The work presented in this thesis contributes to the understanding of the
dynamic behaviour of large power transformer windings under short circuit
forces. A simple yet accurate method of prediction of electromagnetic forces
is developed and used as input to the dynamic mechanical model. In develop-
ing this model the mechanical properties of oil-impregnated pressboard have
been investigated and measured in a specially designed rig which simulates
the typical power transformer environment. Assumptions have been made
regarding these properties to enable them to be meaningfully incorporated in
a dynamic model of a transformer. Predictions made using the model have
been compared with actual measurements on a transformer and a correlation
within 20%-30% was achieved. The work demonstrated the importance of
mechanical prestress to ensure that no serious nonlinearities will be encoun-
tered in the mechanical behaviour when short-circuit forces are present in a
power transformer. It was also found that for small radial deflections, the
axial and radial behaviours are independent. This work provides a theoreti-
cal basis for further work in which precise determinations of the mechanical
properties of oil-impregnated pressboard can be used to model the dynamic
behaviour of a large transformer to a high degree of accuracy.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/4764 |
| Date | 17 April 2008 |
| Creators | Minhas, Muhammad Salman Aslam |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 4394927 bytes, 13716 bytes, application/pdf, application/pdf, application/pdf, application/pdf |
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