Ten Best Practices for Communication, Control, and Supervision of Unattended Facilities (Part 1)

Managing an urban infrastructure (electricity, gas, water of any kind, or radio, television, or mobile coverage) requires controlling a large number of small, autonomous facilities distributed geographically without nearby personnel, and which, for the most part, must operate autonomously. It is evident that the management of these sites must cover needs that are very different from environments such as industry or home automation. Their control cannot fail—we all know the chaos that a blackout causes in an urban environment—nor can information be lost for their management, but at the same time, there is usually no personnel in the vicinity or a large communication channel with the facility. Thus, from Logitek M2M, in this post, we propose a set of actions to prevent errors, increase safety, guarantee control, and ensure a rapid response in the control, communication, and supervision of these unattended facilities. A “Ten best practices for communication, control, and supervision of unattended facilities” that we will see in two consecutive posts. These are the first 5 points:

1) Having appropriate elements for your system is non-negotiable. These facilities usually operate in demanding environments, and this must be taken into account. As much as the control and communication elements may be in electrical cabinets, these sites often suffer extreme temperatures in summer and winter, accumulate dust, have small electrical variations, humidity… that is, the elements must be ruggedized, installable on DIN rails, with extended temperature and humidity ranges, and have some electrical flexibility. Even if it has various functionalities or a large processing power, an electronic board without this type of encapsulation is not a viable solution. 2) Ensure power supply. Most unforeseeable power losses are usually of short or medium duration, never more than half a day, which is why having a power redundancy for the site is usually useful and sufficient. This system can be a double voltage connection from another substation or provider, an autonomous UPS, or even batteries recharged by solar panels. Obviously, whenever the main connection fails, it must be reported to the system. 3) Autonomous control. Under any circumstance or problem, the facility must function or, at least, minimize risks. To meet these premises, an edge computing architecture is the most reliable option.

The control of the facility, its programming, and logic of action must be in the control elements of the site itself—typically RTUs. Obviously, the control center (CC) must interact with the RTUs, parameterize them, activate one program or another, etc., but the facility must be able to work autonomously in case of loss of communication with the CC. Another reason to justify this way of working is the characteristics of the communication networks. Obviously, they do not have the same latencies, nor is the same bandwidth available in an F.O., wired, or Wi-fi network as in a site connected by GPRS. That delay of seconds can cause accidents—over-voltages, for example—in a large number of devices while the control equipment continues to wait for a response from the CC. The architecture that the IoT so much favors, where all the data is sent to a Cloud and the elements that interact with it make the decisions, should not be applied, or at least, not today. 4) PUSH strategy. In line with autonomous control, the facility managers must be notified immediately if a specific alert or action has occurred, without waiting for the CC, in its supervision routine, to discover that something serious has happened. The RTUs must be able to send messages actively for situations where it is not advisable to wait for them to be consulted. This implies using specific communication protocols and/or more traditional methods such as SMS or emails. It is noteworthy that this strategy has a derivative. A PUSH strategy does not make sense without automatic alarm management that allows establishing, for a specific problem, a Workflow of who to notify—taking into account schedule and calendar—, how, and whether the RTU should wait for confirmation or not.

5) Interoperability. Anyone who has worked with facilities of this type knows that, typically, both elements that are considered obsolete—but that are still functional—and the new devices that have been installed to add functionalities coexist. Faced with this problem, one must avoid putting different control elements or parallel intelligences that create a kind of technological Frankenstein. This always entails that the system managers must know multiple different technologies, each with its particular software, a different technical support, etc. Thus, if you want to centralize the control and communications of the unattended site in a single element, you should opt for RTUs with interoperability features. That implies knowing how to interact with:

• Different physical media: radio, RS232, RS485, Ethernet…
• Electrical signals: Discrete I/Os, relay, 4-20 mA/0-10 V AI…
• Protocols: Modbus, DNP3, IEC-60870, SNMP, proprietary developments…
• Other market intelligences such as Siemens, Omron, Rockwell…

You can access the second part of the post from here.

You can download the Ten best practices for communication, control, and supervision of unattended facilities from here.