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Cable fault location methods (Megger)
The document discusses various methods and technologies for locating faults in power cables, detailing procedures and technologies for pre-location and pinpointing fault locations. It covers fault construction types, electromagnetic methods, reflection measurement techniques, and the importance of gathering comprehensive data for effective fault identification and repair. Additionally, it highlights the Norned project as a notable example of high-voltage direct current (HVDC) technology and emphasizes the company's commitment to developing reliable test equipment for the electrical supply industry.
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Cable fault location methods (Megger)
- 1. 1 OVERVIEW CABLE FAULT LOCATIONMETHODS Daniel Salathe
- 2. 2 Agenda What do Iknow? Procedure for fault location in Power Cables Cable Construction Different Cable faults Pre – Location Methods Arm Multishot NorNed World Record Megger Products
- 3. 3 WHAT DO IKNOW Fault pre-location can be confusing and misleading if general rules are not observed. Another discussion point are the possible varieties that can be used for fault pre-location. This presentation is intended to bring some light into the questions
- 4. Fault DC Hipot VLF 0.1Hz Periodic Maintenance Test Aging External damage In Operation after installation after repair Acceptance Test Reasons for fault location Repair Cable Tracing Fault Identification Prelocation Fault Cable Identification Pinpointing Fault Location in Power Cables
- 5. Cable Type Joints Termination Material Manufacturer P-P /P-N Sheath Insulation Road work on track Conduit? What happened Where Fault DataDetails Age Previous faults Faults in the vicinity History Only the Comparison of all details will provide the full picture Fault location is the combination of ALL available information
- 6. Repair Cable Tracing Fault Identification Prelocation Fault CableIdentification Pinpointing “Teleflex TDR” “Cable Radar” “Impulse Echo” “Reflectometer” Isolation Tester “Megger” 0 … 10 kV DC Tester VLF Tester Low resistance < 10 – 100 Ω High resistance > 100 Ω Isolation Tester DC Tester Sheath to soil (0 … 5 kV) Which phases are affected? Phase – to – Phase Phase – to – Sheath Phase – to – Soil Sheath – to – Soil Identify affected phase, fault resistance, breakdown voltage Fault identification
- 7. TDR “Teleflex” “Cable Radar” “Impulse Echo” “Reflectometer” ARMArc Reflection Method ARM Plus, ICE, Decay, Decay Plus ARM Burning with Burn Unit Sheath fault HV Bridge Voltage Drop Method Burning permanent conversion Low resistance <10 ... 100 Ohm High resistance >100... ∞ Ohm High resistance, wet fault Fault to earth (soil) Repair Cable Tracing Fault Identification Prelocation Fault Cable Identification Pinpointing Fault Prelocation
- 8. RF radio frequency 50/ 60 Hz power frequency 100 – 150 Hz: Subsea applications 400 … 1000 Hz: low coupling, long range 1 … 10 kHz: coupling, low interference 10 … 80 kHz: high coupling, water pipes Minimum (Null) Maximum (Peak) SuperMax SignalSelect current direction indication Method Frequency Passive (no transmitter): 50 / 60 Hz, RF radio frequency Active: Direct galvanic, with conn. cables Inductive Clamp on energized cables Inductive Antenna terrain survey Connection Repair Cable Tracing Fault Identification Prelocation Fault Cable Identification Pinpointing Cable tracing
- 9. Fault Locating inPower Cables - Pinpointing - Audio Frequency: Twisted – Field – Method (core – core) Minimum distortion (core – sheath) Low resistance SWG Surge Wave Generator and Digiphone High resistance Step – Voltage – Method with DC step voltage Audio frequency step voltage to earth (sheath fault) Repair Cable Tracing Fault Identification Prelocation Fault Cable Identification Pinpointing Fault Pinpointing
- 10. Pulse Method forenergized Cables Audio frequency signal direction identification with inductive clamp connection Pulse Method Pulse direction Pulse intensity Twisted – Field – Method Audio Frequency Twisted – Field – Method Multi Conductor Cable Energized Cable LV Pulse Method Audio frequency signal direction ident. with inductive clamp connection Single Phase Cable Repair Cable Tracing Fault Identification Prelocation Fault Cable Identification Pinpointing Cable Identification
- 11. Partial Discharge Test Isolationtest (Megger, Easytest) DC test (PILC) Short DC Test max. 5 min. (XLPE) VLF 0.1 Hz (60 min, 1.7 … 3 Uo) Soak test (24 h energized at Uo) Resonance / 50 Hz test Sheath test Acceptance Test Repair Cable Tracing Fault Identification Prelocation Fault Cable Identification Pinpointing Repair and re-commissioning Commissioning of electrical installations International standards require a norm conform testing of electrical installations before re-energizing! Laws
- 12. Shielded segmented cable Typically LV 3or 4 conductor plus shield Faults mostly internally Unshielded segmented cable Typically LV 3 to 5 conductors Faults to ground and between cores Shielded concentric cable Typically MV/HV 1 conductor plus shield Faults between Core and shield Shielded concentric cable Typically MV/HV 3 conductors with own shield ea. Faults between Core and shield Core to core fault unlikely except for extreme external damage Belted cable w. common shield Typically MV 3 conductors Faults between Core and core and shield Fault location difficult due to multiple path Core - core likely Cable Construction Types
- 13. Open circuit Resistive Multiple Phase resistive Phaseto phase Resistive Open circuit Flashing Phase to phase Flashing Cable Faults internal
- 14. Sheath Fault Earth Fault Important Pointfor earth contacting cable faults There is a high danger to cause injury, when applying HV or even Surging Cable Faults – Earth / Sheath faults
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- 16. Flashing Fault (voltagedependent)
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- 19. 19 The different (HV)Fault Prelocation technologies
- 20. 20 Reflection measurement The mostcommon approach is a reflection measurement A reflection measurement should be conducted before any other type of measurement or test, just to obtain the full „picture“. It will show the cable in its full distance and with many details. In some cases, if the fault resistance is sufficiently low, it will also show the fault without further HV support. All of the “ARM” technologies are combinations wit the common reflection measurement with High Voltage.
