Nov 2020
Electricity Distribution
Nov 2020
Sep 2022
UK Power Networks and South Eastern Power Networks
Rona Mitchell, Paul Williams
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Network Innovation Allowance
ED - Network improvements and system operability
Asset Management and LV & 11kV Networks
The Croydon area of UK Power Networks, until the 1930s, ran on a DC electricity distribution network. When this finally transitioned to AC to align with the rest of the UK, the low voltage network was not updated to three-phase equipment. Ever since, this has been run as a two-phase system which uses special distribution transformers, LV pillars and link boxes. It is known as the Scott Network, named after the engineer who designed it. It is believed that this type of LV distribution system is unique to the whole of the UK.

Due to the increase in DC electronic equipment being connected to the distribution network, such as EVs, batteries and solar PV, there has been an increase in research around whether or not it may be suitable to transition some low voltage networks to DC.

The legacy Scott link boxes are at the end of their service lives and must be replaced. To our knowledge, there are no suitable two-phase double busbar LV link boxes available on the market today. Although it is possible to use two 4-way link boxes designed to run on a three-phase network, to replace one Scott link box, this limits the ability for the network to be run on DC in the future.

Additionally, the possibility of producing a double-busbar LV link box has the potential to enhance LV network operability and reliability. Such a product is also not available on the market and has to our knowledge, not been developed and tested before.
The objective of the project is to develop a piece of plant that can be used as a modern like-for-like replacement link box for the Scott Network.

Desired outcomes:

-          Link box for Scott Network developed and tested to understand whether it is ready for BAU rollout

-          Understand the likely customer savings from using a single Scott link box replacement instead of the existing solution of using two 4-way link boxes.

-          Understand the potential for reduced customer disruption if link box replacements can be made more quickly, reducing roadworks in the Croydon area
Develop a design for a device to maintain the ability for the Croydon LV network to be run on DC, which is an area of increased research.