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Does the power factor in three phase system depend on the phase sequence?
Wiki User
∙ 12y ago
No. It depends on the inductive and capacitive reactance of the load.
Wiki User
∙ 12y ago
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Three phase voltage in india?
It is 230V single phase and 440V in 3 phase system at 50 Hz.AnswerIf the single-phase voltage is 230 V, then the three-phase voltage must be 400 V, not 440 V. The line voltage is 1.732 times the phase voltage.
What is the difference between phase angle and phase difference?
Although we use the term 'Phase angle' it's also an angle referred to another phasor (voltage or current).For example,conventionally when expressing power factor, we use 'voltage' as the reference. So the 'phase angle' of a particular phasor is the phase difference between our reference (voltage) & the phasor.As the gist, both mean the same except that 'phase angle' is the direction of the phasor w.r.t. positive x direction (reference)..AnswerBy definition, phase angle is the angle by which a load current leads or lags a supply voltage.Phase difference is the angle between any two electical quantities -for example, the angle two phase voltages of a three-phase system.
Why is a three phase four wire distribution system used?
A three phase four wire system allows for two voltages from a single three phase transformer. The transformer configuration is a wye or star connection. It is used in commercial and industrial applications. Apartment buildings are now starting to use a three phase four wire service distribution system. Some wye connection voltages are 120/208 volts, 480/277, and 600/347. The lower voltage is derived from the sq root of 3 divided into the three phase voltage.
What is the difference between Load Current Line Current and Phase Current?
A load current is a current drawn by an electrical load. In other words, it is the current flowing from the source to the load.For a single-phase system, a line current is a current flowing through the line, or 'hot', conductor, while the current through the neutral conductor is called the neutral current.For a three-phase system, the three 'hot' conductors between the load and the source are called 'lines' and, so, the currents passing through them are called 'line currents'. For a three-phase system, loads are either connected between line conductors (delta-connected system) or between each line and the neutral (star- or wye-connected system), and represent the phases -so the currents passing through the loads are called 'phase currents'.For a balanced three-phase system, the line current is 1.732 times the value of a phase current, where the phases (loads) are connected in delta. For phases (loads) connected in star (or 'wye') the line current is numerically-equal to the phase currents.
Power factor is not greater than unity?
Yes. Power factor is never greater than one, nor less than negative one. It is the cosine of the phase angle, and is the ratio of true versus apparent power.A negative power factor can occur in the case of a generator.
What is the symbol of phase sequence?
The symbol of phase sequence is RYB
What is phase sequence in 3-phase system?
The potential of each line of a three-phase system is displaced from the other two by 120 electrical degrees. The sequence, or order, in which the potential of each line reaches its peak value is termed the 'phase sequence' of the system. The 'normal' phase sequence of an alternator is considered to be the 'positive phase sequence', is arbitrarily assigned colours (e.g. red-yellow-blue, etc.), numbers (e.g. 1-2-3), letters (e.g. A-B-C), or a combination of letters or numbers (e.g. L1-L2-L3). If that alternator should run backwards, or (far more likely) if its terminals were disconnected and then incorrectly reconnected, the the sequence would be A-C-B (etc.), which would be considered to be 'negative phase sequence'. Before connecting two generators (or two complete transmission/distribution systems) together, their phase sequence must be confirmed as being the same. Reconnecting a three-phase motor with the wrong phase sequence would result in it running in the reverse direction and, possibly, damaging its load.
What is the difference between positive sequence and negative sequence arrangement?
The order in which the voltage of the coil reaches to the maximum value is called the Phase Sequence.POSITIVE PHASE SEQUENCE: If the coil is rotated in anticlockwise direction, the phase sequence will be Positive Phase Sequence, i.e., R-Y-B or A-B-C.NEGATIVE PHASE SEQUENCE: If the coil is rotated in clockwise direction, the phase sequence is called Negative Phase Sequence, i.e., R-B-Y or A-C-B.NOTE: Phase Sequence is of great importance in parallel operation of three phase transformers and alternators.
What is the effect of Phase sequence change in 3 phase supply?
It is important to keep the phase sequence the same throughout the system but it is more important to connect the transformers up with the right polarities. Never close a delta connection without a test fuse wire first, for correct transformer polarity connection.
How Negative phase sequence relay work?
How Negative phase sequence relay work
What the use of phase sequence indicator?
In indicator there is a led light source. It gives us the presence of the current source by indicate its light. If the phase of the indicator is not equal to the supply voltage then it can not give us the presence of current source by its led light off. If the phase of indicator is equal with the mane supply phase then its remaining bright and continuous gives us the indication of current source.ANSWER'Phase sequence' is the order, or sequence, in which each of the line voltages of a three-phase system reach their peak values. If 'normal' phase sequence is considered to be A-B-C (or R-S-T, etc.), then 'reverse phase sequence' would be A-C-B. Phase sequence is very important if, for example, you want to ensure that your three-phase motors rotate in the correct direction. So, after disconnecting them for maintenance, you can confirm the phase sequence of your incoming conductors by using a phase-sequence meter, before you reconnect that motor.
What significance has a power factor in an unbalanced system?
A three-phase 'unbalanced' system refers to the load, as the supply voltages are unaffected by load. So the phase-angle and, therefore, the power factor of each phase will be different -i.e. there will be three different power factors.
What is the symmertrical components of three phase system?
Symmetrical components are a good way to represent out-of balance currents in 3-phase power supplies. In general an unbalanced set of currents in a 3-phase system can be represented by three compents, which are an in-sequence component, an out-of-sequence (rotating oppositely) component, and a zero-sequence component. At a high-power substation there would be meters for all three components of the current. When the currents are perfectly balanced only the positive sequence current would be non-zero.
What is zero sequence impedence?
Zero sequence impedance indicates a homopolar symmetrical component. It is a term used in electrical engineering within a three-phase system of linear combinations.
What is negative phase current?
Negative Phase Sequence is Phenomena generally found in motors,the formula for positive phase sequence is : Ip= Ir + a * Iy + a^2*Ibthe formula for negative phase sequence is : In= Ir + a ^2* Iy + a*IbAs 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.CommentNegative 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.
How the three phas e system generate?
Three coils ( Suppose: A, B and C ) are placed at 120 degree from each other in uniform magnetic field. The coils are rotated at uniform angular speed ( Suppose: omega ) ( unit: radian per second ). Emfs are induced in each coil. As coil B is placed at 120 degree from coil A, emf induced in coil B lags behind that of A by 120 degree. If the three phase voltage are equal in magnitude, the sum of the three phase voltage is zero. This can be shown by different ways. ( e.g. Vector sum ). The order in which the voltage of the coil reaches to the maximum value is called the phase sequence. ( Phase sequence is of great importance in parallel operation of three phase transformers and alternators ). Phase sequence R-Y-B is known as the positive sequence, while R-B-Y is known as the negative sequence. Phase sequence can be checked by using phase sequence indicator. Phase sequence can be reversed by interchanging any two terminals.
Sequence of phases in the cell cycle?
Interphase## G1SG2ProphasePrometaphaseMetaphaseAnaphaseTelophaseMitosisCytokinesis
