A transmission utility's experience to date with transformer protection systems

This presentation investigates a number of design, operation and lifetime management experiences of transformer protection systems installed on National Grid Electricity Transmission (NGET) networks. The presentation considers the policy, application design and operational experiences under the following categories, particularly since the move to numeric protection: policy and application design; operational experience to date; and maintenance and post-commissioning support. Examples of protection mal-operations during transformer energisation are discussed in the presentation. A bespoke transformer overall protection scheme is presented for the application of the scheme on a transformer banked with a long cable circuit (>5 km).