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High Voltage Switchgear SF6 Maintenance

SmartTrak® 100 Mass Flow Controller

Just like the main circuit breaker in your home, city grids have main on/off switches called switchgears. When these high voltage switchgears open or close, huge "lightning-like" arcs of electricity are created. If not maintained correctly, these sparks can causeHigh Voltage Switchgearwidespread power outages and pose a safety risk. To avoid these dangerous sparks, power companies have traditionally filled the sealed vessels that house these switches with oil. In an effort to substantially reduce the environmental footprint and cost of switchgears, they introduced the use of SF6 (Sulphur Hexafluoride), a highly effective insulator. Unfortunately, SF6 is a costly, maintenance intensive and potentially environmentally damaging solution.

Over the years, installations have started to show signs of SF6 breakdown, decomposition and leakage. Given the fact that SF6 is also a potent greenhouse gas, 22,000 times more dangerous to the ozone layer than CO2, power companies are now required by law in the European Union, under the Kyoto Protocol, to monitor vessel top-off and leakage.

SIERRA'S SOLUTION

Responding to this challenge, Sierra worked in partnership with Energy Maintenance Technologies (EMT), in Luton, England, the leading supplier of predictive maintenance test solutions for the utilities industry to develop a comprehensive solution. The resulting EMT Assero SF6MFU is a portable, fully-automated SF6 top-off and fill operation system.

This device is the size of a small suitcase, battery operated, and has many alarm options. Data logging includes SF6 used and end pressure stored on a CF card for traceability. Data can be sent to a website via a General Packet Radio Service modem.

The key to the SF6MFU's performance is an accurate mass flow controller to regulate the SF6 entering the vessels. Every SF6MFU includes a Sierra SmartTrak® 100 mass flow controller, a pressure transmitter, a battery monitor and guarding system, overshoot pressure protection, a data logger with CF card and/or GPRS modem. These are all controlled by Sierra's HMI touch screen management system. All internal communication takes place over a Modbus network which eliminates drift and transfers all information quickly and reliably.

In the utilities sector, the EMT Assero SF6MFU has proven to reduce labor costs by fully-automating the SF6 top-off and fill process and help utility companies comply with the strict greenhouse gas regulations of the Kyoto Protocol.

Here's what makes Sierra's SmartTrak 100 an ideal choice:
  • Patented, inherently linear Laminar Flow Element (LFE) design
  • Provides smooth and flexible valve performance
  • Pilot Module allows user to switch between ten pre-programmed gases, change setpoint value and source, set zero, span and full scale, modify engineering units, choose output signal...and much more
  • Has more robust electronics than other industry mass flow controllers