Project overview

Morson Projects were appointed by Carillion to support them with the engineering for a new shunt reactor bay which was installed as an extension to the existing 400kV substation at Cilfynydd.


A new shunt reactor bay comprising equipment detailed below was installed as an extension to the existing 400kV substation at Cilfynydd 400kV Substation.  The works incorporated all civils and associated protection and control.  The reactor for the bay was supplied, installed, erected and Stage 1 was commissioned by ABB under a direct contract from National Grid.  The interfaces to the ABB works were civils, HV connections to the bushings, LV connections to the marshalling kiosk, earthing connections and overall commissioning. There were also temporary works and temporary arrangements required for the delivery of the ABB Shunt Reactor.

The new circuit was connected to an extension of the existing Main and Reserve Busbar 2 to the North East corner of the Substation.

A summary of the works at Cilfynydd is as follows:

Summary of what was added:

  • 400kV 200MVAr Shunt Reactor
  • Alstom GL316X circuit breaker with point on wave opening
  • 400kV CMM01 Pantograph disconnectors with integral earth switch
  • 400kV CMM01 Stand-alone earth switches
  • 400kV surge arrestors
  • 400kV current transformers
  • New bund, plinth and noise enclosure
  • New electrified boundary fence around new shunt reactor bay
  • Electrical and mechanical interlocking of new Shunt Reactor 4 bay
  • Post Insulators
  • Busbars and connections
  • New PRR with Protection and Control Relay Panels and DC system
  • Extension to the SCS with a new remote wall box in the new PRR

Summary of what was removed:

  • Removal of the existing electrified boundary fence in the North East corner adjacent to the Rassau and Imperial Park circuits.

Summary of what was modified:

  • Existing Busbar protection, synchronising, CB Fail, Interlocking, AC and DC Supply rings to accommodate the new bar extension.
  • Control modifications to integrate and extend the existing SCS.
  • Changes in nomenclature to existing MB2 & RB2 earth switches.

Design and Installation:

  • Cilfynydd is an existing double busbar substation. Main and Reserve Busbar 2 to the East of the substation were extended and a new SHR4 bay added.  The new bay was connected to the busbar extension via pantograph disconnectors. The bay comprised the following equipment; Shunt reactor, Surge arrestors, combined pantograph disconnectors / earth switch, free standing earth switches, circuit breaker, CTs, post insulators, busbars and connections.
  • There were no stages of work; the new circuit was built off line with final connections to the existing busbars done under pre booked busbar outages.
  • The existing fence line was removed and extended to include the new bay.

Morson Projects undertook all design work for this project including complete protection and control designs and remote end designs.

Our Services

Delivering the project requirements to an agreed Statement of Work (SOW), the Morson Projects team carried out services to include:

  • Virtual Engineering
  • Primary & Secondary Engineering