Transcript
Introduction to Auto-Correction of CT Hookup
Good afternoon, everyone, and welcome to today’s white paper webinar. Today, we’re talking about a feature that’s in the Bolt that autocorrects common hookup mistakes.
It’s not uncommon to have a recording where one of the CTs was installed backwards, so the arrow doesn’t point towards the load. Or perhaps phase A and B CTs were swapped with A and B voltage, so A voltage is not paired up with A current or any combination of this. You can have multiple issues with the hookup, and it’s not always straightforward to hook up the unit correctly. Sometimes in a confusing cabinet with a lot of wiring, it may not be obvious which direction points towards the load, and especially in a CT cabinet.
Software-Based Correction Options
To fix that, we have a feature that’s in the Bolt and also our iOS software and in PQ Canvass that allows you to either manually correct for these hookup issues or have the Bolt automatically sense and then correct for these.
The corrections involve either flipping the polarity of a CT electronically in the device or swapping channels one, two, or three around on the current, so that the current matches up with the voltage or any combination of those. So this can be done in software in the Bolt without having to physically change the hookup in the device itself.
Automatic Correction During Initialization
To do this automatically, you can enable automatic correction either in the iOS software or in PQ Canvass, and that will send that to the Bolt so that when you initialize the Bolt and it initiates a two-minute countdown, it will sense these sort of hookup problems.
If it senses a hookup problem, it will indicate that with the LED patterns on the Bolt itself, so that you then have a chance to fix it manually if you’d like to. It will also pop up, I believe, with the iOS software during the countdown if you’re connected and tell you that there’s a problem and with a suggested correction. That gives you a chance during the countdown if you would like to actually reach in and change the CTs or move things around. But it’s a lot safer to let the CTs stay as they were and let the Bolt correct that for you.
Manual Phase Mapping
If you do this manually, in the iOS software you have what’s basically a phase mapping ability where you can touch channel one, for example, and drag it to channel one, two, or three. This is a mapping between the physical channels of the Bolt itself, channels one, two, three, and the logical channels that it’s using inside the Bolt for determining what’s phase A, B, and C.
If, for example, you have phase A and B swapped, to fix this in the software, you’d tap on channel one and drag it to channel two, and vice versa for two and one, and that effectively swaps channel one and two on the Bolt.
Fixing Multiple Problems
In addition to what we’re showing here in figure two is a second problem. Here in this example, phases A and B are swapped, but phase C is on the right connector, but the CT orientation is backwards. It’s not pointing towards the load. So this indicator indicates that we’ve made that 180 degree polarity change on channel three. So here we’re actually fixing two different problems with this fix.
Viewing Corrections in Recordings
This persists throughout the recording. This hookup change is part of the recording. It’s recorded with the data so that you can then after the fact see what was done to the data, and you can actually look at waveforms uncorrected or corrected. If you’d like to see the raw hookup, you can do that in live waveforms or in the waveform captures in PQ Canvass.
Here we’re showing some examples of viewing this. You can view it in the vector diagram. You can view it in the live waveforms. In a recording, we’ll jump to PQ Canvass here. I have a recording loaded for a Bolt, and this is the header information that you’re familiar with with every recording, and this is the phase correction section.
We click on View. This shows you what has been done to the data. Here, no corrections have been made. It’s a straight one for one. Logical channel one is physical channel one for all three inputs, and nothing’s been inverted. So this was a normal hookup.
If there had been some swaps, you’d see what we saw in the paper with lines going from, mapping from one channel to a different channel or a polarity indicator indicating that one of the CTs has been flipped. Any combination of these are possible. You can even have rolled phases where all three phases are mapped to a different one, like A to B, B to C, and C back to A if you have the phase rotation opposite on voltage and current.
Automatic Correction Workflow
Again, if you have this initialized to automatic, the Bolt will make this correction at the end of the two-minute countdown. Within a few seconds of the end, it will prompt you, and if you’re using the iPhone software, that it’s going to do that or give you a chance to fix it yourself. But if it’s automatic, it’ll just go ahead and do that, and that correction is saved with the data.
Here in the paper, we show how to view this in the iOS software. You can also view the waveforms either way. So here in figure eight, you can toggle back and forth between, in a waveform capture, the original uncorrected hookup or the corrected hookup. If you wanna see the before, if you think maybe you made a mistake on the correction and you would like to undo that, that’s certainly possible in the data.
Permanent Installations and Remote Correction
This can also become useful if you have a permanent installation. If you’re using a Bolt in a permanent situation and it’s been installed, and you don’t recognize that there was a hookup issue until after the fact, you can always reinitialize in PQ Canvas, and that will take effect at the beginning of the recording.
So if you do this remotely with remote communications with the Bolt, or again, you can do this live with PMI view with an iOS device or the PMI view that’s a PC-based app.
iOS App Hookup Detection
Here we’re showing screenshots from the iOS app, so this works on the iPhone or with an Apple tablet with Wi-Fi communications. This is showing that it’s warning you it has detected a hookup problem, and again, you could fix this manually. It’ll tell you what to do to fix it manually if you wanna actually reach back in and move the CTs around. But now you don’t have to. You can use the software to either manually fix it in the software or let it automatically do this.
How the Detection Logic Works
The logic it uses to detect this in the first place is looking at the phase angles between voltage and current. Ideally, there’s almost no phase angle difference between voltage and current. Or if it’s a delta, there’s a fixed 30 degree phase angle shift between voltage and current. And if it sees a very large phase angle difference, it’ll iterate through the different combinations and pick the one that minimizes that total phase angle difference.
If you have a question later, give us a call anytime at 1-800-296-4120 or send us an email at support@powermonitors.com. Everyone, have a great afternoon. Thanks for attending.