Electric actuators ensure SIL 2

Louise Smyth

As biofuels become increasingly popular in Scandinavian power plants, their complex and variable nature imposes extra challenges for equipment – including valve actuators.

Around 50 valves in the straw-fired power plant in Lisbjerg, Denmark are fitted with latest-generation SA electric actuators from the German manufacturer AUMA. All the actuators are centrally controlled via Profibus DP V1 communications. Featuring intelligent autodiagnostics, the actuators facilitate predictive maintenance and asset management.

One especially important actuator drives a damper that allows the waste heat recovery condenser to be bypassed for maintenance. Since a failure here could force a plant shutdown, this actuator has to fulfil special safety requirements. AUMA supplied a combination of an SA 14.6 actuator, AC 01.2 SIL actuator controls and GS 250.3 gearbox that meets the stringent requirements of Safety Integrity Level (SIL) 2. The actuator accomplishes the safety function Safe Open.

AUMA’s modular SA multi-turn and SQ part-turn actuators with AC 01.2 SIL integral controls are TÜV-certified for use in safety-related systems up to SIL 3 (in redundant system architecture) and fully comply with the second edition of IEC 61508.

The Lisbjerg power plant, commissioned in 2016, supplies 38MW of electricity and 78MW of district heating to the city of Aarhus. The plant burns up to 240,000 t/y of straw, supplemented when necessary with up to 50% wood chips.

For more information visit Auma

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