Hello friends, today I am going to tell you What is Polyphase System?: If you also want to know, then keep reading this article completely.
What is Polyphase System
If we talk about phase or phase more than one phase, then by that we mean the armature coil present in the machine. If we assume that the armature of a machine has one coil, then the machine is called single phase, if it has two phases then it is called double phase and if there are three phases then it is called triple phase etc. If there is more than one, then we call it Polyphase System.
Two or more phase systems are called multiple phase systems. Kala refers to the number of coils in the machine. If the displacement of the coil in two phase system is 90° electric then it is of Vikla. Tricycle machines have an angle of 120°. Hence, in n number phase machines, the phase difference will be 360°/n.
If we talk about an art, then a phase current and voltage are represented by a single wave in it, but in multi-phase machines, the waves of current and voltage depend on the number of coils. We displace this coil at certain angles according to the phase. For example, the angle of displacement of the armature of two-phase machines is 90° and 120° in three-wheel and 60° in septum-bladed machines, the number of phases or phases in multiphase machines other than two-phase machines 360 Number of coils formula is determined on.
Advantages of Polyphase System
- high strength coefficient
- uniform torque
- automatic motors
- high output power of motor
- high efficiency of motor
Need and Advantage of 3-phase system
The three phase system has the following advantages over single phase or phase system:
(i) The output of a three-phase motor or generator of the same size is greater than that of a single-phase motor or generator.
(ii) Three-wheel motors are self-propelled whereas all single-phase motors are not self-propelled except for commutator motors.
(iii) Torque is the same for three-wheel motors, while all single-phase motors, except for speed converter motors, have pulsating torques.
(iv) The power factor of three-wheel machines is higher than that of single-wheel machines.
(v) The efficiency of three-stage machines is higher than that of single-stage machines.
(vi) Due to the pulsating armature reaction in single-phase generators, it is very difficult to operate them in parallel without damper coils whereas in three-phase generators there is no such thing.
(vii) A three-phase transmission line for a given distance at a given voltage at a given power requires less copper than a single phase line.
By phase sequence, we mean the sequence in which the maximum value of voltage is obtained in all three phases. According to this, if the direction of the machine is running, then first the value of coil R will be maximum and after rotating 120° or 27/3, the coil Y and after rotating 240° or 4r/3, the coil B will get the maximum value of voltage i.e. we It can be said that the phage sequence will be RYB. But if the direction of running of the machine is made anticlockwise instead of clockwise, then the order of maximum voltage in different coils will become RBY instead of RYB.
So if we want to change the direction of rotation of the machine then we have to change the phase sequence which changes the direction of motion.
Interchanging the two phases of a three phase induction motor changes its direction. Therefore, it becomes necessary that the power distribution department should keep the phase sequence correct, otherwise the direction of induction motors, which are used in almost all the works in modern era, will keep changing and as a result, the person who uses the motor will face a lot of trouble. Will have to face
Note: If the phase sequence is RYB, YBR, BRY then the direction of motion will not change but if the phase sequence is changed to RBY, YRB or BYR then the direction of the motor will be reversed as before. Phages are also expressed by RYB, abc and 1,2,3, but most are expressed by RYB.
Generation of Three Phase Voltage
Three identical coils A1, A2, B1, B2 and C1, C2 are situated in the magnetic field of a permanent magnet or electromagnet as shown in figure (a).
These coils are mounted on the shaft by displacing it at a distance of 120°. The six terminals of each coil are connected separately at the spindle ends.
A coil A1 A2 is shown connected to a slip ring. When these coils are rotated counter-clockwise, then according to Faraday’s law of electromagnetic induction, the V.V. (emf) is inspired. In V. Va. The magnitude of the forces depends on the position of the coils in the magnetic field. Let the plane of the coil A, A, be perpendicular to the magnetic field and zero V.V. Getting inspired. When this coil is rotated 90°, the coil cuts the maximum flux and the maximum V.V. is generated.
When the coil A1,A2 is rotated 180° and 360°, again the vivab. Zero induces and when the coil is rotated by 270°, the voltage generated. The value of minus (-) will be.
Is the three-way method better than the single-art method?
- Having the same size, the output power of a multiple phase generator or motor is relatively more than a single phase motor or generator.
- Multi phase induction motors are self starting but single phase motors are not self driven. The torque of the tricycle is homogeneous but the torque of single-bladed motors is of pulsating nature.
- The efficiency of multi phase motors is higher than that of single phase motors.
- The power coefficient (PF) of three phase machines is higher than that of single phase machines.
- The transmission of fixed power up to a certain distance is more in the triple phase system than in the single phase system. It also seems less.
- Due to the pulsating armature reaction in single-phase generators, it is difficult to run them in parallel without damping coils, whereas there is no such problem in tri-phase generators.
what did you learn today :-
Now you must have come to know What is Polyphase System?, Advantages of Polyphase System, Need and Advantage of 3-phase system, Phase Sequence, Generation of Three Phase Voltage . You must have got the answer of all these questions very well.
I hope that you have liked the information given by me, if you have any question / suggestion in your mind, then you can tell me by commenting below, I will definitely answer your comment. If you liked this post then you can also share it with your friends and relatives.