Weather Guard Lightning Tech

How Active is Active Pitch Control for Wind Turbines?

In this episode of Uptime, Joel Saxum and Allen Hall sit down with the CEO of AC883, Lars Bendsen. AC883, a Canadian ISP specializing in blade repairs, has gained recognition for their unique approach to pitch alignment during the frozen ground season. Pitch misalignment is a topic of growing importance in the wind energy industry, and in this discussion, Lars shares his insights on its impact and challenges. He raises thought-provoking questions about the effectiveness of active pitch management and its potential limitations in practice. Join us for this engaging conversation as we delve into the complexities of pitch alignment, mass imbalance, and other critical aspects of wind turbine maintenance.

Sign up now for Uptime Tech News, our weekly email update on all things wind technology. This episode is sponsored by Weather Guard Lightning Tech. Learn more about Weather Guard’s StrikeTape Wind Turbine LPS retrofit. Follow the show on Facebook, YouTube, Twitter, Linkedin and visit Weather Guard on the web. And subscribe to Rosemary Barnes’ YouTube channel here. Have a question we can answer on the show? Email us!

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AC883 – https://www.ac883.com

AC883 Interview

Allen Hall: We’re here at CanREA with Lars Bendsen of AC883. If you are familiar with AC883, they are an ISP up in Canada that does all kinds of blade repairs. And one of the more interesting things that they do that’s unique is pitch alignment. So this is pitch alignment season when the ground freezes over and they take their equipment out and make sure your blades are pointing in the right direction.

And which Evidently, it is a thing that a lot of blades are not pointed in the right direction.

Joel Saxum: Yeah, Lars has shared that with us. Big problems all over the place.

Lars Bendsen: It’s for sure a topic that’s become more and more evident. There’s more and more people out there doing the same or similar way of detecting a pitch misalignment.

Yeah. Of course, there’s more awareness around it now than there was when we started doing it with our methods of doing it. So it’s for sure become a topic. There are also more engineering reports coming out from NREL. And from sorry, from the German Institute as well. Yeah. So there’s ton of rebar coming out of the damages that misalignment causes.

Joel Saxum: Yeah, it’s like running a car down the highway without an alignment on the front

Lars Bendsen: end. You’re gonna just… It’s funny, if you have your right tire and your car is unbalanced, you go in right away to get it changed. Which you don’t do with your turbine, you just let it run. Yeah, because turbines are cheap, right?

Yeah, exactly. It better cost any money.

Joel Saxum: Ha! We’ve been talking with Lars, of course, always great conversations, the knowledge that he has. And the AC 883 team and we’ve stumbled upon a theory that we want to talk about. So it, with the knowledge of pitch alignment and what you guys see out in the field, and of course seeing all kinds of different OEMs and issues that pop up, you’ve come across one specifically that we’ve been talking about.

Want to share that with us?

Lars Bendsen: Absolutely. I think it’s me throwing it out there and also to get some great feedback. So it’s my theory. And what we have seen is the the topic on active pitch. Which means you’re twisting the blades half a degree every time you pass the tower. And the reason they do that is?

Let’s do it because if you take some of the the, what do you call it, the What do you call it? I lost the word, right?

Joel Saxum: What do you call it? It’s like Wind buffeting causing

Lars Bendsen: deflection. Take the other way so we don’t have that and you can actually run in higher winds as well. Okay,

Joel Saxum: yeah. Yeah, because you don’t want that way if you’re running in high wind speed and there’s a lot of force coming by when that tower passes or when that blade passes the tower each time you get like a basically a pressure area of wind

Lars Bendsen: and what they’re trying to do is it’s a little bit of a reversed wake yeah going like that yeah and you get them by more pressure on the tower so that’s why i’m trying to avoid it and that means all you can actually expect the design envelope that’s not my theory that’s a fact by using active pitch you’re extending to this the same you design envelopes, you get more megawatts out of the same turbine.

Allen Hall: So it’s an efficiency move? It’s supposed to be, yeah. Now, you go out and measure hundreds or thousands of blades while they’re running, right? The turbines are running, you’re actually watching as the blades sweeps in front of the tower and you’re determining pitch alignment from that little snapshot there.

So you can see where active pitch alignment happens, right? Yeah,

Lars Bendsen: we should be able to see it. But we can’t. So we have clients that, we asked him to take the active pits off. So we have, I have a more true measurement off the blades of the rotors state, so to speak, but some of them forgot to do it or cannot do it himself.

