New customer substation with a private low voltage network

How does New customer substation with a private low voltage network work, step by step?

1. 1

   Step 1: Establish the arrangement with the operator

   The designer and the operator agree where the high voltage supply will be brought to, where the ownership boundary sits, what equipment each party provides, and what access the operator requires to its own assets. That boundary determines who maintains what for the next thirty years, so it is documented precisely rather than described loosely. The operator will also state its requirements for the arrangement of its equipment, its separation from customer plant and its access at any hour, and those requirements shape the compound before anything else does.

2. 2

   Step 2: Size the substation for the scheme and its future

   Sizing is a decision about the future as much as the present. The immediate charging load sets the minimum, but on most projects it is worth sizing for a planned second phase, because the marginal cost of additional capacity at the time of installation is far below the cost of revisiting the arrangement later. The designer establishes the demand, the diversity and any load management intended, and produces a capacity that the client signs off knowing what it does and does not allow for.

3. 3

   Step 3: Design the private low voltage network

   From the substation, the private network distributes to the charging bays. The designer sets out the distribution arrangement - how many circuits, where they run, how the bays are grouped, where the boards and pillars sit - together with the metering and the provision for the control and communications the operator of the chargers needs. Every parameter of that design, including protection, is determined by the designer for the specific installation. The design also decides what spare provision is built in, because spare ways in a board are cheap and adding them later is not.

4. 4

   Step 4: Design the compound and the civils around it

   The substation and the associated equipment need their compound: hardstanding, bases, ducts, drainage, security, delivery access and maintenance clearances. The operator's equipment and the customer's equipment sit within it under the separation the operator requires. Duct routes from the compound to the charging areas are set out with spare capacity, and everything below ground is coordinated with the existing services on site. The compound is a substantial construction item and is programmed as such.

5. 5

   Step 5: Secure the land rights and the consents

   The operator will normally require a lease or transfer of the ground its equipment occupies, together with rights of access at any time and rights to bring its cables across the land to reach it. On leasehold or multi-owner sites that involves parties who have no interest in the project's programme, and it routinely takes longer than the technical work. Planning and other consents for the compound run alongside. These matters are started early because they are the ones most likely to delay energisation.

6. 6

   Step 6: Build the civils and install the equipment

   The compound, bases, ducts and cable routes are constructed, surveyed as built and proved clear before the equipment arrives. The substation and switchgear are delivered under a lift plan and set on their bases. Cables are pulled and terminated. All of this electrical work is carried out by competent qualified people, and where it involves any existing live equipment on the site it proceeds under permit with the equipment treated as live until proven otherwise. Sequencing matters, because the operator's programme and the site programme have to meet at energisation.

7. 7

   Step 7: Commission the substation and the private network

   Commissioning covers the high voltage equipment, the transformation, the low voltage distribution, the metering and the control and communications, and it is carried out by competent qualified people to the designer's specification with the results recorded. Energisation is a planned operation agreed with the operator in advance. Nothing is left to be sorted out afterwards, because a private network that is energised with outstanding items becomes a live installation with defects in it.

8. 8

   Step 8: Hand over the asset with its obligations

   Handover is not just drawings. The client receives the as-built records, the operating and maintenance information, the schedule of what is owned by whom, the connection agreement, and the inspection and maintenance regime the installation requires. Someone competent has to be nominated as responsible for the high voltage installation, and the arrangements for access, for emergency response and for periodic inspection are set out and understood. This is the step that turns a construction project into an asset that can be safely operated.