Instrumentation specialist Intertec has launched an explosionproof programmable controller for precision temperature regulation of process instrumentation and analyser enclosures in hazardous environments, the company reports.
Suitable for use with any of Intertec’s range of explosion-proof electric heaters, the new generation Smart Controller 2.0 brings increased flexibility to thermal management. Advanced facilities include fieldbus networking, extensive monitoring and diagnostic routines, programmable temperature ramping, data logging and temperature monitoring with user-definable limits.
The controller has a switching capacity of up to 10 A, enabling it to be used with explosionproof heaters with power ratings as high as 2 300 W, depending on the ambient and required enclosure/equipment temperatures and the heater supply voltage.
Heater systems based on the new Smart Controller 2.0 may be used to accurately control the temperature of equipment, or the surrounding air in an enclosure or cabinet, and are suitable for use with analytical instruments that need to be maintained at high temperatures, and located in hazardous environments.
Typical applications include analysers handling difficult media in oil, gas and petrochemicals processing plants. When used in conjunction with an Intertec CP xxxTHERM HI explosionproof heater, the controller provides an all-in-one solution that does not require separate safety certification. The complete controller/heater system is approved to international explosionproof standards.
Intertec’s new digital proportional-integral-derivative (PID) controller provides a high level of accuracy and functionality. Operating as a remote terminal unit (RTU), it uses the Modbus RTU communications protocol over an RS485 serial network to facilitate easy integration with existing process control systems, the company reports.
As many as 31 controllers can be set up and monitored in one branch of a network, while the company has created a new suite of computer software and LabView VI drivers that enable a wide set of attributes to be programmed. These include the controller’s P and I terms, a user-defined ramp for temperature increase against time and the heater’s temperature limit.
The software also features an easy-to-use data logging function, which provides a graphic record of temperature values retrieved over time from each controller. Additional facilities allow the controller to be used as a temperature monitor to pro- vide a digital output when the temperature is within a user- defined range. This could be used to control a cooling fan for example.
Housed in aluminium, the smart controller has an Inter- national Protection rating of 66, and all external surfaces have a saltwater-resistant finish. The PID controller, and all associated electronics, are fully encapsulated in silicone, with the electrical terminals accessible in a separate compartment.
Power to the heater element is handled by a proportional, triac-based control circuit, which uses zero-voltage switching to increase efficiency and reduce electromagnetic interference.
There are two versions of the controller, with the standard version featuring a compact housing, measuring 57 mm × 125 mm × 80 mm, which is suitable for use in explosive atmospheres in the Atex rating system for zones one, two, 21 and 22.
Further, the controller incorporates three temperature sensors. One is integrated in the controller housing for measuring local cabinet temperature, and another is embedded in the heater itself, together with a temperature-sensitive fuse to ensure that its surface temperature never exceeds the specified rating.
The third is an intrinsically safe KTY silicon temperature sensor, mounted at the end of a cable, which can be freely posi- tioned in the instrument enclosure, or embedded in the equipment that has to be kept at a constant temperature.
The standard version of the controller features a built-in bicolour liquid crystal display indicator, which provides a useful local diagnostic aid by showing any deviation from the set point temperature and highlighting the occurrence of any heater error.
Intertec reports that it can supply the smart controller and the customer’s chosen heater as a complete package.