UPTOWER SOLUTIONS

Can a yaw ring be repaired on a wind turbine? A wind turbine yaw ring that has suffered damaged teeth can be repaired. The repair can be done by competent technicians equipped with the right precision machine. The repairs are done directly in the wind turbine tower/nacelle. The whole yaw ring does not need to be replaced. This naturally saves significant costs. Removing the whole yaw ring and installing a new yaw ring means the whole nacelle must be removed first. This involves a crane and other logistics as well as lost production during downtime.

How is the yaw ring repaired? The repairs of the yaw teeth are performed uptower without the need to disassemble any wind turbine parts. The Danish company, CNC Onsite, has developed a precision machine and a method - both of which are patented - that technicians employ to repair yaw ring teeth in a range of wind turbine types. How is the yaw ring repaired? The wind turbine yaw ring is located below the nacelle. The space around the yaw ring itself can sometimes be tight. CNC Onsite’s precision machine is designed to fit into the limited space available. The process for yaw ring repair is simple. The precision machine is programmed by the technician and then mills away the damaged yaw teeth automatically. This leaves a pocket which has grooves, ridges and threaded holes that are used to hold the new replacement teeth firmly in place. The new pre-fabricated teeth come in segments which have from 1 tooth to 6 teeth depending on the damage and the turbine type. The new yaw ring teeth, which have been designed to fit the damaged yaw ring exactly, are then inserted into the pocket. The new segment is mechanically fixed in place and slots in like a jigsaw piece thanks to the matching pattern on both the new segment and inside the pocket.

How many yaw ring teeth can be repaired? It is possible to do consecutive repairs and in principle all teeth on a yaw ring can be replaced by this method

How many wind turbines are affected by damaged yaw ring teeth? There are no exact numbers but it is estimated that 5-10% of all turbines will experience damages to the yaw ring to some degree during its lifetime. These 5-10% are not evenly distributed across the fleet. It is more often seen that some sites are more exposed to this type of damage due to site conditions. These parks will often have a higher percentage of affected turbines, while other will have lower percentages or none at all. However, usually if one yaw ring has damage, more than one wind turbine will suffer from the same type of yaw ring damage within that site. CNC Onsite therefore recommends that all wind turbines are checked for yaw ring damage before the repair team arrives to repair the wind turbine yaw rings.

How quickly can the yaw ring technicians come to the wind farm/park? CNC Onsite’s yaw ring repair technicians can be onsite in a matter of days from received purchase order depending on where in the world the yaw ring repairs need to be conducted. The service is offered worldwide. How long it takes to repair the yaw ring depends on how many teeth are damaged and other factors like accessibility to the wind turbine. The CNC machine is hoisted up in the nacelle in several parts and is then assembled in the small space around the yaw ring. The average time for yaw ring repair is between 8 and 12 hours per segment.

What does it cost to repair a yaw ring? Compared to the alternative which is to replace the whole yaw ring when the teeth are damaged, the yaw ring repairs conducted by CNC Onsite’s team will cost a fraction of the replacement of the whole ring. This is because the whole yaw ring replacement involves a crane to lift off the nacelle, more manpower and safety precautions, which are all costly but also the wind turbine downtime is costly. Each case has a different cost calculation. No case is exactly the same when it comes to damaged yaw ring.