Fluke 5540A, Руководство оператора

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Calibrator
Function Menu Common Features and Functions
41
Reference Junction
Note
The Reference Junction softkey and slide-out menu are not available for TC Types X or Z
(10 µV/°C or 1 mV/°C).
The Reference Junction slide-out menu is available in the Single Output menu TC Source, and
Measure menu TC Measure functions.
The Reference Junction softkey selects the internal or external temperature reference source. The
reference source indicates the ambient temperature contribution to the thermocouple output, which is
taken into account when simulating an accurate temperature output. Select
Internal when the selected
thermocouple has alloy wires and the isothermal block internal to the Calibrator. Select External when
you use an external isothermal block, and when the selected thermocouple has copper wires.
To edit the reference junction:
1. Tap the
Reference Junction softkey to toggle from INTERNAL to EXTERNAL . When you select
EXTERNAL , the Reference Junction button appears on the lower left of the Display.
2. Tap the Reference Junction button to open the Reference Junction slide-out menu.
3. Use the numeric keypad to enter the external reference junction temperature.
4. Tap the
Apply button or push
E
. This closes the menu. The Calibrator copies the entry to the
Reference Junction area of the screen. Tapping x instead of Apply closes the menu without saving
changes.
Note
The unsettled indicator (open yellow square) that occasionally appears in the upper left of the
Display indicates an internal adjustment to the measured isothermal block temperature and is
normal. If it appears for more than 10 seconds (nominal), or if it appears to flash continuously,
check to see that you are not externally heating the thermocouple connector or wires, or that
more time is needed for thermocouple path temperatures to come to equilibrium.
Lows Softkey
The Lows (Low Potential Output Terminals) softkey is available in all Dual Output menu functions. The
Lows of both channels must be tied together at a single point. This can be done internally, with the
Lows TIED/OPEN toggle set to TIED (default), or externally at the DUT with the toggle set to OPEN .