moct ppt

The Seminar Topic is basedThe Seminar Topic is basedOnOn

MAGNETO OPTICALCURRENT TRANSFORMER

Presented By-Presented By- Aishwarya Verma(Aishwarya Verma(09020110902011))

The Seminar Topic is basedThe Seminar Topic is basedOnOn

MAGNETO OPTICALCURRENT TRANSFORMER

Presented By-Presented By- Aishwarya Verma(Aishwarya Verma(09020110902011))

CONTENTSCONTENTS

Introduction CT purpose and Demerits MOCT- principle, design, working. MOCT block diagram Applications Pros and Cons Conclusion

INTRODUCTIONINTRODUCTION

An accurate electric current transformer is a key component of any power system instrumentation.

The MOCT measures the electric current by means of Faraday Effect.

Conventional current transformers becomes more and more bulky and costly.

MOCT ViewMOCT View

CT Purpose and Demerits CT Purpose and Demerits

PURPOSE OF CT: It feeds the current coils of indicating, metering

instruments and protective relays Watch over the current’s in the circuit

DEMERITS OF CT: The insulation structure has to be designed carefully to

avoid electrical field stress, which could eventually cause insulation breakdown.

Less reliability

MOCT MOCT

MOCT measures the electric

current by means of

FARADAYS EFFECT. Michael faraday discovered

that the orientation of linearly

polarized light was rotated

under the influence of the

magnetic field.

PRINCIPLEPRINCIPLE

“ The light propagated in a piece of glass and the rotation angle was proportional to the intensity of the magnetic field”.

MOCT-PrincipleMOCT-Principle

=n=nVIVI ‘ ‘I ‘is the current to be measured,I ‘is the current to be measured, ‘ ‘’ ’ is the permeability of the material,is the permeability of the material, ‘ ‘n’ is the number of turns of the optical path.n’ is the number of turns of the optical path. The Faraday effect outlined in eqn is a better format to The Faraday effect outlined in eqn is a better format to

apply to an MOCT, because the rotation angle in this apply to an MOCT, because the rotation angle in this case is directly related to the enclosed electric current.case is directly related to the enclosed electric current.

It rejects the magnetic field signals due to external It rejects the magnetic field signals due to external currents which are normally quite strong in power currents which are normally quite strong in power system.system.

P1 = (1 + Sin 2 )P0/2 P2 = (1 - Sin 2 )P0/2 P0 : optical power from the light source, : the Faraday rotation angle, P1 and P2 : optical power delivered by the detectors.

P1 = (1 + Sin 2 )P0/2 P2 = (1 - Sin 2 )P0/2 P0 : optical power from the light source, : the Faraday rotation angle, P1 and P2 : optical power delivered by the detectors.

DESIGN DESIGN

1. The optical sensor consists of two separate clamp-on parts.

2. Linearly polarized light is arranged to pass through the optical glass prism to pickup the Faraday rotation signal.

3. The polarization compensation technique is applied at each corner of the prisms

WORKING WORKING

MAGNETO-OPTICAL MAGNETO-OPTICAL SENSORSENSORMAGNETO-OPTICAL MAGNETO-OPTICAL SENSORSENSOR

Almost all transparent material exhibits the magneto-optical effect or Faraday Effect, but the effect of some of the material is very temperature dependent, and they are not suitable for the sensing material.

MOCT made out of SF-57 materials can achieve higher sensitivity.

BLOCK DIAGRAM BLOCK DIAGRAM

APPLICATIONAPPLICATION

The MOCT is designed to operate in a transparent manner with modern electronic meters and digital relays, which have been adopted for a low energy analog signal interface.

The design approach is to redefine the interface point as to input the analog to digital conversion function used by each of these measurement systems.

Pros and Cons Pros and Cons

PROS: No risk of fires and explosions. No need to use metallic wires to transfer the signal and

so simpler insulation structure than conventional current transformer.

High immunity to electromagnetic interference.

CONS: Temperature and stress induced linear birefringence

in the sensing material causes error and instability.

CONCLUSIONCONCLUSION

This magneto optical current transformer 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 .