Future Ready

Phase Switch System

Project Data

Start date:


End date:





National Grid’s Future Energy Scenarios show that irrespective of the scenario, energy demand is going to increase by 25% between now and 2038. It is expected that most of the new demand will be connected to low voltage distribution networks. This in turn is likely to cause a larger phase imbalance than currently observed. Domestic load is normally connected to one phase. Once one phase of a transformer or underground cable reaches its maximum rating then LV network reinforcement needs to be considered.

What is the project about?

The project will:

  • Demonstrate that the PSS can become a solution to reduce unbalance between phases and monitor its impact on the LV feeder or distribution transformer.
  • Demonstrate that the benefits delivered by the PSS of releasing capacity and estimating its longevity are realistic.
  • Assess the impact of moving demand from one phase to another.
  • Develop a methodology that will indicate how long the benefits are likely to deliver benefits based on the Future Energy Scenarios demand growth.
  • Validate the CBA showing the benefits of this alternative solution.

How we’re doing it

During the Catapult Energy Systems funded Smart Urban Networks project, Low Carbon Electric developed a Phase Switch System (PSS) which unlocks current and voltage headroom by switching phases between adjacent distributor segments in real time. This addresses load unbalance caused by rapid/uneven uptake of LCTs. The PSS has been demonstrated at the Power Networks Demonstration Centre (PNDC) and has reached the physical LV network demonstration phase. The project will identify transformers and/ or LV feeders where the PSS could be used to release capacity by correcting the unbalance.

What makes it innovative

LCE have developed the PSS to move customer demand from one phase to another without causing a supply interruption.

What we’re learning

The project will demonstrate that the PSS is a solution to defer transformer replacement and/or LV mains cable overlays by improving the level of unbalance between LV phases.

The CBA will confirm that benefits can be realised and the PSS can be used by distribution planners to resolve network issues expected over the next 20 years as demand increases by 25%.

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