Figure 7: KM82 Circuit Board Module
(housing cover removed)
NOTE: The zero and span adjustments are multi-turn potentiometers (pots) that have no stops on the ends of their travel;
however, they have a slip clutch to prevent damage from over-adjustment. The pots also make a clicking noise when they
have reached adjustment limits.
5. Apply a 4.0 mA signal to the input. Locate and adjust zero trim pot to achieve a 3.0 psi output. The output will increase
with clockwise rotation of the zero trim pot. If calibrating an I/P module with a 10-50 mA input signal, apply a 10.0 mA
signal to input.
6. Increase input signal to 20.0 mA (50 mA for 10-50 mA units). Locate and adjust span trim pot to achieve a 15.0 psi
output. The output will increase with clockwise rotation of the span.
7. Recheck zero setting by repeating Step 5. The span adjustment may affect zero setting.
8. Repeat Steps 5, 6 and 7 until proper adjustments are obtained.
Adjusting the Minimum Pressure Cutoff Feature:
The APEX 8000 positioner with I/P Transducer has a “Minimum Pressure Cutoff” (MPC) feature, which allows the user to
set the positioner. When the input signal falls below a user-adjustable current, the pressure output falls rapidly to approxi-
mately 1.7 psi, causing the valve to move to the failure position. This feature is generally used when the service requires a
tight shut off or to prevent throttling near the valve seat. To adjust this feature, refer to Figure 7 and perform the following:
NOTE: The following procedure applies only when the minimum pressure cutoff feature will be used.
NOTE: The zero and span settings of both the positioner and I/P transducer should be verified as accurate before the
minimum pressure cutoff feature is enabled and adjusted.
1. Connect the I/P module to a 30 to 150 psi air supply pressure.
2. Remove the I/P module housing cover.
WARNING: Be certain power to the I/P module is discon-nected before removing the housing cover in
explosive atmospheres; otherwise personal injury may occur
.
