Wireless and battery-free sensing at Yorkshire Water
19 Sep 2007
The trial at the Esholt Waste Water Treatment Works in Bradford is part of a £120,000 R&D project at Yorkshire Water to optimise its facilities, in part by increasing the reliability of its equipment. The company has previously installed conventional hard-wired systems to send and record performance data, but these were difficult and expensive to install, and proved unreliable.
Perpetuum’s PMG7 microgenerator is powering wireless sensor nodes developed by RLW Inc of State College, Pennsylvania. The sensors record and transmit vibration and temperature data using only the existing vibration of industrial equipment to power itself without the need for additional power supply.
“Vibration energy-harvesting is the simple idea that vibration of a piece of plant or machinery could be turned into an electrical signal," said Perpetuum CEO Roy Freeland. "Using a magnet and coil arrangement, based on the Faraday Principle, we have found a way to successfully transform the kinetic energy of the vibration into a useful low-power electrical signal.”
Yorkshire Water installed six devices on motors and blowers in the waste incinerator’s plant during late 2005. The environment is especially challenging, with large potential for interference to the data signal from many platforms and steel works.
Each piece of equipment has a unique signature vibration reading and the devices were installed to measure and transmit the vibration spectra. Once the system is fully developed, should the vibration reading change, for example as a result of a bearing overheating, operators would be alerted immediately.
According to Peter Boruszenko, R&D engineer at Yorkshire Water: “The microgenerators have generated enough electricity and data from day one. They have also transmitted data reliably and without any interruption. Tests to date show that vibration energy-harvesting is now a practical and feasible method of powering wireless condition monitoring.”
Having completed phase one and proven that the device is reliably sending data, Yorkshire Water is now looking at how best to interpret the data generated, linking it to appropriate software that will recognise trends and alert the operator when problems occur.
If this phase II stage is successful, devices could be deployed throughout the facility and potentially at many other Yorkshire Water sites, including on remote motors at isolated sites. With further developments, the device will be able to alert operators to any problems directly by a text message to their mobile phone or via the regional telemetry system.
Designed to resonate at mains frequency (50 or 60Hz) with a bandwidth of ±0.2Hz on any AC induction or synchronous motor-powered equipment, the PMG7 can generate up to 5mW. This is enough to power a wireless transmitter sending up to 6Kbytes of critical data every few minutes, or smaller amounts of data - such as a temperature reading - several times a second. It is designed to operate in most industrial environments and at minimal vibration levels (25mg).
