Rtd Installation; Figure 20: Explosion-Proof Rtd, Disassembled - ABB 266 MODBUS User Manual

RTD installation

To use the flowing temperature of the process stream a resistive thermal detector (RTD) must be installed. Dependent upon the
classification of the area, either an explosion-proof RTD or a non-incendive RTD should be installed. An explosion-proof RTD
should be used in DIV 1 areas; and a standard RTD, non-incendive, may be used in DIV 2 or general purpose areas.
The RTD shall be a platinum 100 ohm @ 0° C, RTD with a temperature coefficient of resistance (TCR) Curve B of .00385055
ohms/ohm/degree C.
If the simulation of flowing temperature is used, then installation of an RTD is not required and the 178 Ω resistor, wired to the
terminal block, must remain in place. See Transmitter wiring in section 3.6.4 for additional information.
IMPORTANT NOTE: Installation of the RTD requires that a thermowell be previously installed in the process
stream and that the thermowell extends into the center 1/3 of the stream.
DIV 1 explosion-proof RTD installation
WARNING – Bodily injury. Conduit requirements for DIV 1 installations are not addressed in this procedure. To
avoid creating a hazardous situation, ensure compliance with the applicable standards, regulations, and
recommendations for installation in the country of use. RTD installation in classified DIV 1 areas should only be
performed by technicians knowledgeable about explosion protection.
Explosion-proof and flame-proof installations require explosion-proof conduit and poured seals or flame-proof
rated cable and cable glands, respectively.
Optionally supplied materials
— RTD probe (DIV 1), (probe length TBD by technician)
— Cable (cable length TBD by technician)
— Teflon
®
tape
Instructions
1. Screw the ½ inch nipple fitting, supplied with the RTD, into the thermowell (Figure 20).
Explosion-proof connection head
2. Separate the top and bottom of the conduit union. Screw the union bottom onto the nipple fitting.
3. Screw the top of the conduit union into the bottom of the explosion-proof connection head. Do not tighten.
4. Unscrew and remove the cover from the explosion-proof connection head.
5. Insert the RTD probe through the opening in the connection head. Holding the probe from below, screw the spring
clockwise down into the center of the wiring block until the top edge of the spring is flush with the top of the wiring block.
Bottom of probe and element
Spring

Figure 20: Explosion-proof RTD, disassembled

½" nipple fitting
½" conduit union
266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB | 25
3 Installation
Thermowell