Fluke 9107 - Manual (Page 34)

HoLd=OFF Hold mode set to off
To change the mode press “UP” or “DOWN”.
HoLd=Aut Automatic mode
HoLd=n.c. Normally closed mode
HoLd=n.o. Normally open mode
Press “SET” to accept the displayed setting.
8.5.3 Scan Hold
In addition to controlling the hold temperature display, a switch can also con-
trol set-point scanning by enabling the scan hold function. When the switch
changes from its normal position to its active position scanning will stop. For
the scan hold to be effective scanning must be enabled and the scan rate should
be set to a relatively low value (see sections 8.4.1 and 8.4.2).
The scan hold is set in the primary menu after the temperature hold mode
setting.
SHoLd=OF Scan hold set to off
To change the mode press “UP” or “DOWN”.
SHoLd=On Scan hold set to on
Press “SET” to accept the displayed setting.
8.5.4 Switch Wiring
The thermal switch or cut-out is wired to the calibrator at the two terminals at
the back of the dry-well calibrator labeled “DISPLAY HOLD”. The switch
wires may be connected to the terminals either way. Internally the black termi-
nal connects to ground. The red terminal connects to +5V through a 10 k
Ω re-
sistor. The calibrator measures the voltage at the red terminal and interprets
+5V as open and 0V as closed.
8.5.5 Switch Test Example
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 ramp and
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8 Controller Operation