PARTIAL DISCHARGE MONITORING
1.
ELECTRICAL DISCHARGESTHE PASSAGE OF ELECTRIC CURRENT THROUGH
MATERIAL WHICH NORMALLY DO NOT CONDUCT ELECTRICITY. HAPPENS WHEN
THE MATERIAL IS SUBJECTED TO VERY STRONG ELECTRIC FIELD. GENERALLY
TRANSIENT IN NATURE, BUT MAY BE STATIONARY WHAT HAPPEN IN A
DISCHARGE?ENORMOUS INCREASE IN CONDUCTIVITY
EXAMPLESPARTIAL DISCHARGES CORONA DISCHARGES LIGHTNING6/29/2009
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PARTIAL DISCHARGE MONITORING
1.1 PARTIAL DISCHARGESWHAT IS PARTIAL DISCHARGELOCALISED
DIELECTRIC BREAKDOWN OF A SMALL PORTION OF A SOLID OR LIQUID
INSULATION UNDER HIGH VOLTAGE STRESS. ELECTRICAL DISCHARGES THAT
DOES NOT BRIDGE THE ENTIRE SPACE BETWEEN THE ELECTRODES
NATURE MAY OR MAY NOT EXHIBIT VISIBLE DISCHARGE SPORADIC THAN
CORONA DISCHARGE
1.2 TYPES OF PARTIAL DISCHARGESINTERNAL DISCHARGES SURFACE
DISCHARGES CORONA DISCHARGES ELECTRICAL TREES6/29/2009 Asean
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PARTIAL DISCHARGE MONITORING
1.2.1 INTERNAL DISCHARGESOCCURS IN INCLUSIONS OF LOW DIELECTRIC
STRENGTHDischarges Cavities HV
Ground
INCLUSIONS CAN OCCUR IN THE FORM OF; GAS-FILLED CAVITIES
OIL-FILLED CAVITIES DIRTS, PAPER, TEXTILE FIBRES OTHER FOREIGN
PARTICLES
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PARTIAL DISCHARGE MONITORING
1.2.2 SURFACE DISCHARGESOCCURS WHEN THERE OCCURS STRESS
COMPONENT PARALLEL TO THE DIELECTRIC SURFACEHV
Ground
THIS MAY OCCUR IN; BUSHING END OF CABLE OVERHANG OF WINDING ANY
POINT ON INSULATOR SURFACE BETWEEN HV POINT & EARTH6/29/2009
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PARTIAL DISCHARGE MONITORING
1.2.3 CORONA DISCHARGESELECTRICAL DISCHARGES CAUSED BY THE
IONIZATION OF THE MEDIUM SURROUNDING THE CONDUCTOR A LUMINOUS
PARTIAL DISCHARGE FROM CONDUCTORS DUE TO IONIZATION OF AIRHV
Ground
CORONA CAN OCCUR IN AIR AND GAS SUCH AS SF6 CORONA HAS SEVERAL
DAMAGING EFFECTS CORONA ALSO HAS MANY USEFUL APPLICATIONS6/29/2009
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PARTIAL DISCHARGE MONITORING
1.2.4 TREESSTARTS FROM DEFECTS IN INSULATION BREAKDOWN MAY OCCUR
IN EXTREMELY SHORT PERIODHV
Ground
TWO TYPES OF TREES; ELECTRICAL TREES WATER TREES DISCHARGE MAY
BECOME VERY UNSTABLE CAUSING TREES TO GROW RAPIDLY TREE FORMATION
MAY TAKE TIME FROM HOURS TO YEARS6/29/2009 Asean Residential School
in Electric Power Enginering 6
PARTIAL DISCHARGE MONITORING
2. WHERE DO PD OCCUR IN ELECTRICAL APPARATUS / EQUIPMENTWITHIN
SOLID INSULATIONGASEOUS OR OIL CAVITY SHARPED0EDGED CONDUCTOR
EMBEDDED IN SOLID SURFACE CONTAMINATION
STATOR WINDING INSULATIONLOOSE OVERHEATED CONTAMINATED
DIRT ACCUMULATION ON INSULATOR AND ARRESTER SURFACEAsean
Residential School in Electric Power Enginering
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PARTIAL DISCHARGE MONITORING
2. WHERE DO PD OCCUR IN ELECTRICAL APPARATUS / EQUIPMENT
(contd)CABLEJOINTS AND TERMINATION CONDUCTIVE PROTRUSIONS IN
DIFFERENT INTERFACES MECHANICAL DEFECTS TRANSPORT &
INSTALLATION
WITHIN SOLID INSULATIONGASEOUS OR OIL CAVITY SHARPED0EDGED
CONDUCTOR EMBEDDED IN SOLID SURFACE CONTAMINATION
TRANSFORMERSAsean Residential School in Electric Power
Enginering
