ProcessMeter 
  Loop Power Supply Mode
   
 29 
Loop Power Supply Mode 
The Loop Power Supply Mode can be used for powering 
up a process instrument (transmitter). While in Loop 
Power Mode, the meter acts like a battery. The process 
instrument regulates the current. At the same time, the 
meter measures the current that the process instrument is 
drawing.  
The meter supplies loop power at a nominal 24 V dc. An 
internal series resistance of 250 Ω can be switched in for 
communication with HART and other smart devices by 
pressing J(Blue). Pressing J(Blue). again switches out 
this internal resistance. 
When loop power is enabled, the meter is configured to 
measure mA and > 24 V dc is sourced between the mA 
and A jacks. The mA jack is the common and the A jack is 
at > 24 V dc. Connect the meter in series with the 
instrument current loop as Figure 10 shows. 
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0 4 8 12162024
Loop voltage w/ 250
Loop voltage w/o 250
Voltage (V)
Current (mA)
 
anw020f.eps 
Figure 9. Loop Power Voltage vs. Current