# Motor restart-inhibit block

Canonical URL: https://eloragrid.ai/symbols/motor-restart-inhibit-block
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: MRB
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: switchgear
Input: Trip and supply-return status
Output: Restart inhibit

Suppresses an automatic restart under the documented post-trip or supply-return condition.

## In plain English

### What this block does

Suppresses an automatic restart under the documented post-trip or supply-return condition.

### A simple example

In a switchroom motor-control panel, a ventilation motor can receive an automatic start request while a local selector and the motor protection determine whether the feeder is available. For this reference, the drawing identifies “Trip and supply-return status” at the input and “Restart inhibit” at the output. Restart permission must follow the operating philosophy.

### What the drawings help you do

Start at the named input: Trip and supply-return status. Identify its source device or document and the state represented on the drawing. Follow the named output: Restart inhibit. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Trip and supply-return status
- Output: Restart inhibit
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Trip and supply-return status → MRB → Restart inhibit
A reading guide. The entry's original illustration and input/output facts describe this application.

- [SEL-710 motor protection and control](https://selinc.com/products/710/)


## What it represents

Suppresses an automatic restart under the documented post-trip or supply-return condition. A motor feeder combines switching, motor protection and an operating command. Starting permission, running feedback and protection trip are different signals even where one relay or controller processes all of them.
In a switchroom motor-control panel, a ventilation motor can receive an automatic start request while a local selector and the motor protection determine whether the feeder is available. For this reference, the drawing identifies “Trip and supply-return status” at the input and “Restart inhibit” at the output. Restart permission must follow the operating philosophy.
Link the motor tag to its contactor, protective device and process permissives. The control diagram must identify stop priority, feedback and restart philosophy without supplying unverified settings. 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: Trip and supply-return status. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Restart inhibit. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Restart permission must follow the operating philosophy.
- Link the motor tag to its contactor, protective device and process permissives. The control diagram must identify stop priority, feedback and restart philosophy without supplying unverified settings.

## Information to show or reference

- Label the source and connection reference for trip and supply-return status.
- Identify the destination and defined state of restart inhibit.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Restart permission must follow the operating philosophy.

## Important distinction

Restart permission must follow the operating philosophy. 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: Switchgear
- Input / boundary: Trip and supply-return status
- Output / connection: Restart inhibit
- Lookup label: MRB is a library lookup label, not a standard device designation.

## Public references

- [SEL-710 motor protection and control](https://selinc.com/products/710/) — SEL. Public technical context for motor-feeder control interfaces. Motor feeder thermal, starting and control functions. 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.