Transcript
Introduction to Voltage Regulation
Good afternoon, everyone, and welcome to today’s white paper webinar. Today, we’re gonna be talking about voltage regulation and how to best analyze this in our cloud-based software, PQ Canvass.
ANSI C84.1 Voltage Regulation Ranges
Before I get into the details of PQ Canvass, let’s review voltage regulation itself for a minute. As the paper describes, most utilities go by ANSI C84.1 for voltage regulation, and this gives two different ranges for nominal voltage.
The heart of this is the fact that there are two different ranges for nominal voltage. Range A is plus or minus 5% of the nominal. So for example, for 120 volt nominal, that would be 114 to 126 volts. The standard says that should be met most of the time, and it’s intentionally vague on what most of the time means, so that utilities can pick their own standard that is appropriate for that environment. Most utilities take that to mean 95% of the time, say for a one-week period, which means they can exceed that 5% of the time.
Range B is for short-term excursions only, plus 6% and minus 13%. So there’s quite a bit more leeway on undervoltage. But again, it doesn’t define how long a short-term excursion is, and it doesn’t say how often you can have these. Most utilities take short-term to mean five to 10, 15 minutes, and this type of excursion is meant for alternate circuit configurations or switching events or perhaps energization of something where the voltage may be low, but for a short duration.
Service Voltage vs. Utilization Voltage
Now, what’s important to keep in mind, especially for utility customers, is the difference between the service voltage, which is what we’ve been talking about, and the utilization voltage. The service voltage is plus or minus 5%. That’s the voltage at the point of connection where the utility hands the voltage off to the customer, typically the meter base.
The utilization voltage is the voltage measured at a piece of equipment inside that customer facility, and that’s going to be different. It’s gonna be, in general, lower because of voltage drop throughout the building wiring, through panels and subpanels and any transformers they have. All those elements have voltage drop due to their resistance. And so the voltage at a piece of equipment is going to be, in general, lower than the service voltage.
So ANSI C84 defines a range for utilization voltage, which goes quite a bit lower than the service voltage. And often a voltage regulation problem boils down to conveying this to the customer, that they’re measuring utilization voltage, and the utility provides the service voltage.
Looking at Voltage Regulation in Power Quality Data
When we talk about voltage regulation, we’re talking about average voltage. So we want to look at one-second or one-minute or even five-minute averages of the voltage. We don’t wanna be looking at voltage sags and swells on a one-cycle basis, like you would for a PQ investigation.
So here are our recommendations in our PC-based software ProVision for looking at voltage regulation. Here we have a graph that only has the averages turned on. We’re not looking at mins and maxes because, again, this is a steady state voltage issue, and steady state by definition means one minute or greater per IEEE, and not a voltage sag situation. If we’re interested in sags, that’s a different PQ investigation, and there we would want the minimums on. But for this purpose, we want just the average.
Turning those off helps simplify the graph for customers. So if you’re making a customer-facing graph, it’s helpful to just have the averages and also change the scaling so that the ANSI plus or minus 5% limits are on the screen. Here we have the scale changed so that you can clearly see the 5% high and 5% low, and that the voltage is well within those limits.
If you leave auto-scaling on, the software will expand the graph so that no matter how small the variation is, it’s gonna fill up the whole graph. So even the small change would go all the way across the graph, and that’s helpful if you’re doing an engineering analysis of the data. But if you’re just trying to show a customer that you’re within the ANSI limits, that can make things more confusing. So this is a good way to make a customer-facing voltage regulation graph.
Real-Time Voltage Regulation in PQ Canvass
Now, this is how you do this in ProVision, but the focus here is on real-time voltage regulation with PQ Canvass. PQ Canvass has tools to generate the graphs like we have in ProVision, but it can also go further and lets you create thresholds and email alerts and text message alerts so that you get notified immediately when an exceedance has happened, so you don’t have to wait till the end of a recording.
So here we have a data file loaded in PQ Canvass, and we’re going to show how to replicate the graphs here in the paper where we are showing the voltage and also showing those annotation limits.
Setting Up Custom Annotations in PQ Canvass
To get started, we’re gonna select RMS voltage. As previously mentioned, you’re going to want a custom axis so that your annotations will show. So in PQ Canvass, we’ll do that by going down here. Select Auto. We’re now in manual mode. And we’re gonna do 110 for the minimum and 130 for our maximum. And this is just for channel one.
Now with that set, we will go to the bottom right and set our custom annotations. So this will be our plus or minus 5%. This will be our plus 5%. And this is a nominal of 120 volts, so we’ll do 126. We’ll make that red, thick, so it stands out. Let’s do dashed. We’ll just say plus 5%. Save that annotation.
We go up here. You can see it’s here for use. We can add another annotation then. We’ll put that 114. This will be our minus 5%. Set that to green, thick, dashed, and we’ll say minus 5%. Save that annotation. It’s there for use. And there you go. It’s that quick and easy. You could then save the graph or print it out, again, for potentially showing to customers. This expedites the process and is quite convenient.
Email and Text Alerts for Voltage Exceedances
As the paper also describes, you can set up email alerts and text messages for these. These alert thresholds are sent to the device itself, and if the device sees a voltage exceedance from those limits, it will send a notification to PQ Canvass, which will then use the distribution list that’s been configured to send notices either via text or email to anyone who needs to know this. So you don’t have to wait until the recording is done to do that.
And of course, in PQ Canvass, with a Seeker or a Guardian or a Tensor or a Bolt, the PQ data is actually streaming to PQ Canvass in real time, so you don’t have to wait till the end of a recording anyway. You could always log in and look at the latest data and look at voltage regulation.
Contact Information
If anyone has any questions about the white paper, give us a call anytime at 1-800-296-4120, or send an email to support@powermonitors.com. Thanks for attending, everyone. Have a great afternoon.