Monday 4 January 2010

Cables no longer required

Completely wireless switching devices for ATEX zones 1, 2, 21 and 22

The new 8074 F series position switches and 8040 F series command devices from Stahl, are truly, completely wire-less solutions for radio signal communication. Requiring neither signal lines nor external energy supply connections, the units can be freely installed in zone 1, 2, 21, or 22 hazardous areas. Users therefore need not worry about any wiring when e.g. retrofitting the command devices into difficult-to-access machines or plants.

Since there is no need to route cables around or over joints or bearings, the switches are particularly suitable for reporting positions from movable ma-chine parts. The switching signals are transmitted on the license-free SDR band at 868 MHz. Up to 300 m maximum radio range outdoors and a 30 m range within buildings ensure that receiving units can usually be placed within safe areas. They are also available with flameproof enclosures.

The Ex switching devices generate the energy required for sending data telegrams by means of an integrated induction generator: when the switching element is actuated, the kinetic energy of the switching process is electrodynamically har-vested, and immediately used to feed the radio module. In contrast to battery-supplied wireless switches, these self-supporting units do not need any regular servicing to remain fully functional.

With a maximum transmitting power of 10 mW and maximum energy quantities of 50 µJ, radio communication according to the EnOcean standard does not amount to a potential ignition source in hazardous areas. Both switching units are suitable for operation in a wide temperature range from -20 to +60 °C. The IP65-protected 8040 F command devices are fitted in a ruggedized metal hous-ing designed to withstand even extremely harsh environmental conditions.

These products are marketed in Ireland through Douglas Control & Automation.

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