F05D Meeting on Damped AC Voltage Testing

Transcription

1 October 28 th, 2008 from pm in San Antonio, TX Agenda F05D Damped AC Voltage Testing 1

2 Agenda F05D Damped AC Voltage Testing Welcome: Introduction On-site testing voltages e.g. IEC High Voltage test techniques Part 3: Definitions and requirements for on-site testing 1. Direct voltage (DC) 2. Alternating current voltage (AC) 3. Very low frequency voltage (VLF) 4. Damped alternating current voltage (DAC) Most in use for on-site testing and diagnosis of HV power cables 5. Lighting impulse voltage (LI) 6. Lighting switch voltage (LS) 2

3 Welcome: Introduction the use of damped AC voltages 1. Damped sinusoidal AC voltage (DAC) are several years applied method for onsite energizing of polymeric and paper insulated power cables and the insulation of rotating machines. 2. On-site applying of DAC voltages is mostly combined with PD measurements and dielectric losses measurements. 3. At present there are three vendors of DAC systems (one in Switzerland and two in Germany). 4. Several comparison test have been done and published in the past e.g. KEMA (1999), CESI (2002), EuroTest (2007) to demonstrate the applicability of DAC voltages for on-site testing of power cables. Welcome: Introduction principals of energizing and PD measurement at continuous AC and at damped AC voltages PD occurrence at continuous sinusoidal AC (e.g Hz) PD occurrence at damped sinusoidal AC (e.g Hz) dielectric losses PD inception voltage PDIV PD inception voltage PDIV PD extinction voltage PDEV PD extinction voltage PDEV PD level in [pc] PD level in [pc] PD pattern information < PD pattern information Test over-voltage destructiveness > Test over-voltage destructiveness 3

4 Welcome: Introduction discussion of the Ad-hoc meeting ICC Spring 2008 Different suggestions have been made to be considered in the future work: 1. The focus of the future DACV document has to be on: a) Basic principles of possible DAC test circuits, voltage generation, and measurement b) Test procedure: voltage application, test duration c) Test and measuring parameters: most important testing and diagnostic parameters 2. and not on the detection of partial discharges (see the IEEE document). 3. Literature list of relevant papers about DACV. 4. Due to the fact that in North and South America only few users are known in addition to survey also utility/service provider experiences from other users in the world are welcome. Welcome: Introduction Conclusions of the Ad-hoc meeting ICC Spring In the IEEE 400 documents all different energizing methods which are in use for on-site testing of power cables have to be discussed. 2. With regard to damped AC voltage (DACV) and based on information as given by experts and users a documentation of DACV in a separate document, according to the lines of IEEE 400 has to be done. 3. All 32 participants supported by voting the proposal to start a Discussion Group on damped AC voltages. 4

5 Agenda F05D Damped AC Voltage Testing F05D Damped AC Voltage Testing Scope and Mission Statement Scope: To collect and to evaluate information and experience as needed to propose a preparation of a Guide for Field Testing of Shielded Power Cable Systems Using Damped AC Voltages Mission: provide information concerning test procedures for shielded cable systems using damped AC voltages and performing diagnostic measurements, 5

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7 Agenda F05D Damped AC Voltage Testing Survey about using DAC voltages General Vendors: 4 Lemke Diagnostics, since 1997 Seitz Instruments, since 1999 Haefely Test (Hubbell HV), since 2001 SebaKMT, since 2001 Number of DAC systems: > approx. 120 Representative user response: 33% Responders type: utilities, service providers Geographic: Europe (72%), Asia (28%), US (??) DAC system application types: MV cable networks, HV cable networks 7

8 Purpose of testing using the DAC voltages voltage testing 23% partial discharge measurement 25% 52% dielectric losses measurement Relevance of combining PD test and the voltage test Yes: 50% No: 50% Voltage testing 18% Max. U test 3xU 0 82% Max. U test 2xU 0 Breakdown during voltage testing: 0%. 2% Before breakdown PD has been measured: 81% Before breakdown no PD has been measured: 47% 8

9 Test voltage level as used for PD measurements Max. U test 3xU 0 18% 9% Max. U test 1xU 0 73% Max. U test 2xU 0 The present standards IEEE 400 is using the name Oscillating Waves (OW). The present IEC is using the name damped alternating voltages (DAC). To avoid any confusion between oscillating voltages in the range of khz and damped AC voltage in the range of 20Hz- 500Hz as there are in use 100% of responders support the proposal to change the name to DAC. Testing procedures Duration time of applying DAC voltages: Number of DAC voltage applications/voltage level: 10 min. up to 30 min. 4x up to 50x Examples of DAC voltage application: a) x at each level: 0.3Uo, 0.5Uo, 0.7Uo, 1.0Uo, 1.3Uo, 1.5Uo, 1.7Uo, 2.0Uo c) For voltage test new cables up to 50x max 2Uo up to 3Uo (depends on safety, age and switchgear type) d) If no PD: 5x at each level: 0.8Uo, 1.0Uo, 1,5Uo, 2.0Uo If critical PD: 20x at each level 0.8Uo, 1.0Uo, 1,5Uo, 2.0Uo till PD significantly increases Two types of tests: 1. new systems 2. aged systems 9

10 Summary 1. Worldwide damped AC voltages (DAC) are in use for testing and PD measurement of new and service aged distribution and transmission power cables; 2. Diagnostic testing may consist of partial discharges and/or dielectric losses measurement and single voltage testing; 3. Regarding the test time there is no uniform testing procedure and the testing times as used till now are maximum 30min; 4. Regarding the test voltages there is no uniform testing procedure and most diagnostic application are limited to 2.0 Uo and for after-laying test are up to 3Uo; Agenda F05D Damped AC Voltage Testing 10

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