01 - OMICRON PD Seminar - Introduction of Partial Discharge Measurement

OMICRON PD Seminar 2013

Electric fields

Introduction, History and Theory of Partial Discharge Measurement

Rene Hummel, Stephan Körber

What is partial discharge ?

Evidence of partial discharges

> Partial discharge (PD) is a localized dielectric breakdown of a small portion of a solid or liquid electrical insulation system under high voltage stress.

> Definition from IEC 60270 Specification: Localized electrical discharge that only partially bridges the insulation between conductors and which can or cannot occur adjacent to a conductor.

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OMICRON PD Seminar 2013

Evidence of partial discharges

Evidence of partial discharges

photo: VATech Hydro Austria

photo: IPH Berlin

Evidence of partial discharges

Evidence of partial discharges

photo: IPH Berlin

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OMICRON PD Seminar 2013

Evidence of partial discharges

Evidence of partial discharges

tracking structures

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Video ...

Partial discharge / total discharge

video: IPH Berlin

photo: TU Berlin

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OMICRON PD Seminar 2013

Electricity around us

Important units

-

electron

-

+

Charge Q [1Coulomb] = [1As]:

-

2nd orbit

Charge in movement = CURRENT!!!

nucleus

The more electrons per TIME interval, the higher is the current Current

=

Charge

per

Time

[A]

=

[Coulomb]

per

[s]

[A]

=

[Coulomb]

/

[s]

Charge

=

Current

times

Time

Charge

=

Current

x

Time



q=

Charge – How to measure? > Time Domain Integration

1st orbit

SI prefixes q=

Most used prefixes:

kilo Volts

q

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[kV]

milli Ampere [mA] micro Farad [µF] nano Coulomb [nC] pico Coulomb [pC]

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OMICRON PD Seminar 2013

Charge – How it is measured

Analog PD measurement systems

> Frequency Domain Integration

> More details in chapter FILTER

PD

PD

pC

pC C

C

R

”Digital” PD measurement systems

R

MPD600 digital PD measurement system with digital filtering Digital Filter + PD Processor

PD

Communications Processor

A D

PD

A D

V

A D USB 2.0

V

0- Detect

+ Power Management

Fiber Optic Cable

Filter is analogue!

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OMICRON PD Seminar 2013

PD measurement with the OMICRON MPD software

What are partial discharges? Partial discharge:

disturbed voltage signal

voltage reading

> Local electrical stress in the insulation or on the surface of the insulation

> Always generates electromagnetic signals

> Often accompanied by an emission of sound, light, heat and chemical reactions test voltage over time

PD activity over time

Types of PD

External PD

> Internal PD > Void discharges, „electrical treeing“

Solid insulation

> External PD > Corona > Surface discharges

Outer semicon

Surface discharge

Corona discharge

Solid insulation Inner semicon Image Source: Andreas Küchler – Hochspannungstechnik

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OMICRON PD Seminar 2013

Internal PD

PD classification

En = 2

Internal discharge in laminated material

Cavity / void discharge

Semicon layer protrusion (stress concentration at the tip)

Lines of electrical field

Void (field strength doubling)

Treeing

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