The document discusses on-site testing of high voltage (HV) cables and gas insulated switchgear (GIS). It describes various test methods for cables, including continuous AC voltage testing, damped alternating current (DAC) testing, and very low frequency (VLF) testing. Continuous AC testing exposes the cable to a steady voltage over time and can find small defects better than short-duration tests. However, VLF and DAC may not be suitable for HV and extra high voltage (EHV) cables as they do not provide enough stress to detect important defects and could damage healthy insulation. The document argues that on-site testing is necessary to evaluate cable condition after installation and diagnose faults, as cables are stressed near their limits
The document discusses on-site testing of high voltage (HV) cables and gas insulated switchgear (GIS). It describes various test methods for cables, including continuous AC voltage testing, damped alternating current (DAC) testing, and very low frequency (VLF) testing. Continuous AC testing exposes the cable to a steady voltage over time and can find small defects better than short-duration tests. However, VLF and DAC may not be suitable for HV and extra high voltage (EHV) cables as they do not provide enough stress to detect important defects and could damage healthy insulation. The document argues that on-site testing is necessary to evaluate cable condition after installation and diagnose faults, as cables are stressed near their limits
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Original Title
28_Bergmann_HV testing of MV and HV Cables and GIS.pdf
The document discusses on-site testing of high voltage (HV) cables and gas insulated switchgear (GIS). It describes various test methods for cables, including continuous AC voltage testing, damped alternating current (DAC) testing, and very low frequency (VLF) testing. Continuous AC testing exposes the cable to a steady voltage over time and can find small defects better than short-duration tests. However, VLF and DAC may not be suitable for HV and extra high voltage (EHV) cables as they do not provide enough stress to detect important defects and could damage healthy insulation. The document argues that on-site testing is necessary to evaluate cable condition after installation and diagnose faults, as cables are stressed near their limits
The document discusses on-site testing of high voltage (HV) cables and gas insulated switchgear (GIS). It describes various test methods for cables, including continuous AC voltage testing, damped alternating current (DAC) testing, and very low frequency (VLF) testing. Continuous AC testing exposes the cable to a steady voltage over time and can find small defects better than short-duration tests. However, VLF and DAC may not be suitable for HV and extra high voltage (EHV) cables as they do not provide enough stress to detect important defects and could damage healthy insulation. The document argues that on-site testing is necessary to evaluate cable condition after installation and diagnose faults, as cables are stressed near their limits
CEPED 2013, Bali, Indonesia Dr. Ralf Bergmann HIGHVOLT Prftechnik Dresden GmbH On-Site Testing of HV Cables and GIS Content: On-Site HV Cable testing Why spend money on HV tests? Physical background: Cable characteristics and test methods Generation of continuous AC test voltages Experience with continuous AC voltage testing Test system examples 2 31/10/2013 On-Site Testing of HV Cables and GIS Content: On-Site GIS testing Test requirements Test procedures Test systems 3 31/10/2013 ON-SITE HV CABLE TESTING - WHY SPEND MONEY ON ON-SITE HV TESTS On-Site Testing of HV Cables On-Site Testing of HV Cables and GIS 4 31/10/2013 On-Site Testing of HV Cables and GIS Jakarta at night With energy transmission by cables 5 31/10/2013 Jakarta at night Without energy transmission by cables 31/10/2013 6 On-Site Testing of HV Cables and GIS Large cable installation in Indonesia in the future PLN to lay $2b submarine cable from Sumatra to Java
Rangga D. Fadillah, The J akarta Post, J akarta | Business | Fri, February 17 2012, 9:19 AM
. The cable will span 700 kilometers connecting Bangko in South Sumatra and Bogor in West J ava. The cable will be used to transmit power supply from South Sumatra, where a number of coal-fired power plants are currently under construction, to meet surging electricity demand in J ava.
