Apr 2013
Electricity Transmission
Transformer Life Management
Apr 2013
National Grid Electricity System Operator
National Grid TO Innovation Team
Click here to send a question to the contact.
Innovation Funding Incentive
Gas Distribution Networks
Asset management of an ageing transformer fleet including tapchangers and the impact of ferroresonance and other low frequency phenomena (GIC & switching).

These projects are combined investigations into the dielectric performance of aged transformer insulation, diagnostic techniques and modelling of anticipated failure rates. Understanding the dielectric behaviour aged transformer insulation at high voltages may allow the better identification of the factors likely to lead to the failure of old transformers. This will allow optimum targeting of the transformer replacement expenditure and the oil and moisture care regime, to ensure system reliability at minimum cost. Transformer failures pose an environmental risk and tend to attract media attention if they involve a fire.

One project aims to establish the material impact when power transformers are exposed to ferroresonance and how an improved understanding can affect the detection and asset management of the entire transformer fleet. The work packages concentrate on:

  • Characterisation of the degradation and failure mechanism in different designs of power transformers associated with ferroresonance. Establish what effect this has on the useful lifetime for a transformer

  • Identify the design features of transformers which are susceptible to ferroresonance

  • Establish a reliable ferroresonance detection technique, which can be incorporated into new transformer protection relays

The final project aims to:

  • Fit a new technology tapchanger (Vacutap) to an existing asset which has a worn out tapchanger on a healthy transformer

  • Monitor the installation on completion to assess the success of the project in order to aid future strategy on this type of problem

  • Achieve extended life of an asset with a reduced maintenance requirement which will deliver cost savings.