Mastering Circuit Breaker Testing: Essential Knowledge and Techniques

The Circuit Breaker is one of the most important pieces of equipment in an electric system since it relays the protection of equipment and safety in the course of operations by interrupting the flow of electrical energy during overloads or faults. Their reliability is based on adequate testing conducted to verify functionality which mitigates problems before failure happens. The purpose of this post is to provide a guide for beginners striving to become experts in Circuit Breaker Testing by providing important knowledge, advanced circuit techniques, and other known techniques in the industry. If you are an electrical engineer, technician, or maintenance professional, this article will help you understand everything needed to optimize performance, ensure compliance, and improve safety. Continue reading to learn how to systematically go about testing circuit breakers while having total confidence in the reliability of your electrical systems.

What is a circuit breaker and why is it important?

A circuit breaker functions as an important safety feature in electrical systems. The device protects circuits from damage due to overcurrent and short circuits. A circuit breaker’s primary function is to cut off the electricity flow whenever a fault is detected to avoid overheating, damage to the equipment, or fire. At the same time, through the automatic disconnection of faulty circuits, the brake device aids in the safety of personnel together with the reliability of electrical systems, making these devices crucial in industrial or residential buildings.

Understanding the role of a circuit breaker in an electrical system

As integral features of safety measures, circuit breakers provide a third line of defense for the continuity and safety of electrical systems. They supervise circuits and instantly turn off the electricity in case of an overload or short circuit. This prevents equipment damage, lowers the chances of starting a fire, and shields people from the dangers of electricity. Advanced circuit breakers now can detect faults in a very short amount of time and with extreme accuracy making them a reliable option for the protection of both household and industrial electrical systems.

Common types of circuit breakers used in homes and industries

Miniature Circuit Breaker (MCB): 

Household electrical systems and low-voltage commercial systems often use MCBs. They protect against overload and short circuit problems. Protection against these overloads is ensured at roughly 100 amps-rated supply. MCBs are very compact in size and can easily be installed which is perfect for home use.

Molded Case Circuit Breaker (MCCB): 

MCCBs are employed in industrial systems due to their ability to support higher current ratings, often ranging from 100 to 2,500 amps. All-purpose devices like these routinely have adjustable trip settings tailored to a variety of industrial uses, which make them more user-friendly and versatile. MCCBs protect against overloads, short circuits, and many advanced cases such as ground faults making this heavy-duty robust device.

Residual Current Circuit Breaker (RCCB): 

RCDs with a small mA rating can very quickly disconnect the supply when an electric shock hazard is detected, leaving the user protected while other equipment within the system is safely operated at the same time. RCCBs serve the main purpose of protecting people against electric shock, this is achieved by being very sensitive to differential current, which literally can take milliseconds if a leakage is detected. They are very effective with protection and sensitivity ratings, like 30mA for self protection, and up to 100mA for the equipment. They provide excellent backing within residential and industrial setups.

An Air Circuit Breaker (ACB) is associated with the electrical installation and provides the necessary control of such installations.

ACBs are used in Heavy Industries for systems with High Voltage. They Are used in systems that have very high electrical currents (more than 6000 Amps). These models use air as a medium to put off the arc and are very useful in cases when there is a need for flexibility in the protection of the circuit. A feature of modern ACB is that it can be operated remotely and the system can be monitored for communication purposes.

Vacuum Circuit Breaker (VCB):

VCBs work perfectly in medium voltage scopes, like power distribution in industries and utilities. The design uses a vacuum as a medium to extinguish the arc during the opening of the circuit. VCBs require lower external intervention and maintenance, giving them a comparative advantage over other types. VCBs are efficient and environmentally friendly, especially in severe conditions.

Oil Circuit Breaker (OCB):

Used in some industrial setups, OCBs are gaining popularity in these days of stiff competition. In higher voltages, they fare well because oil is used for extinguishing the circuit-breaking arc. They have been known to excel in performance but are getting outdated because new technologies have poured into the market.

Ground Fault Circuit Interrupter (GFCI):

GFCIs are a type of specialized circuit breaker that protects from ground faults by determining the differences between the incoming and outgoing current and interrupting the mid-circuit. GFCIs are typically used in locations with high moisture levels like bathrooms, showers, and outside, and offer greater protection in domestic environments. They are vital to averting electrical shock and are required by electrical codes in several regions of the world.

