A temperature controller is an instrument used to control temperature. The temperature controller takes an input from a temperature sensor and has an output that is connected to a control element, such as a heater or fan.

To accurately control process temperature without extensive operator involvement, a temperature control system relies upon a controller, which accepts a temperature sensor such as a thermocouple or RTD as input. It then compares the actual temperature to the desired control temperature, or setpoint, and provides an output to a control element.

The controller is one part of the entire control system, and the whole system should be analysed in selecting the proper controller. The following items should be considered when selecting a controller:

1. Type of input sensor (thermocouple, RTD) and temperature
range
2. Type of output required (electromechanical relay, SSR,
analogue output)
3. Control algorithm needed (on/off, proportional, PID)
4. Number and type of outputs (heat, cool, alarm, limit)

There are three basic types of controllers:

1) On-off
2) Proportional
3) PID

Depending upon the system to be controlled, the operator will be able to use one type or another to control the process.

The IMO family of temperature controllers offers a compact front panel arrangement that combines a digital display with a basic touch panel. The controllers are ideal for industrial environments where the space occupied by large control panels is seen as non-productive and expensive.

Bringing users significant cost savings, the controllers employ a ‘reduced’ front panel which provides real-time viewing, as well as the ability to override communication with the control panel and make manual adjustments locally.

The temperature controllers come in a range of standard DIN sizes, from 24 x 48mm (1/32 DIN) to 96 x 96mm (1/4 DIN). The range also includes a unique blind controller which comes in a 22.5mm slim DIN rail casing with dual 4-digit display.

The complete range has multi-selectable input, including a large range of thermocouples, RTD's, current (4-20mA) and voltage (0-10V) inputs. PID with auto tune, PD or on/off modes can be selected on all models and a selection of outputs is available, such as Relay, Signal voltage, 4-20mA or 0-10V DC. One alarm comes as standard on all models. The units have IP66 protection for the font covers and a wide operating voltage of 100-240VAC or 24VAC/DC.

A second alarm option gives flexibility of control and the heater burnout alarm option gives more protection to the controlling system. Other options include Heat/Cool outputs, 2 Set point selection, RS485 communications with Modbus or IMO protocol and Master/Slave capabilities.