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Practical Experience with State-of-the-Art Surge Arrester Monitoring - - PowerPoint PPT Presentation
Practical Experience with State-of-the-Art Surge Arrester Monitoring - - PowerPoint PPT Presentation
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
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TRIDELTA
Tridelta Meidensha GmbH
3 Philipp Raschke, 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)
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TRIDELTA
Tridelta Meidensha GmbH
4 Philipp Raschke, 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
- 2. Recommendations for arrester current interpretation and decision making
123rf.com
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TRIDELTA
Tridelta Meidensha GmbH
5 Philipp Raschke, 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
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TRIDELTA
Tridelta Meidensha GmbH
6 Philipp Raschke, 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
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TRIDELTA
Tridelta Meidensha GmbH
7 Philipp Raschke, 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
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TRIDELTA
Tridelta Meidensha GmbH
8 Philipp Raschke, 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
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TRIDELTA
Tridelta Meidensha GmbH
9 Philipp Raschke, 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
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TRIDELTA
Tridelta Meidensha GmbH
10 Philipp Raschke, 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
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TRIDELTA
Tridelta Meidensha GmbH
11 Philipp Raschke, Tridelta Meidensha GmbH
Leakage current – humidity ingress influences (lab test)
High effect on peak current Highly fluctuating values Low effect on resistive current
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TRIDELTA
Tridelta Meidensha GmbH
12 Philipp Raschke, 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
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TRIDELTA
Tridelta Meidensha GmbH
13 Philipp Raschke, Tridelta Meidensha GmbH
Cases and Recommendations
Case A Case B Case C Case D Case E
Sudden spike in peak curent Later fall back to drop-off value Arrester is ok Affected by heavy rain, humidity Check for pollution Periodical spikes in peak current fall back, rising drop-off value Surface is polluted Check and clean the arrester Current goes back à Arrester ok Cyclic resistive current swing Temperature or voltage fluctuation Imprecize compensation model Check the monitoring device setup Arrester ok Very high fluctuating peak currents Low change in resistive current Arrester surface is clean Humidity ingress immediate replacement Succesive rising values of resistive And peak current MOV degradation Check more frequent, call the Manufacturer, replace preemtively
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