Automation is a process where sensors/transducers are employed to 'sense' the signal, one or more controllers 'guiding' the operation involved and the desired output is achieved in the form of actuators/motors/physical parameters such as temperature/pH in a factory.
Sensors:
Pressure sensors
Position transducers
- linear
- rotary
Proximity sensors
- capacitive proximity sensors
- inductive proximity sensors
- photoelectric proximity sensors
Temperature sensors
- Resistance Temperature Device (RTD)
- Thermocouple (TC)
- Thermistors
Humidity sensors
These sensors measure the relative humidity by converting the signals to desired voltage/current output.
Level sensors
Used to measure the level, for e.g. water level in a tank/ chemical level in a container.
Load cells
These are utilised to measure the weight in electronic form.
Inputs:
Analog input
4-20mA current input
0-10V voltage input
Digital inputs
push buttons
Controllers:
Process indicators
Timers
Counters
Temperature controllers - PID
PC-based controllers
Input-output modules
Programmable logic controllers (PLC): AC/DC inputs & outputs
Variable speed drives (VSD)/ Variable frequency drives (VFD)
Converters:
Converters are used to change the signal type from one to another. This conversion may take a form of analog signals to digital signals (ADC) or changing the signal medium such as RS232 serial type to RS485 two-wire type.
Actuators:
Based on the controller output, actuators would perform the desired action to change the controlled variable. These are mostly motion-oriented, for e.g. motors, solenoid valves, electromagnetic relays etc.
- Solenoid valves (electrically controlled valves)
- Motors such as steppers, servos, permanent magnet types
- Voltage-controlled electromagnetic relays
Software:
Automation configuration software (between h/w and s/w)
Automation display software ( to display the controlled parameters)
Supervisory control & Data acquisition (SCADA)