The cable will be able to transmit power with a total capacity of up to 3,000 megawatts [MW] from Sumatra to J ava, Nasri explained. . 31/10/2013 7 On-Site Testing of HV Cables and GIS Bali crossing with overhead cable or subsea cable 31/10/2013 8 On-Site Testing of HV Cables and GIS Beautiful landscape should not be destroyed by overhead lines On-Site Testing of HV Cables and GIS Save energy transmission and distribution by cables is essential Cable connections are and will be even more in the future a backbone of transmission and distribution systems especially due to the special conditions of Indonesia Interconnections of islands Energy distribution in growing cities Protected areas (national parks, recreation areas, tourism) Because of power demand increase, the cables are stressed often to its maximum load capacity (and sometimes higher) An unexpected break down of the cable may result in fatal consequences for the customer (outage for hours) and the utility (penalty) 9 31/10/2013 31/10/2013 10 On-Site Testing of HV Cables and GIS Is on-site testing of HV cabls after installation necessary? Consequently, an evaluation of the cable condition based on on-site testing is technically and economically necessary HV cable seems to have a proven and quite simple design in respect to other components like transformers HV cable will be manufactured in a highly automated way, failures caused by humans are minimized HV cables have to pass an intensive test program in the factory Significant works will be done at site, like jointing Small mistakes can result in mayor failures
Withstand tests covered by IEC standards On-Site Testing of HV Cables and GIS Different testing during lifetime of a cable Manufacturing D a m a g e
M i s t a k e
W i t h s t a n d
T e s t i n g
T e s t i n g
D i a g n o s i s
Transportation Installation W i t h s t a n d
T e s t i n g
Power frequency 50/60 Hz Operation Power frequency 50/60 Hz Cable life R e p a i r
A g e i n g
11 31/10/2013 W i t h s t a n d
T e s t i n g
On-Site Testing of HV Cables and GIS Requirements for dedicated on-site test methods After installation or repair Load during on-site test should correspond to operational stress Negligible ageing caused by on-site test Easy adoption to different test requirements as voltage, cable capacitance cable losses etc. Designed for easy and frequent transportation, assembly and operation 12 31/10/2013 Diagnostic testing Failures should be discovered easily Negligible ageing of the remaining cable by the on site test PHYSICAL BACKGROUND: CABLE CHARACTERISTICS AND TEST METHODS On-Site Testing of HV Cables and GIS 13 31/10/2013 On-Site Testing of HV Cables and GIS Possible Defects in Cables Crack Delaminating Protrusion at semicon surfaces Void Vented-tree (length 2.38 mm) at semicon surface combined with electrical tree Source: ABB Energiekabel GmbH Water tree combined with electrical tree 14 31/10/2013 On-Site Testing of HV Cables and GIS General Characteristics of HV Cable Operation: electrical field control by capacitance (C) at 50 Hz HV Equivalent circuit at AC stress XLPE Cable: tan = i c >>i r C R Ground 15 31/10/2013 Examples for Typical Cable Geometry On-Site Testing of HV Cables and GIS Cable Class Rated Voltage Insulation thickness Field strength at inner semicon, voltage peak at 50 Hz MV cable 24 kV 5.5 mm 4 - 5 kV/mm HV cable 138 kV 17.8 mm 7 - 10 kV/mm EHV cable 400 kV 26 mm 12 - 15 kV/mm 16 31/10/2013 Differences of MV, HV and EHV cables relevant for HV testing Technical Consequences Field strength increases with cable voltage MV cables tolerate relatively large defects in operation, very small defects can lead to breakdown of EHV cables Example: small voids of the same size - in a 10 kV cable joint may be harmless, - may be dangerous for a 30-kV cable, - cause quick breakdown in HV and EHV cables (Result from: M.U. Zuberi, A. Masood, M.F. Khan, Ekram Husain & A. Anwar: Estimation of partial discharge inception voltages due to voids in power cables, Aligarh Muslim University, India) More sensitive tests for HV and EHV cables