In this article, we delve into electronic pressure sensors that convert measured pressure into a standard electrical current signal, typically within the 4 to 20 mA range. Below, we break down the key features of these devices in just a few minutes.
Key Features of Electronic Pressure Sensors
- Power Supply: These sensors are powered by a direct current source, usually 24 V. The current flows from the transmitter to the controller and back to the source in a series circuit.
- Advantages of Current Signals: Current signals are unaffected by voltage drops in the connections, ensuring stable measurements.
- Signal Ranges and Diagnostics:
- 4 mA: Represents the lowest level of the range, equivalent to zero pressure.
- 20 mA: Represents the highest pressure level.
- 0 mA: Indicates a system failure detectable by the controller.
- Types of Pressure Sensors:
- Low-Pressure Sensors: Range from 0 to 10 bar (0 to 147 PSI).
- High-Pressure Sensors: Range from 0 to 30 bar (0 to 441 PSI).
The relationship between pressure and current is linear, as seen in typical performance graphs.
Verification Procedure for the Sensor
- Functional Test
Using a 24 V power supply:- Connect the positive terminal to the appropriate sensor pin (e.g., pin 3).
- Place an ammeter in series between the signal pin (e.g., pin 1) and the power supply’s negative terminal.
- Ensure to check the manufacturer’s specifications for proper connection details.
- Pressure Simulation with Nitrogen
- Attach a nitrogen cylinder with a manually adjustable regulator set to 10 bar to the sensor’s inlet.
- Gradually increase the pressure from 0 to 10 bar, observing the current variations on the ammeter:
- At 0 bar, the sensor should generate 4 mA.
- At 10 bar, it should generate 20 mA.
