Instruction Manual

Instruction Manual
D200158X012
4194S Controllers
December 2011
19
Remote Set Point Option
The capability to adjust the controller set point from a remote location is available with all 4194S controllers. This
option is designated by the letter M in the type number.
Auto/Manual Option
Controllers with the auto/manual option (designated by the letter E in the type number) have piping on the output
side of the relay as shown in figure 3‐5. Supply pressure to the relay is also applied to the manual loader. The manual
loader, functioning as a regulator, applies pressure to one side of the plastic tube and to the auto/manual switch.
Output pressure from the relay registers on the other side of the plastic tube as well as in the auto/manual switch.
When the auto/manual switch is in the MANUAL position, the output of the manual loader is channeled through the
auto/manual switch and becomes the output of the controller. When the auto/manual switch is in the AUTO position,
the output of the relay is channeled through the switch to become the output of the controller.
Before the auto/manual switch is operated, the output of the relay must equal the manual loader output to avoid
bumping the process. Adjusting the set point varies the pressure on the left‐hand side of the plastic tube. Adjusting
the manual loader knob varies the pressure on the right‐hand side. When the pressures are equal, the metal ball is
centered in the tube. Pressure imbalance forces the ball to one end of the tube where it forms a seal, blocking air flow
through the tube.
Figure 3‐5. Schematic of Auto/Manual Option
AUTOMATIC
POSITION
OUTPUT PRESSURE
TO FINAL CONTROL
ELEMENT
SUPPLY
PRESSURE
RELAY
AUTO/MANUAL
SWITCH
MANUAL LOADER
MANUAL
LOADER
KNOB
MANUAL
POSITION
AUTO/MANUAL
SWITCH
OUTPUT PRESSURE
TO FINAL CONTROL
ELEMENT
PLASTIC TUBE
METAL BALL
RELAY OUTPUT PRESSURE
SUPPLY PRESSURE
MANUAL LOADER OUTPUT PRESSURE
48A5230‐A
A2999‐1