SFG — SF6 circuit breaker 7.2–36 kV, up to 4000 A, up to 63 kA
SFG is a series of medium-voltage SF6 circuit breakers for 7.2, 12, 24 and 36 kV with an earthed tank and a self-compression (puffer) interrupter. The breakers are intended primarily for power plants, where stable interruption in severe duties is required, and also for substations and industrial switchgear. Rated currents reach 4000 A and breaking currents 63 kA.
- Types
- 6-SFG-40/63, 10-SFG-40/50, 20-SFG-25A/40A, 30-SFG-25A/40A
- Rated voltage
- 3.6/7.2, 12, 24, 36 kV
- Rated current
- 600–4000 A
- Breaking current
- 25 / 40 / 50 / 63 kA
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The properties of SF6 give stable interruption both of ordinary short-circuit currents and of the currents in severe duties typical of generator circuits, that is, out-of-phase earth fault and loss of synchronism of the generator. When interrupting magnetizing currents the chopping current is low, and the overvoltage does not exceed twice the applied voltage. When interrupting capacitive currents there are no restrikes. Hence the breakers can be installed in all circuits without additional surge arresters, which simplifies the bay scheme.
The electric spring operating mechanism requires neither compressors nor high-capacity batteries, and when there is no supply the operations are performed manually. The withdrawable design in an earthed tank makes maintenance safe. SF6 is chemically inert and non-flammable. The rated SF6 pressure is 0.5 MPa at 20 °C, the alarm operates at 0.45 MPa and the lockout at 0.4 MPa. The interrupting time is 5 cycles, and the breakers comply with the Japanese standard JEC-2300.
The compact self-compression interrupter together with the earthed tank noticeably reduced the dimensions of the bay. For example, a 34.5 kV TGBA bay with this breaker and a single busbar system occupies only 2 m² (1.2×1.65 m). For substations in cramped buildings and for the refurbishment of existing switchgear this is often a decisive argument.
The 6/10 kV range includes the 6-SFG-40 and 6-SFG-63 for 3.6/7.2 kV with breaking currents of 40 and 63 kA, and the 10-SFG-40 and 10-SFG-50 for 12 kV with 40 and 50 kA. The rated currents of this range are 1200, 2000, 3000 and 4000 A. The 20/30 kV range consists of the 20-SFG-25A and 20-SFG-40A for 24 kV and the 30-SFG-25A and 30-SFG-40A for 36 kV, with a breaking current of 25 or 40 kA and rated currents from 600 to 3000 A.
On the manufacturer's website the SFG series is classified as discontinued. For existing 10-SFG-40 breakers the company offers replacement with compatible 10-VPR-40D(GV) vacuum breakers, so the modernization of existing bays can be carried out without replacing the cubicles.
Technical specifications
| Types | 6-SFG-40/63, 10-SFG-40/50, 20-SFG-25A/40A, 30-SFG-25A/40A |
|---|---|
| Rated voltage | 3.6/7.2, 12, 24, 36 kV |
| Rated current | 600–4000 A |
| Breaking current | 25 / 40 / 50 / 63 kA |
| Interrupting time | 5 cycles |
| SF6 pressure (20 °C) | 0.5 MPa rated; 0.45 MPa alarm; 0.4 MPa lockout |
| Interrupter | self-compression (puffer), earthed tank |
| Operating mechanism | electric spring |
| Standard | JEC-2300 |
Request a price and lead time
SFG — SF6 circuit breaker 7.2–36 kV, up to 4000 A, up to 63 kA. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8535 21 00 00 |
|---|---|
| HS, 6 digits | 8535 21 |
| CN (EU) | 8535 21 00 |
| HTSUS (USA) | 8535 21 00 00 |
| China customs tariff | 8535 21 00 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
Are surge arresters needed with SFG breakers?
No, when interrupting magnetizing currents the overvoltage does not exceed twice the applied voltage, and when interrupting capacitive currents there are no restrikes.
What is the SF6 pressure in the breaker?
Rated pressure 0.5 MPa at 20 °C, alarm at 0.45 MPa, lockout at 0.4 MPa.
What can replace 10-SFG-40 breakers in existing bays?
The manufacturer offers compatible 10-VPR-40D(GV) vacuum breakers for 12 kV.
Similar equipment from other manufacturers
