A Review of Commonly Used DC Arc Models

Abstract

The dc arc hazard is a great concern to industry. Quantitative arc hazard assessments are performed on dc systems to determine a nearby worker's potential incident energy exposure during an arcing event. Four viable dc assessment methods are reviewed in this paper. The most widely used model for predicting dc incident energy is based on Lee's theoretical arc model; the electrical arc power is determined from the maximum power transfer theorem, and the arc is depicted as a spherical radiant source with uniform heat transmission in all directions. Like Lee's model, Ammerman's model assumes complete conversion of electrical arc energy into thermal energy, but arc power is determined from an iterative technique constrained by arc power and circuit characteristics. Ammerman incorporates multiplying factors which account for the higher incident energies associated with arcing in enclosures. Based on dc arc testing, the applicability of an existing software package has been extended to dc systems through multiplying factors, and equations for dc rail and transit systems have also been developed. Model derivation is examined in this paper for suitability to arcing in general and dc specifically. Model performance is assessed using the available limited data (ac or dc). Example calculations are provided.Index Terms-Ammerman's model, arc flash hazard, dc arc model, dc transit systems, Ralph Lee model.

An Adaptive Reclosing Scheme Based on Phase Characteristics for MMC-HVDC Systems

“…The time instant when applying the detecting voltage is defined as 0. The arc model is simplified as resistance because the arc is usually resistive [28].…”

Comparative Analysis of Experimental DC Arc Flash Results to Industry Estimation Methods

“…The theoretical models used were the NFPA 70E -2015 [14], NFPA 70E -2018 [2], and maximum power, Stokes and Oppenlander, and Paukert methods using ETAP 19.5.0. There are additional theoretical models as summarized in [15], but these five methods are the focus for the comparative analysis.…”

“…The PPE category method, Article 130.7(C) (15), is applicable for AC and DC systems of specified parameters, such as voltage, available fault current, equipment type, working distance, and arc duration. If the parameters are outside of those specified, this method cannot be used and the incident energy calculation method must be used.…”

Circuit-Based Mathematical Model of an Arc Heater for Control System Development

“…The first step in analyzing a nonlinear system is usually to linearize it, if possible, around some nominal operating point and analyze the resulting linear model [23]. The initial phase in the linearization process was to take the partial derivatives of the Resistance function R (I, V), and determine which variable has the most effect (or highest rate of change) on the arc resistance as shown below in equation (2,3).…”

“…Circuit breakers are one such common area of research where the arc is viewed from the standpoint of a quick extinguishment for overcurrent protection. For example, the time taken to extinguish an arc is of particular importance within arc flash analysis where the goal is to reduce the incident energy in which an employee may be exposed [1], [2]. The useful areas of the arc include technologies such as welders, gas lighting, arc furnaces, and arc heaters.…”