# Material on SCADA



## Aerofrank (Oct 3, 2010)

I notice there is a SCADA question in the NCEES 2009 question booklet. I have no knowledge of SCADA, and if anyone can direct me to any websites etc., which may have material on SCADA, I would gladly appreciate it. Would like to be prepared for any SCADA questions, which may arise on the Electrical Power PE exam. Thanks as always.

AeroFrank


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## cableguy (Oct 3, 2010)

Honestly, that question could have been labeled just about anything data acquisition related - but they stuck the buzzword "SCADA" in there. It could have been a protective relay.

I think it falls more under CTs and PTs than it does SCADA, honestly. They just mentioned it as a buzzword, in my opinion. If you're going to study up on anything, study up on Current Transformers and Potential (Voltage) Transformers. They *will* be on the test, I'm sure. I think it's highly more likely to see a differential relaying question (using current transformers) on the exam.

In regards to SCADA, there are a few things they might ask, though I doubt it. For example, in SCADA, your resolution of reading depends on your A/D converter and your input voltage range. Maybe they'd ask "A SCADA remote telemetry unit uses a 0 to 5 volt DC input with a 12 bit analog to digital converter. What is the voltage resolution?". That would be a SCADA question. Beyond that, I don't know if they could ask much, as they never delve in to SCADA protocols in the sample exam, comm lines aren't really applicable, computer databases &amp; displays aren't really applicable, etc.


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## joshtrevino (Mar 31, 2011)

cableguy said:


> Honestly, that question could have been labeled just about anything data acquisition related - but they stuck the buzzword "SCADA" in there. It could have been a protective relay.
> I think it falls more under CTs and PTs than it does SCADA, honestly. They just mentioned it as a buzzword, in my opinion. If you're going to study up on anything, study up on Current Transformers and Potential (Voltage) Transformers. They *will* be on the test, I'm sure. I think it's highly more likely to see a differential relaying question (using current transformers) on the exam.
> 
> In regards to SCADA, there are a few things they might ask, though I doubt it. For example, in SCADA, your resolution of reading depends on your A/D converter and your input voltage range. Maybe they'd ask "A SCADA remote telemetry unit uses a 0 to 5 volt DC input with a 12 bit analog to digital converter. What is the voltage resolution?". That would be a SCADA question. Beyond that, I don't know if they could ask much, as they never delve in to SCADA protocols in the sample exam, comm lines aren't really applicable, computer databases &amp; displays aren't really applicable, etc.


Cable guy:

I saw this post today. Out of curiosity, what would be the solution to your stated example?


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## MA_PE (Mar 31, 2011)

IIRC

5 volts / 2^12 = 0.00122 volts

Note that for ranges less than zero (-5 volts to + 5 volts) one bit will be reserved for the sign.


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## cableguy (Mar 31, 2011)

MA_PE has it correct. If it's a +/- 5V input on a 12 bit converter (which I've also worked with), the MSBit is sign, and its resolution is half the above number (err, rather, it's 2x the above number, .00244 V/bit).


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## sam314159 (Mar 31, 2011)

For stuff I consider "left field" like SCADA, EMS, PLC, Ladder Logic, LVDT, SMPS...etc. I just went to Wikipedia and printed out the sheets on those topics then I stuck everything in my binder. I skimmed over it and will just take the binder with me.

When you say CT and PT problems, do you mean really basic stuff like what's on the sample exam? You think they might go into more detail like CT saturation or accuracy classes?


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## cableguy (Mar 31, 2011)

Wikipedia printouts would definitely help on the exam.

I don't see saturation or advanced parameters entering the test. The questions they asked were really basic. Just know how to handle delta wye transformers with wye delta CT's, that kind of thing. There's all kinds of things they can ask just by connections.


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