Transcript MAGNETIC OPTICAL CURRENT TRANSFORMER

MAGNETO OPTICAL
CURRENT
TRANSFORMER
Presented By:
Shivankit Bansal
1207749
Final Year
Electrical Deptt.
Drawbacks of Current T/f
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The insulation structure has to be
designed carefully to avoid
breakdown.
Electric current path of primary bus
has to be designed properly to
minimize the mechanical forces.
Violent destructive failures.
ABSTRACT:
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MOCT technology provides solution to many
of the problems of conventional current
transformer.
Quite new technology-in research stage.
Provides no Electromagnetic Interference.
No need to break the conductor to enclose
the optical path in the current carrying
circuit.
A TYPICAL MOCT
MOCT SYSTEM
CONFIGURATION
What is it?
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Passive optical current transducer
which uses light to accurately measure
current on high voltage systems.
Measures current by means of
Faraday’s Effect.
Determines the rotation angle &
converts into a signal of few volts
proportional to the current.
COMPONENTS:
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Sensor head located near the current
carrying conductor.
An Electronic Signal Processing Unit.
Fiber Optical Cables linking these two
parts.
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The sensor head consists of optical
components.
The signal is brought down to signal
processing unit by means optical fiber
cables.
Signal Processing Unit basically converts
the optical signal into suitable electrical
form.
As no metallic wires are needed therefore
it provides better insulation.
MOCT PRINCIPLE:
Contd.
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A polarizer is used to convert the
randomly polarized incident light into
linearly polarized light.
Orientation rotates an angle  after the
light has passed through the magnetooptical material because of Faraday Effect.
Analyzer converts the orientation
variation of polarized light into intensity
variation with two outputs.
The outputs are send to photo detectors.
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Proper wrapping of optical path around
current carrying conductor is required.
Can be achieved by folding the optical
path by means of reflections.
Total Internal Reflections & Metal
Reflections are good ways.
Prisms should be designed to keep the
light linearly polarized.
Phase shift should be avoided.
A program in FORTRAN is used for the
performing the entire operation.
Electronic Circuit for
MOCT
APPLICATIONS:
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Most suited for outdoor type
applications.
It meets the protection class accuracy
as specified by IEC 60004-8.
The optical design enables accurate
measurement of fault currents.
Makes the output signal insensitive to
shock & vibration.
ADVANTAGES:
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No risks of fires & explosions.
Simpler insulation structure.
High immunity to Electromagnetic
interferences.
Wide frequency response.
Larger Dynamic Range.
Low voltage outputs-compatible with
the inputs of digital to analog
converters.
DISADVANTAGES:
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Temperature and stress induced
linear birefringence in the sensing
material causes error and instability.
The accuracy of MOCT is so far
insufficient for the use in power
systems.
CONCLUSION:
This magneto optical current transducer eliminates many of the
drawbacks of the conventional current transformers. In an
conventional current transformers, there is a chance of
saturation of magnetic field under high current, complicated
insulation and cooling structure, a chance of electro magnetic
interference etc.
By applying Faraday’s principle this transducer provides an
easier and more accurate way of current measurement. This
MOCT is widely used in power systems and substations
nowadays. And a new trend is being introduced, which known
as OCP based on adaptive theory, which make use of accuracy
in the steady state of the conventional current transformer
and the MOCT with no saturation under fault current
transients.
THANK YOU