So they’re running with active pits because depending on what access they have to their own controller from the OEM. Yeah, or what service they have, they might be don’t even have access to do it. Yeah. They have to call the OEM. to take the active pitch away. And that’s way too common in the industry.

That shouldn’t happen. It’s that’s, I think that’s a different topic. Yeah. Of the balance between Mona and OEMs, that’s a different topic. Yeah. that we have seen with or without active pitch, there’s no difference in the misalignment. When

Joel Saxum: that blade comes by and it’s supposed to be moving that half degree back and forth, when you guys are doing your pitch alignments with your actual laser instrumentation, you don’t actually see it.

We don’t see it.

Allen Hall: Now is that a, a, a. A function of the pistons that are driving the blade not functioning properly, which is a thing because you see a lot of oil and a lot of debris around those pitch actuators.

Lars Bendsen: I think it’s it’s many things. It could be the pitch actuator is not working properly.

That’s one of the issues. Yeah. I also, but it’s more consistent. So if it was that issue, it would be the, it would be only on one blade, but it’s on all three blades. If that was the real

Joel Saxum: issue. If the pitch motor was bad, you would see it on, one of them would be bad or something like that. Just

Lars Bendsen: be oil everywhere.

Yeah. Okay. But we don’t. So my theory is, and based on the real, what we call experienced technician in the field, is that it doesn’t work. So in theory, if you see we have the blade that’s 50 meters long, running on, on rated speed, let’s say 7 or 8 meters per second. We have about 40 to 50 ton of pressure onto the blade as it swipes down to 40, about 40 tons of pressure to the blade.

And we have a two horsepower motor, a two kilowatt motor up here, trying to switch it plus minus five degrees, but in an angle of 10 degrees with 15 RPM. And that

Joel Saxum: blade itself weighs 10

Lars Bendsen: tons? And yeah and the flexibility in the blade, which you, it’s built in because you want to have a flexible blade.

So how is that going to work? You want a two horsepower motor? 50 meters down, turn a turn a flexible blade with 40, 40 tons of pressure on. Your theory is starting to make sense. That’s my two cents. I’m interested to hear if anybody… I doubt probably a ton of those listening are gonna disagree with me, and that’s okay.

That’s what we’re here for. That’s my theory, and that’s what I’ve heard and what I have seen. And also talking to pitch guys, they love it. Because they’re selling a lot of pitch cylinders. We’re getting a lot of pitch cylinders. Because the thing is here, you’re basically only… twisting the rubber sealing.

You’re not actually moving anything. The rubber is flexible itself because it has to be. So you’re just twisting the rubber sealing and that got worn out so the blade

Joel Saxum: is not moving. So what you’re saying is when that blade is sweeping down and it gets near the tower at six o’clock, that the pitch, the active pitch management is engaging that motor to turn that blade a half degree and then turn it back.

But because of the forces on the blade, it can’t actually do that. At a two horsepower motor. And so it’s just basically spinning the motor or pitch cylinder is just spinning in itself up top.

Lars Bendsen: Yeah it’s because there’s a rubber ceiling up here. Yeah. So it basically just twisting the rubber ceiling and not actually doing it.

And I think even if it didn’t, even if it didn’t, was either it was a fixed connection without a rubber seal, then would it then be able to do it 50 meters down

Joel Saxum: with 40

Lars Bendsen: it just strip the motor. I would’ve just strip the

Joel Saxum: motor. Yeah. Either way, if this thing is doing this. It’s moving like that. And if you’re talking 15 RPM for the rotor, that’s four times, or what’s

Lars Bendsen: the math on that?

That’s 45 times.

Allen Hall: Yeah, 45

Lars Bendsen: times

Joel Saxum: a minute. That’s a lot of movement

Lars Bendsen: within that thing to get hot, constantly. So my theory, and based on what we have seen, there’s no difference in our system, whether they use it or not.

Allen Hall: How would they know that the system worked in the first

Joel Saxum: place? They would have had to have had tested

Allen Hall: it.

They would have had to have laser shot it, right? How would you know… You can obviously see the motor working, if you’re up in the cell. You can see that twist happen. But how do they know what’s happening way down at the tip? I believe,

Lars Bendsen: of course, you can see the control system that is working.

