Dollands Moor AC/DC Changeover System and Detailed Design

Dollands Moor AC/DC changeover is an isolation transformer based changeover scheme at the operational boundaries between Eurotunnel, HS1 and Network Rail infrastructures in Folkstone. This AC/DC changeover is part of a strategic freight link between the UK and Europe.

Phase 1 of the project renewed 3 isolation transformers, phase 2 of the project installed an additional 2 isolation transformers to re-instate the isolating sections. Navitas were engaged by Siemens to undertake the following scope of work:

• System modelling of the AC/DC changeover scheme to assess fault currents, touch voltages and induced voltages;

• Protection co-ordination assessment and protection settings;

• Transformer earth fault protection design;

• Scheme earthing and bonding design;

• Lighting and LV design;

• Isolation diagrams and instructions;

• DC stray current measurements.