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In Britain they run systems that deliver gas and electricity across the entire country. In the North Eastern states of the US, they provide power directly to millions of customers. They hold a vital position at the centre of the energy system. They join everything up. National Grid’s job is to connect people to the energy they use. From the warmth and light they rely on at home, and the power which keeps their factories and offices going, to the infrastructure and technologies that are essential parts of our modern lifestyle.
National Grid Plc required a method of recovering 4-20mA signal data from two online analysis systems manufactured by GE/Syprotec.
The HYDRAN 201Ri is a general transformer, fault-gas analyser, giving an analogue output of 4- 20mA for a range of 0-2000ppm of dissolved gas in the insulating oil. The HYDRAN gives a combined output based upon two main gases, hydrogen and carbon monoxide.
These units are widely used across electricity utilities around the world as a method of continuously monitoring the assets health, providing advance warning of developing fault conditions which may lead to a failure.
Substations built around ‘air-insulated’ design rely on the natural electrical resistivity of the air for insulation and have by nature a large footprint. Typical sizes are around 200 by 300 meters.
Retro-fitting data recovery systems in these substations, which rely on hard-wired cables, can often cost many thousands of pounds and can take several days to install. By utilising cross-site wireless technology these costs can be brought down to a minimum and installation times can be reduced to hours.
The major obstacles to overcome were:
- Reliable long range transmission in a substation environment, where large amounts of concrete and steel structures lie directly in the path of any radio transmitter-receiver pathway.
- Battery powered transmitters that would remain operational in terms of power and reliability when exposed to the environment of an air-insulated substation.
The National Grid solution was installed and comprised 1 Invisible Systems GPRS Gateway, 1 ambient temperature probe and 3 transmitters. The transmitters broadcast across distances of ~100m and 200m respectively.