4-Wire Remote Installation - Emerson Micro Motion 3711 Configuration And Use Manual

Maintenance and Troubleshooting
15.18.2

4-wire remote installation

If you have a 4-wire remote installation (see Figure A-1):
1. Power down the Model 3711.
2. Remove the core processor lid.
Note: You may disconnect the 4-wire cable between the core processor and the Model 3711, or leave
it connected.
3. Loosen the captive screw (2.5 mm) in the center of the core processor. Carefully remove the
core processor from the sensor by grasping it and lifting it straight up. Do not twist or rotate
the core processor.
If the core processor pins are bent, broken, or damaged in any way, the core
processor will not operate.
To avoid damage to the core processor pins:
• Do not twist or rotate the core processor when lifting it.
• When replacing the core processor on the pins, be sure to align the guide pins
and mount the core processor carefully.
4. Using a digital multimeter (DMM), check the pickoff pin resistances by placing the DMM
leads on the pin pairs. Refer to Figure 15-3 to identify the pins and pin pairs. Record the
values.
Figure 15-3 Sensor pins
Resistance temperature detector return /
There should be no open circuits, i.e., no infinite resistance readings. The LPO and RPO
readings should be the same or very close (± 5 ohms).
5. Using the DMM, check between each pin and the sensor case.
186
Lead length compensator
Lead length compensator
(common)
Resistance temperature detector
( + )
(1) LLC for all sensors except T-Series and CMF400 I.S. For T-Series sensors, functions as
composite RTD. For CMF400 I.S. sensors, functions as fixed resistor.
CAUTION
Right pickoff
(1)
( + )
( – )
Right pickoff
( + )
Left pickoff
( – )
Left pickoff
( + )
Drive
( – )
Drive
( + )
®
Micro Motion Model 3711 Gas Flow Computers