Drax Power Ltd Switchgear Upgrade

The contract required the upgrade of an obsolete Reyrolle manufactured ‘TJV’ IDMTL electromechanical over current relay with a modern, digital, protection relay incorporating a ‘high-set instantaneous trip’ function on seventeen 11/3.3 kV circuits at Drax Power Station. TP Power Services elected Siemens Reyrolle Argus-C 7SR11 relays as the digital equivalent to be combined with RMLG test blocks for more efficient testing and commissioning so that each circuit could be isolated, upgraded and commissioned within one day in order to support the stations outage programme. Direct interchangeability was obtained through detailed design studies of the existing wiring schematics and settings with considerations to be made for future upgrades.

Reyrolle Argus C Relay

Review of existing relay and protection settings and wiring schedules
Design and fabrication of ‘carrier plates’ to mount new digital relays into the existing ‘cut-out’
Pre-assembly and wiring of modern relays and test blocks into ‘carrier plates’ at TPPS factory
Preliminary programming, secondary injection testing and trip-function testing at TPPS factory
Removal of obsolete overcurrent relays and redundant wiring
Installation of pre-assembled digital relay sets, wiring and input of final alarm and trip settings
Final commissioning, function and witness testing to local circuit breaker and control room
Updating of ‘as-installed’ wiring schematics and handover to client in AutoCAD format
Completion of process QA documents, auditing and final handover for client records


Current feedback has highlighted the technical competency, efficiency and flexibility shown by TP Power Services to support the station’s outage schedule and ensuring the integrity of the relays replaced to date.


TP Power Services site engineers have completed the installation of the 17 circuits in conjunction with Drax’s outage schedule.