Arc Flash Fault Research Articles

High-Speed Arcing Fault Detection: Using the Light Spectrum

Unlike short circuit faults in power systems, arcing faults produce intense light during fault events. Light-sensing technology has been under development to detect arc faults since the 1980s. Currently, optical fiber and point sensors are two types of light sensors applied, along with the simultaneous overcurrent mechanism, for arc-flash relays. Due to the characteristics of light sensors, sensitivity and reliability of the relay may be affected by ambient light. This article proposes a new approach for arc-flash fault detection by using the spectrum of light. Electromagnetic radiation means different elements would emit spectra with unique wavelengths when their atoms are excited. Elements can then be identified if a specific emission spectrum is detected during the excitation period. In general, copper and aluminum are commonly used for conductors. By examining the light spectrum, arc flash can be accurately and quickly detected. In this study, copper and aluminum are applied as conductors. The light spectrum for both materials is measured and recorded by an optic spectrometer during the arcing incidents. The results show that accuracy and reliability of the lightbased arc-flash fault-detection operation can be improved by using the proposed method.

Reducing Arc-Flash Hazards: Installing MV-Controllable Fuses on the Secondary Side of the Transformer in a Pumped Storage Plant

The Mitigation of arc-flash incident energy is important to increase safety. One method is to reduce the duration of the arc flash by using protective relays to sense an arc-flash fault. This method requires a supply-side switching device that will respond to the protective relaying fast enough to mitigate the incident energy. In many existing installations, medium-voltage (MV) controllable fuses are already installed to provide transformer protection. Before the development of an MV-controllable fuse, the MV fuse would have to be replaced with an MV circuit breaker or circuit switcher to have relay control of the MV protective device. This replacement would have significant equipment and construction costs and require extensive equipment outage time. The MV-controllable-fuse method uses the existing fusegear protecting the primary side of the transformer. The protective relay senses the arc fault and signals the controllable fuse to change to a fasteracting time-current response. The incident energies can be reduced from 200 cal/cm2 to lower than 8 cal/cm2 on the secondary side of the transformer. This article reviews an installation using an MV-controllable fuse to mitigate the incident energy on the equipment connected to the secondary side of the transformer.

Arc flash fault detection in wind farm collection feeders based on current waveform analysis

High impedance faults (HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse due to the limited fault current values and the situation is worse in wind farms. The mostly adopted HIF detection algorithms are based on the 3rd harmonic characteristic of the fault zero-sequence currents, whereas these 3rd harmonics are very easy to be polluted by wind power back-to-back converters. In response to this problem, the typical harmonic characteristic of HIF arc flash based on Mayr’s arc model is first analyzed, and the typical fault waveforms of HIF in wind farm are presented. Then the performance of the harmonic based HIF detection algorithm is discussed, and a novel detection algorithm is proposed from the viewpoint of time domain, focusing on the convex and concave characteristic of zero-sequence current at zero-crossing points. A HIFs detection (HIFD) prototype implementing the proposed algorithm has been developed. The sensitivity and security of the algorithm are proved by field data and RTDS experiments.

Phase-Based Digital Protection for Arc Flash Faults

This paper presents the real-time implementation and experimental performance evaluation of the phase-based digital protection against arc flash faults. The tested digital protection is based on extracting the high frequency components from fault currents triggered by an arc flash fault. The desired high frequency components are extracted using a filter bank that is composed of five exponentially modulated Kaiser window-based high-pass filters (HPFs). The structure of the used filter bank is selected to ensure extracting high frequency components with nonstationary phases, which represent a unique signature of arc flash faults. Such a signature allows detecting and identifying arc flash faults, as well as initiating responses against such events. The performance of the phase-based digital protection is experimentally evaluated for a laboratory $3\phi$ system that supplies linear, nonlinear, and dynamic loads. Test results demonstrate fast, accurate, and reliable detection, identification, and response to arc flash faults. In addition, test results show that the phase-based digital protection has minor sensitivity to the type of arc flash fault or supplied loads.

Extracting the Phase of Fault Currents: A New Approach for Identifying Arc Flash Faults

This paper proposes a new approach for detecting and identifying arc flash faults in power systems. The proposed approach is structured to extract the phases of transient frequency components present in arc flash fault currents. The desired phases can be extracted by processing fault currents using a modulated filter bank that is composed of high pass finite impulse response (FIR) filters. These filters are designed by using the Kaiser window method to achieve linear phase responses. Extracting the phases of transient frequency components, present in arc flash fault currents, can provide signature information for accurate and fast detection and distinguish of an arc flash fault. The proposed phase-based approach is implemented for off-line testing to evaluate its performance. Test cases of parallel and series arch flash faults are conducted for supplying linear, non-linear, and dynamic loads. Simulation and off-line results demonstrate the validity, accuracy, speed, and reliability of the phase-based approach to detect and distinguish arc flash faults with minor sensitivities to the load type and arch flash type.