CNC Onsite’s Innovative Yaw Ring Repair Method

Søren Kellenberger, sales director at CNC Onsite, joins the Uptime
Spotlight to discuss their uptower yaw ring repair method. He
describes the root causes of yaw ring failure, makes projections
for the future, and introduces CNC Onsite's patented yaw ring
repair solution. Their portable precision machine can be lifted
uptower to replace a damaged yaw ring, potentially saving operators
significant downtime and repair costs. Fill out our Uptime listener
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www.weatherguardwind.comIntelstor - https://www.intelstor.com Allen
Hall: When wind turbine yaw gears fail, operators face a costly
choice. Hire a crane for a complete replacement or attempt a risky
repair. This week we speak with Søren Kellenberger, sales director
and partner at CNC Onsite. CNC Onsite brings precision machining up
tower. Making yaw gear repairs faster and more reliable without
using an expensive frame. Welcome to Uptime Spotlight. Shining
light on wind energy's brightest innovators. This is the Progress
Powering Tomorrow. Allen Hall: Søren, welcome to the show. Thank
you very much, Allen. And thank you for inviting me. Well, we want
to understand first, what is causing yaw gear to break? teeth to be
damaged in some of these turbines, because the photos I have seen
are remarkable. The teeth are just gone. How does that happen?
Søren Kellenberger: I think there can be a number or there can be a
number of reasons. And it, it depends a little bit, I think, on the
turbine, how the yaw ring was designed and stuff like that. But if
you look at some of the older turbines the yaw ring. Wasn't
hardened. So there, in many cases, you'll just see wear and tear
from years of of use, operation. And typically in a, in a wind
farm, you have a dominating wind direction, right? So, Especially
in Denmark, it's mainly blowing from the west. So all our wind
turbines are pointing that direction most of the time, which means
that they are yawing within a limited area of of the yaw ring. So a
limited area is taking the majority of, of the wear cycles. So, so
therefore they, you, you see some, some local wear and tear and,
and finally they will be worn down razor sharp basically and, and
break off eventually. So, so that can be, be just one cause of, of
the, of the failure. We also see sometimes that even though they
are hardened, they, of course, they don't wear that much, but they
will more break off and probably. Due to some extreme loading and I
guess that can be caused by either some, some misaligned yaw gear
it can be extreme loads. You have some sites where you have Really
wind directions changing very fast that is causing unforeseen loads
on the turbine. So you have actual extreme loads that are, that are
higher than the design loads. You could probably also sometimes see
foreign objects that are, are falling into the, to the ying and
being squeezed between the ying and your gear, causing some, some
damages. So. There are a number of, of different reasons for, for
these damages, I guess. Joel Saxum: Do you see anything
environmental? Like in my mind, I think of these Arctic turbines,
right? The ones that are operating in this, in the extreme cold.
When, when metal gets cold, it gets brittle. Do you see more, more
yaw teeth get damaged in those territories as others, or is it just
kind of across the board the same? Søren Kellenberger: No. We
haven't seen that, that these cold condition turbines are affected
more than than others, but we do see that the weather conditions
play a significant role. And. If you have maybe your ring damages
on two to 5 percent of, of, of your turbine fleet, then they will
not be evenly distributed across your different parks. It tend to
be that if you have an effective park due to some special weather
conditions in that area, you seem to have a lot of problems in that
one park, and you can have other parks that will run perfectly fine
for, for your the entire lifetime without any issues on, on the yaw
ring. Well, at least these inspections aren't super difficult.