It does its job. They can see that. Of course, the actuator is moving. They can see that. But it’s a physical moving down on the blade. Can you see it? We’re producing power on the last third of the blade. Yeah. Whatever, from the tip up. Yeah. One thread up, that’s where you’re losing power. But do they actually move down there?

We can’t see it.

Allen Hall: So if you can’t see it, that means that either one or two things is happening. Either it’s not moving the blade at all, or you’re putting some unique torsion into the blade. The blade’s absorbing the rotation you’re trying to impose on it, so you’re twisting the blade every time it comes around the

Lars Bendsen: tower.

But it’s interesting, if it was working as it’s supposed to do, then we would see a difference, because every blade is different. All blades are handmade, so unless they have exactly the same twist, which is, I doubt they would have, but if

Joel Saxum: they had, you would see different levels of deflections. Yeah.

But, either way, the design of active pitch management is going to have a wear part in the pitch cylinder, it’s going to introduce structural fatigue within the blade, so is the juice worth the squeeze even if it was? Because we’re saying that’s not working as a

Lars Bendsen: theory. Yeah, I don’t know the theory behind the blades, if it really has that high an impact.

That’s, somebody had to read more school books than I have to figure that out. So I don’t know that, only from an engineering perspective, because the blades are flexible. Anyhow, they have to be built flexible. And just the fact that they have to be built flexible is that, my theory is, it doesn’t work.

You cannot twist that 50 meter blade in that short time, 45 times per minute, and come back. So that’s my true sense from the, from my experience.

Joel Saxum: So if you were, if you had an operator sitting with you right now at the table across from us, and they had active pitch management in their turbines, what would you tell them?

Lars Bendsen: Depending on the wind scheme, you have to be careful about that. What wind scheme do you have? Let’s say in low wind, very low wind, you might be, would have that twist. I don’t know why you would use it in low wind. Why would you need it? No, I agree. That’s my point. In high wind, I cannot see the need for it.

I can’t. But I would love to see if somebody would argue against me and tell me why I, my theory is wrong and show it to me physically. I want to see that twist coming. I would love to see it. I hope it works.

Joel Saxum: Because otherwise it would just be like, Hey, I know you have this in your turbines, but shut it off.

Cause you’re just causing yourselves. You’re not you’re actually costing yourself more because now you have another O and M part that you have to. Oh yeah. Yeah. Yeah.

Allen Hall: Because the concept between. By active pitch from a blade standpoint as blades get longer is you could make lighter blades you could use that flexibility to your benefit make the blades lighter He transports a whole bunch of money materials, right?

That’s the thought process in it But if it doesn’t actually do the task, then you’re really at a big risk But also it’s a major problem

Lars Bendsen: the theory behind this also take the load off the tower, right? So that’s right that means you can cruise happy. You can increase Your design criteria from, I’m just saying 2 megawatt to 2.

3 megawatt, as an example, by having four enforced active bits. If it doesn’t work, are you then going over your design envelope, or are you just squeezing it to 105%?

Allen Hall: So I want to take this discussion over to mass and balance. Yeah. So mass imbalance seems like it’s a more peculiar failure mode or not so much failure mode a missed opportunity.

I’ll call it that especially on a blade Swap out. Yeah, they have a blade damage problem They’re gonna put a new blade on it and they just slap on a new blade That doesn’t necessarily mean that blade is matched with the other two that already exists so now they have this kind of this really weird rotation aspect where It seems like two of the blades are moving faster than the third one.

Yeah, true. How do you detect that, and, first, describe that. Like, how do you measure to know that one blade is off weight wise? Okay.

Joel Saxum: The first part, you gotta start with getting the blades

Lars Bendsen: served. Yeah, first of all, we need to, when we are measuring, first things first, we’re getting the same angles so they are all aerodynamically aligned.

Okay. Start there. Okay. And after that, then we’re measuring the mass imbalance. And we’re doing on a rotation because we come to call it shiang. If everything works well, it should be 120 degrees between the blades, right? But it, we are measuring the plus and minuses time that comes down a long time or many degrees is that delta from blades A to blade C to blade B, how much is they in between?

And if one is always coming down, a heavy blade coming down faster that way, then it goes up slower to the next one. So we measuring the delta between and the rotational speeds ’cause it should go like. 100 right? But it has always this, if you have the mass imbalance.

