In recent years the requirements have increased for redundancy and advanced communication protocols for mission-critical fuel oil systems, especially in large data centers. As these requirements are being met, system architecture becomes very important to ensure that the correct communications network is actually accomplishing the boots-on the-ground intent for an owner.

Redundant…..or Not?

Today’s network technology is allowing fuel system components to communicate more reliably in more complex applications that demand true redundancy.

The use of relays to pass information between components is still common in the controls world. In order for one component to pass information to another it uses a contact closure to complete a circuit. On large systems, this often requires hundreds of relays and wires connecting panels and components. If the system requires backup redundancy it takes twice as many components, conduit, and hardwiring. This can increase project costs and contribute to a more difficult startup, checkout, and troubleshooting environment.

As PLCs became more common replacing relays so did communication protocols allowing all the needed information to be passed between the PLCs on a single cable. Having this ability made installation, troubleshooting, and future expansion of systems easier. Typically these systems are installed in a bus, star, or line topology using unmanaged switches or daisy-chaining the components together. This network architecture design can be great in certain applications and is commonly used in office environments for computers.

One Potential Big Problem

However, this network architecture has no way to automatically overcome a single-point network failure. Any bad cable, switch, or connection can disrupt one component or the entire system. In the case of a master panel controlling many system panels, the entire fuel oil system can go offline and interrupt the fuel supply to emergency generators.

Line (daisy chain) network architecture

Bus network architecture

Technology Answers the Call for Help……..So the Call for Fuel is Answered

To solve this problem, some fuel systems are now being installed using fiber optic or Ethernet ring topology with managed network switches. These networks are faster and smarter. Redundant A & B master control panels are now able to be connected to all of the fuel system components with an additional connection between them completing the ring.

Ring network architecture

The Alarm is Sounded but the System Keeps Working to Ensure Uptime

If a component of the network fails, the switches know and automatically convert the topology from a ring to a bus configuration keeping all panels in communication with each other until the problem is found and corrected. The switch even has the ability to generate a system alarm so the problem does not go unnoticed. Maintenance is also improved. If a panel is powered-down to be worked on and the internal network switch is offline, all of the remaining panels remain online and unaffected.

There is no one-size-fits-all answer to what is best for all projects. Generally speaking, for small projects with a limited number of components (such as day tanks) located close together, an electro-mechanical design with relays hard-wired and homerun is appropriate. But when the systems get larger with many components or with long distance runs, PLCs can bring the cost to construct down and a ring network architecture can increase the reliability.

Ring topology architecture can be the answer to the requirement for a high level of reliability and redundancy at many mission-critical facilities. The failure to communicate can become the failure to operate.