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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.
Alexane Shanahan
Wiki User
∙ 12y ago'Phase sequence' is the sequence, or order, in which the three line potentials of a three-phase sequence reach their maximum values relative to each other. By general agreement, 'normal' or 'positive' phase sequence occurs in the same order in which lines are normally identified, i.e. red-yellow-blue, brown-black-grey, A-B-C, R-S-T, etc. (according to national standards). 'Negative' phase sequence occurs when these potentials occur in the opposite order, i.e. red-blue-yellow, brown-grey-black, A-C-B, R-T-S, etc. The effect of applying a negative phase sequence to a three-phase motor is to cause it to reverse direction.
Wiki User
∙ 11y agoThe order, or sequence, in which the potential of each line conductor in a three-phase system reaches its maximum value, is called the phase sequence of that system. By general agreement, the sequence A-B-C (or R-S-T or 1-2-3, etc.) is considered to be the normal, or 'positive', phase sequence, whereas the sequence A-C-B (or R-T-S or 1-3-2, etc.) is considered to be the 'negative' phase sequence.
If a three-phase motor has been connected in such a way that a positive phase sequence applies, then it will rotate in a particular direction. If the motor is then disconnected, and inadvertently reconnected with two line conductors interchanged, then the sequence will then be a negative phase sequence, and the machine will rotate in the opposite direction.
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What is neutral negetive sequence current?
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.
What is the return path in three phase three wire line?
out of three phases present one or two of them are negative and remaining +ve current flows back through negative
Does DC have a single phase and a three phase supply?
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).
In delta connection what is formula for phase current?
Line current = 1.732 x Phase CurrentCommentOnly for balanced loads.
Phase difference between voltage and current at resonance?
The power factor is a measure of the phase difference. If they are exactly in phase the PF = 1. If they are 180 degrees out of phase PF = 0.
How do you calculate negative phase sequence current?
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.
What is phase angle in ac?
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.
What is neutral negetive sequence current?
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.
What is phase current?
A phase current is the current passing through a phase, whereas a line current is the current flowing through a line.
How Negative phase sequence relay work?
How Negative phase sequence relay work
What is the return path in three phase three wire line?
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 tranformer test?
How do you zero phase current transformer test
When will there be any current in phase?
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.
Does DC have a single phase and a three phase supply?
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).
Why line current is greater than phase current in delta connection?
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.
Can current be negative?
A negative current only signifies direction.
How do you calculate the total input current from a 3-phase power source when the current from each phase is known?
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'!
