Monday, November 19, 2012

Are RTUs dead?

Which definition of RTUs do you mean? Do you mean Reach The Universe? Yes, these RTUs will live forever. Let me know what you mean by RTU.

When we talk about RTUs, we should differentiate between functions, I/Os and processor platform. In the past (some 10 years ago) an RTU was more or less well defined by its functions, I/O wires/terminals and platforms. Many of them are still in use and a lot more will be installed in the years to come.

Today we have many many more functions (those we know well, and those we could think of), hardwired I/Os, serial I/Os (Ethernet, ...), hierarchies of I/Os (or RTUs or just IEDs), and many more very powerful platforms.

Whenever we talk about an RTU, we should list the functions it implements, hardwired I/Os, serial I/Os (Ethernet, ...), hierarchies of I/Os (or RTUs or just IEDs), and the powerful platform. I have seen yesterday a substation ruggedized box with an 8 port Ethernet switch, some 20 I/O wired terminals, with IEC 61850 and other protocols, and programmable applications (C/C++, IEC 61131-3 CoDeSys, simple web PLC). Is this box an RTU, a bay controller, a PLC, a gateway, a substation computer, (condition) monitoring device, an Ethernet Switch? Its a bit of everything!

In my experience utility people use a new name for the "interface" to a substation: Substation Gateway.

In any case we should describe what we mean by a term (e.g., RTU), and should describe any box independent of its name.

"Names are sound and smoke", it says in Goethe's Faust. To make sure this is not the case, companies are putting a lot of money on name inventors. The name RTU was invented some 20+ years ago - a good name so far. We can keep the name - but have to define what we mean.

What do you think about this interpretation: RTU = Reach The Universe (of a substation or power plant or ...). That is broad enough to cover everything.

We have tried many times to find a name for IEC 61850 - we failed so far. We should not try anymore to find a name. A single name would mis-lead. If we talk about IEC 61850 we have to clearly describe what we mean!! Just saying: My device conforms to IEC 61850 doesn't mean anything. What does IEC 61850 Edition 2 mean? Nothing!! There is NO IEC 61850 Edition 2 at all! What? See some discussion:


The issue is that the semantic is carried by a name. The semantic MUST be defined by somebody. If many definitions exist then we have to be very careful. Ask always what people mean by RTU, IEC 61850 Edition 2, Fizzlipuzzli, ... You belief to know what RTU and IEC 61850 Edition 2 mean. Are you sure? And you agree, that you do not know what Fizzlipuzzli means (except a few people that know me). I don't know what Fizzlipuzli means either. ;-) ... it is something nobody knows. I use it for a function or a device to make sure that nobody associates it with something real he/she knows.

During the first meetings of the IEC 61400-25 (IEC 61850 extensions for wind turbines) we had a serious discussion on "Reports" ... we could not reach an agreement. Because I was discussing the IEC 61850 Report(ing Model). The other person discussed a Report from a turbine containing 10 minute statistical values of wind speed and power produced etc. That's the reason lawyers first define the terms they use in a contract!!

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