Self-powered transmitter opens up new installation possibilities

25 September 2013

ABB has developed a standalone, self-powered temperature transmitter with WirelessHART, which is said to offer a cost effective and maintenance-free alternative to wired or battery-powered devices.

Wireless instruments offer the ideal solution in applications where it could be costly or impractical to run cabling. Battery-powered WirelessHART technology allows for rapid and easy instrument installation to allow operators to monitor new process information to improve plant visibility.

However, the battery will eventually need replacing. Although it is possible to prolong battery life this can slow down the data transfer rate and will affect the instrument’s response time.

ABB’s self-powered temperature transmitter has been developed to overcome these issues. It features a built-in thermoelectric generator (TEG), the device uses the Seebeck Effect to harvest electrical energy from thermal energy. The temperature difference between the ambient and the pipe temperature produces a voltage difference, which is used to power the device. This technology enables the transmitter to be fitted onto a steam or process pipe, with the latent heat being used to provide the power needed for operation.

To help protect against the risk of a power failure, for example if the process medium or steam flow is deactivated or the temperature gradient falls below the 30K needed to power the device, the device also includes a back-up battery. Under ordinary circumstances, this battery should hardly ever need to be used, giving it a potential operating life of up to 20 years.

The status of the device can be relayed via WirelessHART to a centralised control system, including ABB’s System 800xa, which offers the necessary functions and tools to integrate wireless devices into the control network.

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