Arc Light and Protection System Overview
1.1 Overview
In China, during medium and low voltage busbar short circuit faults, the key equipment and personnel injuries are primarily caused by arc light. However, most of China's medium and low voltage busbars are not equipped with rapid busbar protection; instead, they only use simple arc extinction devices and transformer backup protection. These protections are less intelligent and have slow response times, often extending the fault clearing time and further exacerbating equipment damage. In extreme cases, it can lead to catastrophic incidents like "burning through the camp," impacting the primary operation of transformers and affecting the safe operation of the entire power grid.
Our Arc Flash Protection System is a newly developed, innovative technology that we have independently designed based on the actual conditions in our country. It incorporates the characteristics of foreign arc flash protection systems and combines industry testing and protection configuration guidelines. This system boasts wide practicality and high reliability. It operates on the dual criteria principle of arc detection and overcurrent detection, featuring rapid protection response and high reliability.
1.2 Causes of Arc Light
There are many causes for arc-over fault in switch cabinets, usually categorized into the following five types:
1) Insulation Failure: Primarily due to insufficient creepage distance of the insulation materials within the cabinet, failing to meet the enhanced insulation requirements. Insulation failures occur in dirty environments or during humid weather. Additionally, with aging insulation materials in switchgear that has been in use for a long time, and under the influence of strong electromagnetic fields, insulation aging can also lead to insulation damage and subsequent failures.
2) Current Loop Defect: Due to insufficient cross-sections at some joints, loose securing bolts, poor contact at the handcart contacts, overheating occurs when high currents pass, leading to fires and subsequent phase-to-phase breakdowns, etc.
3) Entry of foreign objects: such as small animals (mice, etc.) entering the switchgear cabinet, or maintenance personnel leaving tools behind inside the cabinet after completion of work.
4) Misoperation: Such as walking the wrong interval, incorrect operation, not grounding the work area, not verifying electricity in the work area, etc.
5) System-related reasons: such as increased system capacity, changed grounding methods, increased cable applications, improper configuration of protective and automatic control devices, and excessive system resonance overvoltage.
1.3 Hazards of Arc Light
The power of short-circuit arc within the switchgear can reach up to 100MW. The energy produced by the arc combustion increases exponentially with the duration of the arc and the variation of the short-circuit current (as shown in the following figure). The high temperature and high pressure generated by the combustion will gradually destroy components, copper bars, and the array of switchgears. The bright arc and toxic gases also pose significant harm to humans.
