Enable The Hold Temperature Display; Mode Setting; Switch Wiring; Switch Test Example - Fluke Dry-Well 9103 User Manual

Enable the Hold Temperature Display

Push UP when the temperature shows to enable the Hold Temperature Display feature. The Hold
Temperature Display shows the hold temperature on the right and the switch status on the left. The
status c means the switch is closed and o means the switch is open. The status flashes when the
switch is in its active position (opposite the normal position). The hold temperature display shows what
the temperature of the well was when the switch changed from its normal position to its active position.
While the switch is in the normal position the hold temperature will follow the well temperature.
If the Scan Control is OFF and the Hold Temperature Display is in use, the temperature at which the
switch is activated does not affect the set-point temperature. However, if the Scan Control is ON and
the Hold Temperature Display is being used, the temperature at which the switch is activated is stored
as the new set-point temperature.
Operation of the hold temperature display is outlined below.
103.5C
UP
c 103.5
To return to the normal well temperature display, push DOWN.

Mode Setting

The Hold Temperature Display function is always in the automatic mode. In this mode the normal
position is set to whatever the switch position is when the set-point is changed. For example, if the
switch is currently open when the set-point is changed, the closed position then becomes the new
active position.
The normal position is set automatically under any of these conditions:
• a new set-point number is selected
• the set-point value is changed
• a new set-point is set through the communications channels

Switch Wiring

The thermal switch or cutout is wired to the Product at the two terminals on the front of the calibrator
labeled SWITCH HOLD. The switch wires can be connected to the terminals either way. Internally the
black terminal connects to ground. The red terminal connects to +5 V through a 100 kΩ resistor. The
calibrator measures the voltage at the red terminal and interprets +5 V as open and 0V as closed.

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, preferably, by collecting data using a
computer connected to the RS-232 port.
13
Well temperature display
Access hold display
Switch status and hold temperature
Dry-Well
Controller Operation