Mitigation of Arc Flash hazard by using protection solution
This paper gives an introduction to the problematic phenomena of arc flashing. For protection engineers important terms and facts in the NFPA 70E standard and the IEEE 1584 standard will be presented. The importance of the fault clearing time will be discussed in detail. Protection schemes which achieve fast fault clearing times for bus faults and feeder faults will be reviewed. In this paper an application will be introduced which is based on the reverse interlocking scheme. Additionally it offers a new solution that achieves a fast fault clearing time for bus faults and close in faults. This is normally the area within a substation, where arc flashing can cause a potential hazard for operators. This application will eliminate the problem of longer fault clearing times for faults close to the bus due to the co-ordination with radial feeders relays. This paper will discuss the necessary settings considerations and will show the limits of this application
Aspects of Arc-Flash Protection and Prediction
Abstract This paper provides a technological review of arc-flash protection of air insulated switchgear. It covers the whole range starting from switchgear design aspects until ultra-fast arc elimination. Special attention is paid to proactive technologies enabling preemptive detection of slowly developing faults. Various arc faults indicating phenomena are examined, and several sensor technologies for online monitoring are evaluated. Because preventive or predictive measures cannot totally eliminate the risk of arc faults, reactive protection by fast operating protection is justified. Two major reactive protection approaches are discussed: the current-limiting approach and the arcing time based approach. The benefits of protection based on simultaneous detection of light and overcurrent are explained. Finally the paper discusses arc elimination technologies and evaluates the concerns related to short-circuit devices.
IEC 61850: open communication in practice in substations
Owing to the large number of protocols for substation communication, devices from different manufacturers or of different generations can often not communicate with each other. The communication standard IEC 61850 permits interoperability without the use of gateways. Through the split of application and communication stack and through the standardized permitted extension of the supporting functions, the long-term validity of the standard is guaranteed. This approach leads to lower investment outlay, less training effort and lower life-cycle costs of substation automation systems. All automation functions as well as the single-line diagram of a substation are described by means of the substation configuration description language. Many migration paths are possible to allow a substation to be gradually IEC 61850-compliant. Existing equipment may be upgraded directly. Existing equipment may also be left intact, and an interface is established between this and any new IEC 61850-compliant equipment which is introduced when the substation is extended.