SFMG generator circuit breaker (GMCB) 20–30 kV, 63–130 kA
The SFMG generator circuit breaker (GMCB, Generator Main Circuit Breaker) is installed in the generator voltage circuit between the generator and the step-up transformer of a power plant. The range of versions covers breaking currents of 63–130 kA and rated currents of 8–22 kA. The devices operate at thermal, combined cycle and nuclear power plants in generator-transformer unit schemes.
- Types
- 20-SFMG-63A, 20-SFMG-100/100A, 20-SFMG-130, 20/30-SFMG-125
- Rated current
- 8 / 11–13 / 15–16 / 22 kA (up to ~44 kA with forced air cooling)
- Short-circuit breaking current
- 63, 100, 125, 130 kA
- Composition
- circuit breaker, disconnector, earthing switch, CTs, VTs and surge arresters in one block
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The breaker interrupts short-circuit currents both from the generator side and from the network side. With it the generator is synchronised at generator voltage, and the station auxiliaries are supplied from the network when the unit is shut down. Without a generator breaker the unit is switched by the HV side breaker, while with a GMCB starting and stopping the generator do not involve it.
The GMCB is assembled as a single block. It includes a circuit breaker (CB), disconnector (DS), earthing switch (ES), starting disconnector (S-DS) and current transformers (CT). The starting disconnector is used in schemes with generator starting from a static frequency converter. The cabinet of voltage transformers and surge arresters (VT & SA) is placed in the lower tier. All mechanisms are enclosed by covers, and the local control panel (LCP) is built into the housing. The self-supporting structure is designed for high seismic resistance.
According to the manufacturer, the arrangement of isolated phase busducts (IPB) and the VT/SA cabinet can be chosen freely. The breaking capacity requirements are reduced, installation and commissioning times are shorter, and there is quick access to the VT and SA. The drive is a low-maintenance torsion-type spring mechanism with high performance.
The range of versions is as follows. 20-SFMG-63A has a rated current of 8 kA and a breaking current of 63 kA. 20-SFMG-100/100A is rated for 11–13 kA and 100 kA, 20-SFMG-130 for 15–16 kA and 130 kA. The version with the highest rated current, 20/30-SFMG-125, has 22 kA and a short-circuit current of 125 kA, and with forced air cooling the rated current reaches ~44 kA.
The breaker is used at thermal, combined cycle and nuclear power plants in unit schemes. The version is chosen by the generator rated current and the expected short-circuit current in the generator circuit. Built-in CTs, VTs and surge arresters reduce the number of separate devices between the generator and the step-up transformer, so the busduct is easier to arrange. For power units with a high generator current, 20/30-SFMG-125 with forced air cooling is chosen. The breaker complements the manufacturer's excitation system and generator protection in the unit's electrical part.
Technical specifications
| Types | 20-SFMG-63A, 20-SFMG-100/100A, 20-SFMG-130, 20/30-SFMG-125 |
|---|---|
| Rated current | 8 / 11–13 / 15–16 / 22 kA (up to ~44 kA with forced air cooling) |
| Short-circuit breaking current | 63, 100, 125, 130 kA |
| Composition | circuit breaker, disconnector, earthing switch, CTs, VTs and surge arresters in one block |
| Drive | spring-type with torsion bar |
| Design | self-supporting, high seismic resistance |
Request a price and lead time
SFMG generator circuit breaker (GMCB) 20–30 kV, 63–130 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
What breaking currents do SFMG versions have?
20-SFMG-63A breaks 63 kA, 20-SFMG-100/100A breaks 100 kA, and 20-SFMG-130 is rated for 130 kA. The 20/30-SFMG-125 version has a short-circuit current of 125 kA.
What rated current is available?
From 8 kA in 20-SFMG-63A to 22 kA in 20/30-SFMG-125. With forced air cooling the rated current reaches ~44 kA.
What does the GMCB block include?
A circuit breaker, disconnector, earthing switch, starting disconnector and current transformers, and in the lower tier a VT and SA cabinet. The local control panel is built into the housing.
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