Switchgear modeling - Inductive loops
Switchgear modeling - Inductive loops
(OP)
Dear all,
I've been performing transient over-voltage studies which involve vacuum circuit breakers (VCB).
In order to simulate the actual phenomena that the VCB causes (mainly high frequency re-igntions), a high frequency model of all the equipment should be included.
I am having a problem comprehending the representation that I have came across of the switchgear. The switchgear is represented as inductance pieces between the breakers and the disconnectes. The inductances would be a representation of the inductive loops caused by the construction of the switchgear and the available current.
I am aware of the idea that the current passing through the busbar of the switchgear would cause a magnetic field which is modelled as an inductance. However I would appreciate if somebody could add to this and provide some more explanation of this representation.
Thank you.
Adam
I've been performing transient over-voltage studies which involve vacuum circuit breakers (VCB).
In order to simulate the actual phenomena that the VCB causes (mainly high frequency re-igntions), a high frequency model of all the equipment should be included.
I am having a problem comprehending the representation that I have came across of the switchgear. The switchgear is represented as inductance pieces between the breakers and the disconnectes. The inductances would be a representation of the inductive loops caused by the construction of the switchgear and the available current.
I am aware of the idea that the current passing through the busbar of the switchgear would cause a magnetic field which is modelled as an inductance. However I would appreciate if somebody could add to this and provide some more explanation of this representation.
Thank you.
Adam






RE: Switchgear modeling - Inductive loops
In addition to modeling the switchgear, you may have to build a more extensive model going back to some source. Like your distribution transformer, service entrance equipment, feeder, etc. Some estimation of the source L,C, and R should be made for these parts of the circuit. At the frequencies of the restrike, don't forget to include the phase to phase and phase to ground capacitances.
This sounds like a job for some specialized modeling s/w that can handle busbar geometries to derive L and C at the frequencies of interest.
RE: Switchgear modeling - Inductive loops
I am asking in general and not for a specific single line diagram.
The modelling of other elements such as a transformer with its surge capacitance and leakage reactance is clear. also the same for modelling cables either by there surge impedance and propagation velocity or high frequency L and C derived from the surge impedance and permittivity.
However for the bus bar it is still not clear to me how to derive the L based on the geometry which you indicated in the last sentence. Is there any literature that refers to this.
Thank you.
Adam
RE: Switchgear modeling - Inductive loops