Line / sump pressure transducer (4–20 mA)

Two-wire loop-powered transducer supplying sump and line pressure to the controller.

Also called: pressure transmitter · sump transducer

How it works

A strain-gauge or ceramic cell converts pressure to a 4–20 mA current proportional to the span. 4 mA = 0 pressure, 20 mA = full span. Loop-powered from the controller's 24 VDC supply.

Specifications

Supply

12 – 30 VDC loop

Signal

4 mA = 0 %, 12 mA = 50 %, 20 mA = 100 % of span

Common spans

0 – 200 PSI, 0 – 232 PSI (16 bar), 0 – 300 PSI

Loop resistance

Do not exceed the transmitter's max load (often 500 – 600 Ω at 24 V)

Parts you can order

• Danfoss

  MBS 3000 pressure transmitter

  060G1133 (0–232 psi, 4–20 mA, 1/4 in. NPT)

  $130 – $320
• Danfoss

  MBS 3000 pressure transmitter

  MBS 3000, 0–500 psi range code

  $150 – $360
• Danfoss

  MBS 3000 pressure transmitter

  060G1133 (0–232 psi, 4–20 mA)

  $130 – $300
• WIKA

  A-10 pressure transmitter

  A-10 (configure range/output)

  $150 – $340
• Gems Sensors

  3100 series transducer

  3100 (configure range/output)

  $160 – $360
• Ashcroft

  G2 pressure transducer

  G2 (configure range/output)

  $180 – $400

Field test procedure

1. Break the loop and read mA in series, or measure across the controller's sense resistor.
2. Compare mA against a calibrated gauge: mA = 4 + 16 × (reading ÷ span).
3. Below 3.8 mA or above 20.5 mA = sensor fault or wiring fault, not a real pressure.
4. Never megger a transducer loop — you will destroy the cell.

Symptoms & probable causes

• Pressure reads 0 with the machine running
  Open loop, reversed polarity, or a blocked sensing port.
• Pressure reads full scale
  Shorted loop or a failed cell.