Yeah, it's pretty obvious when they are missing. Allen Hall: What's
the effect when they're missing teeth like that? Is it, is, is the
turbine just not able to yaw anymore or is it, it really, it risks
some structural overloading when that happens? Søren Kellenberger:
Yeah. I mean, in in the beginning, I guess you, you won't be able
to, to yaw. So at least you, you, it would be less accurate if you
have. where it will start being less accurate. And that will of
course cause some loss production. Potentially if, if you are
misaligned on your, your system, you're also introducing unwanted
loads to your, to your turbine. So I guess it could have also other
consequences when you are other than. Just lost production when,
when you have a yaw misalignment. But yeah, in, in the end you
won't be able to to yaw the turbine if you have too many damaged
teeth. Allen Hall: So is the turbine sent out an alarm when that
happens? Is it just a, a complete shutdown? The turbine just says
no more. I can't move and I'm stopped or it doesn't recognize that
this is even a failure. To be Søren Kellenberger: honest, Alan, I'm
not 100 percent sure. And I think it depends also on, on on the
turbine how, how, how new or old they are and how advanced their
control systems and condition monitoring systems are. Some of them,
they just have on off on the, on the yaw gears. And, and they won't
recognize that, that one yaw gear is just spinning in free air but
you can have others that have more advanced control systems where,
where you can see that some of the yaw gears are suddenly using a
lot more power to to yaw the turbine, which will indicate you have
some kind of yaw issue. If it's a bad yaw. A broken yaw gear or if
it's some teeth missing in that area where that yaw gear is placed
you, you can't probably tell, but, but there are different warning
systems possibilities, but again, depending on how old or how
advanced your, your turbine is. Allen Hall: Wow. So this is really
serious. It's just beyond just the tooth missing. The consequences
for the chairman can be quite dramatic. Now, CNC on site,
obviously, is all about doing machining. How do you go about fixing
this problem? Søren Kellenberger: Basically, we have a a smaller
CNC controlled, three axis CNC controlled machine that we bring up
tower and these machines are adapted to the different different
requirements. Turbine types. As you can imagine, the turbines were
not designed for these kinds of repairs. So the design engineers
originally didn't leave much space for for a machine in those
areas. But so, so we, we customize the machines to fit the
different turbine platforms and, and. Basically we use the internal
crane of of the turbine to hoist the, the machine components to, to
the turbine. Use the internal crane to, to position it at the yar
ring. And then we mount the machine on, on the Yar ring itself.
Which also gives us the advantage that even if the turbine is
moving a little bit due to, to wind we are moving along with it. So
it doesn't influence our our accuracy when, when machining. Allen
Hall: That's quite impressive. Cause the alternative is, and what
I've seen is you lift the whole, you take the blade set off and
then you lift the whole in the cell off and then you go in, you try
to replace the yaw gear, which is super expensive. Søren
Kellenberger: That is, that is very, very expensive. Allen Hall:
Yeah. So you're really talking about taking up some precise
machining equipment up tower. Doesn't really matter if the wind's
blowing or not. You're, you're fine. You're all inside. And you're
going in and machining what remains of those teeth. I mean, I, I
want to have a sort of a dentist equivalent of this. So it's like
you have a broken tooth and, and the dentist comes in and goes,
okay, we're going to grind that tooth off and we're going to smooth
out. And we're going to put a replacement. On top of it, like a
crown, right? It's basically a crown. So that process takes how
long to do once you kind of uptower in your starting the machining
process. Søren Kellenberger: If we if we use like the, the Vestas
V90, three megawatt platform as a sort of baseline then it takes we
have, we have our, our teeth segments, our crowns. If you, if you
want in in segments of of six teeth and it takes roughly one day to
once we are open and ready to, to replace six teeth. So for a
replacement, you need to consider one day of hoisting and getting
in place and then. One day for, for each segment you need to, to
install and then one day to, to pack up and clean and get back
down. So so we, we get quite a fair bit done in a week. Joel Saxum:
Yeah, that's, that's impressive. So, so there's a couple of
activities here that have to be done, right? Of course, you're
getting up there, you mount the CNC equipment. That's one big part
of it. But then you're, you're, you're milling up tower. So you
have to deal with, you guys have a, you have a system to deal with
all the filings and tailings and catching all that stuff. And then,
and then once you put the new teeth or the new teeth get in place,
is, are they welded in place or how are you, how are you attaching
that? Søren Kellenberger: No we bolt them in place.