Span Error

Scaling Accuracy

Unlike a zero offset which shifts the entire curve by a constant amount, this type of inaccuracy multiplies with the magnitude of the signal. If a pressure sensor has a one percent span error, the reading will be correct at zero but will be off by one bar when the actual pressure is one hundred bars. This effect is often caused by changes in the sensitivity of the sensing element or the gain of the amplification circuitry.

Calibration Adjustment

Technicians correct this problem by adjusting the gain of the signal conditioner until the output matches the reference at the maximum point. Regularly checking for span error ensures that measurements remain accurate across the entire operating window of the device.

Tolerance Guarding

Engineers must account for the maximum possible deviation when setting safety limits for industrial processes. Maintaining a low span error is critical for applications that require high precision at the upper end of the measurement scale.