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PARTIAL DISCHARGE MONITORING
2. WHERE DO PD OCCUR IN ELECTRICAL APPARATUS / EQUIPMENT
(contd)CONTAMINATED GIS APPARATUSMETALLIC PARTICLEFLOATING
FIXED
MICRO-PROTRUSION TRIPLE-POINT JUNCTION
BUBBLES WITHIN LIQUID INSULANTAsean Residential School in
Electric Power Enginering
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PARTIAL DISCHARGE MONITORING
3. EXAMPLE OF DISCHARGE SIGNAL 3.1 PULSES IN A.C. VOLTAGE
PULSES VERY STATISTICAL VERY RANDOM IN NATURE BURST TYPE PULSE
OCCURS IN ANY HALF CYCLE
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PARTIAL DISCHARGE MONITORING
3.2 EXAMPLE OF DISCHARGE PULSES DUE TO DAMAGED CABLE JOINT
SIGNAL OBTAINED FROM OPTICAL RECEIVER VERY RANDOM IN NATURE
SIGNAL RECEIVED FRON CAPACITIVE COUPLERAsean Residential School
in Electric Power Enginering
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PARTIAL DISCHARGE MONITORING
4. EFFECTS OF PARTIAL DISCHARGESMAY BE SERIOUS & LEADING TO
BREAKDOWN CUMULATIVE EFFECT MAY LEADS TO TREEING REPETITIVE PROCESS
MAY CAUSE IRREVERSIBLE MECHANICAL & CHEMICAL DETERIORATION CAN
CAUSE TRACKING EQUIPMENT DAMAGE ELECTROMAGNETIC INTEFERENCE OZONE
PRODUCTION POWER LOSS Asean Residential School in ElectricPower
Enginering
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PARTIAL DISCHARGE MONITORING
5. MONITORING OF PARTIAL DISCHARGES 5.1 INTRODUCTIONPD
MONITORING PROVIDES EFFECTIVE EVALUATION OF POWER SYSTEM APPARATUS
OR COMPONENTS ON-LINE MONITORING PROVIDES INFORMATION ABOUT
PROGRESSIVE DEGRADATION UNDER OPERATIONAL STRESS AVOID COSTLY
BREAKDOWN COMPLEMENTS OTHER ON-LINE MONITORING SUCH AS VIBRATION
AND TEMPERATURE EFFECTIVE TOOL FOR CONDITION-BASEDMAINTAINANCE THE
TREND OF PD ACTIVITY GIVES INFORMATION ABOUT AGING MECHANISM
MONITORING ALLOWS THE COLLECTION OF SUFFICIENT DATA FOR RELIABLE
MAINTAINANCE ALLOWS PREDICTIVE MAINTAINANCE Asean Residential
School in ElectricPower Enginering
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PARTIAL DISCHARGE MONITORING
5.2 WHAT PD MONITORING INVOLVEAT LEAST FOUR PROCESS ARE REQUIRED
FOR EFFECTIVE DISCHARGE MONITORING ACTIVITIES; DETECTION OF THE
DISCHARGE ELECTRICAL OR NON-ELECTRICAL METHODS MEASUREMENT OF THE
DISCHARGE QUANTITIES ELECTRICAL LOCATION OF THE DISCHARGE SITE
NON-ELECTRIC, SEPARATION OF ELECTRODES, ELECTRIC PROBES, TRAVELLING
WAVES EVALUATION RECOGNITION, MECHANISM, EVALUATION6/29/2009 Asean
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PARTIAL DISCHARGE MONITORING
5.3 DETECTION OF PARTIAL DISCHARGESPARTIAL DISCHARGE MEASUREMENT
OR DETECTION USEFUL AS DIAGNOSTIC TOOL FOR ELECTRICAL POWER
EQUIPMENT DETECTION & MEASUREMENT TECHNIQUES DEPEND ON TYPES OF
POWER SYSTEM EQUIPMENT OR APPARATUS PARTIAL DISCHARGES CAN BE
DETECTED USING ELECTRICAL AND NON-ELECTRICAL METHODS
5.3.1 ELECTRICAL METHODS
WIDELY USED USE OF CAPACITIVE, INDUCTIVE AND CAPACITIVEINDUCTIVE
SENSORS ON-LINE AND OFF-LINE IMPORTANT QUANTITIES INCLUDES APPARENT
CHARGE, PD INCEPTION VOLTAGE, NUMBER AND DISTRIBUTION OF
PD-PULSESAsean Residential School in Electric Power Enginering
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PARTIAL DISCHARGE MONITORING
