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With twisted shielded pair
thermocouple extension wire, an IRt/c can be mounted as far as 1,000 ft (300
meters)
from the readout device, even in a very fierce
electrical noise environment. The extraordinary noise
suppression characteristics designed into
the IRt/c make this possible, without using a transmitter.
The IRt/c housing is electrically isolated from
the signal leads and is connected to the shielded
ground of the extension cable. For long distances,
the twisted shielded extension cable should
be used, and the shield connected to a good electrical
ground.
A demonstration test was performed
with a 1000 ft (300 m) coil of
twisted shielded pair of extension wire,
with 100 ft (30 m) unwound, connecting an IRt/c
to a fast (100 msec response) A/D conversion module
to a computer. As a noise generator, a 60 Hz
10,000 volt transformer and spark generator was set
up to spark within 6 inches (15 cm) of the wire. The
test results showed less than 0.1°C of noise at any
relative position of the wire, spark, and transformer.

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