movement of overhead conductors due to short circuit forces
movement of overhead conductors due to short circuit forces
(OP)
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?
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RE: movement of overhead conductors due to short circuit forces
I always supposed that wires were set so that physical contact was never possible.
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