The importance of redundancy in industrial automation systems

For critical applications with a 24/7 workload and operating a very high loss, a failure that entails plant shutdown can result in a loss to the business. Availability processes like these, found in Oil & Gas, Sugar & Ethanol, Hydroelectric Plants, Agroindustry, among other markets, require the use of redundant systems to prevent the plant from stopping working if the equipment becomes unavailable. The use of this type of architecture practically eliminates the need to stop the system for maintenance, increasing operational safety and the reliability of the automation system, as well as optimizing costs and business performance.

In this article, we will talk about the importance of redundancy in industrial automation systems and the benefits of using an architecture with this feature.

What are redundant systems and why are they use?

Redundancy in industrial automation means maintaining duplicated or triplicated systems to ensure the availability of critical processes and devices. Used in a wide variety of industrial demands, such as Petrobras` FPSOs operating in the pre-salt, the functionality ensures the plant`s operation even if the equipment responsible for the control or some part of the network architecture is unavailable.

There are several reasons to use redundant architecture systems, but it’s common sense that robustness, availability and security form the tripod that supports this type of methodology:

Robustness – ability to tolerate failures and continue operating the process.

Availability – as the name makes clear, it is about the full potential of the system being available whenever necessary.

Security – more than just data protection, the word security here relates to functional security, which protects the physical integrity of both process operators and the company`s assets.

The benefit of using the hot stand-by method

Among the types of redundancy most used in the industry is hot stand-by, a technique in which one or more modules are in standby mode while the main equipment is operational. In this type of architecture, the standby modules work in synchronize with the active equipment and, if a failure is detected, it is ready to become operational immediately. In order to avoid losses between equipment changes, the stand-by module must be synchronized and updated with the same settings as the main equipment.

In addition to the dynamic switching between primary and standby equipment, the procedures for the start-up, operation and maintenance phases are also as simple as for non-redundant systems, saving time during key use cases.

System initialization

A single configuration download is enough to configure the controller pair. All configuration received by the primary device is transferred to the standby equipment online via the synchronism channel.

Replacing a Failed Controller

User intervention is not required to update the configuration of a new control module attached in the application. The inserted equipment is automatically recognized by the system, receiving all the online configuration and parameterization of the controller in operation from the redundant synchronism channel.

Add new remotes and/or I/O modules without process interruption

It is possible to expand the current system to add the reading of new sensors without interrupting the process.

In advanced PLC families, the I/O modules count on hot swap support. The functionality, also known as hot-swapping, allows the replacement or removal of components present in a PLC without having to turn it off. That is, these components can be handled while the controller is still operating.

The procedure consists of updating the backup controller and then applying synchronism between CPUs. The feature minimizes system downtime for maintenance, further increasing the application`s level of availability.

Update controller logics without process interruption

You can update the controllers` software to add new critical logics without the need to stop the process. To do this, just update the backup controller and apply synchronism between CPUs.