ThermoWorks 9103 HART SCIENTIFIC FIELD DRY-WELL TEMPERATURE CALIBRATORS - Manual (Page 28)

7.4.4 Switch Test Example
This section describes a possible application for the switch hold temperature
display feature and how the instrument is set up and operated.
Suppose you have a thermal switch which is supposed to open at about 75°C
and close at about 50°C and you want to test the switch to see how accurate and
repeatable it is. You can use the temperature hold feature and the scan function
to test the switch. Measurements can be made by observing the display or, pref-
erably, by collecting data using a computer connected to the RS-232 port. To
set up the test, follow the steps below.
1. Connect the switch wires to the terminals on the front of the calibrator
and place the switch in the well.
2. Enable set-point scanning by setting the scan to “ON” in the primary
menu (see
Section 7.3.1 ).
3. Set the scan rate to a low value, say 1.0°C/min. (see Section 7.3.2 ). If the
scan rate is too high you may lose accuracy because of transient temper-
ature gradients. If the scan rate is too low the duration of the test may be
longer than is necessary. You may need to experiment to find the best
scan rate.
4. Set the first program set-point to a value above the expected upper switch
temperature, say 90°C.
5. Set the second program set-point to a value below the expected lower
switch temperature, say 40°C, in the program menu.
6. Collect data on a computer connected to the RS-232 port. Refer to Sec-
tion 8 for instructions on configuring the RS-232 communications
interface.
7.5 Set-point Resistance
To display the Set-point Resistance, press the “SET” and “DOWN” keys simul-
taneously when the temperature is displayed. When the “SET” and “DOWN”
keys are released the temperature is again displayed.
7.6 Temperature Scale Units
To toggle between °C and °F, press the “SET” and “UP” keys simultaneously
when the temperature is displayed.
7.7 Secondary Menu
Functions which are used less often are accessed within the secondary menu.
Pressing “SET” and “EXIT” simultaneously and then releasing accesses the
secondary menu. The first function in the secondary menu is the heater power
display. (See
Figure 4 on page 20.)
9103 Dry-Well
User’s Guide
24