- 21. 21 Pre – LocationMethods Pre – Location Methods from our well known CENTRIX Cable Test Van System
- 22. 22 CFL System Concept Faultclassification Fault Prelocation Fault pinpointing 1 most likely 2 ignition voltage limited at 20kV 3 flashover/ breakdown at the fault position 4 LV cap- stage 5 depending on different factors, e.g.: Signal attenuation, Tripping energy of the breakdown, sometimes the range is wider
- 23. 23 Fault classification FaultPrelocation Fault pinpointing • Arc Reflection Measurement • Damped discharge of a capacitor via inductance • Pulse generation from TDR 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 24. 24 Fault classification FaultPrelocation Fault pinpointing • Arc Reflection Measurement • Damped discharge of a capacitor via inductance • Pulse generation from TDR 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 25. 25 Pre – LocationMethods Fault classification Fault Prelocation • ARM 1st measure a TDR Trace without hv shot from a hv capacitor first trace - “healthy” 2nd measure a TDR Trace with hv shot from a hv capacitor Second trace – “fault” • Decay Plus • ARM Burning 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J Fault distance Cable length • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Fault pinpointing
- 26. 26 Fault classification FaultPrelocation Fault pinpointing 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J 1st measure a TDR Trace without hv shot from a hv capacitor first trace - “healthy” 2nd measure a TDR Trace with hv shot from a hv capacitor Second trace – “fault” Fault distance Cable length • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 27. 27 Fault classification FaultPrelocation Fault pinpointing 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J 1st measure a TDR Trace without hv shot from a hv capacitor first trace - “healthy” 2nd measure a TDR Trace with hv shot from a hv capacitor Second trace – “fault” Fault distance Cable length • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 28. 28 Fault classification FaultPrelocation Fault pinpointing up to max. 32 kV 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay HV Capacitors ARM • ARM – for cable length of a few km • cables with moisture problems or oil filled joints • max. Pulse amplitude 160V, 20µs • 15 TDR traces while one HV Shot Pre – Location Methods
- 29. 29 Fault classification FaultPrelocation Fault pinpointing • Arc Reflection Measurement Plus • Damped discharge of a capacitor via a resistor and extended fault burning time with an LV Capacitor • Pulse generation from HV Pulse 350V or 1500V 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 30. 30 Fault classification FaultPrelocation Fault pinpointing 1st measure a TDR Trace without hv shot from a hv capacitor first trace - “healthy” 2nd measure a TDR Trace with hv shot from a hv capacitor Second trace – “fault” 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J Fault distance Cable length • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 31. 31 Fault classification FaultPrelocation Fault pinpointing 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J 1st measure a TDR Trace without hv shot from a hv capacitor first trace - “healthy” 2nd measure a TDR Trace with hv shot from a hv capacitor Second trace – “fault” Fault distance Cable length • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 32. 32 Fault classification FaultPrelocation Fault pinpointing 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J 1st measure a TDR Trace without hv shot from a hv capacitor first trace - “healthy” 2nd measure a TDR Trace with hv shot from a hv capacitor Second trace – “fault” Fault distance Cable length • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 33. 33 Fault classification FaultPrelocation Fault pinpointing 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors ARM Plus • ARM Plus – for cable length more than ARM • cables with moisture problems or oil filled joints up to 32 kV ignition voltage • Extend fault burning time with a second capacitor • max. Pulse amplitude 350V or 1500V • single TDR trace while one Shot Pre – Location Methods
- 34. 34 Fault classification FaultPrelocation Fault pinpointing • Impulse Current Envelope, Direct decoupling of the discharge current signal in the ground wire path of the surge capacitors 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 32 kV HV Capacitors Pre – Location Methods
- 35. 35 Fault classification FaultPrelocation Fault pinpointing • Impulse Current Envelope, Direct decoupling of the discharge current signal in the ground wire path of the surge capacitors • Display on the TDR as transient wave shape curve • Measure the fault distance with cursors 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay Symbol image Fault distance up to max. 32 kV HV Capacitors Pre – Location Methods
