ELK is the family of gas-insulated switchgear (GIS) from Hitachi Energy, formerly ABB. The ELK-04 covers up to 170 kV, the ELK-14 up to 300 kV, the ELK-3 up to 550 kV, the ELK-4 up to 800 kV and the ELK-5 up to 1,200 kV, with SF6-free EconiQ versions. This sheet summarizes the variants, their monitoring and the commissioning tests.
What it is and where it is used
ELK is the family of gas-insulated switchgear (GIS) from Hitachi Energy, which ABB used to manufacture; that is why it is also known as ABB ELK-04 or ABB GIS. In a GIS, busbars, circuit breakers, disconnectors, earthing switches and instrument transformers sit inside metal enclosures filled with insulating gas, which cuts the footprint to a fraction of a conventional substation.
They are used in cities, power stations, industrial plants, polluted or high-altitude sites, and anywhere land is scarce. For the principle and the parts of this type of substation, see GIS substation.
Variants: ELK-04, ELK-04 C, ELK-14, ELK-3, ELK-4 and ELK-5
| Model | Application | Main difference |
|---|---|---|
| ELK-04 | Up to 170 kV | Up to 4,000 A and 63 kA at 170 kV, modular design |
| ELK-04 C | Up to 145 kV | 60% less SF6 than its predecessors, 800 mm bay |
| EconiQ ELK-04 | 145 kV | SF6-free: CO2, O2 and C4-FN mixture |
| ELK-14 C | Up to 245 kV | Compact version, 50 kA and 3,150 A; three-phase enclosure with single-phase insulators and front access to the operating mechanisms |
| ELK-14 / EconiQ ELK-14 | Up to 300 kV | Transmission at 230 and 245 kV; SF6-free version at 300 kV |
| ELK-3 / EconiQ ELK-3 | Up to 550 kV | Extra-high voltage; EconiQ at 420 and 550 kV |
| ELK-4 | Up to 800 kV | Extra-high voltage |
| ELK-5 | Up to 1,200 kV | Ultra-high voltage |
| PASS (BLF) | Up to 170 kV | Hybrid module, a compact bay for air-insulated substations |
In older substations you will find references such as EXK-01 or ENK; for those, the nameplate and the project dossier are the source of the data.
Main features
- Gas compartments: each section (breaker, busbars, disconnectors) is a separate compartment divided by barrier insulators, with its own density monitor. See SF6 density monitor.
- Self-blast (auto-puffer) circuit breaker with a spring or hydraulic operating mechanism, depending on the voltage level.
- Integrated instrument transformers, conventional or sensor-based, depending on the project.
- Connections: to cable, to overhead line through SF6-to-air bushings, and directly to a transformer.
- Monitoring: gas density and, when specified, online partial discharge.
The pressures and compartments of a GIS are explained in GIS pressures and gas compartments, the internal fault in internal fault in a GIS and arc test, and the interfaces with cables and transformers in GIS interfaces with cables and transformers.
Ratings and dimensions published by the manufacturer
Hitachi Energy publishes the maximum ratings and the bay width on each product page, which is a good starting point for knowing what to expect from an ELK GIS before opening the project dossier:
| Model | Voltage | Short-circuit current | Rated current | Bay width |
|---|---|---|---|---|
| ELK-04 | 145 kV | 40 kA | up to 4,000 A (depending on the design) | 1,200 mm in the 170 kV design |
| ELK-04 | 170 kV | 63 kA | 4,000 A | 1,200 mm |
| ELK-04 C | 145 kV | 40 kA | 3,150 A | 800 mm |
| ELK-14 | 300 kV | 63 kA | 4,000 A | 1,680 mm |
| ELK-14 C | 245 kV | 50 kA | 3,150 A | — |
The ELK-04 pages state indoor or outdoor installation and an ambient temperature range of -30 to +40 °C; for the ELK-14 they also state both installation options and a rated peak withstand current of 170 kA. These are catalog values for the model: those of an installed unit are on its nameplate and in its dossier, and may be lower.
Insulating gas and applicable standards
A classic GIS uses SF6 as the insulating medium and as the arc-quenching medium in the breaker. The EconiQ versions replace SF6 with a mixture of CO2, oxygen and a small percentage of fluoronitrile (C4-FN). In practice, equipment with an alternative gas mixture needs its own gas-handling instruments and procedures: the SF6 analyzer and cylinders cannot simply be reused for the mixture, and the filling pressures and density monitor thresholds are different. For an SF6 GIS, gas quality is monitored according to the gas-handling standard for new and in-service equipment; see SF6 gas analysis and SF6 low-pressure alarm.
As for standards, GIS above 52 kV is specified in IEC 62271-203. The circuit breaker, disconnector and earthing switch that make it up follow the relevant parts of the IEC 62271 series (100, 102, and 209 for cable connections). The on-site tests of a new GIS are defined in IEC 62271-203 itself and agreed in the contract.
