Samson 5857, Mounting And Operating Instructions, Page: 29 / 80

EB 5857 EN 6-3
Operation
6.1.2.1 Indication with LEDs
The actuator with positioner has a red and a yellow LED which indicate the operating state of
the actuator through a blinking pattern. The LEDs are located underneath the cover on top of
the actuator (see Fig. 6-2).
6.1.2.2 Direction of action switch
The position of the direction of action switch determines the actuator's direction of action.
Î
See Fig. 6-2.
− Switch position A: Direction of action increasing/increasing (>>)
The actuator stem retracts as the input signal increases.
− Switch position B: Direction of action increasing/decreasing (<>)
The actuator stem extends as the input signal increases.
Actuator stem extended
− For globe valves: Valve closed
− For three-way mixing valves: Port A
à
AB open, B
à
AB closed
− For three-way diverting valves: Port AB
à
A closed, AB
à
B open
Actuator stem retracted
− For globe valves: Valve open
− For three-way mixing valves: Port A
à
AB closed, B
à
AB open
− For three-way diverting valves: Port AB
à
A open, AB
à
B closed
A
B
AB
AB
A
B
A
AB
B
AB
A
B
Mixing valve for mixing service
Diverting valve for mixing service
For diverting service
For diverting service
Flow pipe
Flow pipe
Flow pipe
Flow pipe
Return flow pipe
Return flow pipe
Return flow pipe
Return flow pipe
Fig. 6-3: Operating principle of three-way mixing and diverting valves