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substation · indoor distribution · low voltage

Indoor 11 kV to 400 V distribution substation single line diagram

This substation single line diagram shows an indoor 11 kV to 400Y/230 V distribution substation for a building. An 11 kV utility cable enters an SF6 ring main unit load-break switch, then passes through a transformer fuse to a 630 kVA cast-resin transformer. A 1000 A low-voltage air circuit breaker supplies the main distribution bus.

Type Schéma unifilaireNorme IEEE Std 315 + ANSI device numberingMoteur schematex-sldMis à jour 22/09/2026
Indoor 11 kV/400 V substation
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La demande

“Draw an indoor 11 kV to 400 V distribution substation single line diagram with an SF6 RMU load-break switch, 63 A transformer fuse, 630 kVA cast-resin transformer, 1000 A LV air circuit breaker, and lighting, power, and HVAC feeders.”

Essayez ensuiteAdd a second 630 kVA transformer and bus tie.Change the HVAC feeder to 500 A.
Ce que contient ce dessin

Comprenez les décisions qui le sous-tendent.

01Indoor MV isolation

An SF6 RMU load-break switch receives the 11 kV cable supply.

02Transformer branch

A 63 A fuse protects the 630 kVA transformer primary.

03Dry transformer

Cast-resin construction suits an indoor equipment room.

04LV main protection

A 1000 A ACB feeds the 400Y/230 V distribution bus.

05Building feeders

Lighting, power, and HVAC loads are independently protected.

Use this for a building-scale indoor substation concept. Room ventilation, fire strategy, protection settings, and local MV standards must be verified.

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FAQ

Questions fréquentes

Why use a cast-resin transformer indoors?

It avoids liquid dielectric fluid and is commonly selected for indoor applications.

What is the RMU switch used for?

It provides compact medium-voltage switching and isolation at the cable incomer.

Does a transformer fuse replace all protection?

No. Final protection design must coordinate MV fuses, LV breakers, and upstream utility devices.