10-04-2017, 09:24 PM
Modeling Transformers With Internal Incipient Faults
The Incipient fault detection in transformers can provide
early warning of electrical failure and could prevent catastrophic
losses. a transformer model to simulate internal incipient faults is described here. deteriorating insulation
models with an internal short circuit fault model are combined here for developing the fault model. based on the physical behavior of aging insulation and the arcing
phenomena an aging
model and an arcing model was combined in parallel.
INTERNAL SHORT CIRCUIT FAULT MODEL
finite element analysis was used to analyse transformer
with an internal short circuit fault. This consisted of three steps:
1) meshing the problem space
into contiguous elements of suitable geometry and assigning
appropriate values of the material parameters like conductivity,
permeability, and permittivity.
2)the model has to be excited to set up the initial conditions.the current source is input
into the subcoil with the maximum number of turns and all the other coils are open-circuited.
3)assuming the boundary conditions: Balloon boundary is adopted in the simulation. Balloon
boundaries model the region outside the drawing space as
being nearly infinitely large.
DETERIORATING INSULATION MODEL
The deteriorating insulation between the turns is a major
cause of incipient internal winding faults in transformers. The aging and deterioration of the insulation is caused by the strong electric
field is applied to the dielectric material . thermal stresses, electrical stresses,
mechanical stresses, moisture etc cause the deterioration. Electrical stresses are caused by
the voltage gradient in the insulation.
for full details, refer this report:
http://psalserver.tamu.edu/main/papers/0...Butler.pdf