Partial discharge switchgear ea tech

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    13-Apr-2017

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  • Partial Discharge Training

  • Apa itu Partial Discharge ? Apa penyebab Partial Discharge ? Bagaimana Mengukur Partial Discharge?

  • Question ....

    Apa saja tipe Isolasi yang kemungkinan ada didalam switchgear ???

  • Dielectric StrengthMaterial Dielectric Strength

    Air ~3 kV/mm

    Mineral Oil ~10- 15 kV/mm

    Polyethylene ~20 kV/mm

    EPR (Rubber) ~25 kV/mm

    Vacuum ~20-40 kV/mm

    Impregnated Paper ~20-50 kV/mm

    XLPE ~20 kV/mm

    SF6 (3.5 bar) ~15 kV/mm

  • Partial Discharge Activity

    Gaseous medium Voids or gaps

    Electrical stress Elektron

    e

    e

    e

    e

  • Teori ....

    Bagaimana sebenarnya Partial Discharge ituterjadi ???!!

    Partial discharge terjadi ketika electrical stressmelebihi 3kV/mm

  • Discharge in Gas ... Untuk medan listrik homogen antara dua

    elektroda Jika E cukup tinggi : akan dimulai dengan ionisasi Elektron akan lebih cepat dan bertabrakan dengan

    molekul Jika kecepatanya cukup cepat : ionisasi akan berlanjut

    karena energi kinetik dari elektron Terjadi reaksi berantai: gas menjadi plasma, maka

    aka terjadi thermo-ionisasi Lalu akan timbul percikan yang mengakibatkan

    breakdown

  • Electrical field

    Untuk medan listrik non-homogen: E tinggi diujung, rendah pada plate

    PD dimulai jika E lebih tinggi daripada E critical Perilaku PD tergantung pada E:

    Voltage level dan ukuran

  • Partial Discharge adalah .....

    peristiwa pelepasan/ loncatan bunga api listrikyang terjadi pada suatu bagian isolasi (padarongga dalam atau permukaan) sebagai akibatadanya beda potensial yang tinggi dalam isolasitersebut.

  • Why Test

    Safety Loss of Supply Asset Management

  • Analysis of MV Switchgear Faults

    Ea Technology, 2006

  • Common Discharging Components

    Component % age of Sources

    Cable Box 36 %

    Circuit Breaker 25%

    Voltage Transformer 20%

    Busbar 10%

    CT Chamber 9%

    General figures based on large database of results primarily on 11kV switchgear

  • Types of Switchgear

    3.3kV to 66kV Indoor Metalclad extensible switchboards Indoor and Outdoor Ring Main Units

  • PD Clasification

    Internal Discharges: occuring in cavities within solid or liquiddielectrics

    Surface Discharges: appearing at the boundary of thedifferent insulation materialsContinuous impact of discharges in solid dielectrics

    forming discharge channels (treeing) in organic materialsCorona discharge occuring in gaseous dielectrics in the

    presence of inhomogeneous fields

  • PD Classification

  • So Why ??

    PD occur

    Electromagnetic

    Radio Light Heat

    Acoustic

    Audio Ultrasonic

    Gases

    Ozone Nitrous Oxides

  • Partial Discharge

    Surface Discharge Internal Discharge

  • Internal Discharge(TEV Detection)

    High Frequency transientsignals from dischargesources

    Travel over switchgearsurfaces

    Detected using capacitivelycoupled probes onswitchgear metalwork

  • Apa TEV itu sebenarnya ??

    Transient : lasting only for a short time; impermanentJadi TEV bisa dikatakan tegangan yang muncul dalamwaktu yang singkat menuju ground.

