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Troubleshooting RTD Instruments
When you are having an issue where an instrument won't read
an RTD sensor or you don't know if the calibrator is connected
properly the PIE 525Plus has a function to measure and display
the fixed or pulsed sensor (excitation) current that the instrument
uses to measure the resistance of the RTD sensor.
Double click the
e
DIAL KNOB at any time the unit is set to
SOURCE
RTD and then turn the
e
DIAL KNOB to move to the second menu
page so the word
DISPLAY
appears at the top of the menu.
Turn the
e
DIAL KNOB to move through the menu until the
cursor is pointing at SENSOR mA. Press the
e
DIAL KNOB to
toggle SENSOR mA ON.
Disconnect all sensor wires from the devices to be calibrated and
connect the PIE 525Plus to the inputs of the device using 2, 3 or 4
wires. The sensor current generated by the instrument will be
indicated on the display followed by the word FIXED or PULSE. Older
single channel RTD instruments used a constant (fixed) current
source to measure an RTD sensor. Smart transmitters, multichannel
recorders and PLC or DCS input cards switch the current source
sequentially through the channels which is seen as an intermittent
(pulsed) current.
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