What Governs the Output from a 0-xV Amplified Pressure Transmitter?

There are a number of pressure transmitters on the market with built-in amplifiers that provide 0V output at zero pressure. However, it is wise to check exactly how the manufacturer has achieved the 0V output.

One of the main problems is that most sensors of this type run from a single-ended supply voltage, and so it is impossible to have 0V output at zero pressure unless the sensor has a built-in negative reference circuit, using a 4-wire principle or requires positive and negative supply voltages.

Power supply

The good news is that most pressure sensors are independent of supply voltage as they have their own onboard power supply regulators, and many of these sensors have adjustable zero outputs via a small screw (potentiometer).

So, for example, a sensor with a 0-10V output will produce 0V at zero pressure and 10V at full-scale pressure. This is the ideal situation. However, what would the system read/register if a wire breaks? In practice, you will find that there are tolerances on both zero and span values.

In addition, you will need to add all the different accuracy and temperature effects, as detailed in the other Engineering Notes in this series.

Amplified Pressure Transmitter Output Signal Graph

In order to demonstrate the principle, the errors are exaggerated (see specific data for individual errors and sensors).

Read more: Index to all of our Technical Notes on Pressure

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