With more and more actuator manufacturers removing on/off control actuators from their product line, the Controls Contractor is forced to find ways to convert the standard threepoint floating actuators (also called tristate) to on/off actuators (also called two position).

Griswold Controls has worked with Siemens to offer a solution with their GDE131.1P actuator.

Floating Actuators

Form C, SPDT Relay

The diagram on this page is the Siemens GDE131.1P wiring diagram.

The contractor will need to add a SPDT relay to their wiring system which costs less than $5. This type of relay output is found on all building automation systems and allows a three-point floating actuator to work in place of an on/off actuator.

It will physically convert a three–point floating actuator with 3 wires to a two wire system. This solution is much less expensive than buying a true on/off actuator since most on/off actuators are also fail–safe and cost twice what a Siemens GDE131.1P.

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