Martel Electronics 3001 - Manual (Page 30)

Figure 18 - Isolated DC Current Input Connection
d) If the UUT is a 2 wire loop powered transmitter that is disconnected from the wiring,
press the key to activate the 3001 internal 24V supply in series with the
current measuring circuit. The top line changes to 24mA LPWR to indicate that the
supply is activated. Press the key again to deactivate the supply, and the top line
reverts to 50mA RANGE.
e) If a 250 ohm resistor is required during a HART calibration procedure, press the
key to switch in the 3001 internal 250 ohm resistor. The word HART is
appended to the top line of the display to indicate that the resistor is switched in.
Press the key again to switch out the resistor, and the display reverts to its previous
state. This resistor lowers the maximum load driving capability from 1000 ohms at 20
mA to 750 ohms at 20 mA.
5.3 Pressure Input
The isolated pressure display uses the same physical pressure connector as the primary
display. It is possible to have both displays selected to pressure simultaneously, showing
the same source in different pressure units. See section 4.9 for a general discussion on
pressure module selection.
a) Connect the pressure module to the 3001 as shown in figure 19.
Figure 19 - Isolated Pressure Module Connection
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