Micro Processor Based Relays

8/6/2019 Micro Processor Based Relays

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MICRO PROCESSOR BASED RELAYSMICRO PROCESSOR BASED RELAYS

BYBY

ER. NIRANJAN SAHUER. NIRANJAN SAHU

NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY, BERHAMPURNATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY, BERHAMPUR


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INTEGRATED CKT. TECHNOLOGYINTEGRATED CKT. TECHNOLOGY

INCLUDES ALL FUNCTION OF CPU.INCLUDES ALL FUNCTION OF CPU.

This miracle on chip is called aThis miracle on chip is called a

micro processor.micro processor.

A microprocessor is a programmableA microprocessor is a programmabledigital device that can perform all thedigital device that can perform all the

functions of the CPU of a computerfunctions of the CPU of a computer

implemented on I/C package by usingimplemented on I/C package by using

LSI or VLSI technology.LSI or VLSI technology.


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Main components of a digitalMain components of a digital

computer are:computer are:CPUCPU

MemoryMemoryInput DeviceInput Device

Output.Output.


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HISTORYHISTORY

1971:1971:--The 1st. MicroprocessorThe 1st. MicroprocessorIntel 4004Intel 4004

(4 beat MP)(4 beat MP) introduced in USA.introduced in USA.

1973:1973:-- Motorola emerged withMotorola emerged with(8 beat MP) 6800/6809.(8 beat MP) 6800/6809.

1978:1978:-- M/S Intel/Motorola/Texas usedM/S Intel/Motorola/Texas used

(16 beat MP)(16 beat MP)1980:1980:-- Again Intel introducedAgain Intel introduced

(32 beat MP)(32 beat MP)


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Main Components of a digital computer areMain Components of a digital computer are

Input Device, CPU, Memory and the Output.Input Device, CPU, Memory and the Output.


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The CPU gets instructions from the memoryThe CPU gets instructions from the memory

and executes them to perform a specific task.and executes them to perform a specific task.

: It stores results in the memory or sends the: It stores results in the memory or sends the

results to Output device as per the programme.results to Output device as per the programme.

: The CPU controls and communicates with: The CPU controls and communicates withmemory, Input and Output device.memory, Input and Output device.

: TCU provides necessary timing and control: TCU provides necessary timing and control

signal.signal.

: Register Array is mint for temporary stage of: Register Array is mint for temporary stage ofdata. The accumulator stores all data but passesdata. The accumulator stores all data but passes

only the required function.only the required function.


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: The microprocessor accepts d.c.voltage: The microprocessor accepts d.c.voltage

proportional to load current.proportional to load current.

: Using a multiplexer the microprocessor: Using a multiplexer the microprocessor

can sense fault current of a number ofcan sense fault current of a number of

circuits.circuits.

: If fault current exceeds the pick up value: If fault current exceeds the pick up valuethe microprocessor sends a tripping signalthe microprocessor sends a tripping signal

to CB.to CB.

: The current signal from CT is converted: The current signal from CT is convertedinto proportional voltage signal by Iinto proportional voltage signal by I--VV

converter.converter.


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: The AC Voltage proportional to the load: The AC Voltage proportional to the load

current is converted to D.C. through acurrent is converted to D.C. through a

rectifierrectifier

: The out put of rectifier is fed to: The out put of rectifier is fed to

multiplexer.multiplexer.

: The microcomputer sends a command: The microcomputer sends a commandto switch on the designed channel of theto switch on the designed channel of the

multiplexer to obtain a rectified voltage ofmultiplexer to obtain a rectified voltage of

a particular circuit.a particular circuit.: The out put of multiplexer is fed to the: The out put of multiplexer is fed to the

AD converter.AD converter.


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: The microprocessor sends a signal to: The microprocessor sends a signal to

ADC for starting conversion.ADC for starting conversion.

: As soon as the conversion is over the: As soon as the conversion is over the

microcomputer reads in digital form andmicrocomputer reads in digital form and

then compares with the pickthen compares with the pick--up value.up value.

: Simultaneously the trip signal is: Simultaneously the trip signal is

operated and trips the Circuit Breaker.operated and trips the Circuit Breaker.


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K1Vdc < K2IdcK1Vdc < K2Idc

Vdc/Idc < K2/K1Vdc/Idc < K2/K1V/I < K or Z < KV/I < K or Z < K

Where K1, K2 and K are constants.Where K1, K2 and K are constants.

The value of K for different zones ofThe value of K for different zones of

protections are calculated and storedprotections are calculated and stored

in the memory as data to obtain thein the memory as data to obtain the

desired characteristics.desired characteristics.


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The levels of voltage and currentThe levels of voltage and current

signals are stepped down to thesignals are stepped down to theelectronic level by using potentialelectronic level by using potential

and current transformers.and current transformers.

The current signal is convertedThe current signal is converted

into proportional voltage signal byinto proportional voltage signal byI to V Converter.I to V Converter.


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Again these signals are fed toAgain these signals are fed to

multiplexer through rectifier units.multiplexer through rectifier units.

Out put of complexer is fed to ADOut put of complexer is fed to AD

converter through a sample and holdconverter through a sample and hold

circuit.circuit.The micro computer reads Vdc andThe micro computer reads Vdc and

Idc calculates the impedance Z seenIdc calculates the impedance Z seen

by the relay and compares with theby the relay and compares with thepre determined value.pre determined value.


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Again these signals are fed toAgain these signals are fed to

multiplexer through rectifier units.multiplexer through rectifier units.

Out put of complexer is fed to ADOut put of complexer is fed to AD

converter through a sample and holdconverter through a sample and hold

circuit.circuit.The micro computer reads Vdc andThe micro computer reads Vdc and

Idc calculates the impedance Z seenIdc calculates the impedance Z seen

by the relay and compares with theby the relay and compares with thepre determined value.pre determined value.


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VmSin. < K1IdcVmSin. < K1Idc

Or VmSin / Idc < K1Or VmSin / Idc < K1

Or VSin / I < KOr VSin / I < KOr ZSin < KOr ZSin < K

Or X < KOr X < K


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The microcomputerThe microcomputer

reads the out put of thereads the out put of thezero crossing detector tozero crossing detector to

examine whether theexamine whether thecurrent has crossed itscurrent has crossed its

zero point.zero point.


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:: As soon as the currentAs soon as the current

crosses its zero point thecrosses its zero point themicrocomputer sends amicrocomputer sends acommand to the multiplexercommand to the multiplexer

to switch on the channelto switch on the channeland gets the instantaneousand gets the instantaneous

value of voltage VmSinvalue of voltage VmSinthrough A/D converter.through A/D converter.


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:: The micro computerThe micro computer

reads X and X1reads X and X1calculates the reactancecalculates the reactance

X seen by the relay andX seen by the relay andcompares with the precompares with the pre

determined value.determined value.


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THANQTHANQ

Micro Processor Based Relays

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