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Why phase angle is zero when voltage and current are in phase?
1 & 3
At what condition the phase angle equal zero?
That means that the voltage and the current are in phase.
What is the phase angle between voltage and current in a purely resistive circuit?
The phase angle between voltage and current in a purely resistive circuit is zero. Voltage and current are in phase with each other.
What is mean by Zero phase Current transformer?
at first what is zero sequence current.. Zero sequence currents, in simple terms, are those found in the neutral conductor. They include the unbalanced 50 Hz currents and the 3rd, 9th, 15th and other triplen harmonic currents. Zero sequence currents appear in the neutral because they do not cancel in the way that 50Hz currents cancel. This is due to the fact that the zero sequence component on one phase is always in phase with the zero sequence components of the other 2 phases. we can say 50 Hz current on one phase, on the other hand, is always 120° out of phase with the other phases 50 Hz current which causes their balanced portions to cancel in the neutral. now, any method of ground current sensing involves detecting zero sequence currents. For solidly grounded systems, connecting the phase current transformers together with a common return allows measurement of zero sequence current in the common lead, if there is no neutral load current. The vector sum of the phase currents is equal to the zero sequence ground current. Under normal load conditions, the vector sum of the three phase currents is near zero. It is not exactly zero as the system capacitive charging current of the load circuit is non-zero. but it is limited value..if it is beyond the limit this zero sequence CT take care of it. All phase conductors are passed through the window of a single CT referred to as a zero sequence CT. Under normal circumstances, the three phase currents will sum to zero resulting in an output of zero from the zero sequence CT's secondary. If one of the phases were shorted to ground, the sum of the phase currents would no longer equal zero causing a current to flow in the secondary of the zero sequence CT. This current would be detected by the relay as a ground fault. Regards, Balaji K APL, Ahmedabad
Compare the phase relationship between the voltage and current in a purely resistive circuit and an RL circuit?
In a pure resistive circuit the voltage and current are in phase. In an inductive circuit they are fro zero to 180 degrees out of phase. If they are in phase the Power Factor is 1 and 180 degrees the PF is zero. The exact amount of the phase difference depends on the specific circuit.
What is zero sequence currents?
Zero sequence is part of symmetrical components; it's a way of looking at three phase power that simplifies the math involved. In general zero sequence current is synonymous with ground fault current.
What is the power factor when the current and voltage are in phase?
The power factor of a load is the cosine of the angle by which the load current lags or leads the supply voltage. So if they are in phase (phase angle is zero), then the power factor must be unity (1).
How power is flowing when voltage and phase angle is maintained same?
Assume you are saying that the current and voltage are in phase and you want to know how power is affected. When Voltage and Current are in phase the Power Factor is 1 and you have maximum power being applied. When Voltage and Current are not in phase, Power Factor decreases from 1 toward zero.
How many degrees are the current and voltage out of phase with each other in a pure resistive circuit?
The voltage and current sine waves cross the zero line at the same time and going in the same direction. The phase angle is 0°. They are said to be in-phase.
How many times does current equal zero in single phase in one hour?
At 50Hz it's 50x60x60 = 180000
Why neutral cross section is half the phase in three phase cable while it has to carry current of summation of all phase..?
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.
What is difference between 0.8 leading and 0.8 lagging power factors?
Power factor measures the phase difference between voltage and current. If they are in phase the Power Factor is one. If the current and voltage are out of phase the power factor is between zero and one. You can describe the PF by saying the current lags the voltage with a PF = .8 or the voltage leads the current with a .8 PF.
