Fault Current Electromagnetic Forces

[hidalgoe]

Hello:

I would like to find technical information on the nature, calculation and structural analysis of electromagnetic forces generated during short circuit conditions for three phase, phase to phase and phase to ground faults.

For example how do you calculate and represent the forces acting upon 3PH,4W busduct during fault conditions. Our structural engineer needs this information to specify the supports for a busduct that is being installed along the face of a concrete wall.

Thanks,

hidalgoe, PE

 

[RalphChristie]

http://www.cda.org.uk/megab2/elecapps/pub22/sec6.htm

 

[Reactorman]

The Web site below has formula's to calculate these forces.

Good luck

http://www.cda.org.uk/megab2/elecapps/pub22/sec6.htm#Electromagnetic Stresses

 

[cuky2000]

Amigo Hidalgoe,

If you are not designing the internal parts of the bus duct, the only relevant information for your civil structural colleague primarily are lineal weight(s), bus duct shape(s) and overall bus physical layout.

SC forces are required for the internal bus bracing. If you purchase a prefabricated bus duct this should have the SC rating. It is the responsibility of the EE to select the bus duct to withstand the expected max. SC in the system.

The civil structural will consider the capability of the support structure to accommodate the additional dead and dynamic load combination imposed by external forces such as seismic, wind or snow load for outdoor sections.

Below is a sample of standard spec section from a bus duct manufacturer.

Short Circuit Force Withstand Ability Non-Segregated phase bus runs in 600V, 5 kV, and 15 kV are designed to withstand three-phase and phase-to-ground short cir cuit current of 78 kA rms asym (132 kA peak) for 10 cycles and 50 kA rms sym for 2 seconds. Momentary 4-cycle withstand ratings up to 158 kA peak (98.8 kA rms asym) are also available. For 27 kV non-segregated phase bus runs, short circuit withstand ratings of 64 kA rms asym (108 kA peak) for 10 cycles and 40 kA rms sym for 2 seconds are standard.

 

[hidalgoe]

Thank you all,

Eugene Hidalgo, PE