SIEMENS Thermoelectric actuator STA121 24VAC/DC, NC, cable 1m

Electrothermal drives STA.. and STP.. do not require maintenance and their operation is silent. After connecting the control signal to the drive, the temperature of the heating element increases and thus causes the expansion of the solid medium. This expansion is translated into linear movement of the valve stem. The valve starts to open after preheating the element, which takes approximately 1.5 minutes, if the heating element is connected from a cold state (room temperature) and the maximum stroke is reached after another approx. 2.5 minutes (230 V) or 3 minutes (24 V). When the power is removed, the expansion element will cool and the valve will be closed.

SIEMENS STA121
● ST..121.. Operating voltage AC/DC 24 V
● Conversion force 110 N
● Connection cables 1 m / 2 m / 2 m without halogen / 5 m
● Direct mounting on valve with M30x1.5 mm thread
● Spindle position 10.8mm (NC), 15.1mm (NO)
● Degree of protection IP54
● Thermal expansion element
● Easy mounting on the drive thanks to presetting
● Durable and maintenance-free

Preset function
The NC drive has a preset function that is active when delivered from the factory. The function allows the actuator to be applied to the valve without the need to apply force and flush the system before commissioning. The function is deactivated when the drive is first started, after which it continues to operate normally. Restoring the preset position, e.g. before disassembly, can be done with a screwdriver or by locking when opening under voltage (see assembly instructions).

NC version «normally closed»: After mounting the actuator, the valve is closed without voltage. Under voltage, the actuator spindle retracts and the valve opens. Valve state with de-energized actuator: closed.

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SIEMENS – Electrothermal actuator STA a STP - Datasheet /en/

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SIEMENS – Electrothermal actuator STA a STP - Mounting instruction /en/