How to Prevent Surge Arrester Accidents | Substation Overvoltage Protection Best Practices

  In high‑voltage power grid operation, surge arresters are critical equipment for substation overvoltage protection. A reliable metal oxide surge arrester mitigates lightning surges and switching overvoltage, safeguards transformer and busbar insulation, and prevents costly grid outages. Improper selection, inadequate testing, aging components, and poor maintenance are the leading triggers of surge arrester accident. To mitigate these risks, State Grid's 18 Anti‑Accident Measures set out comprehensive technical requirements for surge arrester accident prevention, widely referenced by global power utilities, EPC contractors and electrical asset owners.

 

  All work related to high‑voltage surge arrester installation, commissioning, testing and retrofitting shall follow well‑recognized industry standards: DL/T 621‑1997 for grounding of AC electrical installations, DL/T 475‑1992 for grounding device measurement, and DL/T 620‑1997 for overvoltage protection and insulation coordination. Proper grounding and insulation matching lay the foundation for stable surge arrester performance; defective grounding will directly compromise the protection effect of your metal oxide surge arrester.

 

Standard Selection & Retrofit of High‑Voltage Surge Arrester

  Correct equipment selection is the first line of defence for surge arrester accident prevention. For all new installations or replacement projects at 110 kV and above substations, metal oxide surge arrester (MOSA) shall be the preferred solution. Legacy ordinary valve‑type arresters deployed on 110 kV‑220 kV networks shall be systematically replaced.

  Compared with older magnetic‑blow and ordinary valve arresters, the modern metal oxide surge arrester delivers superior non‑linear characteristics, low residual voltage and stable anti‑aging performance, making it the mainstream choice for worldwide substation overvoltage protection. Project teams must enforce strict arrester type‑selection governance. Mismatched or incorrectly‑specified high‑voltage surge arrester models are strictly forbidden, as wrong selection will cause protection failure and catastrophic equipment damage.

 

Surge Arrester Live‑Line Test & Periodic Maintenance Regime

  Regular inspection and testing are essential to uncover hidden defects before a surge arrester accident occurs. Operating metal oxide surge arrester units require routine condition assessment via arrester live line test, with root‑cause analysis triggered whenever abnormal readings appear.

  For 35 kV and above metal oxide surge arrester, qualified arrester live line test can substitute conventional scheduled power‑outage testing, reducing downtime for substation assets. For critical 500 kV ultra‑high‑voltage installations, full power‑off performance testing shall be performed every 3‑5 years to verify arrester health status.

   Conductive current measurement forms a key part of surge arrester maintenance. Readings shall be taken before and after every thunderstorm season. Lightning‑prone periods bring frequent overvoltage stress; trending conductive‑current data helps operators detect internal degradation, dampness or insulation defects early. Timely troubleshooting reduces the probability of sudden surge arrester accident during storm surges.

 

Arrester Online Monitoring for Real‑Time Condition Supervision

  To strengthen day‑to‑day asset management, 110 kV and above high‑voltage surge arrester in substations should be fitted with conductive‑current monitoring meters. Deploying arrester online monitoring allows continuous tracking of operating parameters instead of relying purely on periodic manual inspections.

  Where arrester online monitoring hardware is in service, site operators shall carry out visual patrols at least once per day, log monitoring data every half‑month, and conduct systematic data analysis. Long‑term data trending enables predictive maintenance: maintenance teams can identify early‑stage aging and internal faults of the metal oxide surge arrester, and implement intervention before failure happens.

 

Avoid Mixed‑Type Installation for Balanced Surge Arrester Load

  Mixed‑type arrester deployment inside one substation creates uneven action‑load distribution and represents a major safety risk for substation overvoltage protection. All 110 kV and above surge arrester within the same substation should adopt identical type and specifications.

  Mixing metal oxide arresters, magnetic‑blow arresters and traditional valve‑type arresters in one station leads to inconsistent response speed, residual voltage and current‑withstand capability. During overvoltage events, individual units will bear excessive stress, accelerate ageing and raise the risk of surge arrester accident. Existing substations with mixed‑model installations shall carry out retrofitting and unified replacement to guarantee balanced load and consistent protection performance across the whole bay.

 

Final Takeaway

  Robust surge arrester accident prevention covers the full equipment lifecycle: selection, procurement, installation, arrester live line test, arrester online monitoring and routine surge arrester maintenance. The requirements from State Grid 18 Anti‑Accident Measures provide practical reference for global utilities, EPCs and plant owners. Properly specified and well‑maintained metal oxide surge arrester greatly improves the reliability of substation overvoltage protection, lowering failure risks for high‑voltage power systems.