NGLA / EGLA — line surge arresters for overhead lines up to 800 kV
NGLA and EGLA are line surge arresters for overhead lines up to 800 kV with energy capability up to 3.6 C. They are installed directly on towers to prevent insulation flashovers and short circuits during lightning strikes and switching. Applications cover 6–750 kV overhead lines in areas of high lightning activity and poor soil, double-circuit lines and lines with underbuilt distribution networks.
- Network class
- up to 800 kV
- Energy capability
- up to 3.6 C
- NGLA
- no spark gap, built-in disconnector, mounting on the conductor, tower or insulator, IEC 60099-4
- EGLA
- with an external series spark gap, no leakage current and no disconnector, IEC 60099-8
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Line arresters remove overvoltages that exceed the impulse strength of the insulator string. There are fewer outages and voltage dips, the line runs more stably and power quality is higher. The housing is made of silicone rubber. Line arresters are especially useful where poor soil gives a high tower grounding resistance and the shield wire does not prevent back flashovers. The set with insulators arrives technically matched, so the fastening and insulation characteristics do not need to be agreed separately. The company supplies line arresters together with polymer insulators as a ready-made set for overhead lines.
NGLA (non-gapped line arrester) has no spark gap and is connected directly to the conductor. Depending on the tower design and suspension, it is mounted on the insulator, the conductor or the tower. It limits overvoltages below the insulation strength level and has high energy capability. The built-in disconnector takes the arrester out of service in thermal overload, and the line keeps working until planned replacement. The product is tested to IEC 60099-4.
EGLA (externally gapped line arrester) has an external series spark gap. In normal operation the gap galvanically separates the varistors from the line voltage. When lightning strikes, the gap breaks down, the arrester limits the earth-fault current from several kiloamperes to several amperes and extinguishes the arc within 10 ms. The circuit breakers at the line ends do not operate and auto-reclosing is not needed. There is no leakage current, the rated voltage and the number of varistors are smaller, and no disconnector or grounding lead is needed. EGLA suits multi-circuit towers with small clearances and live-line installation, and is tested to IEC 60099-8.
The number and locations of line arresters are calculated with the company's own software using the CIGRE method. Line, tower and insulation parameters, grounding resistance and lightning activity are taken into account. It is therefore often enough to equip individual phases or sections to obtain the required lightning performance at minimum cost.
Line arresters are also used to limit switching overvoltages, to compact lines and to raise the capacity of existing lines. With them the shield wire can be dropped, and during live work the permitted clearances can be temporarily reduced.
Technical specifications
| Network class | up to 800 kV |
|---|---|
| Energy capability | up to 3.6 C |
| NGLA | no spark gap, built-in disconnector, mounting on the conductor, tower or insulator, IEC 60099-4 |
| EGLA | with an external series spark gap, no leakage current and no disconnector, IEC 60099-8 |
| Extinction of follow current (EGLA) | within 10 ms, without circuit breaker tripping |
| Housing | silicone rubber |
| Service | calculation of installation locations by the CIGRE method |
Request a price and lead time
NGLA / EGLA — line surge arresters for overhead lines up to 800 kV. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8535 40 00 00 |
|---|---|
| HS, 6 digits | 8535 40 |
| CN (EU) | 8535 40 00 |
| HTSUS (USA) | 8535 40 00 00 |
| China customs tariff | 8535 40 00 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
How does EGLA differ from NGLA?
EGLA has an external spark gap, so it has no leakage current and needs no disconnector, and it extinguishes the arc within 10 ms. NGLA is connected to the conductor without a gap and has a built-in disconnector.
For what overhead line voltage are these line arresters made?
For networks up to 800 kV with energy capability up to 3.6 C. In practice they are installed on 6–750 kV overhead lines.
Must every tower of the line be equipped with line arresters?
No, the number and locations are determined by calculation using the CIGRE method, taking into account grounding resistance and lightning activity. It is often enough to equip individual phases or sections.
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