PHASE SEQUENCE CHECKER FOR THREE PHASE SUPPLY SUBMITTED BY

ABSTRACT A 3-ph supply of 440V AC 50Hz is fed to a logic circuit comprising of NAND gates and OR gates to detect the sequence of R, Y, B by triggering a monostable timer 555. While the sequence is not there the triggering to the timer is missed which is indicated by an LED driven from the output of the 555 timer.

BLOCK DIAGRAM

HARDWARE COMPONENTS: TRANSFORMER (230 – 12 V AC) VOLTAGE REGULATOR (LM 7812) RECTIFIER FILTER 555 TIMER NAND GATE (4011) IN4007 LED RESISTORS CAPACITORS

POWER SUPPLY Bridge rectifier 5v Regulator 230 V AC 50 Hz 5V DC Filter(470µf) 12V step down transformer

CD4011-NAND GATE Functional Diagram of CD4011 NAND gate truth table input B input A output 1 Functional Diagram of CD4011

Features Four Independent 2-input NAND Gates Standard Pin Configuration Wide Operating Voltage Range Operating Temperature to 85oC Low Power TTL Fan out of 2 driving 74L Compatibility or 1 driving 74LS 5V±10V±15V parametric ratings Symmetrical output characteristics Maximum input leakage 1 mA at 15V over full temperature range

555 TIMER The 555 Timer IC is an integrated circuit (chip) implementing a variety of timer and multivibrator applications. The original name was the SE555 (metal can)/NE555 (plastic DIP) and the part was described as "The IC Time Machine". Depending on the manufacturer, the standard 555 package includes over 20 transistors, 2 diodes and 15 resistorson a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8)

PIN DIAGRAM OF 555 The 555 timer IC is a simple 8 pin DIL package IC. It can: be used as a monostable be used as an astable source or sink 100mA use supply voltages of 5v to 15v disrupt the power supply - use a decoupling capacitor!

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