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Circuit breaker testing solutions
Efficiently testing circuit breakers is crucial for safety, reliability, and cost-effectiveness. With Megger’s circuit breaker testing solutions, you can ensure proper operation, prevent electrical hazards, minimise downtime, and extend equipment lifespan
With over 40 years of experience, the world’s leading experts trust our comprehensive portfolio of circuit breaker testing solutions to meet the demands of the job — and the industry.
With Megger’s solutions, you can perform safe tests on circuit breakers through various methods, including test of insulation, low resistance, trip- and close time, and more, to confirm correct operation.
By utilizing our field-proven equipment and following a robust circuit breaker test procedure, you can effectively assess breaker performance, identify potential failures, and prevent costly downtime.
Our solutions provide unparalleled accuracy and speed, allowing you to efficiently test your equipment and ensure the safety and reliability of your entire electrical system.
Frequently asked questions
There are many reasons for testing circuit breakers. Some of the most important are to ensure they:
- Protect expensive equipment
- Prevent outages that lead to loss of income
- Provide reliability of the electricity supply
- Prevent downtime and darkness
- Perform as expected
The two predominant standards are:
- IEEE C37.09 IEEE Standard Test Procedure for AC High Voltage Circuit Breakers Rated on a Symmetrical Current Basis.
- IEC 62271-100 High voltage switchgear and controlgear – Part 100: Alternating current circuit breakers.
NETA also has acceptance testing (NETA ATS) and maintenance testing (NETA MTS) specifications that cover a broad range of electrical equipment, including circuit breakers.
First, make a reference measurement (footprint) of the circuit breaker when it is new and use this to compare future tests. Use the default settings for speed calculation points. Alternatively, if the circuit breaker is older, check to see if several breakers of the same type are available to test. Compare results with other circuit breakers of the same kind. These should be from the same manufacturer and model type, not just the same rated voltage and current. Also, you can make some checks within the test. For most breakers, all three phases should be within 1 to 2 ms of each other, but occasionally a 3 to 5 ms difference may occur for some older breakers. When the breaker has multiple breaks per phase, the difference between contacts in the same phase should be approximately 2 ms or less. On modern circuit breakers, the trip times should be between 20 to 45 ms, with close times taking longer but generally less than 60 ms.
Testing should be done at various stages in the life of a circuit breaker, including:
- Development
- Production
- Commissioning
- Maintenance/fault tracing
- After service (re-commissioning)
The manufacturer typically provides a list of the parameters you should check and the range of values you should expect. The list can vary by breaker design, but if none is provided, at a minimum, you should measure the following:
- Main contact times
- Pre-insertion resistor (PIR) contact times, if present
- Max contact time difference between phases
- Stroke
- Overtravel
- Rebound
- Velocity
- Coil current
- Station voltage
- Contact resistance
More about circuit breaker testing
Contact us to talk about your unique circuit breaker testing needs. One of our experts will reach out to you to offer more information and assistance.
Additional Resources
Take a deeper dive into circuit breaker testing through our comprehensive guides.
Circuit Breaker Testing Guide
Understand what it takes to keep circuit breakers at peak performance.
“Interpreting the Test Results for High Voltage Circuit Breakers”
Take decisive action during commissioning, maintenance, or troubleshooting.
DC Test of Vacuum Integrity
First trip analysis anticipates faults before they
become critical.
How to Test Low-Voltage Circuit Breaker Ground Fault Protection - Part 1
See the challenges of ground fault testing using primary injection.
A Guide to Low Resistance Testing
Learn how to select the right instrument and how to interpret the results.
Testing Protection Systems in a DC Traction Substation
Get the lowdown on a more efficient alternative to short circuit testing.
