Lake Shore Model 331 Temperature Controller User’s Manual
4.4.4
Thermocouple Sensor Input Setup (Model 331X-TX only)
The following thermocouple screens are only displayed when the Model 331 hardware is configured
at the factory with one or two thermocouple sensor inputs; being Model 331X-T1 or T2.
The user has the choice of two different input voltage ranges: ±25 mV and ±50 mV. The ±25 mV
range is recommended for cryogenic applications or higher temperatures less than 500 K. Since
thermocouple voltage can exceed 25 mV on some thermocouple types, the ±50 mV range is
recommended for temperatures above 500 K.
The voltage range for Inputs A and B is set independently. To setup a thermocouple sensor input,
press the
Input Setup
key. The first screen appear as follows.
Select With °®
Input Setup Input A
Use the
s
or
t
key to toggle between Input A and B. Press the
Enter
key.
Select for InputA °®
Type Thermo/25mV
Use the
s
or
t
key to cycle through the sensor types shown in Table 4-1, with “Thermo/25mV” and
“Thermo/50mV” being the relevant choices. Press the
Enter
key. Proceed to Paragraph 4.4.3.1 to
select a room-temperature compensation or press the
Escape
key to return to the normal display.
4.4.4.1 Room-Temperature
Compensation
Room-temperature compensation is required to give accurate temperature measurements with
thermocouple sensors. It corrects for the temperature difference between the instrument thermal
block and the curve normalization temperature of 0 °C. An external ice bath is the most accurate
form of compensation, but is often inconvenient. The Model 331 has built-in room-temperature
compensation that is adequate for most applications. The built-in compensation can be turned on or
off by the user. It operates with any thermocouple type that has an appropriate temperature
response curve loaded. Room-temperature compensation is not meaningful for sensor units
measurements.
NOTE:
Room temperature compensation should be calibrated as part of every installation.
To turn room temperature compensation on or off, press the
Input Setup
and press
Enter
until the
following display appears.
Select for InputA °®
Room Comp On
Use the
s
or
t
key to turn room-temperature compensation on or off, then press the
Enter
key.
The default setting is On. If curve is set to “None” the room-temperature compensation selection is
automatically turned off.
4-10
Operation
