What is an On-Off Controller?

What is an On-Off Controller?

On-Off Controller Definition

An on-off controller is defined as a control system that fully opens or closes the control element when the process variable crosses a preset level.

Working Principle

The on-off controller works by fully opening or closing the output value, causing the process variable to change direction and cycle continuously.

Example of Application

A typical example is the cooling fan control in transformers, which activates based on temperature levels.

Actual response curve

Dead Time

Practical systems experience a delay, known as dead time, between the control signal and the action.

Ideal vs. Actual Response

The actual response curve of an on-off control system differs from the ideal due to the presence of dead time.