. The output is measured and it is found that the output current peaks 3 seconds after the input voltage - so the output lags the input, meaning the circuit has a capacitive reactance. What is the phase of the output relative to the input?
Since T=10 and the phase difference in seconds is 3 the solution is simple:
360 / 10 * 3 = 108 degrees
So; the output lags the input with a phase difference of 108 degrees.
A phase current is the current passing through a phase, whereas a line current is the current flowing through a line.
How do you zero phase current transformer test
Current is always flowing in the phase due to the continuous voltage application. the current in phase can be used when it is given a - ve terminal or earth the current would complete the circuit.
Because if you apply Kirchhoff's Current Law to the junction between the line current and the two phase currents, the line current is the phasor (vector) sum of two phase currents. For a balanced load (only), this works out to 1.732 x phase current.
The current is the same in the three live wires. The voltage can be described as the line voltage (phase to neutral) or the phase voltage (phase to phase) which is larger by a factor of sqrt(3). So a line voltage of 230 v corresponds to a phase voltage of 400 v.
Add them upAnswerThere is no 'total' current in a three-phase system. The current flowing in each line (not 'phase') is considered separately. And you most definitely don't 'add them up'!
Balanced Star (Wye) Connected Systems:Line Voltage = 1.732 x Phase VoltageLine Current = Phase CurrentBalanced Delta Connected Systems:Line Voltage = Phase VoltageLine Current = 1.732 x Phase Current
The phase angle between voltage and current in a purely resistive circuit is zero. Voltage and current are in phase with each other.
You will need to determine the power per phase, and add them up to give the total power of the three-phase load. To do this, you will need to multiply the phase-voltage by the phase current by the power factor -for each phase.
Line current = 1.732 x Phase CurrentCommentOnly for balanced loads.
All current is the passage of electric charges from one terminal to another through a conductor so there is no real difference in the type of current that flows in a 3 phase system compared to a single phase system.
The current carried by the neutral of a three phase four wire system is the un balanced current. If the three phase system was completely balanced on all three phases there would be no need for a neutral, eg a three phase motor. This neutral current will be less that the phase current so a reduction in the neutral size is allowed.