Fluke 6102, User Manual

Page: 44 / 66

6102 Micro-Bath User’s Guide
Secondary Menu
36
Switch Wiring 9.4.3
The thermal switch or cutout is wired to the calibrator at the two terminals on the back
of the Micro-Bath labeled “DISPLAY HOLD”. The switch wires may be connected
to the terminals either way. Internally the black terminal connects to ground. The
red terminal connects to +5V through a 100 k
:
resistor. The calibrator measures the
voltage at the red terminal and inte5V as open and 0V as closed.
Switch Test Example 9.4.4
This section describes a possible application for the temperature hold 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 do the following
steps.
Connect the switch wires to the terminals on the back of the Micro-Bath and 1.
place the switch in the well.
Enable set-point scanning by setting the scan to “ON” in the primary menu ( 2. see
Section 9.3.1).
Set the scan rate to a low value, say 1.0°C/min. ( 3. see Section 9.3.2). 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.
Set the first program set-point to a value above the expected upper switch 4.
temperature, say 90°C.
Set the second program set-point to a value below the expected lower switch 5.
temperature, say 40°C, in the program menu.
Collect data on a computer connected to the RS-232 port. Refer to 6. Section
9.11, Serial Interface Parameters, for instructions on configuring the RS-232
communications interface.
Secondary Menu 9.5
Functions which are used less often are accessed within the secondary menu. The
secondary menu is accessed by pressing “SET” and “EXIT” simulta neously and then
releasing. The first function in the secondary menu is the heater power display. (See
Figure 7 on page 32.)
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