Bill Linne

Problem resolved. Took the processor and modules off the rail and turned them upside down, tapping them firmly on a piece of clean paper. Not too surprisingly, some small specs of steel collected on the paper. Examining the mounting rail, I found chips there, too (much larger). None of the chips I captured seemed really large enough to be of harm, but obviously at least one of them was lodged in a bad spot. Upon reassembly, all works fine. Now to see if anyone actually admits culpability. All the craftsmen on this job seem to be "a cut above" the norm, but obviously this is not cool. I'll let the construction management firm sort it out. Bill

I agree with your intermittent comms diagnosis, but there is an A/O in position 9 that is working just fine. I'll probably disassemble and reassemble the entire rail over the weekend (Sunday), and swap some known good components into this system if need be. Just thought somebody may have run into this before. Bill

If a 3-phase transformer is rated at 750kva, it has a capacity of about 900 amps. The question is, can I expect to support 900 amps on each phase, or 900 amps total of all three phases? I believe it to be the latter, but need to be sure. Thanks, Bill Moderator corrected p.s. I see I can't edit the misspelling in the title bar. "Laoding" should be "Loading".

It is important to understand that AT THE TRANSFORMER (a few hundred feet from the load center with the ammeter), we installed current loops on the secondaries of each of two 750kva transformers. We were taking the total of the three current loops on EACH transformer and adding them to determine total load one each transformer. That method is incomplete; you add the three (phases) and then divide by three (because all three legs are not exactly evenly loaded). I repeat this only because it is NOT intuitive. And two reputable firms gave me wrong info. Now, at the load center, the same 900-amp number we were seeing at the transformer was being properly displayed as 300 amps (give or take) because the built-in monitoring device was doing the math properly. But because of the massive amount of rewiring being done here during this project, it was not clear that I was looking at basically the same "juice" being calculated two different ways. Make more sense now? Bill

I agree, and I lost more than a little sleep over this issue. But the new load center that is now the major load on the transformer in question, has built-in current/voltage/harmonics monitoring. It, too, shows about 300 amps of load. That's what was bugging me; knowing the only significant load was in the 300-amp ballpark, where in hell was the other 600 amps going? This Plant is 35+ years old, I thought I really understood the power distribution, but could not assure myself of the situation/solution. I hate to change anything (in this case, re-distribute load) without thoroughly understanding what is going on and what will be the result of the change. I'm really glad it worked out as it did! Bill

In addition to Bob's question, I'd ask if the PC in question is running an HMI package.

Electrical engineer was here. I have the answer, and some explanation/clarification of my original question. The answer, in short, is 900 amps per phase. What I've done is install current transformers on each secondary phase, and add-up the resulting current draws. So, with approximately 300 amps being drawn on each phase, my Scada display of the 900 amp total is incorrect; that result must be divided by three. Bottom line is that I am operating well within capacity and am therefore a happy camper once again. Thanks for the reply's! Bill

Interesting take, thanks. I've got an electrical engineer en route today to size-up the situation for me. So far the two most direct answers I've gotten indicate that 300 amps per phase would be fully loaded.

Thanks for the reply, but I never suggested using only one phase. The question is, if measuring the load on each phase, can I expect to support rated capacity on each leg (phase) or is rated capacity the total draw on all three legs. Two other sources (Acme Transformers and Square-D) tell me that for my 750kVA 4160x480-volt transformers, 300 amps on each leg (total of 900 amps) is fully loaded. Bill

Good suggestion, Wulfgar, but no joy. Tried opening a file, opening the database, click the MOVE button, move the window, save and close the file. When I re-open, database back on the left. So, repeat paragraph one, this time going on-line and making some tag comment edits. Save and close the file. Re-open, back on the left. I know there is some way to do this, and when I once again learn it, I'll certainly make a bold note of it. Not a big deal, just a recurring, preventable nuisance. Thanks for your input, Bill

I know there is a way to cause the tag lists in 5k to open somewhere other than the left-hand edge of the on-screen work area. I know it, because I've done it; I just don't know how I did it. I like it to open at the right-hand edge of the area. Any hints? Thanks, Bill

Up and running! Works perfectly as designed. I am thinking about modifying your version to eliminate the year and milliseconds to better suit what our Operators want. Very generous of you to share all that work. Thanks again! Bill

