GDT
Gas-discharge protection tube
A gas-discharge tube provides a documented surge-protection path through gas breakdown.
SLD / Schematic
IEEE / ANSI · GDT
ANSI/IEEE gas discharge tube symbol
IEEE-oriented protective gas discharge tube: electrodes within a sealed envelope that conduct when voltage exceeds breakdown.
In plain English
What does ANSI/IEEE gas discharge tube mean?
A gas discharge tube places protective electrodes inside a sealed gas-filled envelope, giving a more consistent breakdown voltage than an open spark gap. It is widely used on telecom lines, data interfaces and as part of hybrid surge protective devices. The publisher's IEEE miscellaneous preview lists a protective gas discharge tube form.
A simple example
This illustration is independent and not the IEEE graphic. A GDT responds more slowly than semiconductor clamps and can hold a low on-state voltage, so it is often combined with other elements. The symbol does not show DC sparkover voltage or impulse rating.
What the drawings help you do
Check DC sparkover and impulse ratings. Look for companion clamp devices in hybrid protection. A gas discharge tube is a sealed gap; an open spark gap is exposed to ambient conditions.
This particular reference
IEEE-oriented protective gas discharge tube: electrodes within a sealed envelope that conduct when voltage exceeds breakdown. A gas discharge tube is a sealed gap; an open spark gap is exposed to ambient conditions.
- DC
- Direct current: electricity flowing in one direction.
- Rating
- A value stating the conditions for which equipment is specified.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: Autodesk IEEE Symbol Preview — Miscellaneous · IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
IEEE / ANSI · Autodesk IEEE-oriented protective gas discharge tube form
Autodesk publishes this block under IEEE Symbol Preview: Miscellaneous. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · GDT
What it represents
A gas discharge tube places protective electrodes inside a sealed gas-filled envelope, giving a more consistent breakdown voltage than an open spark gap. It is widely used on telecom lines, data interfaces and as part of hybrid surge protective devices. The publisher's IEEE miscellaneous preview lists a protective gas discharge tube form.
This illustration is independent and not the IEEE graphic. A GDT responds more slowly than semiconductor clamps and can hold a low on-state voltage, so it is often combined with other elements. The symbol does not show DC sparkover voltage or impulse rating.
How to read it
- Check DC sparkover and impulse ratings.
- Look for companion clamp devices in hybrid protection.
Information to show or reference
- State sparkover voltage.
- Show earth connection.
- Identify hybrid protection stages.
A distinction that matters
A gas discharge tube is a sealed gap; an open spark gap is exposed to ambient conditions.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Autodesk IEEE Symbol Preview — Miscellaneous
Exact public IEEE-oriented category page listing the protective gas discharge tube form.
IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
Graphic-symbol standards context and official status; not a source of reproduced artwork.
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.
Explore related references
Put the reference into a drawing workflow.
Elora Grid helps electrical teams work with drawings, specifications and equipment information. Explore the drafting workflow or join the early-access waitlist.