# Station DC feeder selectivity boundary

Canonical URL: https://eloragrid.ai/symbols/station-dc-feeder-selectivity-boundary
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: SDFSB
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: substations
Input: DC feeder protective devices
Output: Defined protection relationship

Shows the protective-device relationship considered when assigning downstream DC fault isolation.

## In plain English

### What this block does

Shows the protective-device relationship considered when assigning downstream DC fault isolation.

### A simple example

In a substation control building, the battery can support breaker trip circuits while the charger AC supply is unavailable. Supervision must identify whether the charger, battery or a downstream feeder is affected. For this reference, the drawing identifies “DC feeder protective devices” at the input and “Defined protection relationship” at the output. Selectivity requires a DC protection assessment.

### What the drawings help you do

Start at the named input: DC feeder protective devices. Identify its source device or document and the state represented on the drawing. Follow the named output: Defined protection relationship. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: DC feeder protective devices
- Output: Defined protection relationship
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: DC feeder protective devices → SDFSB → Defined protection relationship
A reading guide. The entry's original illustration and input/output facts describe this application.

- [MicroGenius S2/S4 battery charger technical manual](https://www.sens-usa.com/hubfs/Controlled%20Files/Manuals/101330_MGS_User_Manual.pdf)


## What it represents

Shows the protective-device relationship considered when assigning downstream DC fault isolation. A station battery system supplies protection, control and other assigned DC loads through a documented charger and distribution arrangement. Charger output, battery contribution and load distribution are related but separately monitored paths.
In a substation control building, the battery can support breaker trip circuits while the charger AC supply is unavailable. Supervision must identify whether the charger, battery or a downstream feeder is affected. For this reference, the drawing identifies “DC feeder protective devices” at the input and “Defined protection relationship” at the output. Selectivity requires a DC protection assessment.
Identify every source, protective device, isolation boundary and return. Battery capacity, DC fault duty, charging settings and ventilation require the selected battery-system design; illustrative circuits do not establish autonomy. 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: DC feeder protective devices. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Defined protection relationship. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Selectivity requires a DC protection assessment.
- Identify every source, protective device, isolation boundary and return. Battery capacity, DC fault duty, charging settings and ventilation require the selected battery-system design; illustrative circuits do not establish autonomy.

## Information to show or reference

- Label the source and connection reference for dc feeder protective devices.
- Identify the destination and defined state of defined protection relationship.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Selectivity requires a DC protection assessment.

## Important distinction

Selectivity requires a DC protection assessment. 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: Substations
- Input / boundary: DC feeder protective devices
- Output / connection: Defined protection relationship
- Lookup label: SDFSB is a library lookup label, not a standard device designation.

## Public references

- [MicroGenius S2/S4 battery charger technical manual](https://www.sens-usa.com/hubfs/Controlled%20Files/Manuals/101330_MGS_User_Manual.pdf) — SENS. Public technical context for station battery and charger distribution. Battery charging modes, DC distribution interfaces and charger alarms. 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.