Circuit Breaker Testing Services Australia
Last reviewed: July 2026 by Matt Geoghegan, CEO, Megavar
Megavar tests high voltage and medium voltage circuit breakers across Australia, at commissioning and through service life, to confirm they will open and close correctly and interrupt fault current within their rated time. Testing covers timing analysis, contact and dynamic resistance, insulation, and gas or vacuum integrity, with every result captured in a clear diagnostic report. Because Megavar also commissions the switchgear and protection around the breaker, circuit breaker testing fits into a single tested and energised outcome rather than a standalone check.
What is circuit breaker testing?
Circuit breaker testing is the measurement and verification of a circuit breaker’s mechanical and electrical performance to confirm it operates within its design limits. It checks how fast the breaker opens and closes, whether the poles operate together, the resistance across the main contacts, the condition of the insulation, and the integrity of the SF6 gas or vacuum interrupter. The results show whether the breaker can clear a fault safely and reliably.
Tests
Timing, contact and dynamic resistance, insulation, SF6/vacuum integrity, mechanism
Breaker Types
Equipment
Standards
Coverage
Australia-wide, four offices
Tests We Perform
Megavar performs the full circuit breaker test suite on a single visit:
- Timing analysis: open, close and trip times, and pole simultaneity
- Dynamic contact resistance measurement (DRM) to assess contact and arcing-contact condition
- Static contact resistance (micro-ohm) across the main contacts
- Insulation resistance and, where required, power factor / tan delta
- SF6 gas analysis or vacuum bottle integrity, by interrupter type
- Coil current and mechanism / travel analysis
- Secondary injection of associated protection where in scope
Breaker Types We Test
Megavar tests every common interrupter and construction type across the medium and high voltage range, including SF6, vacuum, minimum-oil and air-blast breakers, in both live-tank and dead-tank configurations.
When Circuit Breaker Testing Is Required
Circuit breaker testing is required at key points in an asset’s life:
- Commissioning of new or refurbished breakers
- Routine condition-based maintenance
- After a breaker has cleared a significant fault
- Before return to service following repair
- As part of substation maintenance and asset management programs
Standards
Megavar tests circuit breakers in line with the relevant international standards, including the IEC 62271 series for high voltage switchgear and circuit breakers and the IEEE C37 series, within the substation framework of AS 2067.
Frequently Asked Questions
HV Reticulation & Distribution Design Services Australia
What is circuit breaker testing?
Circuit breaker testing measures and verifies a breaker’s mechanical and electrical performance, covering timing, contact resistance, insulation and gas or vacuum integrity, to confirm it can open, close and interrupt fault current safely within its rated limits.
What tests are performed on a circuit breaker?
A full test covers timing analysis (open, close and trip times and pole simultaneity), dynamic and static contact resistance, insulation resistance, SF6 gas or vacuum integrity, and coil current and mechanism analysis. Associated protection can be secondary-injection tested where in scope.
Why is circuit breaker timing important?
Timing confirms the breaker opens fast enough to interrupt a fault within its rated time and that all three poles operate together. Slow or unsynchronised operation can leave a fault uncleared or stress the system, so timing is a core acceptance and maintenance measurement.
What is dynamic contact resistance measurement?
Dynamic contact resistance measurement (DRM) records resistance across the contacts as the breaker operates, revealing the condition of the main and arcing contacts that a static reading alone cannot show. It is a key diagnostic for ageing or heavily duty-cycled breakers.
How often should circuit breakers be tested?
Breakers are tested at commissioning, at routine maintenance intervals set by the asset owner, after clearing a significant fault, and before return to service following repair.
What standards apply to circuit breaker testing?
Circuit breaker testing aligns with the IEC 62271 series for high voltage switchgear and circuit breakers and the IEEE C37 series, within the substation framework of AS 2067.
Can Megavar test SF6 and vacuum circuit breakers?
Yes. Megavar tests SF6, vacuum, oil and air breakers across the MV and HV range, selecting the right interrupter-specific checks such as SF6 gas analysis or vacuum bottle integrity.
Ready to commission your substation? Contact Megavar today on 1300 730 499 or visit our contact page to request a quote.
Why Choose Megavar
- Practising HV test engineers using the Omicron CIBANO 500 and TM-series analysers
- Testing and commissioning under one roof, so breaker results tie into the wider substation outcome
- Four offices: Hobart, Launceston, Adelaide and Newcastle
- ISO 9001, ISO 14001 and ISO 45001 accredited, licensed in every state and territory
- Clear diagnostic reports with pass/fail against rated values
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