104
RFT9739 Rack-Mount Transmitter Instruction Manual
Replacing Older Transmitters
continued
Step 2
Determining type of RTD in the sensor
Determine whether the sensor has a platinum or copper RTD
(resistance temperature detector). The type of RTD determines how the
transmitter and sensor must be wired and configured.
All sensors shipped after October 1986 have
platinum
RTDs. For older
sensors, or if the date of manufacture is not known, follow these steps to
determine the sensor's RTD type:
a. Identify the sensor serial number on the tag that is attached to the
outside of the sensor case.
• If the sensor serial number is higher than 87263, the sensor has a
platinum
RTD. See "Installing the RFT9739 transmitter", page 105,
if the sensor serial number is higher than 87263.
• If the serial number is 87263 or lower, check resistance values as
described below.
b. If the sensor and transmitter were properly wired with Micro Motion
color-coded cable, the orange and violet wires provide temperature
detection. These wires were connected to RE-01 terminals 3 and 9,
or RFT9712 terminals 3 and 7, or RFT9729 terminals CN1-14d and
CN1-16d. The yellow or shield wire from the orange/violet pair, which
was connected to RE-01 terminal 6, or RFT9712 terminal 4, or
RFT9729 terminal CN1-12d, provides temperature lead length
compensation.
Use a digital multimeter (DMM) to check resistance between the
orange, violet, and yellow wires. Refer to Table F-1 to determine the
sensor's RTD type. Contact the Micro Motion Customer Service
Department for further assistance.
• In the U.S.A., phone 1-800-522-6277, 24 hours
• Outside the U.S.A., phone 303-530-8400, 24 hours
• In Europe, phone +31 (0) 318 549 443
• In Asia, phone 65-770-8155
c. Proceed to Step 3, page 105.
Table F-1. Resistance values for determining RTD type
Wire colors
Resistance if RTD is platinum
Resistance if RTD is copper
Resistance if RTD is open
Violet to orange
110
Ω
at ambient temperature (70
°
F)
Open (infinite resistance)
Open (infinite resistance)
Violet to yellow
110
Ω
at ambient temperature (70
°
F)
110
Ω
at ambient temperature (70
°
F)
Open (infinite resistance)
Orange to yellow
0-10
Ω
Open (infinite resistance)
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