magoo2
Electrical
- May 17, 2006
- 857
I'm interested in knowing from this group what tools or techniques are available to model the movement of 2 parallel conductors carrying short circuit currents of approximately 3000 to 6000 amperes. The application is for an electric utility line in which a short circuit occurs between 2 of the 3 phase conductors.
Under these conditions, the faulted wires move apart and, following the interruption of current by a protective device, the wires often swing back together and make contact causing a new short circuit 1000 ft or so ahead of the original short circuit location.
My own efforts to model this situation follows Coulomb's law. In representing the span of wire, I modeled each of the wires as a pendulum at a length equal to the average sag of the wire. In an iterative calculation, I start with initial spacing when short circuit occurs. Then I increment the calculation, the new spacing reduces the repelling force. I calculate the displacement, velocity and acceleration of the 2 wires and repeat the calculation.
My objective is to start with the normal spacing and see if there's a likelihood of the wires coming together. If it is likely then I try changing the spacing or height of one to see if that avoids the collision. A collison means that another protective device operates and makes it a larger area of customers that are affected.
In a more rigorous sense, how could one model this situation? Since the wire follows a catenary path, can this be represented rather than the simpified way that I did it?
Under these conditions, the faulted wires move apart and, following the interruption of current by a protective device, the wires often swing back together and make contact causing a new short circuit 1000 ft or so ahead of the original short circuit location.
My own efforts to model this situation follows Coulomb's law. In representing the span of wire, I modeled each of the wires as a pendulum at a length equal to the average sag of the wire. In an iterative calculation, I start with initial spacing when short circuit occurs. Then I increment the calculation, the new spacing reduces the repelling force. I calculate the displacement, velocity and acceleration of the 2 wires and repeat the calculation.
My objective is to start with the normal spacing and see if there's a likelihood of the wires coming together. If it is likely then I try changing the spacing or height of one to see if that avoids the collision. A collison means that another protective device operates and makes it a larger area of customers that are affected.
In a more rigorous sense, how could one model this situation? Since the wire follows a catenary path, can this be represented rather than the simpified way that I did it?
