AUMA FQM fail safe units
11 September 2019
AUMA has supplied electric actuators fitted with FQM fail safe units to ensure the continuous cooling water supply at Volvo Car Group’s bodywork plant in Olofström, southern Sweden even in the event of a power failure.
The Volvo Personvagnar AB Karosskomponenter factory makes structural components for Volvo cars. Sheets of steel are heated to up to 950 °C before being pressed into shape. The ovens used to heat the panels rely on water cooling to protect critical parts. Continuous cooling is vital to maintain production and to avoid costly damage.
In normal operation, the plant’s cooling water is pumped around a closed loop. If the normal cooling system is interrupted, the plant switches to once-through emergency cooling using water from the municipal supply. Changing over to emergency cooling must function even in the event of a power failure.
AUMA, therefore, supplied two SQ 07.2 part-turn actuators with AC 01.2 actuator controls and two FQM 07.1 fail safe units for the cooling system valves. The FQM fail safe units use mechanical energy, in the form of a constant-force spring motor, to open or close valves when electric power is not available.
If cooling water is lost for whatever reason, a safety PLC issues an emergency shutdown signal to both fail safe units in sequence. The first FQM unit closes the inlet and outlet valves of the normal cooling circuit. Both valves are closed simultaneously by means of a lever arrangement. The second FQM unit opens two valves for emergency cooling, also by means of a lever arrangement: one connected to the municipal water supply, and the other to divert the water to drain once it has done its job.