Transcript
Introduction
Power quality issues cost industries billions every year, and most of them never get properly diagnosed. If you work in the field, you know the frustration. Welcome to Power Quality Decoded, brought to you by Power Monitors Incorporated. Find us at powermonitors.com.
Hello, and welcome to another Power Monitors webinar. This week we’re gonna be talking about our white paper on delta and line-to-line voltage. We’re gonna go through a couple different phases. We’re going to talk about what is delta voltage? When are delta voltage configurations used? What’s the value of knowing about your line-to-line voltage in a wye configuration system? Let’s get started.
Three-Phase Power Systems and Wye Configuration
Three-phase power systems are the typical power input for commercial and industrial applications. Unlike your single-phase power which comes into a home, one live wire and one neutral, three-phase system delivers power on three live conductors, with voltage that’s 120 degrees apart.
You can see here we’ve got a couple graphics. You’ve got your typical wye configuration hookup here, which is one kind of three-phase hookup. This is where all three of the phase windings are connected with one end joined together at a common neutral. Kinda looks like the letter Y.
In this setup, your line-to-neutral voltage is the voltage between a given line and the neutral, which is typically what you’re measuring in a wye hookup with any power monitoring recorder. And your line-to-line voltage is the voltage between any two conductors. The reason you would use a wye setup is that you can supply both a single-phase voltage and you can combine two legs to create the higher voltage by combining two phases.
Delta Voltage Configuration
Delta voltage, also known as line-to-line voltage. Over here you got your three-phase delta setup. This is where all three of your phase windings are connected in a closed loop, which is a triangle, which also looks like the Greek letter delta. There is no central neutral point in a delta setup.
You’re gonna see a lot of delta configurations in heavy machinery. That’s because it works well for three-phase induction motors. It provides higher starting torque for quite a bit of heavy machinery. You’re also gonna see them a lot in power transformers.
Hooking Up Your Recording Monitor
Typically, if you’ve got a wye configuration system, you would hook up your recording monitor in a wye configuration, as we showed in those diagrams above. And if you’ve got a delta system, you would be hooking up a delta configuration, because the calculations internally are going to be a little bit different.
Why Line-to-Line Voltage Matters in a Wye System
However, there are reasons you might actually care about the line-to-line voltage in a wye configuration system. Some of the things you can identify while you are analyzing a wye system are load imbalances and transformer anomalies. You got a transformer that’s beginning to have issues, you’re gonna be able to diagnose this simply more effectively by looking at the line-to-line voltage. If you have phase issues, you’re going to see dramatic changes in the delta voltages that you might not pick up on just looking at line-to-neutral voltages.
Load Imbalances
We have a handful of examples here of things you can find. Load imbalances — you’re gonna be looking at your phase angle as well as your voltage magnitudes, and that’s gonna create an asymmetrical vector diagram. So if you’re looking at a vector diagram, you’d be able to see that, but if you’re just looking at a strip chart recording, it’s not going to be immediately obvious unless you were to look at the delta voltages.
Transformer Issues
Transformer faults have specific characteristics that’ll cause disproportionate delta voltages. You’ll get delta voltages that’s quite high between one of the pairs of lines and the others will be significantly lower.
Neutral Shift Considerations
One thing you need to keep in mind is that if you do have a derived neutral in your delta system, you are gonna wanna take a look at the measurement there as well. If you’ve got a significant voltage between that derived neutral and actual ground, it can give you a neutral shift which could mask these issues and give you some odd-looking data.
Using PMI Recorders and PQ Canvas
We’ve talked about why you might want to look at your delta voltage. I’m not gonna step a whole lot on the other white paper we have. That’s White Paper 383. You’ll see it’s linked there right at the bottom of this white paper.
If you are interested in using a Power Monitors recorder, the Seeker, the Bolt, and the Guardian on current firmware are able to provide data to PQ Canvas, are able to capture both the wye, the line-to-neutral voltage, and the line-to-line voltage of the same system in that wye configuration. At the same time, you’re able to look at and see both of those, able to switch back and forth.
I should also mention that if you were to use PMI View to download a recording from a device that is not streaming to PQ Canvas, or if it’s not in a place it can easily stream data, you could also download that recording off of the device with PMI View and upload it into PQ Canvas to take a look at those delta voltages.
All right. Well, thank you for joining us, and we’ll see you next time.
