Report: Incident of Arc Flashing at 132KV Grid Station.

Report: Incident of Arc Flashing at 132KV Grid Station. 

What is an arc and what factors contributing to arcing?

An arc fault is a type of electrical explosion that can produce two byproducts: an arc flash and an arc blast. The arc flash is the light and heat produced by the explosion, while the arc blast is a pressure wave that follows.

There are many factors that can contribute to an arc flash incident, including the racking in and out of circuit breakers in substations. This process of inserting or removing circuit breakers from low or high voltage switchgear cubicles can be dangerous and potentially expose individuals to lethal arc flash hazards.

Report of the incident

On the early morning of December 9th, 2022, an incident occurred at the 132/11KV Grid Station located on Arain Road in Sukkur. The incident occurred during a trolley rack in/rack out operation, and involved an arcing situation that caused significant damage to the CTs of the feeder.

Upon receiving reports of the incident, the P&I team quickly responded to the grid station and took steps to identify and repair the fault that had occurred. They replaced the contacts of the relay and repaired the CTs, taking care to ensure that all necessary repairs were made, and that the equipment was properly functioning.

Despite their efforts, the HSE Engineer raised a number of concerns regarding the safety measures in place at the grid station. Specifically, they noted that employees were not wearing Arc Flash Personal Protective Equipment (PPE) and that there had been no arc flash study or risk assessment conducted. They also pointed out the absence of protective mets in front of the switchgear and the lack of mechanical interlocking to prevent the circuit breaker from being racked in while closed. Additionally, the fire suppression system failed to work properly during the incident.

Upon further investigation, it became clear that the staff at the grid station had not been adequately trained or made aware of the hazards present at the facility. This lack of training and awareness is a significant contributing factor to the incident, as it likely contributed to the failure to follow proper safety protocols and procedures.

In conclusion, the incident at the 132/11KV Grid Station was a result of negligence on the part of the facility management and owners. It is essential that steps be taken to address the safety concerns raised by the HSE Engineer and to ensure that all employees are properly trained and made aware of the hazards present at the facility. This will help to prevent similar incidents from occurring in the future and ensure the safety of all personnel working at the grid station.

 

More about Arc Flash and Arc Blast

An arc flash is a type of electrical explosion that produces intense light and heat. The temperature of an arc flash can reach extremely high levels, ranging from 2,800 to 19,000 °C (5,000 to 35,000 °F). For comparison, the surface temperature of the sun is estimated to be around 5,500 °C (9,932 °F). The extreme heat produced by an arc flash can ignite clothing and cause serious burns to anyone within a few feet of the explosion. The arc flash can also melt metal, cause damage to the lungs and eyes, and potentially lead to hospitalization or death. It is important to take proper precautions when working with electrical equipment to prevent arc flash incidents.

An arc blast is a type of pressure wave that is generated as a result of an arc fault, a type of electrical explosion. The force of an arc blast can be powerful enough to knock down a full-grown technician or cause damage to equipment. In addition to physical injuries, arc blasts can also have negative effects on hearing and brain function. The blast can also cause loose equipment, tools, machinery, and debris to be propelled through the air, potentially causing additional damage or injury. It is important to take proper precautions when working with electrical equipment to prevent arc blast incidents.