Wind turbine owners are responsible for ensuring that the safety equipment used by personnel working the towers is always maintained and in perfect working order. But we get the impression that a number of turbine owners are not aware that such items as work cages and service lifts must be inspected, tested and approved once annually to fulfill safety requirements in most states.
The law says the owner must keep a certification journal with dates of the latest inspection. This journal also must describe the inspection and testing of all safety equipment in the turbine tower in detail. The certification journal must be present when authorities perform a check.
There is some difference in laws from state to state, but in general the requirements for maintenance are the same. And it will always be the owner’s responsibility to ensure that safety equipment works and is regularly tested and maintained.
Equally important is technician training. During training courses, such as those offered by my company, technicians learn about safety in relation to fire, evacuation and rescue from towers. Courses include theory but also rely heavily on practical exercises in towers. For example, one compulsory exercise consists of a trainee playing the role of an unconscious worker. His colleagues fasten him to the safety equipment contained in the rescue and evacuation unit which must be in the nacelle and then lower the unconscious worker and themselves to the ground.
This is a situation which we hope will never occur in the real world, but one which it is extremely important for employees working in towers to have been trained in. And the owner is responsible for ensuring that the personnel working in the towers are trained to use the safety equipment and that their training is kept up to date.
Other equipment is installed in the towers to protect and assist workers as they go about their jobs. Work cages mean that technicians avoid having to climb up and down the tower using the ladder. The cage will take them and their tools to the turbine nacelle. Cages can be stopped at any point in case there is work to be performed within the tower itself. When the doors open, the drive mechanism typically is disabled and technicians can work from the lift or they can climb out on the ladder.
Many towers also include a ladder system with a pre-mounted fall protection system. It is a statutory requirement that all ladders in wind turbine towers must be equipped with a safety system to prevent service technicians from falling from the ladders if they lose their footing or suddenly become ill. The fall protection system should stop the service technician after he or she falls a few inches. It remains locked until either the technician can continue alone or can be helped by colleagues.
The system developed by Avanti is based on a rail in the middle of the ladder. The service engineer’s harness is fitted with a click-on runner which clicks onto the rail. The runner is fastened to the engineer’s harness with a hook similar to those used by rock climbers.
The runner can be clicked on the anti-fall system anywhere on the ladder. The fall protection system is designed with a fixed rail on the ladder, which means several technicians can use the system simultaneously. When using wire-based systems, a technician must wait until his colleague has reached the nacelle before he or she can use the system.
Systems also are available that make it easier for technicians to climb towers. In simple terms, such systems are an endless rope which runs from the bottom to the top of towers. In some instances it is connected to a motor at the base of the tower. When the technician links to the system a hook and yanks the rope, the system lifts and lowers the equipment. If the technician stops climbing, the system also stops and starts again after a gentle yank on the rope. This type of system can reduce the risk of injuries to engineers’ knees, arms, shoulders and feet. These devices are not an anti-fall protection system. Instead, they are an aid for technicians and must always be used together with an approved anti-fall system.
One of the latest new safety designs is a special anchor which can be easily and quickly attached to a ladder anywhere technicians may need it. The technician securely clicks onto the anchor with a hook and is thus protected against falls no matter at what height he is working.