Data and Industry Insights

Industry data indicates that RCCBs and MCBs integrate a major percentage share of the total revenue of circuit breakers due to their adoption on residential and commercial sides. While VCB and ACB applications are growing together with the development of industrial infrastructure and renewable energy systems, which shows the amount of reliable and energy-efficient protection devices is on the rise. On the other side, the market of intelligent circuit beakers with IoT connection is growing rapidly and it is expected to reach a valuation of some billion by 2030 as industries place greater emphasis on better control and monitoring.

How a circuit breaker ensures safety and prevents damage

As central elements of an electrical system, circuit breakers help reduce risks of electric shocks or equipment damage. They stop the flow of current in case of overloads, short circuits, or ground faults in order to mitigate overheating, electrical fires, or damage to the device.

Breakers have significantly improved due to new technological innovations. For example, the use of IoT devices has made it easier to monitor electrical systems as smart circuit breakers can provide fault diagnostics as well as preemptive maintenance alerts which, according to market predictors, will reduce downtime by 25%. In further studies, AFCIs were shown to help mitigate electrical fires by 50% in both residential and industrial settings.

There is improvement in the reliability of the circuit breakers due to material and design innovations. For instance, high-performance vacuum circuit breakers (VCBs) are known to be the most reliable of all electrical installations because of their long operational life of about 30,000 to 50,000 operations under normal conditions. Similarly, advanced air circuit breakers (ACBs) have the capacity to interrupt currents up to 6300 amps which protects them from damage in large-scale industrial use. Because of these qualities, these circuit breakers are very important in enhancing electrical safety and efficiency in operation with both modern and traditional infrastructure.

How to test a circuit breaker?

Steps to perform a circuit breaker test

Visual Inspection

To start, assess the general condition of the circuit breaker by sight. Scrutinize the individual contacts, bimetallic components, and the outer casing for indications such as wear, corrosion, and overheating. If the circuit breaker parts appear damaged or worn, they are likely to reduce the breaker performance and the parts might need replacing.

Insulation Resistance Test

To test the insulation resistance of the breaker’s terminals to the frame, utilize an insulation tester (megohmmeter). Typically, a value of 1 MΩ is deemed acceptable but may be less than ideal depending on the company. If the number is lower than this, the electrical installation may indeed fail the insulation test.

Contact Resistance Test

To test the resistance of the soldered contacts of the circuit breaker, use a micro-ohmmeter. If the resistance is exceedingly high, greater than a specified value such as 100 micro-ohms for low voltage air circuit breakers, this can signal deterioration of the contact surfaces leading to overheating of the breaker during operations.

Overload Tripping Test

To test the time-current characteristics of the breaker, apply a current that is greater than the operational current limit of the circuit breaker. The trip of the breaker should happen in conjunction with the delay time of the manufacturer. If there are any timing discrepancies, it might indicate an issue with calibration or the tripping mechanism is faulty from the exhaustion of parts.

Short Circuit Tripping Test for the circuit breaker box.

Develop a short-circuit simulation by injecting a current that is several times more than the rated value. This tests the breaker’s ability to trip instantaneously on critical fault conditions. Make sure the breaker trips within the predefined response time (usually sub milliseconds).

Mechanical Operation Test 

Manually actuate the circuit breaker to its limits several times and check if its mechanical components are functional. Make sure that resetting and operating do not experience any blockage or delay. In design requirements, the operational lifespan is expected to be closer to thirty thousand to forty thousand cycles.

Dielectric Voltage Withstand Test 

Expose the breaker to very high voltages (usual values range from 2.5 kV to 3.5 kV for low voltage breakers) during a test for insulation failure due to overvoltage. This test is to verify the insulation withstands limits during extreme conditions.

Thermal Imaging Analysis 

Scan the circuit breaker with an infrared thermal imager while it is in operation, paying attention to normal and abnormal cooling surfaces. Internal faults, loose connections, and overloading conditions are indicated by abnormal temperature gradients and require further action.