Allen Hall: So that, that is torture on a gearbox and a drivetrain, right?

Absolutely. Main bearings?

Lars Bendsen: So there is a, there are two things. If, then one thing is the aerodynamic balance, unbalance. If it’s within reason, whatever that means, within a degree, of course it has an impact on the drivetrain. But if you have extreme aerodynamic imbalance, four or five degrees, which we have seen, then that’s equally bad as mass imbalance.

So back to the mass imbalance. Let’s say now we have aerodynamically balanced. Now we have the mass imbalance. And as you said, change the blade. We had some that should be weighted out. They should be balanced. Everything should be good. The client did not tell, then the clients do not tell us if they have a blade repair.

They tell us after the fact. Oh, why is this one out? Oh, by the way, we actually changed the blade. So on one of them we found there was 82 kilos missing in chamber number two. 82 kilos missing. The turbine could not run over 70 meters per second. It was stalling. Sure. And the blade tip on, you see the, what do you call it?

When you see the rotation from the side, the blade tip delta was five feet. It was one meters and one meter 20. So

Joel Saxum: like basically as the blades passed the tower, one of them was closer to the tower by

Lars Bendsen: five feet. It was actually, no, it was closer to away from the tower. Okay. Because if you see those 82 kilos missing.

It’s not heavy enough, not big enough. It’s actually, it’s further away from the tower. And that was a median 20, so that’s 4 feet. You can see that with your blind eye. We can see it and we can hear it. We can hear the whistling. Yeah, that’s crazy. 100%.

Allen Hall: What percentage of blades have mass imbalances out there?

Lars Bendsen: From what we have seen, we have done about 1, 000, 1, 200 blades. Might be more, not blades, but turbines. Might be done more, I can’t remember. But turbines from. Zero to four years old and say four to eight and over age. Let’s try to do that. The newer turbines is about 15, 20 percent out of bounds.

And once you move up, then you’re about 30 to 35%. And once you get over eight years old, it’s 35 to 50 percent out. Whoa. And that’s, I could go more detailed, but that’s rough numbers. For sure, sorry, but GE turbines older than eight years. That’s 50 percent out. Gemesa turbines, 8 years old, we had a site of more than 100 turbines.

52 were out of bounds. So that’s some examples. Okay, that’s a

Allen Hall: lot. That’s a lot. Way more than I was thinking it was. And that’s mass imbalance or pitch

Lars Bendsen: imbalance? That’s aerodynamic. Aerodynamic

Allen Hall: imbalance. Yeah. Okay. And mass imbalance, where do you think the

Lars Bendsen: number is?

I don’t, I can’t, it’s hard to quantify. I can’t do that because we only see it if we are being called out. All via catching it by

Joel Saxum: coincidence. One of the things that I always wondered about is insurance case, blade gets swapped out. A lot of times they say, hey, we gotta put three new blades up because we can’t find one.

Or if they have a safe harbor blade sitting at the O& M building, hey, that one actually, the weight cert’s close enough, da. Would you recommend that, hey, if you’re gonna swap a blade out, no matter if it’s one blade, or you’re doing a whole rotor set, if it’s a case like that. Come out and get the pitch alignment

Lars Bendsen: checked.

Should for sure get it done anyhow when you’re changing one blade. Yeah. Because the zero mark doesn’t really give you much. It’s not very accurate. Yeah. So we have to get the message somehow, or get it adjusted. Could be the vowel laser, or someone else, but you need to get it mapped out.

Another thing that’s important is that, the spec sheet from the one turbine we had that was really severe, that was a spec sheet from from LM. Tells you where the weight is. And it turns out that person who made that balance did not follow that spec sheet. She was just missing 82 kilos. Wow. So that’s another thing as well.

ISPs, independent contractors, seems not always being educated to the work they do. Sure. Yeah. Yeah, that’s an industry wide problem. That’s industry wide, but also many turbines are, of course, mostly placed in rural areas. So how do you get qualified? Yeah,

Joel Saxum: it’s tough. That boils down to the technician issue that we’re always talking about.

