The mining industry has a reputation for being a high-risk business – these risks vary but are often serious and in some cases life threatening.
The sustainability of the mining industry relies largely on safety, so it is important for miners to protect themselves accordingly.
Mining doesn’t have to be unsafe. In fact, with the introduction of strict safety legislation and protocols, as well as advances in safety equipment, the industry has seen its fatality rate drop over time.
Although the goal of zero harm has not yet been achieved, it remains the standard that mining companies continue to strive towards. Personnel safety is paramount for utilities and industries, including oil and gas, water and wastewater, and metals and mining. Among the dangers faced are arc flashes.
According to the National Fire Protection Association (NFPA) 70E: Standard for Electrical Safety in the Workplace, an arc flash “is a dangerous condition associated with the release of energy caused by an electrical arc”.
Arc flashes pose a very serious risk to the industry – so SEL has developed Arc-Flash Protection at the Speed of Light to address arc flash challenges.
Causes of arc flashes
The energy produced by an arc flash event is proportional to the voltage, current, and duration of the event.
It is measured in terms of arc flash incident energy (AFIE), calibrated in cal/cm2, and in turn used to determine the level of personal protective equipment (PPE) required to protect personnel from injury during an arc flash event. PPE is designed to protect workers from serious workplace injuries or illnesses resulting from contact with electrical or other workplace hazards.
Arc flashes occur when the insulation or over-air isolation between energised components within an electrical circuit is compromised.
Arc flash events can be caused by numerous factors, such as the shorting of two phases, which creates a phase-to-phase fault.
Common examples that cause phase-to-phase faults include dropped tools, accidental contact by maintenance personnel, the buildup of corrosion or conductive dust on conductors, and the presence of pests – like mice, rats or snakes – which come in contact with energised conductors.
Arc flash events can cause dangerous and potentially fatal levels of heat, ultraviolet radiation, blast pressure, flying shrapnel, and deafening sound waves. To remedy this, design engineers have a few options to reduce system voltage or fault currents, including grounding practices and the application of currentlimiting fuses.
However, the best and most direct way to reduce arc flash hazards is to reduce fault-clearing times, thereby reducing the overall incident energy, or to eliminate the need for personnel to be in harm’s way by using remote operation.
Benefits of SEL Arc-Flash Protection
- High-speed tripping: SEL relays reduce arc flash hazards by significantly reducing the total fault clearing time.
- Incident energy reduction: The faster the extinction of the arc flash event, the smaller the incident energy. SEL relays detect arc flash hazards and send a trip signal to the breaker in as little as 2 milliseconds.
- Improved safety: SEL arc flash detection (AFD) decreases the fault-clearing time, which reduces arc flash hazards, improves safety, and lowers PPE requirements. To validate the arc flash protection performance, a series of tests were performed at a high-current laboratory. In these tests, arc flash incident energy levels were reduced by 88% using SEL technology.
- Reduced damage to switchgear: With arc flash hazard protection, equipment damage is minimised during an arc flash event, returning affected equipment to service faster and with less expense. In addition, power system availability is maximised.
- Maintained selective coordination: Arc flash events trigger an immediate response, while coordination is maintained with downstream protection for external faults.
- Simplify procedures: AFD is always enabled. An operator or technician doesn’t have to modify protective settings before and after performing live work to be protected from arc flash events. Reduced potential arc flash energy also simplifies PPE requirements, limiting the requirement of bulky ‘moon’ suits and other movement-restricting PPE.
- Stay outside the danger zone: Remain a safe distance away by remotely obtaining metering, event, and maintenance information from the relay with Ethernet or serial communications. Optional delayed breaker tripping or closing via push buttons allows personnel to move to a safe distance.
- Service and support: The SEL 10-year worldwide product warranty is proof of SEL’s confidence in the high-quality products the business designs, manufactures, sells and supports. This stated warranty and impeccable track record for never charging a customer to replace or repair a defective product are the best substantiation of true quality and durability. Worldwide, SEL support teams provide customers with local sales and technical service. The business’s commitment to quality extends through a product’s installation and life as part of customers’ critical infrastructure. Application and integration engineers, customer service representatives, and sales managers truly understand the importance of local support. SEL provides personalised, regional technical support to its customers from more than 85 offices, and contributes significantly to the sustainability of the mining industry.