Project at a glance:
| Client | UK Distribution Network Operator |
| Project | St Osyth 33kV OHL Connection |
| Type | Concept and detailed design |
| Sector | Electricity distribution |
| Location | South East |
| Duration | 18 months |
St Osyth
The brief
A major solar farm required a 33kV connection to a nearby overhead line. The DNO’s overhead line tower, built in the 1940's, was fitted with a rare inline circuit switch connected at cross arm level and operated from a manual lever at ground level. Adjacent to the tower, at the point of connection, was an 11kV wood pole overhead line. This provided limited access for the installation of the new structure.
The approach
BPI undertook a detailed study of the existing tower and produced a review of the various health and safety issues for the installation and ongoing operation of the new point of connection. It was agreed that the method of connection must produce minimal mechanical load transfer into the existing tower, otherwise the inline circuit switches could operate incorrectly. Innovating with a radical design, BPI produced a patented solution known as POC-MASTTM, now becoming an industry standard solution at both 33kV and 132kV. POC-MASTTM is designed for each point of connection, based on the latest euro codes and using a folded steel mast. It is assembled at ground level and erected using a hydraulic ram, requiring minimal working at height. With a mass concrete or screw anchor foundation, minimal curing time and ground excavation is needed.
The challenges
The project had short design timescales, with a small footprint requiring a permanent connection to an existing tower with old circuit operating equipment. POC-MASTTM minimised the mechanical load which could affect the operation of the existing circuit switches.
The delivery
The POC-MASTTM provided a safe, cost effective solution ensuring working at height was minimised. Although this was the first time this solution was used in the UK, the design and installation was safely delivered to time and programme. It also reduced the 33kV cable connection length by 350m. Winner of the Construction News Innovation Award in 2015 and finalist in the UK Energy Innovation Awards in 2015, the POC-MASTTM solution is now fully operational, and a number of other projects are planned.
