Circuit breaker testing solutions

Q: Are there any standards regarding circuit breaker testing?

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.

Verify breaker operation to protect networks and critical assets

Circuit breakers must operate instantly and correctly to protect your power system. Megger’s testing solutions help you measure opening time, contact speed, and coil current, giving you the insight needed to confirm operation, detect emerging issues, and maintain protection system integrity.

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Ensure protection operates when faults occur

Perform circuit breaker maintenance safely with Megger’s advanced testing solutions. Purpose-built technologies and proven test methods help you verify breaker condition while maintaining safe working practices and protecting personnel and critical equipment.

Prevent failures that lead to outages and damage

Breaker failures can lead to extended outages and equipment damage. Megger’s diagnostic tools help engineers detect mechanical wear, contact degradation, and performance issues early, ensuring reliable protection and reducing the risk of unexpected failure.

Understand breaker condition and performance

Use diagnostic data to support condition-based maintenance and identify breakers at risk of failure. Megger’s testing solutions give you the insight needed to plan maintenance, optimise capital investment, and make informed asset management decisions.

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More than 40 years of experience

Ensure the safe and efficient distribution of power with our tried and tested solutions, supported by our extended industry experience and expertise.

Safety first

Minimise your exposure to hazard and get peace of mind knowing that Megger’s circuit breaker testing equipment places safety at the forefront of any operation. An example of this is the DualGround™ technology introduced over 20 years ago, enabling timing test with both sides of the circuit breaker grounded, which now has become an industry standard.

Cutting-edge equipment

Our advanced technology ensures accurate, reliable, and efficient testing across various breaker types. Our solutions meet the most stringent industry standards, delivering unparalleled performance and peace of mind. Partner with us for cutting-edge testing solutions that enhance safety, reliability, and efficiency in your electrical systems.

Accuracy and speed

With Megger’s advanced technology and user-friendly interfaces, you can streamline your testing process, minimising downtime and maximising efficiency. Trust in our equipment to provide precise data and support the safe and reliable functioning of your critical electrical systems.

Frequently asked questions

Why test circuit breakers?

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

Are there any standards regarding circuit breaker testing?

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.

I don’t have data from the manufacturer on my circuit breaker. How can I analyse my results?

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.

When should a circuit breaker be tested?

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)

What should I measure when performing circuit breaker testing?

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.