Lightning arrester and method of manufacturing and assembling the same

1. A lightning arrester comprising:

a serial unit including

a nonlinear voltage resistor block formed with a stack of a plurality of nonlinear voltage resistors, and

a compression spring that is arranged at one end of the nonlinear voltage resistor block and that exerts a predetermined reaction force on the nonlinear voltage resistor block in its stacking direction;

a pair of electrodes arranged to sandwich the serial unit in its stacking direction;

a plurality of insulating rods arranged around the serial unit along its stacking direction to couple the electrodes;

a plurality of fastening members that fastens the insulating rods and the electrodes; and

an insulating outer covering member that integrates internal elements including the serial unit and the insulating rods by directly covering the internal elements, wherein

each of the electrodes has

a plurality of insulating-rod inserting holes for inserting end portions of the insulating rods, and

a plurality of fastening-member mounting holes each being perpendicular to a corresponding insulating-rod inserting hole, and

both end portions of each of the insulating rods have a fastening-member through hole such that the insulating rods and the electrodes are fastened by inserting the fastening members through fastening-member through holes and mounting the fastening members on the fastening-member mounting holes.

2. The lightning arrester according to claim 1 , wherein a distance between the electrodes is set such that the reaction force is exerted on the serial unit by the compression spring.

3. The lightning arrester according to claim 1 , wherein each of the electrodes includes a joint portion with a joint hole for inserting a clamping member to connect the lightning arrester to another lightning arrester by stacking the lightning arresters.

4. The lightning arrester according to claim 2 , wherein each of the electrodes includes a joint portion with a joint hole for inserting a clamping member to connect the lightning arrester to another lightning arrester by stacking the lightning arresters.

5. A method of manufacturing a lightning arrester including a serial unit that includes a nonlinear voltage resistor block formed with a stack of a plurality of nonlinear voltage resistors and a compression spring that is arranged at one end of the nonlinear voltage resistor block and that exerts a predetermined reaction force on the nonlinear voltage resistor block in its stacking direction, a pair of electrodes arranged to sandwich the serial unit in its stacking direction, a plurality of insulating rods arranged around the serial unit along its stacking direction to couple the electrodes, a plurality of fastening members that fastens the insulating rods and the electrodes, and an insulating outer covering member that integrates internal elements including the serial unit and the insulating rods by directly covering the internal elements, the method comprising:

forming a plurality of insulating-rod inserting holes for inserting end portions of the insulating rods and a plurality of fastening-member mounting holes each being perpendicular to a corresponding insulating-rod inserting hole on the electrodes;

forming a fastening-member through hole on both end portions of each of the insulating rods;

inserting the both end portions of each of the insulating rods into the insulating-rod inserting holes, respectively;

exerting the tension on the serial unit by the compression spring in a direction of compressing a distance between the electrodes;

aligning the fastening-member inserting holes with the fastening-member through holes;

inserting the fastening members through the fastening-member through holes; and

fastening the insulating rods and the electrodes by mounting the fastening members on the fastening-member mounting holes.

6. A method of assembling a lightning arrester by using an assembly jig, the lightning arrester including a serial unit that includes a nonlinear voltage resistor block formed with a stack of a plurality of nonlinear voltage resistors and a compression spring that is arranged at one end of the nonlinear voltage resistor block and that exerts a predetermined reaction force on the nonlinear voltage resistor block in its stacking direction, a pair of electrodes including an upper electrode and a lower electrode arranged to sandwich the serial unit in its stacking direction, each electrode having a plurality of insulating-rod inserting holes for inserting end portions of a plurality of insulating rods and a plurality of fastening-member mounting holes each being perpendicular to a corresponding insulating-rod inserting hole, the plurality of insulating rods arranged around the serial unit along its stacking direction to couple the electrodes, each insulating rod having a fastening-member through hole on both end portion of each of the insulating rods, a plurality of fastening members that fastens the insulating rods and the electrodes, and an insulating outer covering member that integrates internal elements including the serial unit and the insulating rods by directly covering the internal elements, the assembly jig including an upper plate and a lower plate arranged opposite to each other at a distance regulated by a predetermined spring load exerted on the serial unit, the method comprising:

fitting one end of each of the insulating rods to the lower electrode;

inserting a jack between the upper electrode and the upper plate; and

assembling the lightning arrester in a state in which a predetermined repulsing force is exerted between the lower electrode and the upper electrode by aligning the fastening-member inserting holes with the fastening-member through holes, and inserting the fastening members through the fastening-member through holes.