Arc Flash Assessment 

Check the arc quenching capability of the arc chute and all other internal parts. Inspect the arc runner and chute for any damages or residues, as an impaired arc management system will reduce fault interruption capability.

Documentation and Reporting

All tests must be captured in compliance with industry guidelines such as IEC 60947 or ANSI/IEEE C37. All departures from the defined operating range must be noted for subsequent correction action or maintenance planning.

Carrying out these tests at specific periods, like once a year or after significant electrical incidents, makes sure that safety requirements are satisfied and that the reliability of the electrical system is preserved. Following proper testing techniques and manufacturer instructions greatly enhances the longevity and functionality of circuit breakers for diverse uses.

Essential tools for testing circuit breakers

Consistent and accurate testing of the circuit breaker needs specialized tools and equipment for performance evaluation and issue detection. Below is a comprehensive list of essential items used in the given range:

Primary Injection Test Set

For Load testing, injection test sets are of critical importance. These devices pass a high current through the circuit breaker for it to work under simulated real operating conditions. They are used as well for assessing the thermal and magnetic trip parts of the breaker. With modern test sets, testing becomes easier and better with the addition of controls, data logging, and issuing performance report automation.

Insulation Resistance Tester

These testers assist in measuring the insulation resistance of the circuit breaker. These devices help resist the application of breakdown voltage for insulation by measuring the resistance. Resistance value helps to decide whether insulation degradation is present or breakdowns in low voltage systems. Through R, high values mean reliable insulation while the R value being lower may require repair or replacement of the insulating material.

Digital Multimeter (DMM)

A digital multimeter is a flexible tool used to measure electrical quantities such as voltage, current, and resistance. A DMM is commonly used for continuity testing while troubleshooting circuit breakers and for checking the operation of the auxiliary parts of the breaker. More advanced features such as data storage and other external connectivity features for enhanced diagnostics are also included in multimeters.

Time-Current Characteristic (TCC) Analyzer is essential for analyzing circuit breaker types.

A TCC analyzer measures the time it takes a circuit breaker to trip for a given level of current. This ensures that in the event of a fault, the breaker can operate as intended to prevent damage to the electrical system. These analyzers’ contribution toward establishing compliance with manufacturers or industry standards is of great help.

Contact Resistance Tester

The contact resistance testers measure the resistance of the circuit breaker contacts for wear, pitting, or contamination. This tool enables predictive maintenance because contact resistances that are too high may cause the device to overheat and become inoperative.

Cameras operating on thermal imaging technology

These cameras enable the non-invasive imaging methods of spotting circuit breaker hotspots. By spotting the areas with excessive heat, technicians can pinpoint malfunctioning places like loose connections, improper torque, or contact arcing. This technology further improves safety and efficiency during testing.

Portable Trip Unit Tester

Trip unit testers are designed to evaluate the effectiveness of the electronic trip units in circuit breakers. These devices simulate fault conditions and ensure that the necessary protection from the breaker is available and utilized.

Hipot Tester (High Potential Tester) is used to inspect the insulation of electrical installations.

Hipot testers are used to validate the integrity of the insulation by passing a high voltage through different components. This guarantees that the circuit breaker, through its operational voltages, will not be made available with high leakage current, minimizing the chances of electrical hazards.

A combination of these specified tools and proper testing protocols offer reliable diagnostics of circuit breakers while increasing their longevity. Moreover, these tools could be improved further with advancements like wireless connectivity and real-time data analysis which would enhance the accuracy and the efficiency of testing. Regular validation and calibration of the equipment also becomes necessary to ensure simple measurements with minimized errors.

Interpreting the results of a circuit breaker test

Like any other machinery, circuit breaker tests are done using a series of steps, or ‘measured values’ such as twisting times, contact resistance, and insulating resistance, which are then compared against the manufacturer-set tolerances. Depending on how drastically these benchmarks are deviated from, an operator may be alerted to issues regarding wear, contamination, or other problems. If these values are within the set limits, the circuit breaker can be considered operational. Values that fall outside of the set limits, however, require additional maintenance in order to be safe and reliable. All these processes and their outcomes should be documented for maintenance purposes as well as reviewed at a later time.

What are the methods of circuit breaker testing?