Surely somebody has come up with a "trick" way to present date-time stamps on Scada. I'm using GSV instructions to time-stamp some events to DINT[7]. Once that data is contained in the DINT, how does one go about concatenating or condensing it into a single piece of information presentable on HMI screens? (Trying to avoid presenting several different tags every time we want one date-time stamp displayed.) We've done this using a script running in the HMI (iFix), but that requires a trigger to run the script rather than updating dynamically when the value changes. I envision a new (text?) tag into which the concatenated data is written. Anyone able to steer me in the right direction? Thanks, Bill

Welcome aboard HandeledException. Looks like just the ticket! Will get into the thick of it over the weekend, and I really appreciate that your first post on this forum was a "home run" for me (I fully expect it will be). Thanks, Bill

Thanks, Bernie. I'll give it a try over the weekend when things are a bit quieter around here. The "bad" part is the number of these time-stamps I'm looking at doing. Was hoping to at least find a method involving indirect addressing that would allow me to create one routine and feed any number of source DINT's into it. The good part is that nothing in the process is dependant on getting this feature working. It is just "nice to have" info. Bill

Unfortunately, that's pretty much what we figured. Thanks for confirming. Would hate to do all that AND THEN find out there is an easier way!

Ah, yes, Bob. The operative words "paying attention" and on top of that, having a clue what it all meant. I'd wager only the techies picked-up on any of that in the first place. It is not like ELF was our only way of staying in communications while submerged. The 1MW VLF transmitter in Cutler, Maine was our mainstay (in the Atlantic pond) for many years. In the winter, they would put a continuous carrier on the air and wind the transmitter up to 2MW long enough to melt the ice off the antenna array. Enough of the good ol days. I don't want to hijack a thread. Bill

Paul: Do you have some Navy experience? Not many people know about the ELF system. I retired with 21+ years of submarine service in 1989. Bill

You are most welcome and thanks for letting us know the resolution. I learned about limits the way we learn most lessons - the hard way. Start-up time, lots of expensive people on-site, general contractor breathing down my neck . . . you get the picture. Bill

In a closed pipe, which is the same diameter for it's entire length, will the measured vacuum be the same at all points along the pipe, regardless of elevation? Specifically, I have a 2" stainless pipe leading from the suction of a blower, up the wall (10 or 12 feet), across the structure, through a valve (now open), and down into a closed basin mostly full of water (a couple feet of air space at the top). We are applying ozone to the water in this basin, therefore must trap the off-gas and run it through an ozone destruct system. The blower mentioned above draws the off-gas through the destruct system and discharges to atmosphere. Heretofore, the blowers ran across the line, and I modulated the valve to establish the desired vacuum in the basin (as measured by a transmitter up at the valve). Now, the blowers are VFD driven, and a new pressure transmitter is installed down by the blowers. The output of the new transmitter modulates blower motor speed. But, when the new (lower) pressure transmitter shows about -1" WC, the transmitter up on the deck is reading closer to -3" WC. (Like I said, elevation difference is about ten to twelve feet.) Sound normal? Thanks, Bill

Problem resolved! Turns out the brand-new Rosemount transmitter had an offset value of 2.5 programmed into it. Set the offset to zero and viola! Thanks for your thoughts and posts. Bill

I'm certainly in no position to argue with you, Ken, but it seems to me that if pipe friction were the issue, the pressure drop would be the other way around. That is, greater vacuum near the source (the blower suction) and less vacuum on the distant end. That's what got me to thinking about the fact that the transmitters are at different elevations (which, to me, should NOT be an issue with air like it is with liquids). That's why I'm posting the question. At least you've offered something to think about, and I thank you for that. Bill

Is there a "Limits" tab in the module configuration window? If so, be sure that the upper and lower limits are not causing your problem (that is, both at the same point, presumably MAX). Bill

Your Communication Path (within the Configuration Tab of the MSG block) will read something like: LocalENB, 2, 192.168.28.1, 1, 0 If memory serves, this basically translates to "Go out the Local ENB, travel to 192.168.28.1 where the ENBT is in slot 1, then to the processor in slot 0. Use a CIP Write (or Read, as appropriate), and you should be good to go. Bill

Yep, perfectly normal, Bob. Smallest unit a MSG will "transport" is one word. Can be any kind of word, so long as the type is the same on both ends (DINT to DINT, INT to INT, REAL to REAL, etcetera). I once errantly wrote a DINT to a PLC-5 Integer file, and while the MSG did not error, it did fill the destination address and the next word in the Integer file of the PLC-5. Bill