Campbell AM16/32B, Руководство по эксплуатации продукта

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AM16/32B Relay Multiplexer 30
C.1.3 AM16/32B reference
An external reference, usually a thermistor, can be located at the AM16/32B, as shown in FIGURE
C-2 . This approach requires an additional single-ended data logger input to measure the
reference. Position the reference next to the COM terminals and, when practical, measure the
thermocouples on SETs that are in close proximity to the COM terminals in order to minimize
thermal gradients.
C.1.4 Thermal gradients
Thermal gradients between the AM16/32B measurement terminals and COM terminals can cause
errors in thermocouple readings. For example, with type T thermocouples, a one-degree gradient
between the input terminals and the COM terminals will result in an approximate one-degree
measurement error. Installing the aluminum cover plate ( FIGURE C-3 ) helps to minimize gradients.
For best results, the AM16/32B should be shielded and insulated from all radiant- and conducted-
thermal sources. When an enclosure is used, gradients resulting from heat conducted along the
thermocouple wire can be minimized by coiling some wire inside the enclosure. This technique
allows heat to largely dissipate before it reaches the terminals. If the AM16/32B is housed in a
field enclosure, the enclosure should be shielded from solar radiation.
FIGURE C-3. AM16/32B aluminum cover plate