AF
Arc-flash fibre loop sensor
Bare optical fibre routed through switchgear that picks up arc light anywhere along its length.
SLD / Schematic
Symbols · AF
Arc-flash point light sensor
Light sensor in a switchgear compartment that detects the flash of an internal arc and signals an arc-flash relay.
In plain English
What does Arc-flash point light sensor mean?
A point light sensor is mounted inside a switchgear compartment, such as a breaker or cable compartment, and detects the intense light of an internal arc. It is wired or fibre-connected to an arc-flash relay that usually also checks for overcurrent before tripping, so light alone from an external source does not cause a trip.
A simple example
The drawing should show which compartment each sensor watches, because the trip zone depends on it. The symbol does not show sensitivity, field of view or the self-supervision used to detect a disconnected sensor.
What the drawings help you do
Identify the compartment each sensor covers. Check whether trip needs light plus overcurrent. A point sensor covers one compartment; a fibre loop sensor covers a long area such as a busbar run.
This particular reference
Light sensor in a switchgear compartment that detects the flash of an internal arc and signals an arc-flash relay. A point sensor covers one compartment; a fibre loop sensor covers a long area such as a busbar run.
- Coil
- A wound conductor that can produce a magnetic field when energised.
- Terminal
- An identified point where a conductor connects.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
Read the source: SEL-C804 multimode arc-flash detection fibre-optic cables
SLD / Schematic · AF
What it represents
A point light sensor is mounted inside a switchgear compartment, such as a breaker or cable compartment, and detects the intense light of an internal arc. It is wired or fibre-connected to an arc-flash relay that usually also checks for overcurrent before tripping, so light alone from an external source does not cause a trip.
The drawing should show which compartment each sensor watches, because the trip zone depends on it. The symbol does not show sensitivity, field of view or the self-supervision used to detect a disconnected sensor.
How to read it
- Identify the compartment each sensor covers.
- Check whether trip needs light plus overcurrent.
Information to show or reference
- Locate each sensor by compartment
- Show connection to the arc relay
- State trip logic
A distinction that matters
A point sensor covers one compartment; a fibre loop sensor covers a long area such as a busbar run.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
SEL-C804 multimode arc-flash detection fibre-optic cables
Public manufacturer page describing point and fibre arc-flash light sensing.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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