OUTPUT WIRING
Relay Connections
To prolong contact life and suppress electrical noise interference due to the
switching of inductive loads, it is good installation practice to install a snubber
across the contactor. Follow the manufacturer’s instructions for installation.
Note: Snubber leakage current can cause some electro-mechanical devices
to be held ON.
SIGNAL WIRING (RTD SENSOR)
RTD sensors are used in applications where a high degree of accuracy is
required. Most RTD sensors available are the 3-wire type. The 3rd additional
wire is a sense lead for cancelling the effects of lead resistance at the probe. The
sense lead connects to TBA #6
(+ signal)
, the common to TBA #7
(-
signal/comm)
, and the excitation to TBA #5
(+ excitation)
. The excitation and
sense leads are generally the same color because they are functionally the same
and may be interchanged at the instrument. Four wire sensors have an additional
sense lead connected
(at the probe)
to the common lead. Leave the extra sense
lead disconnected when using a four wire probe with the IMR.
Always refer to the sensor manufacturer’s instructions for probe wiring
connections, if available.
Two wire RTD sensors may be used with the IMR by shorting TBA #5 to TBA
#6, if the distance between sensor and instrument is not too great
(<30ft)
. The
total lead resistance can be used to predict the temperature error for 2-wire
sensors, according to 2.5°C/
W
of lead resistance.
Note: Extended cable runs can be made provided the lead resistance is less than
20
W
/lead and the resistance is equal in each lead. For further information see
“Appendix B - Specifications” or consult factory.
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