Referencing “Closed” Vs. Referencing “Open” - Siemens LMV3 series Technical Instructions

LMV Series
For example, if an actuator was selected to have a counterclockwise rotation and is referencing
on the "open" side, the actuator will drive 20.6° past the open (90°) position before each
startup.
Most valves / dampers can rotate past the open (90°) position, so it is common to set all
actuator referencing directions to "open".
NOTE: Valves / dampers must not torque against mechanical stops during referencing.
8. Couple actuators to the valves / dampers. Actuators must not torque against mechanical stops
on the valve / damper when at home position. Adjust home positions if necessary.
NOTE: Actuator shaft couplings must compensate for both angular and parallel shaft
misalignment due to the mounting bracket. Solid (rigid) shaft couplings are not acceptable in
most applications, especially when formed or welded mounting brackets are used. Couplings
should have little to no backlash, and are a safety relevant part of a linkage-less system.
NOTE: Make absolutely certain that when the actuators are at or near 0° (as indicated on the
AZL display) that the valve / damper the actuator is coupled to is in the CLOSED (minimum
flow) position. An exception to this is some back-flow type oil burners, where a wide open oil
valve will result in minimal flow through the oil nozzle.
SCC Inc.
Figure 4-4: Referencing "Closed" vs. Referencing "Open"
Page 15
Technical Instructions
Document No. LV3-1000
Section 4