Arc Flash Protection is more and more important for people and equipment. This article will introduce the arc flash protection from definition, types, etc.
What Is Arc Flash Protection?
Arc flash protection, also known as arc flash mitigation solutions, primarily refers to a series of measures taken to protect people and electrical equipment from arc flash hazards, arc flash damage, or arc flash events.
What is Arc Flash Protection Types?
Passive, Active & Preventive Arc Flash Protection
According to the arc flash protection goals, there are three types of arc flash protection: passive arc flash protection, Active arc flash protection, and preventive arc flash protection.
The passive arc flash protection is primarily designed to ensure personnel safety, which is typically built into electrical equipment. For example, many electrical projects choose Arc-Resistant switchgear instead of ordinary switchgear to protect workers standing adjacent to the switchgear.
Active arc flash mitigation solutions are designed to improve arc flash safety and reduce arc flash damage. These arc flash protection solutions will reduce the available incident energy by clearing the arc more quickly. For example, in MV/HV electrical switchgears, engineers usually like to install arc flash relays to reduce total arc clearing time. Some people also adoptmaintenance witchgear, Fast-acting fuses, circuit breakers, and relays, etc.
The preventive arc flash protection is designed to make arcing faults less likely to occur. The common method includes safer operations at a distance, Proper equipment maintenance, additional barriers or compartmentalization in equipment, etc.
Personal & Equipment Arc Flash Protection
According to the arc flash protection objects, there are personal arc flash protection and equipment arc flash protection.
The personal arc flash protection mainly refers to arc flash PPE, arc flash trainning & arc flash labeling. Arc flash PPE includes arc flash suits, helmets, face shields, hoods, coveralls, coats, gloves, shoes, etc. When workers enter the workplace involved arc flash risk, they need to wear suitable arc flash PEEs as required by the arc flash training and the arc flash label of the equipment. There are four types of PPE categories from PPE category 1 to 4. Just choose suitable arc flash suits according to your arc rating.
Equipment arc flash protection mainly refers to installing arc flash relays or arc quenching in the electrical equipment. As for arc flash relays, there are only light-sensing arc falsh relay and light & current sensing arc flash relays.
When Is Arc Flash Protection Required?
When there are arc flash risks for electrical equipment or people, arc flash protection is needed.
As for electrical equipment, arc flash protection is usually used in HV/MVsubstations swtichgear & transformer.
As for workers, arc flash protection is needed whenever tasks involve working on or near energised electrical systems, including:
- Testing live circuits.
- Racking circuit breakers.
- Operating switches and disconnects.
- Maintenance of distribution boards, switchgear, and motor control centres.
How to Choose Arc Flash Protection?
As for people, the common arc flash protection is wearing arc flash protective equipment. But how to choose arc flash clothing? Choosing appropriate arc-rated clothing is similar to buying regular clothing, but there are two particularly important steps to consider:
- First, you need to determine the incident arc energy using an arc flash monitoring tool to determine the arc flash hazard level.
- Secondly, refer to local arc flash protection standards and the determined arc flash level to select the appropriate type of arc-rated clothing.
As for equipment, the common arc flash protection is installing an arc flash relay. How to choose an arc flash relay?
- When selecting an arc flash protection relay, you should first understand the type of arc flash relay you need, whether it’s light-sensitive only or both light and current-sensitive.
- Secondly, select the appropriate protection relay and quantity based on the protected area. If you need to protect four feeder cabinets, you may need an arc flash relay with four arc sensor channels.
- Then, confirm the certification standards that the arc flash protection relay needs to meet.
- Finally, confirm the arc flash clearing time of the arc flash protection relay. As the duration of the arc flash increases, the generated arc energy increases, and the consequences of the arc flash event become more severe. This means that the shorter the arc flash clearing time, the safer the equipment and personnel. Therefore, when choosing an arc flash protection relay, you need to confirm the time within which your equipment needs to trip to avoid an arc flash event (i.e., the relay’s reaction time). Currently, most arc flash relays on the market can control the arc flash clearing time to within 10ms.