Post on 07-Apr-2018
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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