Yeah, right training

Allen Hall: is what just one thing Back me up on the GE aero dynamic alignment issue. Is that just a wear and tear on the structure, that the twisting of the blade, having done so many cycles, that it doesn’t, they don’t behave the same as the age? Because that would make sense to me. That on…

Yeah. Structural fatigue, yeah. It’s a structural fatigue issue. I think

Lars Bendsen: also that’s so the GE, of course, is electrical bits. There could be an encoder that doesn’t work properly. Or might be the controller get the signal, it does move. But actually it doesn’t. So that’s one thing, and then of course the, I’m just saying the Vestas, the the Siemens, that’s hydraulic bits.

And there you see that’s leaking pit cylinders they’re wandering because they’re slowly leaking, so you don’t get the movement they think they

Joel Saxum: get. What? It’s easier to see that if you’re up in the nacelle, or looking in the hub, it’s easier to see a problem with the hydraulic bits.

Lars Bendsen: Electrical bits you can’t really see it. Yeah.

Allen Hall: So if that’s so prevalent. What kind of AEP loss is that? That turns into power production issues. Yeah.

Lars Bendsen: There is power production. You’re losing power in the low wind area. Not as much in the high wind area. You trade off in high wind, you get way more vibration.

Yeah. But you’re losing, you have less vibration in low winds, but you’re losing power in high wind. You get way more operation where you’re using your gear pass.

Joel Saxum: Yeah. You’re wearing

Lars Bendsen: components out prematurely. You’re gonna pay either way, , you’re gonna pay in little bit one way and missing production. Yeah.

Allen Hall: What are the first signs that you know you may have a pitch alignment issue? Is the SCADA system chipping off before you’re in high wind conditions? Are you getting alarms, let’s say? Something is wrong?

Lars Bendsen: Vibration alarms. Vibration alarms, you get that from the ABA. A lot of vibrations in this turbine.

It’s stalling after seven meters per second. Let’s check that. And then we’re going out and then we’re digging into it. And mostly we find out it is a aerodynamic imbalance or a mass imbalance.

Allen Hall: I know one of the… issues from GE more recently over in Europe was they had a couple of blades snap off and then they traced it back to a single sensor in the turbine now I’m catching it soon enough, like there’s an issue with the sensor.

Yeah, that’s the story we’re being told today. Yeah, I’ve seen that story a couple times now, so it seems to be a pretty consistent story. So if that’s the case, is that basically a load imbalance, an aerodynamic imbalance, then that it’s not catching…

Lars Bendsen: Of course, if you don’t catch the vibration regardless of where it’s coming from, already there you have an issue because then again you’re going to pay later. If it’s from, if that could have been caught by the sensor working and thereby you could adjust your blade, I don’t know, but that’s an option.

Allen Hall: What’s the issue though? Is it an aerodynamic imbalance? Not shipping the sensor. Forget about the sensor for a minute. The sensor is there to capture gross errors, right? So if they had a gross error, and in a blade, which would cause the blade to fatigue and break, I would assume that’s a vibration sensor of some sort and that the issue would be, could

Lars Bendsen: be as simple as pitch alignment.

Could be, yeah. But we see, vibration level, we see that caused by both. Okay. The shorter vibration level could be caused by aerodynamic imbalance, but that’s more a vibration level. If you have a massive imbalance between the oscillation of the tower, and then you’re down to the foundation, and then you’re really in trouble.

Allen Hall: Yeah, because I think that has a lot to do with repowering. So we talked to Onyx Insight for instrumenting towers for the amount of sway they have. Yeah. There’s a couple of companies doing this, but basically they’re monitoring the towers from the sway they have because it helps them determine the structural integrity of the foundation when they go to repower.

Put a slightly bigger blades, maybe a slightly bigger generator on this thing. They have to know what the foundation is doing, and it takes 12 months to do it. But my guess is that when they monitor some of those turbines, they must be seeing some decent amount

Lars Bendsen: of sway. We are seeing, we can see sway up to 600, 700 millimeters.

Half a meter and more. Whoa. But one thing is the sway, but what if we have the isolation?

Allen Hall: It’s not back and forth, it’s left and right. No, it’s actually elliptical. Yeah, it’s elliptical right. Yeah. That’s a big problem for a

Lars Bendsen: foundation. That’s why we have seen, tower collapse and we have seen the change of foundations.

It’s out there. We went to sites where basically there’s no dirt around the foundation because it’s all shaken apart. Wow. It’s horrible. Sometimes it’s scary, but you see a lot of stuff, but I do believe by, we were one of the first movers doing this. We have a ton of people doing it with different technologies.

