Tridelta Meidensha GmbH INMR Congress 2017 – Barcelona-Sitges Practical Experience with State-of-the-Art Surge Arrester Monitoring Devices TRIDELTA 1 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH INMR Congress 2017 – Barcelona-Sitges Leakage Current Evaluation - Questions to Solve How can I identify arrester defects using leakage current monitors? How do I differentiate between arrester defects and side effects? How can I reduce mistakes and misinterpretations in leakage current monitoring? TRIDELTA 2 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH smartCOUNT Fieldtest 2017 Fieldtest 2017 – testing smartCOUNT surge arrester monitor under real conditions • Stage 1: Substation Hermsdorf (solved) • Stage 2: Substations in South America, Asia, Europe – 12 Substations (running) TRIDELTA 3 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH smartCOUNT Fieldtest 2017 1. Experiences about arrester current behaviour under various conditions • Ambient temperature and sunlight radiation • Poor voltage quality • Outages, earth fault conditions • Fog, rain, humidity • Surface pollution • Humidity ingress • Varistor degradation 123rf.com 2. Recommendations for arrester current interpretation and decision making TRIDELTA 4 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current - Temperature influences MOV current is highly temperature sensitive • Influences of ambient temperature falsifies the significance of surge arrester health assessment • Temperature compensation is possible but depends on precise compensation models • Every MOV differs in it´s compensation model according to brand, class, diameter • Wrong compensation models lead to overcompensation (partial shading as well) Overcompensated current values Current drops at high temperature Good compensation model à Stable values TRIDELTA 5 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current – Voltage influences MOV current is highly voltage sensitive • Voltage fluctuations falsify the significance of surge arrester health assessment • Error ranges of >80% are possible • Voltage harmonics increase the error range in the calculated resistive current • Voltage fluctuation influences can be compensated by a voltage correction model • Voltage harmonic influences can be compensated by means of a field probe Fluctuating resistive current due to fluctuating voltage and 3rd harm. Content in voltage TRIDELTA 6 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current – Fog, rain and humidity influences Impact of Fog, rain and humidity on the arrester current • Light rain doesn´t influence the total arrester current • Heavy rain, fog and humidity produce wet surface layers on the insulater; surface current impacts the total arrester current Total current affected by heavy rain and humidity Rain and Humidity during recorded leakage current fluctuatio TRIDELTA 7 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current – Surface pollution influences (lab test) Impact of surface pollution on the arrester current (results from test-lab) • Reoccuring salt fog fastly creates a conductive salt layer on the arrester housing (coastal climate) • Wet salt layers conduct high surface currents, dry salt layers conduct a smaller but still significant current • Arrester current is influences by the resulting surface current and affects the arrester condition assessment • Peak current is heavily influenced, minor effects on resistive current (surface current is sinusoidal) • High peak currents during salt spray periods, rising drop-off value hour 2 4 6 8 10 12 14 16 18 20 22 24 2 4 6 8 10 12 14 16 18 20 22 24 2 4 6 8 10 12 14 16 18 20 22 24 Voltage (24kV) x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x saltfog (conc. 10g/L) x x x temperature (50°C) x x x x x x x x x x x x x x x Test cycle in weather chamber • Rising temperature, Humidity and salt spray in the morning • High temperature and dry condition during the day • Low temperature at night TRIDELTA 8 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current – Surface pollution influences (lab test) Porcellain housed SA High pollution level High surface current High impact on total arrester current False arrester condition assessment Easily determine grade of pollution Silicone housed SA Low pollution level No surface current No impact on total arrester current Correct arrester current assessment TRIDELTA 9 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current – humidity ingress influences (lab test) Impact of humidity ingress on the arrester current (results from test-lab) • Humidity ingress is most common reason for arrester breakdown • Simulation in testlab: 4cl water inside arrester; accelerated humidification in heat chamber (40°C); arrester current logging TRIDELTA 10 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current – humidity ingress influences (lab test) High effect on peak current Highly fluctuating values Low effect on resistive current TRIDELTA 11 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Leakage current – degradation effect (lab test) Stage 1 Stage 2 Stage 3 Stage 4 Ur total [kV] 41,70 39,05 33,83 28,49 Uc [kV] 33,36 31,24 27,06 22,79 Utest [kV] 25,50 25,50 25,50 25,50 U/Uc 0,76 0,82 0,94 1,12 Stage 1 Stage 2 Stage 3 Stage 4 Ur MOV 6 [kV] 6,95 4,30 4,30 4,30 Ur MOV 5 [kV] 6,95 6,95 1,73 1,73 Ur MOV 4 [kV] 6,95 6,95 6,95 1,61 Ur MOV 3 [kV] 6,95 6,95 6,95 6,95 Ur MOV 2 [kV] 6,95 6,95 6,95 6,95 Ur MOV 1 [kV] 6,95 6,95 6,95 6,95 • Significant effect on resistive current • Noteble effect on peak value • Steady rise of current without regression TRIDELTA 12 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH Cases and Recommendations Case A Case C Case D Case B Case E Sudden spike in peak curent Periodical spikes in peak Cyclic resistive current swing Very high fluctuating peak Succesive rising values of current currents resistive Later fall back to drop-off Temperature or voltage value fall back, rising drop-off fluctuation Low change in resistive current And peak current value Arrester is ok Imprecize compensation model Arrester surface is clean MOV degradation Surface is polluted Affected by heavy rain, Check the monitoring device Humidity ingress Check more frequent, call the humidity Check and clean the arrester setup immediate replacement Manufacturer, replace preemtively Check for pollution Current goes back à Arrester ok Arrester ok TRIDELTA 13 Philipp Raschke, Tridelta Meidensha GmbH
Tridelta Meidensha GmbH smartCOUNT Thank you for your attention M.Sc. Philipp Raschke Tridelta Meidensha GmbH Research & Development pras@tridelta-hermsdorf.de Meet me at our booth TRIDELTA 14 Philipp Raschke, Tridelta Meidensha GmbH
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