The delay in the response of a measuring instrument to a change in the measured quantity is known as measuring lag. Thus it is the retardation delay in the response of a measurement system to changes in the measured quantity. This lag is usually quite small, but this small lag becomes highly important when high-speed measurements are required. In the high-speed measurement systems, as in dynamic measurements, it becomes essential that the time lag is reduced to a minimum. Measuring lag is of two types:
- Retardation type: In this type of measuring lag the response begins immediately after a change in measured quantity has occurred.
- Time delay: In this type of measuring lag the response of the measurement system begins after a dead zone after the application of the input.