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GL 318 / GL 318X
Live tank circuit breaker up to 800 kV
Reliable, Economical and Easy-to-Use

GE’s GL 318 and GL 318X live tank circuit breakers for outdoor installation feature third generation self-blast interrupter chambers and spring-operated mechanisms (FK). These field–proven interrupter chambers operate on the energy optimized self-blast principle. The FK3 type mechanisms equip the entire range of circuit breakers with more than 180,000 references worldwide.

The GL 318 and GL 318X are field-proven and time-tested in high voltage switchgear, providing high mechanical endurance and very low restrike probability according to IEC 622271-100 class M2 & C2. The circuit breakers include a disconnecting option allowing for quick, easy installation. For simplified maintenance, the closing resistor is located in the same gas volume as breaker chamber.


High Quality Components

The GL 318 and GL 318X live tank circuit breakers provide high reliability based in part on high quality components, including:

  • Single pole operating design
  • Four self-blast Interrupter chambers and two spring mechanisms per pole
  • Spring mechanism FK3 equipped with a position indicator visible from outside
  • Field-proven, temperature-compensated density monitor with two-stage transducer and three-color dial
  • Easy access to the SF6 filling connection (type DILO)
  • Sealings suitable for temperatures down to -60 °C
  • Hot-dip galvanized steel parts and mechanism housings made completely of aluminum

Flexible Options

  • Standard low voltage equipment provided, additional equipment is available
  • Composite insulators are available
  • Seismic dampers for high seismic request can be provided
  • Pressure relief system for passive protection of both substation and personnel
  • RPH3 controller: Pont-on-wave tripping and closing relays
  • CBWatch: compact and modular circuit breaker monitoring solution
  • Closing resistors solutions (CL 315D) to limit high and damaging overvoltages

Installation and Maintenance

  • Preset at factory before shipping; no adjustments necessary during installation and commissioning
  • Disassembly of interrupter chamber without removal of entire pole column possible

Advanced Testing

The live tank circuit breakers meet the requirements of national and international standards.  This has been confirmed by comprehensive type tests according to the latest IEC standards.

Certified Quality

GE’s quality (ISO 9001:2008), environmental (ISO 14001:2004) and occupational health and safety (OHSAS 18001:2007) management systems determine the development and production procedures for the high voltage circuit breakers. These systems ensure the high quality of the products and services, which are confirmed by regular audits.


Breaker Type   GL 318 / GL 318D GL 318X / GL 318XD
Number of breaks / phase   4 4
Rated normal voltage kV 800 800
Rated normal current* A 4,000 5,500
Rated frequency Hz 50/60 50
Rated dielectric withstand (up to 1,000 m)* (to earth / accross open device)
- At power frequency
- At lightning impulse (1.2 / 50 µs wave)
- At switching impulse

kV (peak)
kV (peak)

2,100/2,100 (+455)
1,550/1,175 (+650)

2,100/2,100 (+455)
1,550/1,175 (+650)
Rated short-circuit breaking capacity
-Periodic component (r.m.s. value)



First pole-to-clear factor   1.3 1.3
Peak short-circuit withstand current kA (peak) 137 173
Rated line-charging capacitive switching   Class C2 Class C2
Mechanical endurance   Class M2 Class M2
Breaking time cycles 2 - 2,3 2 - 2,3
* For other values, please contact Grid Solutions.