There are several technologies on the market for surge protection in power grids:

  • Metal oxide varistors (MOVs)
  • Triggered spark gap
  • Gas-filled spark gap (GSG)
  • CITEL GSG+MOV (CITEL VG-Technology)


This technology is the exclusive and patented CITEL technology based on special gas-filled spark gaps (GSGs). These components, the result of over 75 years of experience in the field of gas discharge tubes, have operating characteristics that are precisely matched to the power grid and are characterized by robustness and stability. Their combination with varistors combines the advantages of both technologies.

CITEL originally developed VG technology for Type 1 low-voltage lightning protection devices and subsequently extended it to Type 2 and photovoltaic applications.

VG technology is used in the following CITEL products:

  • DAC1-13VGS: Type 1+2+3 - AC-Combined arrester, Iimp: 12,5 kA je Pol
  • DAC50VGS: Type 2+3 - AC-Combined arrester, Imax: 50 kA je Pol
  • DS250VG: Typ-1+2+3-AC-Combined arrester, Iimp = 25 kA
  • DUT250VG: Typ-1+2+3-AC-Combined arrester, 3-phase, Iimp = 25 kA
  • DS130VGS: Typ-1+2+3-AC-Combined arrester, Iimp = 12,5 kA
  • DS40VGS: Typ-2+3-AC-Combined arrester, Imax = 40 kA
  • DS60VGPV: Typ-1+2-DC-Combined arrester for photovoltaics, Iimp = 12,5 kA
  • DS50VGPVS: Typ-2-DC-Sure protection device for photovoltaics, Imax = 40 kA

Advantages of VG Technology

1. Gas-filled spark gap (GSG)

VG 1

CITEL's VG overvoltage arresters use special gas-filled spark gaps (GSGs). These key components - the result of over 75 years of experience in the field of gas discharge tubes - are designed to protect electrical networks and ensure maximum electrical stability.

Increased reliability

2. The best protection levels with the highest discharge current

VG 2

GSGs can discharge very high surge currents (Iimp, Imax) at a very low protection level (Up). Previously, such characteristic data could only be achieved by combining a type 1 and a type 2 surge protection device.

→ Combined arrester type 1+2+3 → Maximum efficiency → Compact design

3. Increased TOV strength

VG 4

VG overvoltage arresters can withstand very high Temporary Overvoltage (TOV) values of up to 450 VAC without compromising their protective function.

→ Increased reliability for areas with unstable power grids

4. No (mains) follower current or short-circuit current

VG 4

In contrast to the 'triggered spark gap' technology, the VG technology does not generate any mains follower current (short-circuit current). This leads to an improvement in availability (no fuse tripping during or after the leakage process)

→ Improvement of the network quality (no network disturbances) → Simple selection

5. Robust and reliable

VG 5

All components of a VG surge protection device are designed to handle high leakage current pulses without any support from auxiliary systems. In contrast, the 'triggered spark gap' technology includes a control circuit in which components with very low power consumption dissipate parts of the surge current. During a low amplitude, low voltage compensation process, the full current is applied to this low power circuit, which ultimately fails.

→ Increased reliability → Increased life expectancy

6. Safe isolation and device status signalling

VG 6

The VG surge protection devices have a safe disconnection system and provide a real-time indication of the status of the internal components. With 'triggered spark gap' technology, the isolator and signaling provide only a message on the status of the control circuit, not on the status of the main protective circuit.

→ Safe and efficient maintenance

7. No ageing

VG 7

Except for transients, varistors always conduct a low current even in normal operation. This current results from the operating current (Ic) and the leakage current (Ipe) and is due to the connection of the varistors to the earthing system. This type of power line can place a heavy load on the varistor over time - especially in DC supply systems - and cause it to age prematurely..

→ Maximum life

8. Simplified decoupling for surge protection

VG 8

In the case of decoupled systems, the surge protection device connected downstream of a VG surge protection device does not require special attention, for example with regard to a sufficient distance between the installation locations, which is required for decoupling between several SPDs. Note: Due to its optimized protection level, the VG surge protection devices can be used without any additional overvoltage protection.

→ Simple to use


The CITEL combined arresters in VG technology offer optimum efficiency and reliability and thus fulfil the decisive conditions for achieving the maximum performance of a protection system.