We rely more and more on electrical and electronic devices for many areas of our lives. But where previously all of these things might have operated independently of each other, it’s now more commonplace to have them connected so that they can influence the state of other systems and devices.
The rapid adoption of ‘smart’ devices in our homes is part of this, but in industry too machines, sensors and other devices are increasingly being linked together.
Simple Control Systems
At its most basic a control system uses a sensor to gather information, which is then used to control another device. Your central heating system works like this, using temperature data from the room thermostat to turn the boiler on and off.
In fact, your heating is a good example of a slightly more complicated control system too, because it also uses a controller to turn the system off and on at specific times, a thermostat to control water temperature and possibly additional sensors like thermostatic radiator valves.
Types of Control System
Suppliers of electrical control components such as http://www.osmelectrical.com/ will tell you that there are two types of control system. A closed loop system – as in our boiler example above – is one where the output, in this case the heat from the boiler, is controlled via a feedback loop in the form of a thermostat.
An open loop system is one where the input affects the output. Again in our central heating analogy, the timer control is closed loop, because it switches the system on and off at set intervals regardless of whether it’s needed. Of course, it follows from this that you can have open and closed loop controls on the same system.
In an industrial situation the control can be fully automatic or it can be semi-automated, using the sensor information to alert a human operator to take action. Systems can be operated remotely, or local controls can be used to override the system or to allow an operator to fine-tune the process. Back to heating again – you might, for example, turn down the thermostat or adjust the timer.
Controls can be simple on/off switching, as with a normal light switch, or progressive, as with a dimmer, allowing you to vary the action taken.