Introduction: The project will deliver tools to analyse what happens to plant with a magnetic circuit when that circuit starts to become saturated because of extreme operating conditions. Examples of this are transformers under ferroresonant conditions, transformers subject to DC currents such as during geomagnetic (sun storm) events, series reactors under fault conditions, quadrature boosters under high load conditions and saturable shunt reactors under normal conditions. Failure to analyse these conditions leads properly either to excessive capital cost in increasing core dimensions, or potential failure in service due to the heating of the magnetic circuit and other steel parts in the transformer or reactor.

Objectives:

The results from this project will be directly used within Electricity Transmission’s Asset Policy and Asset Engineering in analysing future and existing designs of transformer for operational aspects of ferroresonance, geomagnetically induced currents (GIC) and over-fluxing. The knowledge may also be useful in post event analysis. 

Expected Benefits: The project will have deemed to have been a success if the industry’s knowledge in this area has been progressed. National Grid will be able to measure this by an improved analysis of the operational aspects for the magnetic circuit of a transformer/QB under high induction conditions.