Is your controller tough enough?

Controllers are the nervous system of the production process. Reliability is important. Controller malfunctions can throw a wrench into your production processes or even paralyze your factory. You need a rugged controller. See three tips to help choose a controller.

Dennis Wylie

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Controllers are the nervous system of the production process. As critical couriers of information and implementers of change, controller malfunctions can throw a wrench into your production processes or even paralyze your factory. The stakes are especially high for manufacturers who operate in extreme conditions.

High temperatures, low temperatures, organic solvents, constant vibration, moisture and condensation—these factors and many others create challenges for manufacturers looking for the right controller for rugged environments.

Choose a reliable controller: 3 tips

How can you choose a reliable controller? Make the right choice. Follow these steps.

1. Recognize the need. This step is simple but too often delayed. Do not wait until something major goes wrong with your controllers and your operation is short-circuited. Be proactive and check out the condition and adequacy of your controllers before a crippling problem occurs.

2. Consider your environmental requirements. Every factory has a unique environment. After deciding you need a new controller, define the conditions of your manufacturing environment, specifically, where the controller will reside. Will it be exposed to extreme heat or cold? What kinds of gases are present? Will salts or corrosives come in contact with the controller? Are vibration, moisture, or condensation issues? How about fungi?

3. Match the controller to the specifications. Now that you have determined the exact environmental conditions of the controller’s future home, take a look at your control-system choices. You essentially have two: a standard control system or a control system designed for extreme environments. Extreme environment controllers function in the same way as standard controllers but come with enhancements for demanding applications, such as conformal coating that extends product life in harsh, corrosive environments, or redesigned ventilation for increased airflow.

For example, controllers are available that operate in a broad temperature spectrum, minus 25 C to 70 C, and meet ANSI/ISA-S71.04-1985 Class G1, G2, and G3, as well as cULus, Class 1 Div 2, C-Tick, CE, ATEX Zone 2, and SIL 2 requirements for increased protection against salts, corrosives, moisture, humidity, and fungal growth. The active controller components are separated on the backplane by vented faceplate segments that provide increased airflow, offer a thermal cushion, and help lower the need for air-conditioning panels.

Extreme environment controllers are ideally suited for corrosive environments, such as those found in oil and gas, wind-turbine, and ship-building applications. They are also well-suited for steel mills, as their machines are constantly exposed to extreme heat.

Price-sensitive managers might opt for a traditional control system and take measures to mitigate the heat, such as adding air conditioning. But that drives up energy costs and increases enclosure space requirements. Air conditioners also create moisture, which can negatively impact machinery, and come with filters that must be replaced by a maintenance worker. These factors add to the cooling cost over the lifetime of the equipment.

Some may decide to forgo the air conditioner, install a traditional control system, and hope for the best. The result: harsh conditions shorten the controller’s life, increase its chance of failure, and call into question the accuracy of the input/output data. These problems could be avoided with the right controller, which avoids the need for an air conditioner or any sort of temperature regulator. Such controllers can meet ISA Pollution Class G1, G2, and G3 standards. Gases and dust don’t have to be a concern, either.

If you manufacture amid harsh conditions, it is crucial to protect production assets. Extreme controllers can provide optimal control in the most rugged environments and lower lifecycle costs, making them a valuable investment.

- Dennis Wylie is ControlLogix controllers product manager, Rockwell Automation. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering, Plant Engineering, and Consulting-Specifying Engineer, mhoske(at)cfemedia.com.

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Read more from Control Engineering about the Allen-Bradley ControlLogix-XT (Extreme Environment) controller from Rockwell Automation below.