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Installation l 3-11
3
Description
Connecting the RTD Sensors
The lower RTD could be the return air sensor for the
setback option if installed or the process protection
sensor depending on the configuration of the system.
The routing of the sensor cables should be neat and
not parallel with the power connections. When a sen-
sor cable must cross over power wiring, the intersec-
tion should be made at right angles to reduce the RFI
noise transmitted to the sensor cable.
Process Temperature RTD Probe
The RTD sensor connections should be made to the control center via the upper
female connections in the side of the control center. The process temperature RTD
is to be located in the hopper delivery air inlet. The connection is 1/8 NPT. The
sensor should be located ¼ to ¾ of the way in to the diameter of the inlet to obtain
the best temperature reading. The controller uses this RTD to monitor and control
the setpoint temperature.
CAUTION: Always disconnect and lock out the main power sources before mak-
ing electrical connections. Electrical connections should be made only by quali-
fied personnel.
1 Turn the disconnect dial on the control center door to the Off or “O” posi-
tion. Lock out the main power (see Page 1-5 for complete lock out informa-
tion).
2
Insert the process RTD probe into the delivery
air inlet on the hopper.
Center the end of the
probe in the inlet so that the tip does not touch
the inlet tube walls. Tighten the nuts to lock the
RTD probe in place.
IMPORTANT: Always refer
to the wiring diagrams that
came with your heater
before making electrical
connections.
ON
O OFF
(continued)