Generating a change at Indian Queens

Karl Young, ABB HV Service Manager, explains why a growing number of customers such as International Power’s Indian Queens power station are upgrading to the latest GCB (generator circuit breaker) technology.
GCBs, located between the generator units and the step-up transformers, provide vital protection for the electrical systems at power stations. When operated it is vital that they function correctly. For a nuclear power station delivering base load operations are rare – maybe once or twice a year. However, a gas fired unit might operate its GCBs a number of times every day. So power generation companies place a major focus on their regular testing, maintenance and overhaul.

Many power stations are fitted with air-blast operated GCBs such as ABB’s DR36. First installed in the 1960s, this design has provided exceptional service. However its complex compressed air operation, increasingly costly spare parts and need for extensive overhaul at six to nine year intervals means that it is no longer the optimum choice. So when the opportunity arises, ABB recommends an upgrade to its new generation of HECS GCBs. This offers the advantages of SF6 technology with a new hydromechanical spring drive, similar to that deployed on ABB’s new generation GIS (gas insulated switchgear) equipment that provides an exceptionally compact installation footprint. Furthermore, the latest generation of GCBs is effectively overhaul-free for periods up to 20 years, needing only minimal interventions to keep them in as-new condition.

Fast-track replacement
Recently, the ABB HV service team carried out a fast-track replacement of a GCB at Indian Queens power station in Cornwall.
The team was called into action after a third party original equipment manufacturer GCB failed in service. The customer took the decision to replace it with an ABB strategic ‘Sharepart’ GCB – an HECS 130XL – which its parent company, International Power, had available in Belgium.
ABB attended site within a couple of days, and within 6 weeks of the first visit we were back to undertake the installation works. The breaker itself was 6 metres up on an exterior gantry and the phase centres meant that there were significant adaptions required for the Insulated phase bars on both sides of the breaker. We also had to accommodate the non standard voltage DC supplies on site. Even so, we were able to install and commission the new GCB in a little over four weeks including all the modifications.
The customer is delighted with the installation and commended the ABB team on a quick response and professional service.

Replacing the GCB at Indian Queens in Cornwall