# Sequence-of-events recorder

Canonical URL: https://eloragrid.ai/symbols/sequence-of-events-recorder
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: SOE
Drawing use: Schematic
Reference families: Manufacturer

Recorder that timestamps changes of state on many binary inputs so the order of operations can be reconstructed.

## In plain English

### What does Sequence-of-events recorder mean?

A sequence-of-events recorder monitors breaker auxiliary contacts, protection trip outputs, alarms and other binary signals, and stores each change with an accurate timestamp. After an incident the list shows which device operated first, which is often impossible to tell from alarms alone.

### A simple example

Timestamp resolution and time synchronisation are what make the record useful. The symbol does not show the time source, such as a GPS clock, or the debounce settings on each input, and without synchronisation records from different devices cannot be merged reliably.

### What the drawings help you do

Identify the time synchronisation source. Check which contacts are wired as inputs. An SOE recorder logs binary changes in time order; a disturbance recorder captures analogue waveforms.

### This particular reference

Recorder that timestamps changes of state on many binary inputs so the order of operations can be reconstructed. An SOE recorder logs binary changes in time order; a disturbance recorder captures analogue waveforms.

### Terms

- Normally open / normally closed: The contact state in the normal condition defined for the drawing.
- Signal: Electrical information passed between devices, rather than necessarily the main power supply.
- Rating: A value stating the conditions for which equipment is specified.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [SEL 2022 Product and Solution Guide: published protection function tables](https://selinc.com/api/download/136012)


## What it represents

A sequence-of-events recorder monitors breaker auxiliary contacts, protection trip outputs, alarms and other binary signals, and stores each change with an accurate timestamp. After an incident the list shows which device operated first, which is often impossible to tell from alarms alone.
Timestamp resolution and time synchronisation are what make the record useful. The symbol does not show the time source, such as a GPS clock, or the debounce settings on each input, and without synchronisation records from different devices cannot be merged reliably.

## How to read it

- Identify the time synchronisation source.
- Check which contacts are wired as inputs.

## Information to show or reference

- List monitored inputs
- Show time source
- State resolution and debounce

## Important distinction

An SOE recorder logs binary changes in time order; a disturbance recorder captures analogue waveforms.

## Facts

- Inputs: Binary contacts and signals
- Key requirement: Synchronised timestamps
- Preview: Functional illustration of the device role; not a product footprint or certified standard graphic

## Public references

- [SEL 2022 Product and Solution Guide: published protection function tables](https://selinc.com/api/download/136012) — Schweitzer Engineering Laboratories. Public product and function guide including event recording and time synchronisation.

## 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.