0
Want this question answered?
Be notified when an answer is posted
Add your answer:
Earn +20 pts
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.
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 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.
What are the procedures for the connection of single and 3 phase circuits?
Single phase connection has 1 phase wire and a neutral wire. Another wire for protective earth. In three phase system, motor can be connected in star or delta. Most AC induction motors are in Delta. Power distribution system is generally 3 phase 4 wire. Transmission system is 3 phase high voltage. Industry uses 3 phase system, where as 1 phase is for domestic, commercial applications. Both 1 and 3 phase system has a frequency. It is either 50 Hz or 60 Hz, depending upon the country or region.
Why is important for three phase supply voltage to be in-phase?
The phase voltages (i.e. line-to-neutral in a 4-wire system, or line-to-line in a 3-wire system) of a three-phase system are displaced from each other by 120 electrical degrees. Each phase voltage, in fact, is rarely in phase with its phase current, as the phase-angle (the angle by which a phase current lags or leads its phase voltage) is determined by the load not by the supply.In general, most loads are resistive-inductive so the phase current usually lags the phase current.So, to answer your question, it's not important that a phase current is in phase with its phase voltage -if that is what you are asking.
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 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.
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.
How do you determine a 3 phase motor and each winding?
To see if the motor is three phase or single phase look at the motor's nameplate. There it will tell you what the voltage needs to be and what system phase the motor needs to be connected to operate properly.
Why 3 phase ac systems is preferred to 4 phase?
3 phase system has more power than a single phase system
How do you turn a 3 phase motor in to a generator?
We can convert a 3 phase ac motor into generator by changing phase sequence of the ac input cable of that motor
What is meant by phase sequence in a polyphase system?
It is the colour coding of the wires from left to right when connections are made to terminals. In Canada it is Red, Black, Blue. By using this standard every connection in the poly-phase (3 phase) system will be the same. Once a motor is phase rotated and marked with the appropriate colours it can be reconnected any where else in the system and run with the correct rotation.
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.
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.
Why 3 phase and single phase?
3 Phase system is for industrial use and 1 phase is for house hold application
How do you convert a 3-phase system to a single phase?
By having a transformer with 3 phase input and single phase out put
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.
