Heat Trace Control Conversion

ryanrydellCase Studies

Quantum Design’s customer, a leading food and beverage manufacturing company, was looking to update multiple outdated and obsolete single point heat trace controllers with a single PLC controller, I/O and HMI. Their equipment was no longer being manufactured or supported by the manufacturer making replacement parts expensive. As the equipment aged new problems were likely to arise more often and if the equipment were to fail there would have been no direct replacement to swap in leaving the customer with lengthy downtimes on their production line while the equipment was being replaced. Though old equipment can sometimes be refurbished, it is usually very expensive and often board level components cannot be replaced. Therefore, they will eventually fail and the same issues would arise.

Through the help of Quantum Design the customer realized that planning ahead with a thought-out timeline and moving forward with updating the system would not only allow their current production to be more efficient, but would also eliminate the possibility of an unpredictable shut down with no planned timeline in the near future.

The new control that was designed by the Quantum Design engineering team provided the customer a single point access for:

  • monitoring temperatures
  • adjusting setpoints
  • unlimited alarming
  • enabling & disabling circuits
  • a pictorial view of circuits
  • remote access for troubleshooting
  • providing information for data collection

The main enclosure of the Heat Trace controls contains two main components which could be described as the brain and the brawn. The brain of the enclosure includes a Contrologix PLC, an Ethernet module and a Panelview HMI. The brawn is made up of remote enclosures with Flex I/O for temperature sensors and heater control.

Normally the main enclosure is mounted along a side wall or even on another floor in an electrical room. With this project Quantum lowered electrical installation costs by using remote I/O, which allows multiple remote enclosures to be connected via Ethernet. By doing this the customer did not have to run the conduit and wiring for all of the I/O back to the main enclosure which could be hundreds of feet away. Control & power wiring were localized to an area, and they instead were able to run 4 wires and a communication cable in a small conduit. This significantly reduced the chances of wiring issues since there was less opportunity for damage to wires and labeling errors.

The Panelview HMI that was added to the system provides a human interface that contains the following controls:

  • heat trace zones that can be turned on or off
  • temperature setpoints that can be adjusted
  • temperatures that can be monitored
  • alarms that indicate potential issues

The HMI also has pictorial views that can show a whole production area or just parts of a production area. Multiple Panelviews, showing the same information, can be mounted throughout a production area to enhance operator visibility.

Additional heat trace zones can also be added to a project of this type with minimal additional cost. Extra IO would be included in the redesign and wired as much as possible at the time of installation. This means adding another zone of control would only involve mounting and hooking up the thermocouple and adding a solid-state relay (spares can also be included in the initial design). Some PLC code would need to be added and a minor update to the OIT (or HMI).

By upgrading their heat trace system, the customer was able to take advantage of some of the benefits of newer technology. Their machine process will be more reliable and they will have access to new features that enhance control and operation. For example, with their old system temperature controllers had to be configured individually. There would be over 100 parameters that would have to be set and the PID loop would have to be tuned through a trial and error method. Also, the operators had to go out to the control panel to see and adjust data. The new system provides connectivity to the network so the operator can do this from the control room.

With the new system, temperature controls can be programmed through a software package or device that allows the parameter to be copied from device to device.

With the new system, temperature controls can be programmed through a software package or device that allows the parameter to be copied from device to device. Almost every controller available now has an auto-tune feature which allows the controller to cycle the process and learn to get pretty close on the tuning parameters for the PID loop. With the newer PLC’s it has become easier to bring the signals into the PLC and perform that functionality directly in the PLC so a discrete device is no longer needed. In addition it provides connectivity for data collection which can be used for troubleshooting, continuous improvement and record keeping.

This project was a success because it gave the operators better control and alarming for the production area. It also gave the production control colleagues operational data for their production system and it shortened the down time for maintenance. Operators no longer have to unwire a unit, uninstall it, find a replacement, install it and wire it back up. Downtime is minimized and possibly eliminated.

Other benefits of an upgrade to any legacy system can include better response from vendors when issues do arise, less costly part replacement, spare parts that are readily available, and more knowledgeable technicians and engineers supporting the system.

The Quantum Design engineering team has many years of experience and is a great choice when upgrading your system. The team has the background, knowledge and experience to support not only the newest technologies but also legacy equipment. With fewer manufacturers supporting legacy equipment our customer needed a team with extensive knowledge in control system upgrades to eliminate extra project costs, reduce hidden problems and to make a smooth transition to the new technology.