Instrumentation

What is a temperature controller and what is the need for a temperature controller?

A temperature controller is a device that can control the heat in equipment for example a furnace will need a temperature controller to control its temperature. The temperature controller can be used to keep the temperature stable in any situation. In case an object is required to be heated or cooled then we can use a temperature controller for this purpose and it will be very useful. This device would compare the sensor signal with a set point and it would perform its calculations related to the changes between these values.

How to select a temperature controller?

In order to select a temperature controller, we need to determine the thermal characteristic of the controlled object so that we can do proper temperature control.

  • We must consider the heat capacity, this would indicate the ease of heating and it would be different for each device
  • Static characteristics, it is the heating capability and this will vary according to the heater’s capacity
  • Dynamic characteristics indicate the startup characteristics of the heating and this will vary according to the furnace and heater.
  • We must also consider the external disturbances because it can cause a temperature change
  • We must consider the type of input sensor
  • We must consider the required output, like if it is electrochemical or SSR

How does a temperature controller works?

A temperature controller can keep the required temperature at a specified value. A temperature controller would have a sensor like an RTD or it could be thermocouple. The temperature controller would check the sensed temperature to the required control temperature and only after this process the output signal is sent.

The temperature controller can control the temperature in industries or in laboratories, this device can control the heating and cooling process. So this device would sense the actual temperature and this temperature will be compared to the user’s set point and if the value deviates then the controller would signal the temperature regulating device and this device could be heating element or refrigeration component to bring the temperature back to the set point.

What are the uses of temperature controller in industries?

Temperature controller can be seen in wide varities of industries, in order to control the manufacturing process. Mostly we can see temperature controllers in plastic extrusion and also in injection molding machines, packing machines, food processing etc.

What are the parts of the temperature controller?

So the tempertaure controller has thermal sensor, A/D converter, microcontroller.relay, and display unit. So the temperature sensor can sense the atmosphere temperature and sends the analog signal to the ADC and it will be converted to digital signal the digital signal is then transferred to the micro-controller and from there the signal will reach the display.

What are the types of temperature controller?

The temperature controller is divided into three types they are

ON/OFF control

In this type there is no middle point, so the output will be either ON or OFF. The ON/OFF controller will only switch the output only when the temperature crosses the setpoint. If the temperature is lower than the setpoint then the output will be ON and it will be OFF if it is higher than the setpoint this type of controller is used where accurate control is not needed.

Proportional control

In this type of temperature controller it will decrease the average power supplied to the heater when the temperature approches the setpoint. This action takes place by turning the output ON and OFF for short time interval.

PID control

This type is the most accurate controller, this controller can provide proportional with integral and derivative control. This device combines the proportional control with two additional adjustments and thus it helps the unit to automatically compensate for the changes in the system.

Ashlin

post-graduate in Electronics & communication.

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