The
project is designed to check the sequence of the 3 phase supply. It is very
important to know the phase sequence particularly for 3 phase motors. For
example, if the 3 phase motor is used for pumping action, any phase reversal
accidentally resulting in wrong sequence could force the motor run in the wrong
direction. This could result in dry run of the motor to develop permanent
fault.
In this
project direct 3-phase AC supply 50Hz is fed through voltage drop arrangement
duly stabilized by zennor diodes to a logic circuit comprising of NAND gates
and OR gates to detect the proper sequence of RYB by series of pulses of fixed
duration.
In the
event of changing the sequence from RYB to say YBR, the combination of NAND and
OR gates develops an output with a missing pulse during the fixed time
duration. This pulse is used in triggering an input signal to a 8051 series
microcontroller through a timer to drive LEDs placed in a circle. In proper
sequence the LEDs run clockwise having received no triggering.
While
the sequence is not there the triggering is done which is indicated by
LEDs running clockwise for some time and then anti clockwise for the next and
so it continues. DC requirement of the circuit is powered from a step down
transformer along with a bridge rectifier ,regulators and filter capacitor. Further
this project can be enhanced by providing a relay to circuit to cutoff the
supply to the load.
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