practical properties of rogowski coil construction - presentation slide

7/28/2019 Practical Properties of Rogowski Coil Construction - Presentation Slide

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David Halomoan MalauElectrical Power Engineering / 18009025Bandung Institute of Technology


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Needs ofCurrent

Sensors in

Power System

FerromagneticCore Coil Sensors

Air Core

CoilSensors


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InductionCoil

Sensors

OperationTheory

Design ofAir CoreCoil

Sensors

CoreBehaviour


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Rogowski Coil

Equivalent Circuitand Frequency

Respons

Practical Aspects

GeometricalProperty

PhysicalParameters

Construction

Low Cost

Construction

Calibration


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Induction Based Coil Sensors also known assearch coils, pickup coils, or magnetic loopsensors.

Special kinds of induction based coil sensors:

Rogowski Coil

Gradiometer SensorsVibrating Coil Sensors

Tangential Field Sensors

Needle Probes


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Simple manufatureWinding materials are commonly available

Example of another type of sensors:

Hall SensorMagnetoresistive

Fluxgate-type

The only one that can be manufactured directlyby the user, low cost; yet accurate. [1]


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Voltage induced to the coil is a function to rateof change of the flux density.


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Parameter Ferromagnetic

Core Type

Air Core Type

Sensitivity High Low

Linearity (Current) No Yes (Few Amperesto Several Hundred

of Kiloamperes)

Linearity

(Frequency)

No Yes (Few Hertz to

Several Hundred of

Kilohertz)


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Where:

A: Minor Axis

B: Major Axis


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In construction, Rogowski coil could be notperfectly rounded around main conductor.

Geometrical property of the Rogowski coil couldbe seen from A/B ratio.

Experiment done by see how A/B ratio influencethe output voltage waveform.


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Results:Output waveform of the Rogowski coil becomeunstable when A/B is small.

Thus errors of amplitude and phase become larger.


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Physical parameters determine the value of output voltage ofRogowski coil

Physical parameters:

a (inner radius)

rw (wire radius)

rc

(core radius)

N (number of turns)


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Done by simulating variating physical parametera (inner radius), rw (wire radius), rc (core radius),and N (number of turns) to see output voltageresults

Simulation done with asumption A/B = 1


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Results:Smaller Rogowski coil (smaller a parameter) givebetter sensitivity.

Value of optimum core radius different throughdifferent value of inner radius.

Bigger N (number of turns) give bigger outputvoltage

Bigger wire diameter make value of N smaller, but

need to be calculated more


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[1] Kojovic, Ljubomir A., et al. Practical Aspects of Rogowski Coil Applications toRelaying. IEEE PSRC Special Report. 2010.

[2] Kojovic, Ljubomir A. Comparative Performance of Current Transformers andRogowski Coils used for Protective Relaying Purposes.

[3] Faifer, M., and R. Ottoboni.An Electronic Current Transformer Based onRogowski Coil. Dipartimento di Elettrotecnica, Politecnico di Milano. Italy.

2008.

[4] Tumanski, S. Induction Coil Sensors A Review. Institute of Electrical Theory &Measurement. Poland. 2007.

[5] Murgatroyd, P. N. and D. N. Woodland. Geometrical Properties of RogowskiSensors. IEE Colloquium on Low Frequency Power Measurement and Analysis.

Savoy Place. 1994.[6] Jingsheng, Liao. Studies of Rogowski Coil Current Transducer for Low

Amplitude Current (100 A) Measurement. College of Electrical and ElectronicEngineering, Huazhong U. of Sci. & Tech. China.

practical properties of rogowski coil construction - presentation slide

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