necessary On-Site Testing of HV Cables and GIS 17 31/10/2013 On-Site Testing of HV Cables and GIS Requirements for dedicated on-site test methods After installation or repair Load during on-site test should correspond to operational stress Negligible ageing caused by on-site test Easy adoption to different test requirements as voltage, cable capacitance cable losses etc. Designed for easy and frequent transportation, assembly and operation 18 31/10/2013 Diagnostic testing Failures/Faults should be discovered easily Negligible ageing of the remaining cable by the on site test VLF On-Site Testing of HV Cables and GIS Field Reduction at Different Test Frequencies Con- tinuous AC 0 20 40 60 80 100 0.01 0.1 1 10 100 %
o f
f i e l d
s t r e n g t h
i n
d e f e c t
c o m p a r e d
t o
h e a l t h y
i n s u l a t i o n
Test frequency in Hz Defect 1 Defect 2 Defect 3 IEEE 400: Conductivity in defects can assume much different values than in the bulk insulation material 19 31/10/2013 On-Site Testing of HV Cables and GIS Requirements for dedicated on-site test methods After installation or repair Load during on-site test should correspond to operational stress Negligible ageing caused by on-site test Easy adoption to different test requirements as voltage, cable capacitance cable losses etc. Designed for easy and frequent transportation, assembly and operation 20 31/10/2013 Diagnostic testing Failures/Faults should be discovered easily Negligible ageing of the remaining cable by the on site test On-Site Testing of HV Cables and GIS Test of AC XLPE Cables with DC is not to recommended Operation: electrical field control by C Testing: DC changes electrical field distribution DC creates space charges on failures (field emission, PD) HV Equivalent circuit XLPE Cable: tan = i c >>i r C R Ground 21 31/10/2013 VLF: Not suitable for HV / EHV Cables Technical Consequences Maximum field for healthy insulation: 30 kV/mm (IEC 62067) 3 or 4 U 0 simply not possible for HV and EHV cables (would damage healthy insulation) VLF at 2 U 0 not able to find important defects VLF not suitable for HV and EHV cable systems On-Site Testing of HV Cables and GIS 22 31/10/2013 What about DAC? Description of test method: Charging the cable with DC voltage, Discharging the cable through an inductance Causes damped oscillation, Usually repeated 50 times. On-Site Testing of HV Cables and GIS -100 -75 -50 -25 0 25 50 75 100 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 V o l t a g e
/
%
o f
t e s t
v o l t a g e
time / s 23 31/10/2013 Test procedure involves charging the cable with DC: Duration up to approx. 1 minute per shot Up to one hour of DC ramp voltage stress for total test duration Cable risk due to space charges exists Quick reversal of test voltage immediately after DC stress DAC Danger for the test object? On-Site Testing of HV Cables and GIS 24 31/10/2013 Undefinedness of DAC test parameters Damping: Influenced by Capacitance of test object Resistances of test system Tan delta of cable Frequency: Depends on Capacitance of test object Inductance in test system Duration of AC stress undefined, 0.4 260 ms/shot On-Site Testing of HV Cables and GIS 25 31/10/2013 Undefinedness of DAC test parameters Duration of AC stress: Undefined 0.4 260 ms/shot Varies by factor 600
30 minutes of continuous AC are equivalent to 6,920 4.5 Million shots of DAC Total testing time: Days 8 Years DC stress during most of the time (Charging takes 99.x % of total test time) On-Site Testing of HV Cables and GIS 26 31/10/2013 DAC Testing Time Insufficient PD activity requires starting electron generated by radiation Smaller defects have less volume Lower starting electron generation probability in a given time Longer PD inception time Longer testing time necessary to find defects Mark Fenger: Experiences with Commissioning Testing of HV & EHV Cable Systems: The Influence of Voltage Level and Duration for Identifying Life Limiting Defects, Kinectrics Inc., Canada On-Site Testing of HV Cables and GIS 27 31/10/2013 On-Site Testing of HV Cables and GIS What voltage wave shape can be used to test XLPE cable reliably and safely? AC voltage in range of 20 to 300 Hz is the only recommended wave shape to test XLPE cable reliably and safely
