Practical Instrument Electronics 820 - Manual (Page 15)

Page 13
Typical
2-Wire
Transmitter
+ IN - REF +OUT-
Transmitter Input
Sensor
Process Signal
Simulated Input
SOURCE
HI
SET
LO
MAX
READ
MIN
READ
Power/Measure mA, Power/Measure % (Percent of 4 to 20 mA)
Choose this function to simultaneously supply power to a 2 Wire
Transmitter while displaying the 4 to 20 mA output of the
transmitter.
Move the power switch w to READ then Double Click the
EZ-DIAL knob to get into the Double Click Menu. Turn the knob
e to scroll through the settings and press the knob to make your
selection. Select mA for the FUNCTION and PWR MEAS for the
MODE. Choose either mA or % and whether you need the 250
Ω
HART resistor active in the loop.
Disconnect one or both input wires from the device to be
calibrated. Connect the red source lead of the PIECAL 820 to
the plus (+) input of the device and the black source lead to the
minus (-).
The PIECAL 820 supplies a nominal 24 volts DC at 24 mA to the
2 Wire Transmitter. The current passed by the transmitter will be
accurately displayed by the PIECAL 820. Calibrate the transmitter
in the usual manner and disconnect the PIECAL 820. Signals
above 24 mA are current limited by protection circuitry with
“OVERRANGE” flashed on the display and the red OVERLOAD
LED lit.