BLADE TIP EXTENSION
FIG4 shows components of a lightning protection system already present inside the blade
FIG4 schematically shows the tip end 24 of the wind turbine blade 18 to which the tip extension 20 (not shown in FIG4) is to be fitted. The blade 18 includes a lightning protection system 60. The lightning protection system 60 comprises a lightning receptor block 62 inside the tip 64 of the blade 18. In this example, the lightning receptor block 62 is a brass block. A lightning receptor (not shown), referred to as a 'blade tip receptor' and typically in the form of a brass bolt, is screwed through the outer shell 66 of the blade 18 and into the brass block 62. The lightning receptor block 62 is hereafter referred to as the 'blade tip receptor block' 62.
schematic
24
tip end
72
dashed line
18
blade blades
64
tip
74
end surface
76
connector
16
rotor
66
outer shell
62
block
60
system
70
down conductor cable
68
polyurethane implant
['1. A wind turbine blade assembly (22) comprising: a wind turbine blade (18) having a tip end (24) defining an end surface (74) of the blade; a blade lightning protection system (60) provided inside the blade and having a blade tip receptor block (62) inside the tip end of the blade; a blade tip connector (76) mounted at a predetermined position to the end surface of the blade and electrically connected to the blade tip receptor block; a tip extension (20) in the form of a sock fitted over the tip end of the blade to extend the length of the blade, the tip extension including one or more lightning receptors (50); a tip extension connector (54) fixed at a predetermined position inside the tip extension and electrically connected to the one or more lightning receptors of the tip extension; wherein the predetermined positions of the blade tip connector (76) and the tip extension connector (54) are selected such that when the tip extension is fitted to the blade, the connecters are mutually aligned and form a push-fit connection inside the tip extension.', '10. A tip extension (20) for the wind turbine blade assembly (22) of any preceding claim, wherein the tip extension is in the form of a sock and comprises an outer shell (28) defining a substantially hollow interior for receiving a tip end (24) of a wind turbine blade (18), and wherein the tip extension includes one or more lightning receptors (50) and a tip extension connector (54) fixed at a predetermined position within the interior of the tip extension and electrically connected to the lightning receptor(s), characterised in that the tip-extension connector being arranged to form a push-fit connection with a blade tip connector (76) provided at the tip end of the blade when the tip extension is fitted to the blade in order to connect the lightning receptor(s) of the tip extension to a lightning protection system (60) of the blade.']