Several technologies exist on the market for AC or DC power surge protection:
• Metal Oxide Varistor (MOV)
• Triggered Spark Gap
• MOV + Gas-filled Spark Gap (GSG)

VG technology is CITEL's exclusive and patented technology based on the use of a specific type of Gas-filled spark gap (GSG) coordinated with a specific Metal oxide varistor (MOV).

This hybrid component is the result of over 75 years of experience in the field of gas discharge tubes and they have a unique set of properties, unlike standard gas discharge tubes, that allow them to be used on powered conductors.

VG provides a robustness and working stability: their association with varistors combines the advantages of both technologies.

CITEL originally developed the “VG” technology for low voltage IEC Type 1 surge protectors and has then extended it to IEC Type 2 surge protectors and Photovoltaic applications.

Advantages of VG Technology


1. Gas-filled-Spark Gap (GSG)

CITEL VG surge protectors are using very specific gas discharge tubes: GSG. These essential components are the result of over 75 years of experience in the gas discharge tube field. They are meant for power networks with very high surge risk and need for electrical stability.
→ Increase reliability

2. Very low clamping level and high surge current rating

GSG are able to conduct very high surge currents (Iimp, Imax) with a very low residual voltage (Up) or voltage protectin rating (VPR). Such characteristics could only previously be reached with the combination of a Type 1 and a separate Type 2 surge protector.
→ VG is equivalent to a combination of IEC Type « 1+2+3 » or « 2+3 » solutions
→ Maximum protection
→ Compact design

3. Increased TOV withstand

VG surge protectors can handle very high TOV levels (Temporary over Voltage) up to 450Vac (on 240Vac systems) without any degradation to the level of protection.
→ Increased reliability for areas with unstable power networks

4. No follow on current

Unlike “Air Gap” technologies, “VG” Technology does not create any follow on current. VG ->Increases service continuity (No tripping of the upstream overcurrent protection device (OCP) during surge events)
→ Improvement of the network quality (no power line disturbances)
→ Easy selection

5. Robustness and reliability

All the components of the VG surge protector are designed to handle high impulse discharge currents without any assistance from secondary systems, protectors or other components. On the contrary, the “Triggered Air Gap” technology includes a control circuit, which uses very low power components, that handle parts of the surge current. During these low amplitude, low voltage transients, this weak circuit will handle the full amount of current and will eventually fail without triggering the spark gap.
→ Increase reliability
→ Better life expectancy

6. Safe disconnection and status indication

VG surge protectors use a safe disconnection system and provide real-time status indication of internal components. For a “Triggered Air Gap” technology, the disconnection and signalization only can provide the status of the control circuit and not the main protection circuit.
→ Safe and efficient maintenance

7. No ageing

During normal operation, in addition to transient events, varistors are always conducting a small amount of current. This current is the result of working current (Ic) and leakage current (Ipe) which is due to the varistors connection to the grounding system. This type of conduction can be stressful to the varistor over time, especially in dc power systems, and cause the varistor to age prematurely.
→ Maximum life

8. Easier surge protection coordination

In the case of coordinated installations, the surge protector downstream a VG surge protector does not need any special consideration, such as a sufficient distance between the two installation locations, in order to ensure proper coordination between multiple SPDs. Note: due to its optimized protection level, the VG surge protector can be used without any additional surge protector.
→ Easier to use

See VG Solutions for AC Power Line Applications
See VG Solutions for DC Power Line Applications