Overview of primary injection testing

Primary injection testing emphasizes sending an electrical current through the current circuit of a circuit breaker. This technique tests the capabilities of the circuit breaker in terms of current carrying capacity, opera business interruption, and endurance. The test is primarily aimed to prove the functionality of primary components, circuitry, and interconnections in highly current-carrying systems. It is used mostly for commissioning, maintenance, and sometimes as a troubleshooting test.

Understanding secondary injection testing

Secondary injection testing facilitates the assessment of protective relays and their circuits with low power, relying on the application of low current to the primary system. The approach consists of injecting an electric signal into the control circuits of the relay, enabling the tester to verify that the relay functions accurately under various circumstances. It is mainly executed to check whether the relay is operational, capable of fault isolation, and provides a safeguard for the system optimally. Secondary injection testing assists in diagnosing the functionality of system protection schemes making it an important tool for such verifications.

Using Megger for insulation resistance testing

Insulation resistance testing is the careful assessment of a device’s insulation which helps to prevent any failures and ensure safety. For this procedure, a beggar can be used which is reliable and most commonly used. It finds the insulation resistance by applying a high DC voltage to the device and measuring the leakage current.

First Step for Insulation Resistance Testing with a Meggar:

Preparation:

• Make sure that any connected pieces of equipment are taken out from the power source to keep one’s safety and avoid any inaccuracies.
• Confirm that the equipment is completely clean for the possibility of yielding uncontaminated test results.

Voltage adjustments: 

• The voltage that is set for the test is proportional to the rating of the tested equipment. For example:
• Low voltage circuits (up to 1kV) are tested with 500V.
• Medium voltage systems are tested with 1000V.
• For any high voltage transformers and cables, these should be set based on the manufacturer’s instructions, particularly in 2025.

Conducting the Test: 

• Attach the appropriate leads to the equipment that will be connected to the Meggar for the test.
• Start the test which will then supply the voltage and measure the insulation resistance in ohms (Ω).

Interpreting the Readings:

• The range of over 1-mega-ohm (MΩ) to gig-ohm (GΩ) will yield exceedingly high resistance to devices with fantastic insulation features.
• In newly installed machinery, the insulation resistance measurement should not drop below 1 MΩ for every kV of operating voltage. Older units may have poorer values but need to stay within the minimum acceptable thresholds of IEEE 43 standard or NETA-ATS for electric machinery and electrical testing, respectively.

Typical Applications:

Cables:

• Testing the insulation resistance of power cables helps to determine whether there are any active or potential weak points on cables or if there has been any degradation. Outcomes suggest moisture ingress or aging as possible culprits.

Transformers:

• To avoid major accidents due to transformer failure, insulation tests on transformers need to be preemptively performed to identify deteriorated winding insulation.

Motors are also fundamental parts of electrical installations:

• Regular assessment of insulation of motor windings aids in identifying insulation failure due to excessive heat, mechanical vibration, or corrosive substances.

Main Points and Factors to Consider:  

Polarization Index (PI):  

• The insulation Polarization Index (PI) is the ratio of insulation resistance at one hundred percent of the time, measured to that at one minute. It describes, with some insight, the condition of insulation over some time. Good insulation is suggested with a PI greater than two and a value below 1.0 is an issue that needs serious action immediately.

Dielectric Absorption Ratio (DAR):  

• Another critical parameter is DAR which is calculated as the ratio of resistance at one minute, and 30 seconds. A healthy insulation is where DAR is found to be greater than or equal to 1.4.
• Performing systematic insulation resistance tests using Megger allows technicians to gauge the state of an asset, plan corrective maintenance actions in an efficient way, and significantly reduce delays caused by electrical breakdowns.

Why is regular testing and maintenance of circuit breakers essential?

Preventing failures through regular maintenance testing

Consistent maintenance testing of circuit breakers is necessary to avoid breakdowns as it helps me anticipate problems before they turn into expensive failures or safety concerns. A proactive method like this lessens the chances of sudden outages while enhancing the circuit breaker’s lifespan and safety and performance standards. As such, I am able to inspect and test the operational components alongside the insulation integrity which guarantees the circuit breakers function effectively under load.

