Transcript
Introduction to Live Data in PMI View
Welcome to today’s Ask a Pro session. I’m Scott Windsor, the lead software engineer, and today we’re gonna be talking about working with live data in PMI View.
In this presentation, we’re gonna cover what the live data pages are and how you get to them: Live Waveform, the Vector Diagram, Live Meter, Live Harmonics, PT and CT Ratios, and Cellular Status.
Overview of Viewing Live Data
We’re looking at the same electrical inputs on different points of view. The live data pages are gonna show us waveforms, phasors, tabular values from a connected device, live updating without interrupting an active recording. And once you’re connected, the device page will show you a series of these options that you can pick.
So let’s switch to PMI View. If you’ve used PMI View before, this will look familiar, but otherwise this is the main landing page where you can select devices. And then in this case, this was a device that I knew the IP of, I entered the IP of USB-connected devices and other devices can show up based on other discovery methods here. We have other presentations that kind of cover how to use PMI View as a whole. Focus on the live data today.
Live Waveform
So if we click on our device, now we’re connected, and you can see right here we have a live data cart, and in there is all the things like we discussed. So if we click on Live Waveform, this is a continuously updating single cycle capture of voltage and current, and it’s the fastest way to confirm that every input is live and the signals look like what you would expect.
There are two viewing modes, and they answer different questions. We have Per Channel, the one we’re on now. That isolates each channel with its voltage and current overlaid, and so we’re evaluating one input at a time. Switch to our Per Measure, clicking this button here. Now we stack all the voltages and the currents together and we’re comparing phase to phase. So that’s useful for confirming our phasor rotation before we move on to the vector diagram.
So what information can we glean from this? A flat trace is a dead input or a lead that was never hooked up. Current on a channel that should be idle points to a clamp on the wrong conductor. And then your typical things like flattened peaks or obvious distortion is apparent at a glance. And it could mean that the device was initialized at the wrong current range and is clipping if you get instead of a nice curve here, nice and flat.
You can see here when you hover over, you can see the instantaneous values, things of that nature. So we also have this PT/CT Ratio control over here. So if you had a CT hooked up backwards, you could enter a negative scalar and flip it without even having to go back and re-hook. And we’ll get into those a little bit more later ’cause there’s some subtle nuances here, mainly being these are display values, but we’ll cover that a little later. And you can toggle on and off channels if for some reason you didn’t wanna see various inputs for whatever you’re trying to assess.
Vector Diagram
Let’s move on to the vector diagram. This will plot your voltage and current phasors on a polar chart and their actual relative rotation. While the waveform tells you whether the signal is alive and clean, this tells you whether the channels are wired correctly relative to each other.
So what kind of wiring errors does this catch? Phase rotation, ABC or ACB, you can read it straight off the diagram. A reverse CT puts its current phasor about a hundred and eighty degrees from where it belongs, so you can quickly see if one is inverted or not. A current reference to the wrong voltage shows a displacement that the load simply cannot explain. A resistive load reading a hundred and twenty degrees is a wiring error, not a power factor.
And you can see here, we talked about the one-eighty degrees. Because I had applied this negative, now it’s aligned with its phase. I can simulate here for had it inverted, you could flip it yourself for the display to make sense.
PT and CT Ratio Control
So let’s talk more about the PT and CT ratio control. With the ratio set, every display reads in the primary side values, so your magnitudes become a direct check against your documentation. So we can scale by whatever we want here, whatever you need. They carry over between the live pages. I had changed it on the waveform page, and as you saw here, when we switched to vector diagram, it had kept that across.
It’ll remember those in PMI View for device by serial number, and it’ll save that. You can close and you can come back, and it’ll still be there.
Now, there are some caveats here. They do not translate down into a recording. They do not travel with the recording, and they don’t apply to the recorded data. So they only scale what PMI View displays. They’re not sent to the device. They only affect what gets measured and, again, what gets recorded. So it’s a display correction only, and it will not adjust the measurements, which means your power measurements would still be wrong, if you had an inverted CT, for example. So it’s just subtle nuance, but it just helps you at a glance with your investigation or, “Do I have it hooked up right?”
Live Meter
Switch here to the live meter. You see that same control carries over. So here is the tabular view of some of the same data. We get to see the RMS voltage, RMS current, among many other things. While the waveform gives you the shape, the vector diagram shows you the relationships. The live meter gives you numbers.
We get to see the values as we compare against maybe a nameplate ratings, site documentation, or a standard. The readings are grouped into cards by category and broken out into channels. So at a glance, you can see it all. This will look very familiar if you’ve used ProVision or PQ Canvas.
Live Harmonics
And then we will look at live harmonics. This breaks the waveform down into its frequency components, showing the magnitude of each harmonic order per channel that are displayed as a bar chart. You can display the magnitudes as RMS magnitudes, what we’re seeing now, or you can switch to a percentage of the fundamental view.
A little hiccup in my connection here. Apologies. Let’s get back in there. I was about to show you we can switch between voltage and current. And then obviously absolute or the RMS magnitudes and the percentage of the fundamental. And you can toggle the fundamental on and off if that is useful to you. We default it off because otherwise you can’t see a lot of that granular data.
So while the waveform view shows you that distortion exists, the live harmonics will show you where in the spectrum it sits and at what magnitude. A few things to keep in mind:
- The harmonic signature should be consistent with the equipment on the circuit. A spectrum that doesn’t match what’s installed is worth investigating before it shows up in a recording.
- THD can be within limits while a single dominant harmonic can exceed its individual limit under IEEE 519. So this per order breakdown is what makes that visible.
- If you’re comparing the live spectrum against a known baseline, this will help show you whether new loads or failed filtering or anything have shifted the distortion pattern.
Cellular Status
And the last screen is the cellular status. This is not a cellular device. I believe I have one we can connect to real quick. Oh, this one is not either. So apologies, I thought this was a cellular device. But we had pictures of that in the white paper of the cellular device screen.
And on that screen, for devices with cellular hardware, this will show you the modem signal quality, network registration, and hardware identifiers. The signal readings, RSRP, RSRQ, and RSSI, sit along quality icons, so you get an immediate read without having to remember what a good RSRP number looks like, for example. So you’ll see like a bar with red, yellow, green coloration like you would on your phone.
The state and registration of the cell, you can see that, and that’ll confirm the modem’s actually on the network that you’d expect and passing traffic. All of this to help you determine that the link is solid before you walk away and miss out on an entire support being able to remove the network details like APN and band are shown there too for sites that require a specific APN or like if your SIM is roaming or something.
Diagnostic View
And we have the diagnostic view where you can see a few things. You could see your internal temperature, did you have your current range and hookup, your circuit type set right in the recording, things of that nature, what firmware version you’re on. So things just to help you get a feel for if the device is configured right or working right, things of that nature.
Bringing It All Together
So to bring it all together, each live page answers a different class of question: shape, geometry, magnitude, spectrum, connectivity. And altogether, they help build a complete picture of what a circuit and its monitoring device are doing right now.
- The waveform catches dead inputs and obvious distortion.
- The vector diagram catches your wiring errors.
- The meter puts numbers to what the visual pages flag.
- The harmonics view shows you where the distortion concentrates.
- The cellular status confirms that your link is up and the signal’s good.
Running through all of that before initialization or right after takes a few minutes and potentially prevents weeks of bad data and follow-up site visits.
Any questions, feel free to reach out to PMI tech support. They’re available twenty four/seven, and they’re more than happy to take your call and answer your questions. Thanks to everyone who tuned in today. Be sure to check out all the links here at the end of the presentation, and see you next time. Have a wonderful day.