How to Troubleshoot the 4 – 20mA Output of Rosemount 3051 Transmitter ~ Learning Instrumentation And Control Engineering Learning Instrumentation And Control Engineering

How to Troubleshoot the 4 – 20mA Output of Rosemount 3051 Transmitter

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One of the most versatile and commonly used transmitters is the Rosemount 3051 pressure transmitter. This transmitter can be used to measure pressure, differential pressure, gage pressure, absolute pressure or a liquid level. The Rosemount 3051 transmitter provides an analogue output (4 – 20mA) with a superimposed HART signal on the 4-20 mA output.

The most common problems with the Rosemount 3051 transmitter are adapted from the transmitter manual and can be used to troubleshoot the 4 – 20mA output whenever the symptoms in the table below are observed during transmitter service:

Symptom Corrective Actions
Transmitter miliamp is Zero
  • Verify power is applied to the signal terminals
  • Check power wires  for reverse polarity
  • Verify terminal voltage is 10.5 to 42.4 Vdc
  • Check for open diode across test terminal
Transmitter Not Communicating with Field Communicator
  • Verify the output is between 4 and 20mA or saturation levels
  • Verify terminal voltage is 10.5 to 42.4 Vdc
  • Verify clean DC power to transmitter (Max. AC noise is 0.2 volts peak to peak
  • Check loop resistance, 250 ohms minimum (PS Voltage - transmitter voltage/loop current
  • Have field  communicator poll for all addresses
Transmitter milliamp reading is low or high
  • Verify applied pressure
  • Verify 4 and 20mA range points
  • Verify output is not in alarm condition
  • Verify if 4 - 20mA output trim is required
Transmitter will not respond to changes in applied pressure
  • Check test equipment
  • Check impulse piping or manifold  for blockage
  • Verify the transmitter is not in  multi-drop mode
  • Verify applied pressure is between 4 and 20mA set points
  • Verify output is not in alarm condition
  • Verify transmitter is not in loop test mode
Digital pressure variable reading is low or high
  • Check the accuracy of test equipment
  • Check impulse piping for blockage or low fill in wet leg
  • Verify transmitter is calibrated properly
  • Verify pressure calculations for application
Digital pressure variable reading is erratic
  • Check application for faulty equipment in pressure line
  • Verify transmitter is not reacting to equipment turning on/off
  • Verify damping is set properly for application
Milliamp reading is erratic
  • Verify power source to transmitter has adequate voltage and current
  • Check for external electrical interference
  • Verify transmitter is properly grounded
  • Verify shield for twisted pair is only grounded at one end






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