5.3.1.1 BASIC ELECTRICAL DETECTION CIRCUITSAMPLE
HV SOURC E
COUPLING CAPACITOR
Z
AMP
DSO
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PARTIAL DISCHARGE MONITORING
5.3.2 NON-ELECTRICAL METHODSCAN DETECT DISCHARGE BUT CANT
MEASURE CHARGE MAGNITUDE CAN LOCATE DISCHARGE SITES EXAMPLES OF
NON-ELECTRICAL TECHNIQUES; CHEMICAL TRANSFORMATION GAS PRESSURE
HEAT ACOUSTIC OPTICAL
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PARTIAL DISCHARGE MONITORING
5.4 MEASUREMENT OF ELECTRICAL DISCHARGE QUANTITIESCHARGE
TRANSFER APPARENT CHARGE DISCHARGE ENERGY DIELECTRIC LOSSES
INTEGRATED QUANTITIES6/29/2009 Asean Residential School in Electric
Power Enginering
q1 = (b + c )V
q = bV2 2 1 p = c U+ U 2
[(
) ( )]
1 W= (b+c)V2 218
PARTIAL DISCHARGE MONITORING
5.5 LOCATION OF DISCHARGE SITESDETECTION OF THE POSITION OF
DISCHARGING SITE LOCATION OF SITE ALONG LENGTH OF SAMPLE ONLY
NON-ELECTRIC TECHNIQUE ACOUSTIC SEPARATION OF ELECTRODES ELECTRIC
PROBES OR ANTENNAS LOCATION IN CABLE BY TRAVELLING WAVES TRAVELLING
WAVE FOR SHORT CABLE AND SWITCHGEAR
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PARTIAL DISCHARGE MONITORING
5.6 EVALUATION OF DISCHARGE ACTIVITYDETERMINATION OF THE TYPES
ESTIMATION OF THE DANGER POSEDHARMFUL WHETHER MINIMUM DETECTED
DISCHARGE IS SAFE
THREE PARTS;RECOGNITION THE TYPE OF DISCHARGE IS IDENTIFIED
MECHANISM MECHANISM LEADING TO DETERIORATION EVALUATION WHAT IS THE
PERMISSIBLE DISCHARGE LEVELAsean Residential School in Electric
Power Enginering
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PARTIAL DISCHARGE MONITORING
6. REQUIREMENT FOR DISCHARGE MONITORING TECHNIQUE OR SYSTEMABLE
TO DETECT THE SMALLEST DISCHARGE ABLE TO DETECT DISCHARGES FROM
ANYWHERE ABLE TO DETECT THE PHASE ON WHICH DISCHARGE OCCUR ABILITY
TO IDENTIFY DEFECTS OR DAMAGE OF THE APPARATUS ABILITY TO LOCATE
PRECISELY THE POSITION NOT AFFECTED BY EXTERNAL INFLUENCES SHOULD
BE ABLE FOR ON-LINE APPLICATION FACILITY FOR REMOTE OPERATION
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PARTIAL DISCHARGE MONITORING
6.2 WHAT ARE REQUIREDCHOICE OF VOLTAGE VLF VOLTAGE SERIES
RESONANT VOLTAGE SOURCE OSCILATING VOLTAGE UNIPOLAR IMPULSE VOLTAGE
CHOICE OF SENSORS SOLENOID COIL SENSOR METAL FOIL ELECTRODE SENSOR
INTERNAL SHEILD ELECTRODE RESONANCE HF SENSOR DIRECTIONAL COUPLER
EMBEDDED CAPACITIVE SENSOR6/29/2009 Asean Residential School in
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PARTIAL DISCHARGE MONITORING
7. EXAMPLE OF ON-LINE PD MONITORING PROJECTTHE PROJECT INVOLVES
ASSESSING HYDROGENERATOR STATOR WINDING CONDITION IN CANADIAN
ELECTRICAL UTILITY IT COVERS A PERIOD OF OVER 10 YEARS PROVIDING
OVER 37000 TEST RESULTS THE ON-LINE SYSTEM DEVELOP SEPARATES PULSE
SIGNAL FROM ELECTRICAL NOISE REDUCE FALSE INDICATION BY MAXIMISING
SIGNAL TO NOISE RATIO DETECTOR FRQUENCY GREATER THAN 40MHz FACTORS
USED IN THE ANALYSESOPERATING VOLTAGE OF STATOR WINDING RATED POWER
INSULATION TYPE WINDING AGE WINDING MANUFACTURER
THE SUCCESS OF THE SYSTEM IS INDICATED WHEN 50% OF UTILITY
GENERATORS ARE EQUIPPED WITH THE SYSTEM6/29/2009 Asean Residential
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PARTIAL DISCHARGE MONITORING
7.1 OUTCOME OF THE PROJECT (contd)ON-LINE PD MONITORING HAS
