什么是弧闪？
While an arc flash is sometimes used interchangeably with “arc fault”, an arc flash is more accurately defined as the light produced during an arc fault. An arc fault is a type of electrical fault that results from the breakdown of an insulating medium between two conductors where the energy is enough to sustain an arc across the insulator (often air) and can cause extreme amounts of light (arc flash), immense heat upwards of 19,000 °C, and a resulting explosive pressure wave (arc blast). 这些因素的结合会造成危险状况，使金属蒸发、破坏设备，并给附近人员带来重大危害。
造成弧闪的原因是什么？
当电流流经导体之间的气隙时就会发生弧闪。 There are several ways this can happen but the most common occurrence is when conductor insulation is worm or broken down.
弧闪继电器是什么？
弧闪继电器是基于微处理器的器件，通过光学传感器检测弧闪现象。 传感器被精心分布于配电板的多个格栅或抽屉中。 安装弧闪继电器能够快速检测到弧闪现象的形成，从而极大地减少弧闪故障造成的总断开时间和释放的能量。 同时减少设备受到的损害，并降低附近人员受重伤的几率。
How Do Arc-Flash Relays Work?
Video transcript:
There are many reasons an arc flash can occur and Littelfuse arc-flash relays can provide superior protection against its damaging results. Littelfuse market-leading arc-flash relay designs deliver reliable, easy-to-install protection. Littelfuse arc-flash relays and sensors are plug-and-play making them as easy to retrofit into existing switchgear as installing them into new equipment. No additional software is required.
Littelfuse arc-flash relays use light instead of current to detect an arc flash in under one millisecond. The fiber optic light sensor detects light throughout the entire length of the fiber. The sensor is ideal to protect buss bars, multiple compartment installations like motor control centers, or areas with many obstructions.
Littelfuse sensors are interchangeable. Giving the flexibility to adjust as needed during installation. The sensor's red flashing light tells you the sensor is installed correctly and working. This visual indication serves as a warning to workers; if they open a cabinet and there's no light they know to close it immediately. Littelfuse recommends mounting one or two sensors per cubicle to cover all horizontal and vertical buss bars, breaker compartments and anywhere there's potential for an arc flash. Littelfuse arc-flash relays have backup trip paths, so if one fails the other is still protecting.
Arc flash relays improve sustainability and life of electrical equipment. They can also help lower the PPE category of protected equipment. An arc-flash relay is an integral part of an arc-flash protection system that can minimize damage, save money, time and lives.
Littelfuse. Expertise applied, Answers delivered.
Call our application experts at (800) 832-3873 to get more information.
弧闪继电器有何重要性？
弧闪继电器是电气柜的必备组件，因为它能减少系统中的入射能量。 While an arc-flash relay cannot prevent an arc flash from happening, it will protect critical assets and workers' safety by reducing the severity of the flash. 弧闪继电器是弧闪保护方案中不可或缺的一部分，能够最大限度地降低损失，节省费用和时间，并挽救生命。
一次典型的弧闪有多少能量？
故障电流为20,000安培的480伏系统其相间故障提供9,600,000瓦功率。 If there is no arc protection and the fault lasts for 200 milliseconds before the overcurrent protection clears it, then nearly 2 megajoules of energy will be released, which corresponds roughly to a stick of dynamite.
The energy formula for an arc flash is:
Energy = voltage × 电流 × 时间
480 V × 20,000 A × 0.2 s = 1,920,000 J
For a given system voltage, two factors can be adjusted to reduce arc-flash energy: time and current. Time can be reduced by using an arc-flash relay, such as the PGR-8800 或 AF0500, to rapidly detect an electric arc flash. 弧闪继电器能使连通的断路器瞬间跳闸，超越任何反时延迟。 可以通过使用限流保险丝或者在发生相对地故障的情况下通过使用高电阻接地来减少电流。
选择弧闪继电器时的主要考虑因素有哪些？
The most important aspects of arc-flash relays are:
- 反应时间、
- 跳闸可靠性、
- 安装简易性、
- 传感器灵活性、
- 软件、
- 传感器设计、
- 避免误脱扣和
- 可扩展性。
阅读以下白皮书，深入了解选择弧闪继电器时需要考虑哪些功能： 挑选弧闪继电器时的关键考虑因素。
弧闪会造成什么后果？
电弧和弧闪是指当电流通过正常状态下绝缘的介质时发生的不受控制、强烈、闪光的电能释放现象。 电弧故障的最常见原因是绝缘故障。 这类故障可能是由于绝缘材料存在缺陷或老化、维护不当或不正确、灰尘、潮湿、害虫和人为错误（测试探针接触到错误的表面或工具滑动并接触带电导体）造成的。
弧闪事件会给人员带来危险，甚至可能致命。 According to OSHA, industrial arc-flash events cause about 80% of electrically-related incidents and fatalities among qualified electrical workers. 即使避免了人身伤害，弧闪也会破坏设备，造成高昂的更换和停产成本。
Contact an Arc-Flash Relay Expert