Negative Phase Sequence is Phenomena generally found in motors,
the formula for positive phase sequence is : Ip= Ir + a * Iy + a^2*Ib
the formula for negative phase sequence is : In= Ir + a ^2* Iy + a*Ib
As the name suggest the sequence of current or the mmf is in reverse order, a reverse order current in stator will produce a reverse order mmf, now this reverse order mmf is rotating in direction opposite to the rotor of the motor, thus the mmf cut is very high and so current induced in stator is considerably high; as for normal mmf it is in direction of rotor so mmf cut is very small thus current induced is very small.
this high current in your rotor leads to overheating of your motor and finally burning of your windings.
Comment
Negative phase sequence is not 'generally found in motors'. But one of the effects of negative phase sequence would be to cause a three-phase motor to reverse direction.
Negative sequence current is defined as 3I2 = (phase 1)*(1angle 0) + (phase 2)*(1angle 240) + (phase 3)*(1angle 120) Negative sequence current is seen in three phase power systems due to natural system imbalance. Also during unbalanced fault conditions such as line to line, Line to ground, and line to line to ground faults. It is not seen in purely balanced three phase faults.
Capacitive reactance is considered negative because it represents the phase relationship between voltage and current in a capacitive circuit. In a capacitor, the current leads the voltage by 90 degrees, meaning that the voltage lags the current. This phase difference is mathematically expressed as a negative sign in the capacitive reactance formula, (X_C = -\frac{1}{\omega C}), indicating that the reactance opposes changes in voltage rather than current.
out of three phases present one or two of them are negative and remaining +ve current flows back through negative
No, there is not. Three phase ,or generally speaking multiphase, circuits are available only for AC (alternating current) systems, because there is no phase shift in DC (direct current) systems. This is because DC power is not sinusoidal (current flows in one direction).
Line current = 1.732 x Phase CurrentCommentOnly for balanced loads.
4/4+4*4=20 is it correct by any means or not ? No this garbage has got nothing to do with negative phase sequence current in 3 phase electrical systems.
It's the amount by which voltage leads current (or vice versa) in the AC circuit. By convention, the phase angle is positive in inductive circuits (where voltage leads current) and negative in capacitive circuits (where current leads voltage).AnswerUnfortunately, the original answer has things the wrong way around. By definition, phase angle is the angle by which the current leads or lags the supply voltage (not the other way around). Therefore, the phase angle is considered negative (current lagging) for an inductive circuit, and positive (current leading) for a capacitive circuit. This is because, for a phasor diagram, counterclockwise is the positive direction, whereas counterclockwise the the negative direction.
Negative sequence current is defined as 3I2 = (phase 1)*(1angle 0) + (phase 2)*(1angle 240) + (phase 3)*(1angle 120) Negative sequence current is seen in three phase power systems due to natural system imbalance. Also during unbalanced fault conditions such as line to line, Line to ground, and line to line to ground faults. It is not seen in purely balanced three phase faults.
A phase current is the current passing through a phase, whereas a line current is the current flowing through a line.
Capacitive reactance is considered negative because it represents the phase relationship between voltage and current in a capacitive circuit. In a capacitor, the current leads the voltage by 90 degrees, meaning that the voltage lags the current. This phase difference is mathematically expressed as a negative sign in the capacitive reactance formula, (X_C = -\frac{1}{\omega C}), indicating that the reactance opposes changes in voltage rather than current.
How Negative phase sequence relay work
out of three phases present one or two of them are negative and remaining +ve current flows back through negative
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.
No, there is not. Three phase ,or generally speaking multiphase, circuits are available only for AC (alternating current) systems, because there is no phase shift in DC (direct current) systems. This is because DC power is not sinusoidal (current flows in one direction).
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.
A negative current only signifies direction.