For PGHD, PGSD, LA-25, and LA-27 LVDTs used in Power Plant Valve Position Applications

The need to identify the approximate Null Position of the core of an LVDT arises when first calibrating the sensor with its signal conditioning equipment. The usual process involves finding null with various instruments and matching that LVDT core position to the mid-point of the range of motion of the valve actuator to which it is attached. To save time and simplify this process, ASG offers the following table that shows nominal Null Position for PGHD, PGSD, LA-25, and LA-27 LVDTs that are commonly used in Power Generation applications for steam valve position feedback to the power plant control system. Because of various tolerance, both mechanical and electrical, this position value in this table must be approximate, but it is close enough to the actual Null Position to permit the LVDT setup and calibration.