Instruction Manual
D101728X012
3710 and 3720 Positioners
September 2017
23
Use the 1/2‐14 NPT conduit connection for field wiring installation. Refer to figures 14 and 15 when connecting field
wiring from the control device to the converter. Connect the positive wire from the control device to the converter's
positive ( + ) terminal and the negative wire from the control device to the converter's negative ( ‐ ) terminal.
Do not overtighten the terminal screws. Maximum torque is 0.45 Newton‐meters (0.45 N
S
m) or 4 pounds force per
inch (4 lbf
S
in).
Figure 14. Field Wiring Diagram
CONVERTER MODULE
TERMINAL BLOCK
FIELD WIRING
INDICATING DEVICE
GROUNDING
SCREW
EARTH SCREW
NOTES:
FOR TROUBLESHOOTING OR MONITORING OPERATION THE INDICATING
DEVICE CAN BE A VOLTMETER ACROSS A 250 OHM RESISTOR OR CURRENT METER
THE 3722 CONVERTER HOUSING FEATURES INTERNAL AND EXTERNAL
GROUNDING SCREWS
2
1
2
1
Figure 15. Circuit Schematic
60 OHMS
60 OHMS
5.6 V
5.6 V
5.6 V
4-20 mA
Diagnostic Connections
For diagnostic testing of control valve packages (valve, actuator, positioner, and accessories), special connectors and
hardware are available. The hardware required for diagnostic connections includes 3/4 NPT pipe nipples and pipe tees
with a
1/8 NPT pipe bushing for the connector. The connector consists of a 1/8 NPT body and body protector. If the
diagnostic connectors are ordered for a positioner with gauges, 1/8‐inch stems are also included.
Install connectors and hardware between the positioner and the actuator.
1. Before assembling the pipe nipple, pipe tee, pipe bushing, actuator piping, and connector body, apply sealant
(key 64) to all threads.
2. Assemble connectors and hardware. Remove standard piping connections, if necessary, and install the diagnostic
connections.
D
3720:
For a diagnostic connection to the instrument pressure output from the converter module, remove the 1/8
NPT pipe plug (key 86) from the 3722 converter housing. Apply sealant (key 83) to the threads of the 1/8 NPT
connector body and install it directly into the housing.
D
3710, 3720:
For diagnostic connections made up of a pipe nipple, pipe tee, pipe bushing, and connector body,
turn the pipe tee to position the connector body for easy access when doing diagnostic testing.
