Transcript
Introduction
Hi, everyone. Welcome to today’s Ask a Pro session. I’m Scott Windsor, the lead software engineer here at PMI, and today we’re gonna be talking about circuit and CT hookup detection with the Seeker+.
In this presentation, we’re going to cover circuit hookup auto-detection, letting the Seeker+ identify the service, automatic hookup and CT mapping, which is matching every CT to the right phase, and the manual overrides that will allow you to take control when the site that you’re monitoring calls for it.
The Problem With Traditional Setup
Setting up a power quality recorder has always meant you have to double-check the circuit type and double-check every CT and voltage lead. When you’re initializing your recording, you’d have to select that in the dropdown box in ProVision™ or PMI View™, whatever software that you were using to set the circuit type.
With the CT on the wrong phase or you clamped it backwards, that can throw off your data, which means that might be an incorrect power sign, invalid power measurements, and incorrect power factor, and you might not notice this until days and weeks later when you have downloaded your recording and you sit down to review the data. So a little too late. The Seeker+ now handles much of that checking for you.
When Detection Happens: The Two-Minute Countdown
Before each recording begins, it automatically identifies the circuit type and corrects some common hookup mistakes. First, let’s talk about when all of this happens. When you start a new recording from PMI View™ or PQ Canvass™, the Seeker+ doesn’t begin the recording right away. It waits until it has power on its channel one and common leads, and then it starts a two-minute countdown.
So if you initialized while you already had power on those leads, it would start right away, but if you were connected with a powered by USB into your laptop, let’s say, then it’s gonna wait until you’ve taken it out in the field and actually hooked it up to real power.
During that countdown, a variety of inputs are checked, such as the CTs and the leads, nominal values are detected, and both of the features that we’re gonna be talking about in more depth today are run during and locked in at the end of countdown. The Seeker+ watches the whole countdown, the whole two minutes, not just right at the end or some little time period in there. So if you have some brief disturbances while you’re hooking it up, you detach a lead, reattach it, it won’t dramatically throw off the detection process.
When the countdown ends, the results get analyzed and then locked in, and they’re saved with that recording when the recording then begins normally. So what we’re talking about there, the results, that’s your hookup type, Y, delta, et cetera, and also your CTs. If anyone has a Bolt™, we had the CT mapping feature in the Bolt™, and we’ve built upon that and extended that to the hookup detection now.
For the best results, you have to have all your leads and CTs connected first before countdown. If there’s nothing to measure, it’s very hard to, or if not impossible, to detect the hookup. But if you have that hooked up first before you’ve connected your channel one voltage lead, then you have the entire two-minute countdown for all those detection steps to be assessing the voltage leads and CTs, et cetera. An easy way to make sure you get a good result is connect the channel one voltage lead last.
Circuit Type Hookup Auto-Detection
The circuit type hookup auto-detection will start there, and so this is looking at your voltage leads. The circuit type describes how the electrical service is wired, Y, delta, and so on. And you can see here on the slide, we detect Y, three-wire delta, four-wire delta, and single phase. I believe that’s also called split phase.
Some of the other hookup types cannot be reliably differentiated from, let’s say, three-wire delta. It’s very hard to tell the two-element delta or the two-and-a-half element, so those have to be set manually. We haven’t found a reliable programmatical way to determine those based on the inputs.
If the Seeker+ can’t detect your circuit type, it doesn’t guess. It falls back to a safe default Y, which processes each channel independently as line to neutral measurements. So at least you’ll have a usable recording, but may not be exactly what you want. And then at that point, you could go in and try to see if it auto-detects again, or use the manual hookup if you had some kind of more unique situation that would prevent it from being detected, such as you don’t have anything energized or don’t have all of your leads hooked up or something like that.
The detected circuit type is the Seeker+’s best judgment based on what it sees during countdown, so it’s still always a good idea to confirm the result matches what the site has before you leave. If you’re in PMI View™, after countdown ends, you can go into the diagnostics page, and it should show you, here’s what the hookup type has been detected as. And I believe ProVision™ has a similar screen where that shows as well.
When to Choose a Circuit Type Manually
So when does it make sense to choose a circuit type for yourself? It’s specifically when the circuit is a two-element delta or a two-and-a-half element Y. We cannot auto-detect those, and those have to be selected manually. And then, of course, any circumstance where the leads are connected in a non-standard way, or if they’re not all connected at the time you’re initializing, starting your recording, or if the circuit has low voltage. So it doesn’t have to be completely off, just not what you would expect normally.
Automatic Hookup CT Mapping
For the automatic hookup CT mapping, we have this already on the Bolt™. This extends also beyond what the Bolt™ does, and it will help map a few of the voltage leads, too, if it detects an issue there. The caveat there is it will never move voltage channel one. That always will be voltage channel one, because that’s what powers your device. So it can’t move that to, say, channel three or four or something like that.
By default, the Seeker+ will use this CT auto-fix mode. That’s what it’ll display as in PMI View™, auto-fix. During the countdown, the Seeker+ checks each CT against the voltages and makes sure every current reading is matched to the right phase. Any corrections are applied when the countdown ends, and all the data you’ll download reflects the corrected hookup. And you’ll also see that reflected in the live data, like your waveforms and things like that.
What Can Auto-Fix Correct?