VLF 0.01 to 1 Hz is not an reliable test method because the test frequency is to far away from the operation frequency of 50 Hz (different behavior of insulation)
DC test can even damage an XPLE cable
Damped AC testing is more an DC test as an AC test, only very few AC cycles 28 31/10/2013 GENERATION OF CONTINUOUS AC TEST VOLTAGES On-Site Testing of HV Cables and GIS 29 31/10/2013 On-Site Testing of HV Cables and GIS Technical Solutions for HV AC Generators T R
L C
T H
C H
C L
MD C C
AC ACTC Compensated transformer ACRL Resonant test system with tuned inductance as series resonant circuit T R
L H
T E
C H
C L
MD C C
AC T R T E
L H
C H
C L
MD C C
AC ACRL Resonant test system with tuned inductance as parallel resonant circuit FC T E
L H
C H
C L
MD C C
AC ACRF Resonant test system with tuned frequency AC f 30 31/10/2013 On-Site Testing of HV Cables and GIS Comparisons of different AC Test Systems Mode of on-site test system ACTC compensated transformer ACRL variable inductance ACRF variable frequency Frequency 50 / 60 Hz 50 / 60 Hz 20 to 300 Hz Quality factor of resonance (5) 40 to 60 80 to 200 Power supply Single / two phase Single / two phase Three phases Specific weight 15 to 20 kg/kVA 3 to 10 kg/kVA 0.5 to 2 kg/kVA Maximum test power per mobile system 0.5 MVA 4 MVA 35 MVA 31 31/10/2013 On-Site Testing of HV Cables and GIS Principle of Pulse Width Control of ACRF Circuit Control and Feeding Unit Exciter Transformer Voltage Divider Test Object Protection Impedance Resonant Reactor 400 V 3~ U E U P Frequency Pulse width U E U P Frequency Test voltage magnitude 32 31/10/2013 On-Site Testing of HV Cables and GIS On-site Testing of Cables: Increasing Power by Reactor Combinations higher voltage longer cables 33 31/10/2013 On-Site Testing of HV Cables and GIS On-site Testing of Cables: Arrangement of an ACRF System, Type WRV T on a Trailer Control and feeding unit Exciting transformer HV reactor HV filter and protection unit Canvas Truck with trailer 34 31/10/2013 EXPERIENCE WITH CONTINUOUS AC VOLTAGE TESTING Particular Tests On-Site Testing of HV Cables and GIS 35 31/10/2013 On-Site Testing of HV Cables and GIS Survey among Users of Continuous AC Test Equipment Total Tests in each Cable Class 13 181 2078 1199 541 188 1 10 100 1000 <50 kV 50...100 kV 100...150 kV150...250 kV250...350 kV350...500 kV N u m b e r
o f
t e s t s
w i t h
C o n t i n u o u s
A C
v o l t a g e
Rated cable voltage U 0 / kV Usage of Continuous AC testing in the field IEEE PES Insulated Conductors Committee Spring meeting 2012, Group F11D 36 31/10/2013 On-Site Testing of HV Cables and GIS PD measurement On-Site Manufacturing D a m a g e
M i s t a k e
T e s t i n g
T e s t i n g
D i a g n o s i s
Transportation Installation T e s t i n g
Power frequency 50/60 Hz Operation Power frequency 50/60 Hz Cable life R e p a i r
A g e i n g
PD PD PD PD PD PD PD 37 31/10/2013 TEST SYSTEM EXAMPLES Particular Tests On-Site Testing of HV Cables and GIS 38 31/10/2013 On-Site Testing of HV Cables and GIS On-site Testing of Cables: Truck with Test System 260 kV / 83 A 39 31/10/2013 On-Site Testing of HV Cables and GIS On-site Test of a 400 kV Cable System, 20 km in London 40 31/10/2013 On-Site Testing of HV Cables and GIS Test of a 400 kV Cable System at the Madrid Airport Courtesy of Pirelli Cables, Italy and UK Installation of test system on-site 41 31/10/2013 On-Site Testing of HV Cables and GIS ACRF Configuration for Testing a 15 km long 400 kV Cable System at Madrid Airport Frequency converters and controls Exciter transformers HV reactors 16H II (9+9) H =8.5 H Voltage divider Blocking impedances Cable under test: 15 km, 3.3 F Test voltage: 260 kV (approx. 1.2 U 0 ) Test frequency: 30 Hz Test power: 42 MVA (50 Hz equivalent: 70 MVA) Feeding power Demand: <400 kVA, 400 V (3 phases) 1 Master Up to 8 Slaves 42 31/10/2013 On-Site Testing of HV Cables and GIS Photos: Courtesy of CEPCO, K.S.A.
