A region of a positive charge formed around an arrester is made as small as possible to effectively suppress generation of an upward streamer. An inner electrode body 2 to be grounded, an outer electrode body 3 provided to surround the inner electrode body with a predetermined gap G, an electrical insulating layer S provided in the gap to hold the inner electrode body and the outer electrode body in an electrically insulated state, and a support 4 that supports at least one of the inner electrode body and the outer electrode body are included, in which the inner electrode body is formed in a rod shape, and the outer electrode body is formed in a cylindrical shape.

The present invention relates to a wind turbine comprising a lightning protection system comprising a waveguide interconnecting a communication device and a signal-carrying structure. In other aspects, the present invention relates to the use of a waveguide in a lightning protection system of a wind turbine, a power splitter and its use in a lightning protection system of a wind turbine.

An underground power cable system including: an underground power cable, and a metallic mesh extending outside of and axially along the underground power cable.

A multilayer protective covering can protect a surface from lightning strikes. The covering includes a bottom conductive layer affixed to the surface and having a first opening that is aligned with a grounding connection so that the grounding connection is exposed through first opening and not in contact with the bottom conductive layer. The covering also includes a dielectric layer affixed to the bottom conductive layer and having second opening aligned with the grounding connection so that the grounding connection is exposed through second opening and not in contact with the dielectric layer. The covering additionally includes a top conductive layer affixed to the dielectric layer and covering the grounding connection. The top conductive layer directs electrical current from a lightning strike on the surface to the grounding connection.

The disclosure includes a method of diagnosing a grounding system of a structure that includes a charge collecting structure conductively connected to the ground via a grounding path, where diagnosing involves an act of monitoring output of a voltage and/or a current and/or an electrostatic detector connected to the grounding path.

Electrical equipment is grounded in order to suppress ground potential rise in a healthy phase due to a failure of a line in a distribution line, to reduce abnormal voltages or prevent the occurrence of abnormal voltages caused by lightning surges, etc., to operate a protective relay when a ground fault occurs, or the like. Grounding is installed by burying a grounding electrode such as a copper rod in the ground and connecting the electrical equipment to be protected with a grounding line, and at this time, a reference value of grounding resistance varies according to the equipment. When grounding electrical equipment such as lightning arresters and transformers, it is necessary to lower a grounding resistance value, but a problem occurs when installing grounding by digging a pit in an urban area to erect an electric pole in that it is difficult to lower the grounding resistance value since it is difficult to install grounding in parallel because roads are paved. Accordingly, the objective of the present invention is to provide an apparatus and a method capable of lowering the grounding resistance value by digging a pit to erect an electric pole, and burying a grounding rod by means of hitting on a side of the pit diagonally in various directions, and installing grounding in series or parallel.

An aircraft of the type disclosed here includes an aircraft fuselage, a wing assembly, a tail assembly, and a surface structure containing a lightning protection device. The surface structure is arranged on the aircraft fuselage, the wing assembly, and the tail assembly. The lightning protection device has a plurality of electrically conductive elements, which are arranged at least as a group of elements in the surface structure. The electrically conductive elements belonging to a group are arranged parallel to one another, at least in some section or sections, and have different spacings with respect to one another, at least in two regions.

A region of a positive charge formed around an arrester is made as small as possible to effectively suppress generation of an upward streamer.

An inner electrode body 2 to be grounded, an outer electrode body 3 provided to surround the inner electrode body with a predetermined gap G, an electrical insulating layer S provided in the gap to hold the inner electrode body and the outer electrode body in an electrically insulated state, and a support 4 that supports at least one of the inner electrode body and the outer electrode body are included, in which the inner electrode body is formed in a rod shape, and the outer electrode body is formed in a cylindrical shape.

A fracturing well site system includes an electric-driven apparatus, a fuel-driven apparatus, an electric-power supply apparatus and a grounding system. The grounding system includes a first grounding terminal which is spaced from each of the electric-driven apparatus, the fuel-driven apparatus and the electric-power supply apparatus by a preset distance. The fuel-driven apparatus and at least one of the electric-driven apparatus and the electric-power supply apparatus are connected to the first grounding terminal, and the first grounding terminal is configured to ground the fuel-driven apparatus and the at least one of the electric-driven apparatus and the electric-power supply apparatus.

Provided is a rotor for a wind turbine, including: a blade, a hub, a pitch bearing being configured to support the blade rotatably about a longitudinal axis of the blade and relative to the hub, and one or more metal arcs for conducting a lightning current from the blade to the hub, the one or more metal arcs including: a first arc portion electrically and mechanically connected to the blade, a second arc portion electrically and mechanically connected to the hub, and a bent portion connecting the first and second arc portions. The metal arcs being configured such that, when the blade rotates relative to the hub, the first arc portion is shifted relative to the second arc portion and a length of the first arc portion is reduced or increased at the expense of an increase or decrease of a length of the second arc portion.