Fluke 9107 - Manual (Page 35)

soak feature (described in detail in the next section) to test the switch. Measure-
ments can be made by observing the display or, preferably, by collecting data
using a printer or computer connected to the RS-232 port. To set up the test do
the following steps.
1. Connect the switch wires to the terminals on the back of the dry-well and
place the switch in the well.
2. Enable set-point scanning by setting the scan to “ON” in the primary menu
(see Section 8.4.1).
3. Set the scan rate to a low value, say 1.0°C/min. (see Section 8.4.2). If the
scan rate is too high you may lose accuracy because of transient temperature
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 hold mode to automatic (see Section 8.5.2).
5. Set the scan hold to “ON” (see Section 8.5.3).
6. Set the number of program set-points to 2 in the program menu (see Section
8.6.1).
7. Set the first program set-point to a value below the expected lower switch
temperature, say 40°C, in the program menu (see Section 8.6.2).
8. Set the second program set-point to a value above the expected upper switch
temperature, say 90°C.
9. Set the program soak time to allow enough time to collect a number of data
points, say 2 minutes (see Section 8.6.3).
10. Set the program function to mode 4 so that the instrument will cycle be-
tween the 2 set-points repeatedly. (See Section 8.6.4.)
11. Start the program (see Section 8.6.5).
12. Collect data on a computer connected to the RS-232 port. Refer to Section
9 for instructions on configuring the RS-232 communications interface. The
data may appear as shown in Figure 7. The maxima and minima are the switch
temperatures.
30 Hart Scientific
8 Controller Operation