Technical specifications and precautions for lightning arrester project installation:
I. Installation technical specifications
1. The distance from the protected equipment is ≤5m (GB 11032-2020 regulations), and a laser rangefinder is used for calibration.
2. Installation height to the ground: distribution type ≥2.5m (pole tower installation), power station type ≥4m (frame installation), error ±50mm.
3. When installing multi-section lightning arresters, use a theodolite to control the coaxiality deviation <1°, and fill the flange gap with silicone rubber sealant (thickness 2±0.5mm).
4. The lead wire of the 35kV lightning arrester uses TJ-50 copper stranded wire (cross-sectional area 50mm²), the contact surface of the wire clamp is treated with CX-12 type power grease, and the bolt tightening torque is 45N·m±5% (verified using a digital torque wrench).
Configuration of voltage-grading ring: 500kV arrester is equipped with double voltage-grading ring (material 6063-T5 aluminum alloy), ring diameter Φ600±5mm, ring spacing 300±2mm, eccentricity detection uses laser centering instrument (deviation exceeds 5mm and needs to be readjusted).
5. JS-8 monitor is installed 1.5m above the ground of grounding down conductor, connected by copper-aluminum transition clamp, and initial leakage current recording needs to be carried out in rainless weather (reference value ≤2mA).
6. Data collection cycle ≤15 minutes, abnormal threshold is set to 150% of the reference value.
Typical fault analysis
In 2022, a 220kV line arrester (YH10W-204/532 type) had a bottom flange breakdown 3 months after it was put into operation. Monitoring during the fault showed: partial discharge: 120pC (standard <20pC) Infrared temperature measurement: temperature difference at flange reached 25K
Transocean Power technicians analyzed the fault as follows:
1. Installation error: The reverse installation of the grading ring caused the electric field distribution to be distorted, and the measured field strength on the surface of the ring reached 8kV/cm (normal value ≤3kV/cm).
2. Material degradation: The silicone rubber umbrella skirt produced electric traces under strong electric fields (the depth reached 0.3mm after SEM observation), which caused surface discharge.
3. Sealing failure: The bottom flange sealant was not filled according to the process (the measured thickness was only 0.8mm), and moisture intrusion caused the leakage current to rise to 5mA.
The grading ring can be corrected, and the insulation repair and flange sealing are treated with double layers. When using torque management, it is also necessary to consider environmental adaptation and data traceability: the installation record contains metadata such as GPS positioning coordinates and meteorological conditions.