Using the IntelliLogger™
38
To remove the fuse, grasp it gently with your fingers or a small set of pliers and
pull straight up to extract it from its white socket base.
Commonly, this fuse is blown during installation of 4-20mA current
channels where the power supply powering the 4-20mA transmitter is
accidentally shorted directly across the logger input channel. To
avoid this inconvenience, always check wiring prior to powering up
system power supplies.
Thermocouple Applications
Following are guidelines for connecting thermocouple type inputs to the ILIM-7
input channel terminal connectors.
T
HERMOCOUPLE
C
ONNECTION
To utilize an ILIM-7 channel as a thermocouple input, configure that channel's Input
Configuration Switch as explained earlier in this chapter.
Channels configured as thermocouple inputs utilize two or three terminal strip
connections per input; a Positive lead, and a Negative lead and optionally a shield.
Figure 3-13; Thermocouple (and optional shield) terminal strip connection
Connect the thermocouple positive and negative (red in USA) leads to the correct pair
of terminals on the module terminal strip. Polarity markings are printed on the circuit
board next to the terminal strip. Polarity is critical, as reverse connected
thermocouples will log positive temperatures as negative temperatures.
Shielded thermocouple wire is recommended in electrically noisy environments for
optimum signal protection. If shielded wire is used, the shield should be connected to
the terminal marked ‘SH’. The Shield serves to conduct away electrical noise picked
up by the thermocouple shield and shunt it to Earth ground. Note that for the Shield to
be effective a wire should be connected from any of the Shield connections on the
ILIM-7 terminal strip and then to a known Earth ground. All Shield connections on the
terminal strip are interconnected so a single Earth ground connection suffices.
C
OLD
J
UNCTION
C
OMPENSATION
(CJC):
For thermocouple measurements, the temperature of the terminal strip connections is
required in the voltage to temperature conversion equation used by the IntelliLogger.
This temperature is measured by the CJC sensor located internal to the ILIM-7
module. Any differential temperature from the metal terminal strip connections to the
CJC sensor on the ILIM-7 circuit board will result in direct measurement errors.
The ILIM-7 is thermally designed to provide good CJC sensor vs. terminal strip
temperature tracking however, to minimize this potential error, avoid installations or
effects that will induce extreme temperature differential. The most accurate readings
will be achieved when the ILIM-7 module has been allowed to temperature stabilize.
In rapidly changing temperature environments, additional accuracy can be achieved if
