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3710 and 3720 Positioners
CONVERTER MODULE
TERMINAL BLOCK
FIELD WIRING
INDICATING DEVICE
1
NOTES:
1
FOR TROUBLESHOOTING OR MONITORING OPERATION THE
INDICATING DEVICE CAN BE A VOLTMETER ACROSS A 250 OHM
RESISTOR OR CURRENT METER
2
THE TYPE 3722 CONVERTER HOUSING FEATURES INTERNAL AND
EXTERNAL GROUNDING SCREWS
Figure 14. Field Wiring Diagram
plate does not have the positioner mounting holes
and purge tube knockout, order a new cover plate.
See the parts list for the specific actuator cover plate
required for each actuator.
1. The actuator cover plate features a purge tube
knockout. Locate the knockout and use appropriate
tools to open this hole in the cover plate.
2. Install the actuator cover plate and then insert the
purge tube with O-ring into the purge tube hole in the
cover plate.
When mounting a positioner to an
actuator with the purge tube installed,
guide the purge tube into the vent
opening in the positioner base plate by
removing the vent screen (key 41) and
then inserting an appropriate tool such
as a screwdriver through the vent
opening into the purge tube.
When the positioner is secured to the
actuator, install the vent screen.
3. Before mounting the positioner, be sure the
second O-ring is properly fitted to the end of the
purge tube. Use care when mounting the positioner.
Be sure the purge tube with O-ring fits into the vent
opening on the rear of the positioner base plate.
18
GROUNDING
2
SCREW
EARTH
SCREW
Note
4−20 mA
5.6 V
Figure 15. Circuit Schematic
4. Secure the positioner to the mounting plate using
the (hex) socket head cap screws (key 46).
5. Install the vent screen in the positioner base
plate.
Electrical Connection for Type 3720
Positioner
WARNING
In explosion-proof applications,
disconnect power before removing the
converter housing cap.
In Class I, Division 1 explosion-proof
applications, install rigid metal conduit
and a conduit seal no more than 457
mm (18 inches) from the converter.
Personal injury or property damage
may result from explosion if the seal is
not installed.
For intrinsically-safe installations,
refer to Fisher loop schematics or to
instructions provided by the barrier
manufacturer for proper wiring and
installation.
Use the 1/2-inch NPT (or M20 thread) 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 NSm) or 4
pounds force per inch (4 lbfSin).
Instruction Manual
Form 5300
July 2005
60 OHMS
5.6 V
5.6 V
60 OHMS
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