Specifications

Table 4-3. Calibration Signal Pressures.

SIGNAL AIR

STROKE

POSITION

3-15 psig (I/P) O-30 psig

0% 3 0

100% 15 30

4-3. CURRENT TO PNEUMATIC (I/P) SIGNAL

CONVERTER CALIBRATION. Calibrate current

to pneumatic signal converter after mounting,

changing mounted position, or when loss of control is

noticed (refer to Section V, Troubleshooting). Use the

following procedures to calibrate the signal converter:

a. Remove protective plastic caps from “Zero” and

“Span” adjustment screws (Figure 4-3).

ADJUSTMENT

4 TO 20 mA

Figure 4-3. Current to Pneumatic Converter

NOTE

Make sure the input pressure rating of the

power positioner is the same as the pressure

rating stamped on the current to pneumatic

signal converter.

Set signal value to 4 mA and adjust “Zero” screw

until output pressure is at 3 psig. Turn screw

counterclockwise to increase pressure, clockwise

to decrease pressure. If output pressure does not

change when screw is turned, turn screw counter-

clockwise until pressure starts to rise.

Set signal value to 20 mA. Adjust “Span” screw

until output pressure is at 15 psig.

Repeat steps b. and c. until no further adjustment

is needed.

Replace protective caps,

4-4. LINKAGE CALIBRATION.

a. m. Check angular travel of power positioner

drive lever at cl&s. Compare this to device

driven lever angular travel. If angular distances

are not the same, use the following procedure to

adjust offset of power positioner drive lever to

the same angle as the device driven lever. When

adjushnent is complete, both operating levers

must be parallel with each other.

1. Measure angle PI J%xn vertical line extending

from shaft hub, to power positioner drive lever

(Figure 4-4). This is the power positioner

drive lever offset.