- 36. 36 Fault classification FaultPrelocation Fault pinpointing 4kV 8kV 1200J 16kV 32kV 1280J 2000J 2400J 2560J • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay ICE • for longer cables of more than 10 km • self generating pulse waves by fault • measure the transients at discharge current • Useful on high voltage cable feeders with Cross bonded joints up to max. 32 kV HV Capacitors Pre – Location Methods
- 37. 37 Fault classification FaultPrelocation Fault pinpointing Decay • for high resistance faults above 32kV • method with self-excitation of the pulse • Display on the TDR as transient wave shape curve • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay method with self-excitation up to max. 80 kV HV- DC Power supply Pre – Location Methods
- 38. 38 Fault classification FaultPrelocation Fault pinpointing Decay • method with self-excitation of the pulse • Display on the TDR as transient wave shape curve • Measure the fault distance with cursors • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay Symbol image Fault distance method with self-excitation up to max. 80 kV HV- DC Power supply Pre – Location Methods
- 39. 39 Fault classification FaultPrelocation Fault pinpointing • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay Decay • for high resistance faults above 32kV • self-excitation of the pulse waves by fault • TDR in transient recorder mode • measure the transients at discharge voltage • Useful on high voltage cable feeders with Cross bonded joints up to max. 80 kV HV- DC Power supply Pre – Location Methods
- 40. 40 Fault classification FaultPrelocation Fault pinpointing Decay Plus • for high resistance faults above 32kV • method with self-excitation of the pulse • single TDR trace while one Shot • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay method with self-excitation up to max. 80 kV HV- DC Power supply Pre – Location Methods
- 41. 41 Fault classification FaultPrelocation Fault pinpointing • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay Decay Plus • for high resistance faults above 32kV up to 80kV • cables with moisture problems or oil filled joints up to 80 kV ignition voltage • Extend fault burning time with a second capacitor • max. Pulse amplitude 350V or 1500V • single TDR trace while one Shot up to max. 80 kV HV- DC Power supply Pre – Location Methods
- 42. 42 Fault classification FaultPrelocation Fault pinpointing • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay up to max. 80 kV HV- DC Power supply Pre – Location Methods
- 43. 43 Fault classification FaultPrelocation Fault pinpointing • ARM • Decay Plus • ARM Burning • ARM Plus • ICE • Decay ARM Burning • for high resistance faults up to 20 kV ignition voltage • to reduce the resistance of the fault called „fault conversion“ up to max. 20 kV HV- DC Power supply up to max. 40 A DC Pre – Location Methods
- 44. 44 ARM BurningARM BurningARMBurningARM Burning
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- 66. NorNed NorNed is a580-kilometre (360 mi) long HVDC submarine power cable between Feda in Norway and the seaport of Eemshaven in the Netherlands, which interconnects the electricity grids of both countries. With a DC voltage of ±450 kV, the converter for the NorNed project has a terminal to terminal DC voltage rating of 900 kV, making it also the highest voltage rating of any HVDC converter in the world. Installation of the first sections was started in early 2006; the final section was laid by the end of 2007. Commercial operation started on the 5th of May 2008 with a capacity auction. The first commercial power transfer took place on 6th of May 2008.
- 67. The Word record! Atthe 2nd September 2013 we tested together with Statnett the NorNed cable with the Teleflex VX
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- 69. The End End verifiedby open and short, Zoom 10x
- 70. The available CableTest Vans Fully atomatic CENTRIX Semi atomatic VARIANT For transmission R 30 Manual system Classic
- 71. The available PortableSystems 3kV … 40kV 500J … 3500J SFX 5 1000J SFX 15 or 25 1150J SFX 16 / 2000J SFX 32 1750J or 3500J SFX 40 1000 or 2000J
- 72. 72 Questions? Power on At Megger,we understand that keeping the power on is essential for the success of your business. That is why we are dedicated to creating, designing and manufacturing safe, reliable, easy-to-use portable test equipment backed by world- leading support and expertise. We can assist your acceptance, commissioning and maintenance testing for predictive, diagnostic or routine purposes. By working closely with electrical utilities, standards bodies and technical institutions, we contribute to the dependability and advancement of the electrical supply industry.