New & Used High-Voltage Breakers for Sale
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Types of High-Voltage Circuit Breakers
SF6 Dead Tank Circuit Breakers
A dead tank circuit breaker houses the SF6 interrupter inside a grounded, gas-filled metal tank, with the high-voltage bushings mounted on top. Current transformers are usually mounted on those bushings, so the breaker delivers metering and protection CTs without separate free-standing units. Dead tank breakers are the standard design in North American utility and industrial substations from 72.5 kV through 550 kV. Buyers choose them for the integrated CTs, a low center of gravity that performs well where seismic qualification is required, and straightforward foundations and connections. Both high-voltage breakers currently listed on Electrical Trader are dead tank units.
Browse dead tank breakers →SF6 Live Tank Circuit Breakers
A live tank circuit breaker places the SF6 interrupter inside porcelain or composite insulators that sit at line potential on top of an insulating support column. Because there is no grounded tank around the interrupter, current transformers are supplied as separate free-standing units beside the breaker. A live tank breaker uses less SF6 and less steel, so it is generally lighter, lower in cost and smaller in footprint than a dead tank unit of the same voltage class. Live tank designs are common at 245 kV and above and are the dominant high-voltage breaker design outside North America.
Browse live tank breakers →Substation Circuit Breakers
Substation breakers are the fault-interrupting devices at every point where a transmission line, power transformer or bus section connects to the substation. Line breakers isolate a faulted line, transformer breakers protect the transformer on its high-voltage side, and bus-tie breakers split or join bus sections. The same dead tank and live tank designs above fill all three roles; the choice between them comes down to voltage class, interrupting rating and site layout rather than the breaker's position in the substation.
Compare dead tank and live tank designs →Both designs use SF6 gas as the interrupting and insulating medium. Gas-insulated switchgear (GIS) is a separate, fully enclosed product that packages breakers, disconnects and bus inside a sealed SF6 enclosure, and is not covered on this page.
Dead Tank vs Live Tank Breakers
| Aspect | Dead tank | Live tank |
|---|---|---|
| Construction | Interrupter inside a grounded, SF6-filled metal tank; bushings on top | Interrupter inside insulators at line potential, on an insulating support column |
| Current transformers | Bushing-mounted CTs supplied on the breaker | Separate free-standing CTs required |
| Footprint | Larger and heavier; foundation carries the tank | Smaller footprint and lighter for the same kV class |
| Seismic performance | Low center of gravity; the usual choice where seismic qualification is required | Tall, top-heavy column; may need bracing or seismic qualification |
| Typical cost | Higher breaker cost, but CTs are included | Lower breaker cost, plus separate CTs, structures and foundations |
| Typical markets | North American utilities and industrials, 72.5–550 kV | Common worldwide and at 245 kV and above; less common in North America |
A dead tank breaker fits when you need integrated CTs, seismic qualification, or a drop-in replacement for the dead tank units most North American substations already run. A live tank breaker fits when space or budget is tight, CTs already exist on site, or the project follows an international layout. Either way, match the rated maximum voltage, BIL and interrupting rating first, then choose the design.
High-Voltage Breaker Voltage Classes
Rated maximum voltage is the highest voltage a breaker is designed to carry continuously, so a breaker is chosen one class above the nominal system voltage — a 145 kV breaker serves 115 kV and 138 kV systems, and a 362 kV breaker serves a 345 kV system.
| Rated maximum voltage | Typical system voltage | Rated BIL | In stock |
|---|---|---|---|
| 72.5 kV | 69 kV | 350 kV | Tell us what you need |
| 145 kV | 115 / 138 kV | 650 kV | View listed units |
| 170 kV | 161 kV | 750 kV | Tell us what you need |
| 245 kV | 230 kV | 900 kV | Tell us what you need |
| 362 kV | 345 kV | 1,300 kV | Tell us what you need |
| 550 kV | 500 kV | 1,800 kV | Tell us what you need |
What to Check Before Buying a High-Voltage Breaker
Voltage class & BIL rating
High-voltage SF6 circuit breakers run 72.5 kV through 550 kV rated maximum voltage. Match both the kV class and the BIL to your substation design; on transmission gear the BIL governs clearances and insulation coordination, not the nominal kV alone.
Interrupting rating
Verify the breaker's symmetrical interrupting capacity, typically 40kA or 63kA, against your available fault current. Fault duty rises as generation is added nearby — size to the study, not to today's reading.
ANSI/IEEE compliance
US transmission breakers are built to the C37 series: C37.04 ratings, C37.06 preferred ratings, C37.09 test procedure. Ask for the type test reports and the nameplate, especially on imported units.
Condition of insulation & bushings
On dead tank units, bushings are the most common failure point and the most expensive single item to replace — request power factor / tan delta results on each. On live tank units, inspect the support and interrupter insulators for cracked porcelain, contamination, and moisture history.
SF6 maintenance
Every SF6 circuit breaker, dead tank or live tank, depends on gas density. Confirm density readings, leak rate history, and whether the density monitor and alarms are functional. Plan for periodic gas quality testing and a certified SF6 handling partner as an ongoing ownership cost, not a one-time step.
POW (point on wave) closing
Also called controlled switching, synchronous closing, or zero-crossing closing. POW control times contact operation to the waveform to limit inrush and switching transients — essential for capacitor bank, reactor, and transformer switching duty. Confirm whether the unit has a POW controller and whether it is supported.