BECOME PROVEN TOOL TO HELP ENGINEERS IDENTIFY WHICH GENERATOR NEED
OFF-LINE TESTING, INSPECTION AND/OR REPAIR THE DATABASE ALLOWS THE
TEST USERS TO IDENTIFY WHICH GENERATORS ARE LIKELY TO SUFFER FROM
INSULATION DETERIORATION THE PD LEVELS DEPEND ON THE OPERATING
VOLTAGE, MANUFACTURER AND THE SPECIFIC TYPE OF PD SENSOR AND
INSTRUMENTATION USED THE PD TREND OVER TIME ALLOWS THE ENGINEER TO
IDENTIFY WHICH STATOR WINDING NEED MAINTAINANCE. FOR THIS, ALL DATA
MUST BE COLLECTED AT THE SAME OPERATING VOLTAGE, LOAD, WINDING
TEMPERATURE AND HUMIDITY SIMILAR MONITORING SYSTEM HAS BEEN
DEVELOPED FOR MOTOR, SWITCHGEAR AND DRY-TYPE TRANSFORMER
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PARTIAL DISCHARGE MONITORING
7.2 PD MONITORING FOR GIS SUBSTATIONTHE DETECTION AND
MEASUREMENT USES UHF COUPLER THAT MEASURES THE RESONANCE PRODUCED
BY DISCHARGE PULSES IT WAS USED IN A 420KV GIS SUBSTATION AND THE
MONITORING DONE OVER 2 YEARS THE SYSTEM WORKED EXTREMELY WELL AND
VERY RELIABLE BASED ON THAT EXPERIENCE, FURTHER IMPROVEMENT HAS
BEEN MADE BY INCORPORATING THE FACILITY FOR CYCLE-BY-CYCLE 3-D
DISCHARGE DATA WHICH CAN BE VIEWED ON-LINE, TIME AND LOCATION
TAGGED AND THE DATA STORED FOR FUTURE RETREIVAL AND INTERROGATION
LATEST SYSTEM INCORPORATE EXPERT SYSTEM WHICH ALLOWS FASTER AND
MORE ACCURATE INTERPRETATION OF THE DATA FOR HIGHER SUPPLY
RELIABILITYAsean Residential School in Electric Power
Enginering
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PARTIAL DISCHARGE MONITORING
8. MAKING MONITORING MORE EFFECTIVE 8.1 REQUIREMENTSSUFFICIENT
DATA DATA OF PD ACTIVITY FROM VARIOUS SOURCESSUSBSTATIONS OF
VARIOUS AGES EQUIPMENT/APPARATUS OF VARIOUS; AGES TYPES
MANUFACTURERS
DETAIL RECORDS OF DATA AND/OR OBSERVATION ELIMINATION OF NOISE
DEVELOP EXPERIENCE OPPORTUNITY AND TRUST SHOULD BE GIVEN TO
PERSONNEL EXCHANGE OF INFORMATION
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PARTIAL DISCHARGE MONITORING
8.I WHAT EFFECTIVE MONITORING GIVESMORE ACCURATE INTERPRETATION
OF DATA OR OBSERVATION AVOID FALSE INDICATION MORE EFFECTIVE
MAINTAINANCELOW MAINTAINANCE COST
AVOID EQUIPMENT / APPARATUS DAMAGE AVOID OUTAGE INCREASE SUPPLY
SECURITY & RELIABILITY ABILITY TO PREDICT THE LIFE SPAN OF THE
APPARATUS6/29/2009 Asean Residential School in Electric Power
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PARTIAL DISCHARGE MONITORING
9. CHALLENGE IN PD MONITORINGTHE GREATEST CHALLENGE TO ALL
ELECTRICAL UTILITIES IS IN MAKING THE BEST INTERPRETATION OF THE
PARTIAL DISCHARGE SIGNALS
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PARTIAL DISCHARGE MONITORING
10. STANDARDSSOME RELEVANT INTERNATIONAL STANDARDS TO BE
REFERRED;
IEC 60270:2000/BS EN60270:2001HV TEST TECHNIQUE-PD
MEASUREMENTS
IEEE 400-2001IEEE GUIDE FOR FIELD TESTING AND EVALUATION OF THE
INSUALTION OF SHIELDED POWER CABLE SYSTEMS
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PARTIAL DISCHARGE MONITORING
THANK YOU FOR YOUR ATTENTION
Professor Dr. Ahmad Bin Darus Dean Faculty of ELectrical
Engineering Universiti Teknologi Malaysia 81310 UTM Skudai Johor
Darul Takzim
6/29/2009
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