Lakeshore 325, Руководство пользователя, Страница: 81 / 166

Lake Shore Model 325 Temperature Controller User’s Manual
Advanced Operation 5-5
Edit Curve (Continued)
NOTE: Typing over an existing reading or temperature will replace that value when you press the Enter key.
To delete a breakpoint, go to point and enter zeros for both the sensor reading and temperature. Press the Enter key, then
the Escape key.
When curve entry is complete, the user must assign the new curve to an input. The Model 325 does not automatically
assign the new curve to either input.
5.2.1.1 Thermocouple Curve Considerations
The following are things to consider when generating thermocouple curves.
• Users may enter temperature response curves for all types of thermocouples. Enter curve data in mV/K format with
thermocouple voltage in millivolts and temperature in kelvin.
• The curve must be normalized to 0 mV at 273.15 K (0 °C). Thermocouple voltages in millivolts are positive when
temperature is above that point and negative when temperature is below that point.
• To convert curves published in Celsius to kelvin, add 273.15 to the temperature in Celsius.
• The temperature range for some thermocouple types may extend below 1 K or above 1000 K.
• The input voltage of the 325 is limited to ±50 mV, so any part of the curve that extends beyond ±50 mV is not usable
by the instrument.
• A message of S-OVER or S-UNDER on the display indicates that the measured thermocouple input is over or under
the ±50 mV range.
5.2.2 Erase Curve
User curves that are no longer needed may be erased. Erase Curve sets all identification parameters to default and blanks
all breakpoint values.
To erase an existing user curve, press the Curve Entry key. Press the
s
or
t
key until you see the following display.
Select With °®
Erase Curve
Press the Enter key. You can press the Escape key any time during this routine to return to the normal display.
Select for Erase °®
Curve 21 User
Use the
s
or
t
key to cycle through the various user curve numbers 21 through 35. You cannot erase the standard curve
numbers 01 through 20. Once the user curve number is selected, press the Enter key. You will see the following
message.
Press Esc. to cancel
or Enter to erase 21
Press the Escape key to cancel or the Enter key to erase the selected user curve. You now return to the normal display.