Protection at the speed of light: Arc-flash protection combining arc flash sensing and arc-resistant technologies

One of the most critical aspects of reducing both personnel injury and equipment damage is through the reduction of the energy available to an arcing fault. The initiation of a trip and the clearing time (opening) of any upstream device is a critical component in the reduction of the resultant arc flash incident energy. Combining technologies that detect and interrogate both arc flash and the associated arc current signatures in combination with arc resistant switchgear or controlgear, can provide a coordinated solution for controlling the level of incident energy at various points within the distribution network. Hybrid systems of this type provide the highest level of personnel protection, along with comprehensive equipment protection, as detection and initiation of tripping is implemented faster than with conventional relaying techniques alone. The reduction of the overall trip time can reduce equipment collateral damage, reconditioning time and lost productivity resulting from downtime. These types of coordinated systems will also lower the personal protective equipment (PPE) requirements based on incident energy. This paper compares several systems including conventional overcurrent protection, zone selective and various light and current sensing systems.