Line surge arresters

We supply non-gapped and externally gapped line surge arresters for overhead lines for up to 800 kV. Line surge arresters offer the most economical and effective lightning protection on new and existing overhead line systems. Special areas of application include e.g. areas with high lightning frequency, poor soil or tower grounding resistance (e.g. for sandy or rocky ground), unprotected overhead lines (without ground wire), reducing switching impulse current overvoltages in high-voltage systems, and providing extended station protection.

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Product overview We offer line surge arresters for system voltages of 12 kV to 800 kV. Siemens line surge arresters can be directly installed without an external spark gap (NGLA, non-gapped line arrester) or with an external spark gap (EGLA, externally gapped line arrester).

Our product families

Non-gapped line arresters (NGLA) – line surge arresters without spark gap

Non-gapped line surge arresters (NGLA) offer a high degree of mounting flexibility and operational reliability. Depending on the tower design and the arrangement of insulators and lines, these arresters can either be installed directly on the insulators or on the tower.

Thanks to their high energy absorption capacity, non-gapped line arresters offer a very high level of protection against overvoltages caused by lightning and network-generated switching impulse current overvoltages.

To galvanically isolate the line surge arrester from the line voltage in the unlikely event of a fault or thermal overload, a disconnector is installed in series. It automatically and immediately disconnects the line surge arrester from the line voltage. This allows the affected overhead line to continue to be used until replacement can be scheduled.

In addition to the line surge arresters, the new ACM advanced monitoring system can be installed to provide arrester condition monitoring. This system monitors wirelessly and provides detailed information about leakage currents and converted energy.

Technische Daten

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Externally gapped line arresters (EGLA)– line surge arresters with external spark gap

EGLA line surge arresters have an external spark gap placed in series that galvanically isolates the active part of the arrester from the line voltage in normal conditions. In case of lightning, the spark gap is ignited and the overvoltage is safely discharged to the ground. EGLA line surge arresters prevent all insulator flashovers caused by lightning strikes. As such, EGLA increases network stability as well as the availability of the overhead line.

An additional benefit of EGLA line surge arresters is that there is no leakage current, because the series gap disconnects the active part of the EGLA from the system voltage.

This compact design is often the only option to install line surge protectors on existing towers with very small clearances.

Siemens EGLA line surge arresters are available for system voltages of up to 550 kV.

All Siemens EGLAs are designed and tested to comply with the latest IEC 60099-8 standard, which became effective in January 2011.

Software analysis for customer-specific applications

Siemens optionally offers software analysis (simulation) based on Cigré studies to examine and conduct preliminary tests of customer-specific applications as a way of determining the optimal, cost-effective solution. With this approach, the customer only needs to equip particular phases or individual line segments with line surge arresters, and can still ensure sufficient lightning protection of the overhead line.

In the first phase of an analysis, all important parameters of the transmission line under study are entered into the simulation software, and the installations to be examined are selected. This approach takes the following factors into consideration:

Line parameters: operating voltage, number of three-phase circuits, ground wire data, length, span length and sag on line, conductor type, diameter, and clearances
Tower data: tower surge impedances and footing resistance, tower geometry (position and distances of the individual phases and any existing ground wires)
Insulator data: arcing distance, connection length, rated lightning impulse withstand voltage
Lightning activity: keraunic level (lightning strokes per year and km²), network topology (elevation profile)
Customer priorities: fewer short interruptions, prevention of phase and multisystem short-circuits, elimination of ground wires