Testing a 4–20mA pressure transducer is a simple and useful skill for anyone working with industrial automation, instrumentation, PLCs, or process control systems. A multimeter can be used to quickly check whether the transducer is receiving power and producing the correct current signal.
In this practical guide, we will test a GORACO GO-PT300S pressure transducer with a 0–100 mbar pressure range and 4–20mA, 2-wire output. The test uses a 24V DC power supply, a 150Ω resistor, and a digital multimeter.
The purpose of this test is not only to verify that the sensor is working, but also to understand how the 4–20mA current signal changes with applied pressure. We will also see how the voltage across the 150Ω resistor can be used to calculate the corresponding loop current.
This is a practical bench test that can be performed before connecting the pressure transducer to a PLC, HMI, Arduino, ESP32, or other control system.
What You Will Learn
By the end of this guide, you will know:
- How to wire a 2-wire 4–20mA pressure transducer for testing
- How to use a 24V DC power supply safely for the test
- How to measure the sensor’s loop current with a multimeter
- How to use a 150Ω resistor to convert current into a measurable voltage
- How to calculate 4mA, 12mA, and 20mA values from the resistor voltage
- How to determine whether the pressure transducer is responding correctly
- What to check if the sensor remains at approximately 4mA
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