Systems and methods for arc flash hazard assessment

Abstract

An arc flash hazard assessment method includes storing electrical equipment data in memory, defining an arc flash model function based on the data, and estimating the model function based on a weighted average of interpolated and extrapolated values. The electrical equipment data may include an operating voltage, a fault current, and a clearing time. The model function is defined for at least three reference voltages V 1 , V 2 and V 3 , with the interpolated value at operating voltage V, between voltages V 1 and V 2 , and the extrapolated value from reference voltages V 2 and V 3 . At the arc flash protection boundary, the estimated model function has a predefined incident energy value of 1.2 cal/cm 2 (or about 5.02 J/cm 2 ), or less.

1 . A computer-implemented method of arc flash hazard assessment, the method comprising:
 storing field data in memory, the field data comprising at least an operating voltage, a fault current, and a clearing time for electrical equipment including a potential arc flash source; and   with a computer processing system in signal communication with the memory:
 defining an arc flash assessment model for an arc flash at the arc flash source based on the field data, the arc flash assessment model including an incident energy function determined for at least three reference voltages V 1 , V 2  and V 3 ; 
 interpolating the incident energy function between reference voltages V 1  and V 2  to define an interpolated value at the operating voltage; 
 extrapolating the incident energy function from reference voltages V 2  and V 3  to define an extrapolated value at the operating voltage; 
 estimating a value of the incident energy function at a working distance from the arc flash source, based on a weighted average of the interpolated and extrapolated values; and 
 outputting the estimated value of the incident energy function to a user interface. 
   
     
     
         2 . The method of  claim 1 , further comprising outputting an arc flash protection boundary to the user interface, wherein the estimated value of the incident energy function has a predefined value of about 1.2 cal/cm 2  (about 5.02 J/cm 2 ) for a working distance defined at the arc flash protection boundary. 
     
     
         3 . The method of  claim 1 , further comprising receiving the field data via the user interface. 
     
     
         4 . The method of  claim 3 , wherein the field data include an electrode gap of the arc flash source. 
     
     
         5 . The method of  claim 4 , wherein the electrode gap defines a separation between at least two three-phase electrodes of the arc flash source, and wherein the arc flash model represents an arc flash event in which plasma energy is ejected from the electrodes, at the electrode gap. 
     
     
         6 . The method of  claim 4 , wherein the arc flash model includes an arc current function determined for at least the three reference voltages based on the fault current and the gap, and further comprising outputting to the user interface an estimated value of the arc current function at the operating voltage. 
     
     
         7 . The method of  claim 6 , wherein the estimated value of the arc current function is obtained by a weighted average of interpolation at the operating voltage between reference voltages V 1  and V 2  and extrapolation to the operating voltage from reference voltages V 2  and V 3 . 
     
     
         8 . The method of  claim 6 , wherein the clearing time for the electrical equipment depends on the estimated value of the arc current function. 
     
     
         9 . The method of  claim 4 , wherein the field data comprise configuration data for the potential arc flash source and the incident energy function is determined at the three reference voltages in dependence on the configuration data. 
     
     
         10 . The method of  claim 9 , wherein the configuration data describe a horizontal or vertical orientation of the arc flash source with respect to a working position on the electrical equipment, such that the estimated value of the incident energy function depends upon the orientation. 
     
     
         11 . The method of  claim 9 , wherein the configuration data describe an enclosure state of the arc flash source, such that the estimated value of the incident energy function depends upon the enclosure state. 
     
     
         12 . The method of  claim 11 , wherein the enclosure state comprises an enclosure dimension and further comprising scaling the incident energy function according to the enclosure dimension. 
     
     
         13 . The method of  claim 1 , wherein the arc flash model further comprises an arc flash protection boundary function determined for at least the three reference voltages V 1 , V 2  and V 3 , and further comprising outputting to the user interface an estimated value of the arc flash protection boundary function at the operating voltage, based on a weighted average of interpolation at the operating voltage between reference voltages V 1  and V 2  and extrapolation to the operating voltage from reference voltages V 2  and V 3 . 
     
     
         14 . The method of  claim 1 , wherein interpolating the incident energy function comprises linear interpolation of the incident energy function to the operating voltage between reference voltages V 1  and V 2 , and wherein extrapolation of the incident energy function comprises linear extrapolation of the incident energy function from reference voltages V 2  and V 3  to the operating voltage between reference voltages V 1  and V 2 . 
     
     
         15 . The method of  claim 14 , wherein estimating the incident energy function at the operating voltage comprises linear weighting of the interpolated and extrapolated values based on a position of the operating voltage between reference voltages V 1  and V 2 . 
     
     
         16 . The method of  claim 1 , wherein the reference voltages are ordered such that V 1 <V 2  and V 2 <V 3 , and wherein the operating voltage is between V 1  and V 2 . 
     
     
         17 . The method of  claim 16 , wherein reference voltage V 1  is approximately 600 V, reference voltage V 2  is approximately 2.7 kV, and reference voltage V 3  is approximately 14.3 kV. 
     
     
         18 . The method of  claim 17 , wherein the reference voltages further comprise at least one of a reference voltage V 4  of approximately 480 V and a reference voltage V 5  of approximately 208 V. 
     
     
         19 . An arc flash hazard assessment system comprising:
 memory for storing input data describing at least an operating voltage, a fault current, and a clearing time for a potential arc flash source in an electrical apparatus;   a processor in communication with the memory, the processor configured to define an arc flash model function based on the input data, wherein the arc flash model function is defined for at least three reference voltages V 1 <V 2 <V 3 ; and   a user interface configured to output an arc flash assessment for the electrical apparatus based on an estimated value of the arc flash model function at the operating voltage, the estimated value comprising a weighted mean of:
 an interpolated value defined by interpolation of the arc flash model function at the operating voltage between reference voltages V 1  and V 2 ; and 
 an extrapolated value defined by extrapolation of the arc flash model function from reference voltages V 2  and V 3  to the operating voltage. 
   
     
     
         20 - 30 . (canceled) 
     
     
         31 . A non-transitory computer-readable storage medium having program code thereon, the program code executable by a processor to perform a method comprising:
 storing field data in memory, the field data describing at least an operating voltage V, a bolted fault current I bf , and a clearing time T of an electrical equipment including a potential arc flash source; and   defining an arc flash assessment model based on the field data, the arc flash assessment model including an incident energy function determined for at least three reference voltages V 1 <V 2 <V 3 ;   interpolating the incident energy function between reference voltages V 1  and V 2  to define an interpolated value at operating voltage V;   extrapolating the incident energy model from reference voltage V 3  through reference voltage V 2  to define an extrapolated value at operating voltage V;   estimating the incident energy function at a working distance from the arc flash source, based on a weighted average of the interpolated and extrapolated values;   determining an arc flash protection boundary with respect to the arc flash source, wherein the estimated incident energy function has a predefined value at the arc flash protection boundary; and   outputting an arc flash assessment to a user interface, the arc flash assessment describing the arc flash protection boundary and the estimated incident energy function at the working distance.   
     
     
         32 - 40 . (canceled)