# Microgrid black-start source selector

Canonical URL: https://eloragrid.ai/symbols/microgrid-black-start-source-selector
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: MBSS
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: microgrids
Input: Black-start resource capability
Output: Selected starting source

Selects an available resource declared capable of establishing the initial electrical reference.

## In plain English

### What this block does

Selects an available resource declared capable of establishing the initial electrical reference.

### A simple example

In a microgrid recovering from a blackout, an available grid-forming source can establish the assigned island reference before compatible generation and eligible load groups are introduced under the validated restoration strategy. For this reference, the drawing identifies “Black-start resource capability” at the input and “Selected starting source” at the output. Resource capability must be confirmed by its documentation.

### What the drawings help you do

Start at the named input: Black-start resource capability. Identify its source device or document and the state represented on the drawing. Follow the named output: Selected starting source. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Black-start resource capability
- Output: Selected starting source
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Black-start resource capability → MBSS → Selected starting source
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Avista Shared Energy Economy microgrid protection and control case study](https://selinc.com/api/download/135486/)


## What it represents

Selects an available resource declared capable of establishing the initial electrical reference. Black-start and restoration control coordinates the establishment of an electrical reference and the gradual return of assigned resources and loads. A dead system, an available starting source and a successful load restoration are distinct states.
In a microgrid recovering from a blackout, an available grid-forming source can establish the assigned island reference before compatible generation and eligible load groups are introduced under the validated restoration strategy. For this reference, the drawing identifies “Black-start resource capability” at the input and “Selected starting source” at the output. Resource capability must be confirmed by its documentation.
Show the prerequisites and confirmation at each control boundary. These original explanatory blocks are not an operating procedure; energization, protection, transformer inrush and motor reacceleration require system-level validation. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation.

## How to read it

- Start at the named input: Black-start resource capability. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Selected starting source. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Resource capability must be confirmed by its documentation.
- Show the prerequisites and confirmation at each control boundary. These original explanatory blocks are not an operating procedure; energization, protection, transformer inrush and motor reacceleration require system-level validation.

## Information to show or reference

- Label the source and connection reference for black-start resource capability.
- Identify the destination and defined state of selected starting source.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Resource capability must be confirmed by its documentation.

## Important distinction

Resource capability must be confirmed by its documentation. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.

## Facts

- Representation: Functional block
- Installation focus: Microgrids
- Input / boundary: Black-start resource capability
- Output / connection: Selected starting source
- Lookup label: MBSS is a library lookup label, not a standard device designation.

## Public references

- [Avista Shared Energy Economy microgrid protection and control case study](https://selinc.com/api/download/135486/) — SEL. Public technical context for microgrid black-start and restoration controls. Storage, protection, black start, load restoration and coordinated island operation. The application text and educational graphic are independently authored; the publisher does not certify this representation.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.