The Hazards Caused by the Faults of Ring - Main Unit High - Voltage Switchgear

I. Power Supply Interruption and Equipment Damage

1. **Failure of Core Components**

   - The ablation of the contacts of the load break switch or the failure of the arc extinguishing chamber may lead

 to the inability to extinguish the arc, causing an internal short circuit of the equipment. In severe cases, it may result 

in the explosion of the switchgear (such as the case in a certain park in 2024).

   - Frequent fusing or refusal to operate of the fuse will lead to local power outages or (transverse tripping),

 expanding the scope of the power outage.

2. **Deterioration of Insulation Performance**

   - Condensation or pollution flashover may cause creepage of the insulators (the surface discharge voltage is lower

 than 30kV), leading to insulation breakdown and the burning of the equipment.

   - The corrosion of metal components increases the grounding resistance (＞4Ω), affecting the reliability of the 

operation of the protection device.

 II. Risks of Safety Accidents

1. **Misoperation and Mechanical Failures**

   - The failure of the five-prevention function may cause personnel to accidentally touch live parts (such as opening 

the cabinet door without powering off), triggering electric shock accidents.

   - The sticking of the operating mechanism or the fatigue of the spring may lead to the failure of opening and closing,

 delaying the opportunity for troubleshooting.

2. **Potential Hazards of Explosion and Fire**

   - When there is a leakage of SF6 gas or the short-circuit current exceeds the standard (exceeding the breaking capacity

 of the equipment, which is 25kA), it may trigger an internal explosion of the switchgear, threatening the safety of 

personnel and damaging the surrounding equipment.

III. Disruption of System Stability

1. **Amplification of Fault Impact due to Ring Network Characteristics**

   - Exceeding the short-circuit current limit of the ring network may cause the equipment to be unable to break,

triggering a chain of tripping and even resulting in regional power outages.

   - The failure or misoperation of the automatic reclosing function will prolong the power outage time and affect the

 continuity of power supply to important users.

2. **Risks of Loop Closing Operation**

   - If the phase angle difference is > 15° during the loop closing and power transfer after a fault, it may trigger system 

oscillations, threatening the stability of the power grid.

IV. Increase in Economic and Operation and Maintenance Costs

1. **Maintenance and Replacement Costs**

   - The replacement of core components (such as the SF6 arc extinguishing chamber and the intelligent controller)

 requires professional technology, and key spare parts need to pass type test certification, which is costly.

   - Environmental treatment (such as anti-pollution flashover coatings and moisture-proof sealing) requires periodic

 investment.

2. **Production Losses**

   - Power outages for industrial users may lead to the halt of production lines. Calculated according to the average

 loss of about $500 per minute in the manufacturing industry, long-term faults will cause significant economic losses.

V. Environmental and Social Impacts

- Pollution flashover faults in coastal areas may lead to frequent replacement of insulators, increasing the risk of 

high-altitude operations for operation and maintenance personnel.

- Frequent power outages affect the quality of residents' lives and may attract the attention of public opinion.

**Countermeasure Suggestions**: By means of condition monitoring (such as contact temperature sensors), regular

 withstand voltage tests (42kV/1min) and standardized operation training, the probability of faults can be reduced. 

For high-risk areas (such as industrial zones), it is recommended to upgrade the breaking capacity of the equipment

 to above 31.5kA and configure an intelligent reclosing controller.