14-04-2011, 04:35 PM
Presented By
AASHISH BHASKAR
ASHISH DHYANI
DINESH BHATT
MAHENDRA SINGH ADHIKARI
[attachment=12229]
INTRODUCTION
APPLICATION
Phase sequence detection system has been specifically designed keeping in mind an essential point of detection of correct phase and protection of equipments by over voltage.
Basically it is useful to connect the any m/c to supply. Because if the phase is not correct and connection establishes than it may be damage and burn out the winding of machine.
This phase sequence detection and controlled power supply system is basically divided into two parts:-
1. Phase Sequence
2. Protection from supply voltage
i. Under Voltage Protection
ii. Over Voltage Protection
APPLICATION:-
1. For giving a controlled power supply, because it can
amplify the voltage if the I/P voltage is less than the
desired range & cut out the input supply when the
I/P voltage is much higher than the desired range, and
protect our equipments.
2. Can be used in Sub-Stations, after maintenances of machines.
3. Can be used in detection of phase sequence R Y B.
TECHNICAL DESCRIPTION &
WORKING OF PROJECT
In this project main components are IC4013 which consists a dual D- flip flop; IC4017 is basically a decade counter which is used to run the LED’S in a proper sequence.
Now firstly the output of any three phase m/c is fed to the input of this system. Now in the circuit there be a arrangement of two transistor T5 and T6. The out put of the transistor is fed into the IC4013.This IC is basically a dual D-flip flop. The property of D- flip flop is- The output is same as the input, means that if input is 1 than, output is also 1.
A mains phase-sequence indicator serves as a hand-tool in checking electrical wiring, especially the wiring of three-phase AC motors. The basic idea of the circuit is that when any (say, Y) of the three phases (RYB), taken as a reference phase, is at negative-going zero voltage, its leading phase (say, R) is positive while its lagging phase (B) is negative, and these states can be easily verified. The circuit comprises two main parts.
The first part comprises transistorized multivibrator, decade counter-cum-LED driver, and LED arrays arranged in a specified fashion, as shown in the figure. The second part comprises the phase-sequence detector followed by phase-sequence sensor operated flip-flop and LED switching transistors. The astable multivibrator section provides clock pulses in the 10 to 1000Hz range to the decade counter and the
LED array section. The LEDs are grouped into two parts to form two distinctive indicators. These two groups are successively driven by Q0 to Q4 and Q5 to Q9 outputs of IC1. Only one of the two groups’ LEDs will turn on sequentially, depending on which of the two transistors (transistor T3 or transistor T4) is on, which, in turn, is dependent upon the phase sequence of the three-phase supply. This becomes clear from the following explanation of the second part of the circuit.
The three phase R Y B are brought to an artificial neutral at the junctions of resistors R17 through R19 to serve as the common reference. As stated earlier, for a given phase sequence, when phase R is at its negative-going zero, phase B is negative. So data-input pin 5 of the flip-flops logic ‘high’ (due to non-conduction of transistor T5). Meanwhile, clock input pin 3 of the FF goes from low to high due to phase R.
The ‘high’ at data pin appears the Q output(pin 1) while Q output remains ‘low’ as long as the phase sequence is clockwise. Therefore the Q output drives transistor T3 to extend the ground path for green LED’S D1 through D10 to show a clockwise-rotating LED ring. When any of the two phase is interchanged (say, after a maintenance work at the power house or repair/ replacement of a three phase transformer), the conditions are reversed, and Q become ‘high’ and red LED’S D11 through D20 are switched on(Sequentially) by transistor t4 to show an anticlockwise-rotating ring.
While testing for the phase sequence, there is no need to keep the device on for long time. A push-to-on read switch
can be used during the phase-sequence testing. If the device is to be used for long periods, use a high capacity battery in place of battery. Also replace 2W resistors to R17 to R19 with fusible-type resistors.
The frequency of the astable multivibrator is unimportant, except that the speed of the LED ring must be easily visible. Zener diodes ZD1 and ZD2 are used for protection of transistor T5 and T6 respectively. For the protection from supply voltage (under voltage and over voltage protection) we use 0.5 KVA transformers for each phase and relay. These transformer and relay are mainly responsible for the protection from over/ under voltage protection.
AC phase:-
Things start to get complicated when we need to relate two or more AC voltages or currents that are out of step with each other. By “out of step,” I mean that the two waveforms are not synchronized: that their peaks and zero points do not match up at the same points in time. The graph in figure below illustrates an example of this.
Out of phase waveforms
The two waves shown above (A versus B) are of the same amplitude and frequency, but they are out of step with each other. In technical terms, this is called a phase shift. Earlier we saw how we could plot a “sine wave” by calculating the trigonometric sine function for angles ranging from 0 to 360 degrees, a full circle. The starting point of a sine wave was zero amplitude at zero degrees, progressing to full positive amplitude at 90 degrees, zero at 180 degrees, full negative at 270 degrees, and back to the starting point of zero at 360 degrees. We can use this angle scale along the horizontal axis of our waveform plot to express just how far out of step one wave is with another