The CTs being connected to the wrong phases. You accidentally hooked up your channel three CT on the channel two and swapped it with the channel two and three, compared to where you hooked up your voltage. The Seeker+ can detect that and programmatically swap those in the recording.
It can also detect if you’ve hooked a CT on backwards, where you would get negative power readings. It would do an inverse of that, again, programmatically, and you would see that reflected in the readings and recording.
And it can also detect a voltage lead connected to the wrong input with caveats. It can’t move voltage one programmatically somewhere else. But it could detect, say you had your channel two hooked up accidentally on the channel four lead. It would say, “Hey, I see that you don’t have any voltage on channel two, but you have it on channel four. Probably you just hooked that up wrong,” and it’ll programmatically swap that in for you.
Things to Keep in Mind
First, voltage channel one powers the recorder and serves as the reference point. So the Seeker+ will never move that, never flip that. Voltage channels two through four can be remapped.
Second, the auto-fix needs current flowing through the CTs during the countdown. If there is little or no load, or the Seeker+ can’t resolve the hookup because of little to no load, it falls back to physical wiring instead of guessing.
Third, power is also expected to flow towards the load. If the site is generating power during the countdown, say a solar installation sending power to the grid, the Seeker+ may treat those CTs as reversed. For those sites, it’s recommended to set the hookup correction mode to either physical, as wired, or manual, where you can specify your manually setting map channel two to four.
Vector Diagram Example
Here is an example, and this was from the white paper. In this example, we’re showing the vector diagram before the circuit auto-detect was run during countdown. The initial one, it defaults to Y, and this was hooked up as a three-wire delta. And in the right side image, it’s the same vector diagram post the countdown running and the auto-detection doing its thing.
You can see in the image, again, this is the same one in the white paper, that it has correctly changed that to detect as a three-wire delta, and the readings reflect that. You can see that especially in the voltage channel two readings in the upper right corner. If you haven’t seen more recent PMI View™, we’ve revamped our vector diagram display to have a little bit more data on it, where you can see things like the circuit type and the channel mapping in the upper right corner.
LED Feedback During Countdown
While all this is happening during the countdown, the Seeker+ LEDs will try to give you some feedback if it thinks you have something hooked up in the non-standard way, as in channel one to channel one, channel two to channel two, et cetera. Or if you’ve chosen a specific circuit type, it will try to do some validation that what you have manually selected as your circuit type. Say you chose three-wire delta, it will step through that and say, “Do the—is what I see on these voltage leads and these CTs, does that match the expectation?” And the LEDs will reflect that state.
This is in the quick start guide, what those states mean. You’ll see a different color for different situations and know, “Oh, it’s not quite hooked up right, I need to check it.” But at the end of it all, it can help correct it for you if you have auto-detect and auto-fix selected. The user manual lists these as well, the LED states. Green is good.
Manual Overrides
Either one of these features, the circuit auto-detect or the CT auto-fix, when you start a recording from PMI View™ on Windows, iOS, or our new Android app, or you’re starting from PQ Canvass™, by default it’ll use auto-detect and auto-fix for the Seeker+. But you’re also able to specify manually the mode that you want.
Do you want a Y hookup? Don’t try to auto-detect. You can select that from the dropdown. And then in the auto-fix for the CT section, you can change that to say, “I want as-wired physical,” or you can select manual, which shows a matrix, and you can map the matrix yourself. Physical or manual is the better choice at sites that generate power, like solar installations, or if you have an intentionally non-standard hookup, whatever that might mean for you.
Either way, the Seeker+ will save the circuit type and hookup correction with the recording, so when you get your recording back, you’ll be able to see what did the device think it was recording as logically inside. And all the apps will display that, and you can review that. So you, “Oh, it swapped channel two on me. I didn’t realize.” So you can work backwards from that.
Best Practices
A few habits to help the Seeker+ get it right:
- Connect all your voltage leads and CTs before the countdown starts. Connecting the channel one voltage lead last takes care of that.
- Make sure the circuit is carrying some sort of load during the countdown.
- Keep the CT arrows, the little indicator arrows on the CTs, pointing towards the load.
- Automatic hookup and CT mapping is a safety net and a good feature, but it’s not a replacement for careful wiring.
- Start a new recording anytime you change the wiring. If you have done your countdown and halfway through you unhook everything, hook it up a totally different way, that probably will throw off auto detection. Simply just start a new recording, and it will do its thing again. Takes another two minutes, but it should get the answer right then.
As always, it’s not a guarantee. It’s a best guess, and it will fall back to physical and Y if it can’t make a determination.
Summary
To bring it all together, these features handle two of the most common hookup problems seen in the field before a recording even begins. Circuit hookup auto-detection identifies the circuit type so the calculations match the service. Automatic hookup CT mapping corrects common hookup mistakes so each CT is matched to its phase and is in the right orientation. When the site calls for it, you have the power to override either one to what you want. And as always, before you leave, confirm the results match the site so that way you’re not hating life days or weeks later.
That just about does it. Be sure to check out all the wonderful links here, especially our Merlin™ demos. If you haven’t seen Ask Merlin™, be sure to text Ask Merlin™ with any of your power quality questions. Tech support’s always standing by if you have questions related to this. And thank you for attending today’s webinar. You can reach out to us anytime by calling 800-296-4120 or emailing support@powermonitors.com. Thank you, and have a good day.