On-site Test of a 400 kV Cable System in Jeddah, K. S. A. 43 31/10/2013 On-Site Testing of HV Cables and GIS On-site Testing of cables: Testing Under Extreme Conditions Photo: Courtesy of Kinectrics
- 20 C
50 C Photo: Courtesy of KEMA Photo: Courtesy of Nexans, Marubeni, CEPCO 44 31/10/2013 On-Site Testing of HV Cables and GIS Max. testable cable length: 100 km
Photos: Courtesy of ABB Power Tech Products, Sweden AC Routine Test Facilities at a Supplier of Submarine Cables 45 31/10/2013 On-Site Testing of HV Cables and GIS ACRF System for MV Cable Testing installed in a Van Control and feeding unit Test voltage lead Exciting transformer HV resonant reactor 46 31/10/2013 On-Site Testing of HV Cables and GIS Voltage range: 3050100 kV Current range: 102550 A Frequency: 20300 Hz On-site Test Systems for Medium Voltage Equipment Application: Mediumvoltage cables Rotating machines Capacitor banks 47 31/10/2013 ON-SITE GIS TESTING TEST REQUIREMENTS On-Site Testing of HV Cables On-Site Testing of HV Cables and GIS 48 31/10/2013 Same Testing Method used: Test with AC voltages (necessary for same behaviour of particles in GIS) Test voltages up to 800 kV Test current in to order of less than up to a few A Duty cycle of a few minutes only On-Site Testing of HV Cables and GIS 49 31/10/2013 ON-SITE GIS TESTING TEST PROCEDURES On-Site Testing of HV Cables On-Site Testing of HV Cables and GIS 50 31/10/2013 Common Duty Cycle of GIS Testing t e s t
v o l t a g e
i n
k V
time in min PD Measurement (few minutes) Test Voltage (few minutes) Conditioning (some minutes) Maximum some ten minutes On-Site Testing of HV Cables and GIS 51 31/10/2013 Standardisation: IEC 62271-203/2nd CD Test Setup Requirements
Need of mobile HV AC test system
Preferably metal-enclosed design
Conventional or UHF PD measurement
Need of mobile HV impulse test system LI up to 1700 kV and SI up to 1200 kV On-Site Testing of HV Cables and GIS 52 31/10/2013 ON-SITE GIS TESTING TEST SYSTEMS On-Site Testing of HV Cables On-Site Testing of HV Cables and GIS 53 31/10/2013 On-Site Testing of HV Cables and GIS AC resonant test system with variable frequency; 1.5 A/ 325 kV Courtesy of Shenyang Kaidi High Voltage Electric, PR China Mobile HV AC Resonant Test System Metal-enclosed test systems with variable frequency based on SF 6 -insulated reactors up to 800 kV and 4.5 A 54 31/10/2013 Mobile HV AC Resonant Test System Advantages
Light-weight small HV AC testing device
Needs no safety clearance during operation
Allows sensitive conventional PD measurement
Very reliable test system also under harsh conditions on site
Easy to operate On-Site Testing of HV Cables and GIS 55 31/10/2013 Connection by HV Lead WRV / G Photo: courtesy of ABB Calor Emag Schaltanlagen AG, Mannheim / Germany 460 kV, 1.5 A metal-enclosed HV reactor HV divider / coupling capacitor HV lead On-Site Testing of HV Cables and GIS 56 31/10/2013 Connection by HV Lead WRV / T 260 kV, 83 A tank type resonant reactor HV lead HV lead Photos: courtesy of China Light and Power Co., Hong Kong On-Site Testing of HV Cables and GIS 57 31/10/2013 On-Site Testing of HV Cables and GIS AC resonant test system with variable frequency; 3 A/ 640 kV Courtesy of AREVA Aix-Les-Bains, France Mobile HV AC Resonant Test System Metal-enclosed test systems with variable frequency based on SF 6 -insulated reactors up to 800 kV and 4.5 A 58 31/10/2013 On-Site Testing of HV Cables and GIS Mobile Modular HV AC Resonant Test System Resonant test system of series M, 600 kV, 10 A Courtesy of ABB, Switzerland Modular test system of variable frequency Series M up to 1200 kV 59 31/10/2013 On-Site Testing of HV Cables and GIS Voltage range: 100680 kV
Current: 0.51.5 (3) A
Frequency: 40300 Hz
On-site Test Systems with SF 6 -Insulated Reactors Application mainly for GIS also multiple application with SF 6 .
60 31/10/2013 SUMMARY On-Site Testing of HV Cables and GIS 61 31/10/2013 On-Site Testing of HV Cables and GIS Summary On-site testing of HV cables and GIS is absolutely necessary Assembly faults in joints and end terminations, particles etc. for GIS For commissioning and condition assessment tests Continuous AC test voltage finds the defects critical for service Testing stress close to operating conditions WRV test systems comply with requirements for on-site testing Easy transportability and handling Modularity Low demand on feeding power 62 31/10/2013 YOUR COMMENTS AND QUESTIONS Thank you for your attention! On-Site Testing of HV Cables and GIS 63 31/10/2013