One of the key criteria for Transpower
when planning for new high voltage substations was to minimize their maintenance. The vast majority of the substations are close to the sea and will be exposed to wind borne salt, promoting corrosion in open air contacts used in disconnectors. The climatic conditions in New Zealand demand high quality switchgear to maximize the power availability for the consumers. New Zealand is subject to high levels of seismic activity, therefore, Transpower has adopted the IEEE 693-2005 HIGH standard for all their switchgear.
To attain a solution with high availability and a minimum of maintenance, ABB chose to offer DCBs (Disconnecting Circuit Breaker).
With a DCB solution, all open air disconnectors are eliminated. The interrupter fulfills the requirement of a disconnector and permits substations to be built with minimized need for maintenance and space, low failure rates, increased safety and low life cycle costs. The safety is increased since maintenance and repair activities are significantly reduced, and during maintenance safe earthing is applied remotely from the control room. The DCBs, together with the current transformers, were earthquake tested and verified in an independent laboratory before delivery.