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Monitoring Solutions
Permanent, remote SF6 Leak detection and Gas Insulated Switchgear Monitoring
The use of distributed fibre sensing offers the power utility operator a number of benefits and advantages over traditional sensing systems, potentially working in parallel with them.
The key areas of application are detailed below and note that some of the benefits are related to DTS systems, some to DTS systems and others use a combination of technologies to optimise the performance.
Similarly, since the distributed fibre systems can be used to monitor many kms of optical fibre from a single unit, then the following applications could be multiple outputs from the same interrogator – thereby amortising the cost across a number of benefits.
SF6 Leak Detection
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Rapid detection of toxic gas release
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Precise location of leak
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Constant or periodic leakage
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Determined using temperature and/or acoustic effects
For the power sector SF 6 is now increasingly used at pressure as an insulator in gas insulated switchgear (GIS) because it has a much higher dielectric strength than air or dry nitrogen . This results in the switchgear being much smaller, lighter and cheaper.
However, SF 6 is a highly potent greenhouse gas , with a global warming potential of 23,900 times that of CO2 . Hence the power utility operators are under pressure to minimise any wastage or leakage with heavy fines applied for every 1kg of escaping product. Hence rapid detection of a small leak of SF6 gas is a vital part of the solution. Detection would lead to an alarm being raised to instruct a shutdown and to initiate further investigation.
Thus, an important part is also assuring the precision of the location of the event and to have a high Probability of Detection and of course very low or zero false alarms.
Any proposed system would require very high reliability and consideration should be given to system architecture to avoid a single point of failure.
DTS technology is frequently used in the detection of
gas leakage, especially in a high-pressure gas pipeline.
In such a case then the system detects the Joule Thompson effect of depressurising gas creating a localised cool spot. The illustration shows a cool spot generated as a result of leaking gas.
SF6 Leak Detection
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Rapid detection of toxic gas release
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Precise location of leak
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Constant or periodic leakage
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Determined using temperature and/or acoustic effects
Switch Gear Monitoring
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Confirming parallel operation of gas filled circuit breakers
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Detecting distinct operation of hydraulic valves
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Confirming parallel operation of multiple circuit breakers
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Detecting gas discharge on tap changers
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Detecting bearing wear on transformer cooling fans
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Detecting abnormal circuit breaker operation on reactors
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