The actuator pictured operates like a twin-coil switch machine. Power is only momentarily applied to change the aspect indicator and arms. If power is continuously applied it will burn out the mechanism. Quickly.
I'm not certain what you ordered or how they operate, but if they are the same as the Viessmann, take warning. Viessman is also sold under the Roco name.
I am using two magnetic reed switches mounted between the rail ties and two relays, one for each aspect change. The magnetic reed switches are operated by Alnico magnets mounted on the bottom of the locomotives. They open and close quickly to trip the relay and momentarily apply power to the actuator.
You could also use photo-electric cells or IR detectors to actuate them too.
The reason for the relays is because the magnetic reed switches are not rated for the current and voltage required to operate the actuator. I'm using 5VDC to energize the coil for the reed switches and the other side of the relay operates a 15VDC 400ma circuit for the semaphore actuators.