SCADA data, which can be done to, might be more data heavy. And more on the backend of the engineering department. Heavy. There’s high speed cameras, different ways of doing it. Sure. But it’s the same issue we’re trying to address. So by we have more people out there doing it. It’s got more awareness, I believe that people know.

Yeah. Oh my be is not only a 83 finding stuff. Yeah. But there’s actually a lot of findings out there.

Joel Saxum: Speaking of finding stuff, Lars, I got a question for you. ’cause this is something that I was actually talking to someone last night about. Is blade bolts. Yeah. So blade bolts, whether it’s pre tensioned, post tensioned, however they’re tightened, Torqued, over torqued, under torqued issues with the torquing guns when they go on, all these different kind of things.

If there was an issue in either the blade bolts torquing, breaking, or say the actual pockets that they’re epoxied into starting to move, Would you guys be able to find that with your pitch

Lars Bendsen: measure as well? I think it would be hard for us to tell that is a root cause. But there’s a lot of boxes we check once we we can see it’s in balance, right?

Check, that’s good. If we still have vibrations, but we have no tower movement, okay, then we might be looking at the drivetrain. Yeah. There could be some gearbox or main bearing issues. If we, is that also in okay, but we still have a lot of sway, let’s check the imbalance, the mass imbalance, which we’re also checking, right?

So we get the report fully from right away.

Joel Saxum: So it’s, so you’re using your pitch alignment methodology as a

Lars Bendsen: diagnostic tool. Yeah, it’s more than just, it’s more than just a, what do you call it measurement tool. We also get a lot of checking boxes. Is it that? Is it that? Is it that? It could be different reasons.

Blade twists. We have detect, we have detected huge what do you call it failures in blades. We had a tip that was twisting five, six degrees compared to the rest, and there was a crack in the blade. That we that was by pure coincidence. That was not why we were on site. But we see a lot of stuff, a lot of boxes you can check.

Once we do that analytics. And it takes seven, eight minutes. That’s it. And we get the whole report. Then we are checking some KPIs if they are okay. And then we move on to the next. Or we analyze a little bit on site. What it is.

Allen Hall: So we’re in the peak pitch alignment season. Because the ground is frozen.

That makes life a lot easier. And

Lars Bendsen: We have more constant wind than in the summer. So we need a constant wind speed. What’s your, what,

Joel Saxum: what are your constraints for actually

Lars Bendsen: doing it? Roughly between four to ten, ten meters per second. But it’s more important we need the number of rotations. We need roughly six RPMs.

That means a GE meters, 37 meters. Slaves, yes, they’re spinning way faster than a 53 meter blade. But roughly 7, 7 RPM would be good for us.

Allen Hall: So then, this is the time to be calling AC883, right? Where at the end of October, the ground’s starting to freeze up in Calgary, clearly. Absolutely.

It’s moving south rapidly because you want to get ready for the season. The peak production season. Yes. And you want to have your blades aligned to get rid of some of these. Exactly. Historical problems that are happening.

Joel Saxum: Or if you want to talk to Lars about his active pitch management. Yeah, you’re going to have to talk

Lars Bendsen: to Lars to definitely talk about that.

Oh, absolutely. I’m happy to take the discussion. And I’m happy to be turned around. I would love that.

Allen Hall: So how do we find you on

Lars Bendsen: the interwebs? Interwebs is just ac883. com. Okay.

Allen Hall: AC883. com. Yeah. It should be right there. Okay. And then also only you can check out on LinkedIn or you can, especially if you have alignment issues, you can reach Lars directly on LinkedIn. Talking about the act of vigilante.

Lars Bendsen: I’m happy to take this discussion. I’m happy to take this discussion. I’m happy to cave in. Totally happy to do that. That’s just my practical two cents. And there’s probably a bunch of engineers that can tell me different. I would love that.

Perfect.

Allen Hall: Yeah. Lars has been fantastic. We don’t get to see you so much just at conferences because we all that’s how this works. But yeah. And this has been great and I, and this has been a great conference in Canada and we appreciate all the support you’ve given to Weather Guard. Yeah.

And it, it’s been fantastic. Really. It has been. Thank you. My pleasure. Really, we appreciate all the effort there. So yeah, you have to take us out for a steak tonight or Joel and I just steak

Lars Bendsen: tonight. . Absolutely.

How Active is Active Pitch Control for Wind Turbines?