Temperature controllers are either single-loop or multi-loop. Single-loop controllers have one input, and one or more outputs to control a thermal system. Multi-loop controllers have multiple inputs and outputs, and are capable of controlling several aspects of a process. More control loops permit controlling and coordinating more process system functions.
Used to automatically set PID parameters for optimum thermal system performance. Capable of accepting a variety of sensor inputs, including thermocouple, RTD and process. The controller senses the rate of temperature increase (reverse acting) or decrease (direct acting) and adjusts the output action to minimize set point over- and under-shoot. PID output action requires a solid state power controller to withstand rapid switching cycles. Auto-tuning controllers can have more than one output channel for alarms, retransmit and serial communications. Selected controllers are available in CE compliant versions.
Some controllers feature a percent power default operation or will de-energize the system upon sensor break. Controllers with NEMA 4X front panels are well suited for wet or corrosive environments.
Used for non-critical or unsophisticated thermal systems to provide on-off temperature control for direct or reverse acting applications. The basic controller accepts thermocouple or RTD inputs and offers an optional percent power control mode for systems without temperature sensors.
This category also includes cartridge thermostats. These units operate on their sheath's thermal expansion and are available in reverse and directing acting modes. They can be wired interconnected or for pilot duty with a relay. The cartridge thermostat can also serve as a non-latching limit controller.
Programmable auto-tuning controllers (see auto-tuning above) are able to execute ramp and soak profiles such as temperature changes over time, along with hold, or soak/cycle duration. Selected controllers are available in CE compliant versions.
These controllers are specifically designed to provide safety limit control over process temperature. They are capable of accepting thermocouple, RTD or process inputs with limits set for the high or low temperature. Limit control is latching and part of a redundant control circuit to positively shut a thermal system down in case of an over-limit condition.
These units can receive two inputs and produce two or more outputs for direct and reverse acting control. They accept thermocouple, RTD, process and event inputs. Auto-tuning (see auto-tuning above) automatically sets PID parameters for optimum performance. Outputs include alarms, events, process, serial communications and data logging. Selected controllers are available in CE compliant versions.
Available in versions that supply 4, 8, 16 and 32 control loops, the controllers can accept thermocouple, RTD, process, linear and pulse inputs. A selected 8 loop version also accepts carbon potential. Auto-tuning automatically sets PID parameters for optimum performance. Job recipe storage permits preprogramming to speed batch setup. Outputs include digital, alarms, events, process, serial communications and data logging. Optional PC communications permits remote operation and monitoring.