Define hysteresis in an instrument and explain its effect on measurement accuracy.

Define hysteresis in an instrument and explain its effect on measurement accuracy.

• A. The delay between input and output.
• B. The power consumption of the instrument.
• C. Difference between output for increasing vs decreasing input; reduces accuracy around the switching point and is used to set deadband.
• D. The size of the instrument.

Answer: (C)

Hysteresis is when an instrument’s output depends on the history of the input, not just its current value. The same input can cause different outputs depending on whether the input is increasing or decreasing, creating a loop in the input–output relationship. This means the trigger point for switching states is different for rising versus falling input, producing a deadband—the range of input values where the output won’t change. That deadband helps prevent rapid on/off switching due to noise around the threshold, but it also reduces measurement accuracy right at the switching point because the exact moment of switching depends on the direction of the input change. In short, hysteresis is about direction-dependent switching and the resulting deadband, balancing stability against precision near the threshold. It isn’t primarily about delay, power consumption, or size.

Hysteresis is when an instrument’s output depends on the history of the input, not just its current value. The same input can cause different outputs depending on whether the input is increasing or decreasing, creating a loop in the input–output relationship. This means the trigger point for switching states is different for rising versus falling input, producing a deadband—the range of input values where the output won’t change. That deadband helps prevent rapid on/off switching due to noise around the threshold, but it also reduces measurement accuracy right at the switching point because the exact moment of switching depends on the direction of the input change. In short, hysteresis is about direction-dependent switching and the resulting deadband, balancing stability against precision near the threshold. It isn’t primarily about delay, power consumption, or size.