IMPROVEMENTS RELATING TO WIND TURBINE BLADE ANTI-ICING SYSTEMS

A wind turbine blade comprising an anti-icing system (30) comprising an electrothermal heating arrangement (35) configured to provide heat to an external surface of the blade, wherein the electrothermal heating arrangement is connected to a power supply interface (38) of the wind turbine blade by way of a power supply conductor (40) and an earth conductor (44). The blade further comprises a lightning protection system (31) having a lightning strike protection device (56) associated with an electrothermal heating element of the heating arrangement, the lightning strike protection device being connected to a lightning down conductor (50) of the lightning protection system leading to a current transfer unit (54) configured to transfer lightning current to a rotor hub, in use. A transient current limiting device (60) is connected in a conductive path (62) between the lightning down conductor of the lightning protection system and the earth conductor of the anti-icing system, thereby permitting induced parasitic currents in the lightning down conductor to earth through the anti-icing system. This provides the benefit of preventing electromagnetic emissions that can, otherwise, cause interference with electronics in the vicinity of the wind turbine. Thus, allowing the wind turbine to comply with established EMC standards.