Commissioning and maintenance points to watch
- Cleanliness and particles. The most studied defect in a GIS is the free metallic particle in the gas, which shows up as partial discharge. That is why on-site assembly is done under controlled cleanliness conditions. The final check is the applied voltage test with partial discharge measurement. See partial discharge test.
- Gas moisture. Each compartment is filled after the air is evacuated, and the dew point or moisture is measured before filling is considered complete.
- Interlocks. The sequence between breaker, disconnectors and earthing switches is tested bay by bay before energizing, including the interlocks with the neighboring bays in an extension.
- Extensions. Connecting a new bay to an existing GIS requires a coupling compartment and, normally, taking the affected busbar section out of service; planning that outage is part of the project.
- Leak tracking. A healthy GIS loses very little gas per year; a sustained density drop in a single compartment is treated as a localized leak and is not compensated by simply topping up.
If you run out of space in an existing GIS
The ELK-04 and ELK-14 are offered in compact versions (ELK-04 C, ELK-14 C) with a smaller footprint. If what you have is a conventional substation that has become too small, see hybrid substation and the PASS modules as an alternative to a full GIS.
Communications and integration
The GIS is controlled from its bay local control cabinet (LCC), with interlocks between the breaker, disconnectors and earthing switches. The signals go to relays and bay controllers, which report to SCADA over IEC 61850; in digital projects, the process bus carries sampled values and GOOSE. See digital substation IEC 61850.
Frequently asked technical questions
- Manual for the ELK-04 and ELK-14 GIS: the operation and maintenance manual comes with the project; Hitachi Energy identifies it by the order number.
- Low-density alarm in a compartment: confirm the temperature-corrected reading and look for the leak in that compartment; the lockout protects the breaker.
- Partial discharge: it is the main indicator of internal defects; it is measured at commissioning and, if monitoring is installed, in operation. See partial discharge test.
- Extending an existing ELK GIS: it requires interfaces compatible with the manufacturer; it is planned using the original project information.
If your equipment is no longer manufactured
GIS with references such as EXK-01 or ENK are still operating in many substations. Depending on the voltage level of the installation, the current equivalent line from Hitachi Energy is the ELK-04 (up to 170 kV), the ELK-14 (up to 300 kV) or the ELK-3 (up to 550 kV). Extending or replacing bays of an old GIS requires reviewing the busbar interfaces, the gas, the interlocks and the control with the manufacturer and with the original project information. Our team designs that change in primary engineering and tests it before energizing.
How we help
We do not sell GIS substations. At Tiza Group we test and commission GIS substations of any make at high and extra-high voltage (contact resistance, breaker timing, instrument transformers, interlocks, protection and control), and we configure their controllers and relays. See circuit breaker testing within testing and commissioning. For SCADA integration over IEC 61850, see IEC 61850. Field work is done in Colombia, or elsewhere on request. Write to us through the contact page.
Related guides
- GIS substation
- Hybrid substation
- SF6 density monitor
- SF6 gas analysis
- Partial discharge test
- Conventional AIS substation
- Siemens 8DN8, 8DN9 and 8DQ1 GIS substation
- GE (Alstom) F35, B105, T155 and g3 GIS substation
- Mitsubishi, Hyundai, Hyosung and Chinese GIS manufacturers
- ABB LTB 145, HPL and EDF circuit breakers (Hitachi Energy)
- GIS switchgear: pressures and gas compartments
- Internal fault in a GIS and arc test
References
- IEC 62271-203, gas-insulated metal-enclosed switchgear for rated voltages above 52 kV.
- Hitachi Energy, product pages for the ELK-04, ELK-04 C, ELK-14 and ELK-14 C with ratings and bay width.
- Hitachi Energy, GIS portfolio and the ELK-04, ELK-04 C, EconiQ ELK-04 and ELK-4 pages.
Frequently asked questions
What is the ABB ELK-04 GIS?
It is the gas-insulated switchgear from Hitachi Energy (formerly ABB) for 145 and 170 kV, with up to 4,000 A and 63 kA at 170 kV according to the manufacturer. There is an ELK-04 C version up to 145 kV, with 60% less SF6 than its predecessors and an 800 mm bay width, and a 145 kV EconiQ version without SF6.
What is the ELK-14?
It is the Hitachi Energy GIS for voltages up to 300 kV, typical of 230 and 245 kV substations. Hitachi Energy also offers it as the 300 kV EconiQ ELK-14, without SF6.
What gas does the Hitachi Energy EconiQ GIS use?
A mixture of carbon dioxide, oxygen and a small amount of fluoronitrile (C4-FN) instead of SF6. Hitachi Energy offers it in the 145 kV ELK-04, the 300 kV ELK-14 and the 420 and 550 kV ELK-3.