  • Internal Partial Discharge

  • Internal Partial Discharge

  • Transient Earth Voltage (TEVs)

    TEV (mV) dB

    1 0

    1.12 1

    1.78 5

    3.16 10

    10 20

    31.6 30

    100 40

    316 50

    1000 60

    1410 63

    http://www.naval.com/help/db-x.htm

  • Internal Discharges (TEV)

    Internal discharge activityTrainsient Earth Voltage (TEV) DetectionHigh Frequency (~ 3 to 80 MHz)

    TEV magnitude is function of The amplitude of the discharges The attenuation of the propagation path

  • Example Internal Discharge

    11kV Cast Resin CTs

    Long term erosion of insulationleading to flashover and failure

  • Example Internal Discharge

    Overhead Cable Termiantion

  • Example Internal Discharge

    Cable termiantion screen termination

  • Surface Discharge(Ultrasonic Detection)

    In severe cases, sound may beaudible

    Less severe deterioration may bedetected using ultrasonicdetecting instruments

    Sound spectrum includes 40 Khz

    Primarily spot checkmeasurements although extendedmonitoring is possible

  • Surface Discharge Activity

    Discharge acrosssurface of insulationtowards earth orphase to phasedischarge

    Often characterisedby low amplitude butvery high dischargerate

  • Surface Discharge Activity Detected byUltrasonics

  • Surface Discharge on 11kV Cast ResinCircuit Breaker Spouts

  • Surface Discharge Activity Detected byUltrasonics

  • Contamination make a Surface PD

  • Moisture Ingress leading to surfacetracking

  • Oil degradation leading surfaceerosion of insulation

  • Corrosion due to PD activity

    1. Greening of fuse caps2. Rusting of securing bolts3. Tracking along the glass reinforcedPlastic fuse bar

    1

    23

  • TEV Background Interference

    MobilePhoneMast

    HV OHL

    Variable speeddrive

    DC Light fitting Radio Mast

    BatteryCharger

  • Possible Ultrasonic BackgroundInterference

  • Practical Non- Intrusive DetectionMethods

    Internal discharge activity Transient Earth Voltage High Frequency (~ 3 to 80 MHz)

    Surface discharge activity Ultrasonic Emission ~ 40 kHz TEV Detection when high amplitude surface discharge

  • PD Instruments

  • UltraTEV Detector

  • UltraTEV Detector

    Ideal for first pass surveys of surface andinternal PD activity

  • UltraTEV Detector

    TRAFFIC LIGHT display indicates PD levels

  • UltraTEV Detector

    ESSENTIAL personal safety device

  • UltraTEV Plus+

  • UltraTEV Plus+

    Quickly locates & mesures surface andinternal PD activity

  • UltraTEV Plus+

    INSTANTLY reveals the condition of assets

  • UltraTEV Plus+

    PLUG-IN OPTIONS for added versatility

  • TEV Functions

    Two TEV display options

    Display with rolling bar graphindication and traffic lightalarm level indication

    Display with amplitude,pulses per cycle and severityvalues

  • Ultrasonic Measurements

    Measurement of surface dischargeactivity in range 7dBV to 68dBV

    40kHz sounds heterodyned to audiobleoutput with high quality headphones

    External Ultrasonic sensor port

    User adjustable alarm thresholds Preset to UltraTEV Detector levels

  • Ultrasonic Features

    Separately adjustable Gainand Volume settings

    Immediate Red/Greenindication based on useradjustable alarm threshold

  • PD Locator

    Measures the amplitude of discharge in dBmV Locates source of discharge through precedence

    detections using both probes, resolution 2ns,0.6m

    ProcedureMeasure background noiseSurvey with one probe onlySource internal if reading on switchgear > 10dB above

    background noiseLocate using 2 probes

  • UltraTEV Locator

  • UltraTEV Locator

    SURVEYS & LOCATES PD activity in allsubstation assets including cables

  • UltraTEV Locator

    MEASURES & RECORDS PD activity in allsubstation assets including cables

  • UltraTEV Locator

    PLUG-IN OPTIONS for greater versatility

  • PD Location

  • Reporting and Analysis of Results

  • Assessment of Partial DischargeActivity in Switchboard

    Partial Discharge Locator (PDL) survey Ultrasonic survey of any air insulated

    components Monitor for one week with Partial Discharge

    Monitor (PDM) Analyse results against historical information

  • Interpretation of results

    Investigate previous failures Is there a common failure mode Check previous results Same switchboard Similar switchboards

    Compare against specific information Compare against general information

  • Analysis Considerations

    Maximum Level of Partial Discharge Maximum Short Term Severity Long Term Severity Working Voltage Equipment component History of failures, if any Circuit importance

  • Partial Discharge Severity Calculations

  • Terimakasih ......