# Microgrid reactive-control authority transfer

Canonical URL: https://eloragrid.ai/symbols/microgrid-reactive-control-authority-transfer
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: MRAT
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: microgrids
Input: Old and new controller availability
Output: Selected reactive-control authority

Coordinates a documented change in ownership of the voltage-support objective.

## In plain English

### What this block does

Coordinates a documented change in ownership of the voltage-support objective.

### A simple example

In an islanded microgrid, the assigned reference source supports bus voltage while other compatible resources share reactive demand according to the selected control method. Grid-connected operation can use a different objective at the PCC. For this reference, the drawing identifies “Old and new controller availability” at the input and “Selected reactive-control authority” at the output. A smooth transfer requires a validated control strategy.

### What the drawings help you do

Start at the named input: Old and new controller availability. Identify its source device or document and the state represented on the drawing. Follow the named output: Selected reactive-control authority. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Old and new controller availability
- Output: Selected reactive-control authority
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Old and new controller availability → MRAT → Selected reactive-control authority
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Microgrid control systems](https://selinc.com/services/microgrids-power-management/microgrid-control-systems/)


## What it represents

Coordinates a documented change in ownership of the voltage-support objective. Voltage and reactive-power control coordinate the AC operating condition of the microgrid resources. A voltage target, reactive-power target and power-factor target represent different control objectives and should have explicit ownership.
In an islanded microgrid, the assigned reference source supports bus voltage while other compatible resources share reactive demand according to the selected control method. Grid-connected operation can use a different objective at the PCC. For this reference, the drawing identifies “Old and new controller availability” at the input and “Selected reactive-control authority” at the output. A smooth transfer requires a validated control strategy.
Show each measured quantity, target and resource capability limit. Control-loop tuning, equipment capability and parallel operation require a validated design rather than an assumed property of the symbol. 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: Old and new controller availability. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Selected reactive-control authority. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- A smooth transfer requires a validated control strategy.
- Show each measured quantity, target and resource capability limit. Control-loop tuning, equipment capability and parallel operation require a validated design rather than an assumed property of the symbol.

## Information to show or reference

- Label the source and connection reference for old and new controller availability.
- Identify the destination and defined state of selected reactive-control authority.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: A smooth transfer requires a validated control strategy.

## Important distinction

A smooth transfer requires a validated control strategy. 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: Old and new controller availability
- Output / connection: Selected reactive-control authority
- Lookup label: MRAT is a library lookup label, not a standard device designation.

## Public references

- [Microgrid control systems](https://selinc.com/services/microgrids-power-management/microgrid-control-systems/) — SEL. Public technical context for microgrid voltage and reactive-power controls. Active and reactive power, generation, load control, operating reserves and system supervision. 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.