The role of NETA standards in ensuring breaker performance

The performance of circuit breakers is always guaranteed with the existence of the InterNational Electrical Testing Association or NETA standards. These standards guarantee complete instructions on the operation, evaluation, examination, and care of electrical equipment, circuit breakers included, which is fundamental for the operational and safety integrity of electrical systems.

NETA standards concentrates more on preventative and predictive checking as a means of service, which includes procedures like insulation resistance testing, contact resistance measurement, and time-current characteristic analysis. For example, as per the best practices provided by NETA, breaker timing tests have the capability of identifying non-productive delays in operation which are symptoms of wear and tear or misalignment of some mechanism parts. Also, getting contact resistance as a routine practice ensures that connections are efficient, thus overheating or energy loss is reduced.

Data points have indicated that using NETA standards boosts system reliability, greatly. The industry case study proved that organizations using NETA standards had increased their reliability by 25% as a result of reduced unplanned outages due to early recognition of equipment deterioration. Also, these practices improve safety regulation adherence, reduce liability risks, and provide an adequate tool for facility managers and engineers.

Implementing NETA’s protocols guarantees performance consistency, safety, and longevity of circuit breakers and strengthens their importance in power distribution systems.

Identifying signs of wear and tear in circuit breakers

Indicators of damage in circuit breakers are overheating, discoloration, and burn marks on parts, usually due to excessive electrical loading. Parts the of the system buzzing, or too much tripping are frequent indicators of a mechanical fault or an electrical fault. Breaker destruction, such as fractures and melting of the enclosure. Moreover, lowered efficiency such as lagging trip mechanism, or nontripping due to overcurrent conditions discloses internal faults. Basic visual inspections and operational tests are essential in recognizing the issues in time for the breaker to be useful.

What safety precautions should a technician consider during circuit breaker testing?

Personal protective equipment for technicians

During circuit breaker testing, technicians must don the proper personal protective equipment (PPE) to ensure their safety. Necessary PPE consists of insulated gloves appropriate for the system’s voltage level, safety glasses or goggles to shield the eyes from electrical arcs or other debris, and arc-rated clothing to guard against burns from electric arcing incidents. Moreover, dielectric footwear should be worn to avoid the ground, and a face shield of the proper rating should be worn if the technician needs to work close to energized parts. Remember to check the state and certification of all PPE before using it to ensure safety regulations are followed.

Ensuring safe handling of voltage and current

Current and voltage must be handled properly to ensure safety and accident prevention during circuit breaker testing. All equipment must be checked for proper grounding to eliminate any electrical shock risks. Before starting any testing procedure, make use of certified voltage detectors to ascertain that all circuits are de-energized. In situations where live voltage circuits need to be worked on, make sure that the system’s instruments used for the tests are rated for the voltage and current levels of the system to avoid erroneous readings or damage to equipment.

Data suggests unclothed personnel are highly at risk when unprotected due to an arc flash generating temperatures of over 35,000 °F. In this regard, barriers and protective insulating tools are advised when working with energized components nestled inside a circuit breaker box. In addition, ‘NFPA 70E’ recommends approach limits must be observed for arc flash protection, for nurses, those limits must be 70 cm.

Subsequently, ensure appropriate load control by watching the current levels for a time while testing to mitigate the chances of circuit overloads. Overloaded circuits can lead to excessive heat, equipment failure, or even catch fire. Current clamps or digital multimeters without overcurrent protection should not be used to detect excessive current flow. These guidelines ensure safe and precise testing while protecting the technicians as well as the equipment.

Understanding the circuit’s load capacity and limitations

It is important to know the design parameters and operating conditions to manage a circuit’s load capacity effectively. The load capacity from a circuit is derived from the current carrying conductors, the insulation rating, and the system design as a whole including the voltage, frequency, and even the region’s environmental conditions. Current research suggests that the majority of residential circuits in the United States are built to support an amperage between 15 and 20 at 120 volts which translates to a maximum load of around 1,800 to 2,400 watts. If the load is exceeded, the insulation can overheat and degrade leading to dangerous conditions.

One option for understanding and assessing the recommended load limitations is to add up the power consumption of all devices connected and make sure that the sum does not exceed 80% of the circuit’s capacity. This recommended guideline is known as the continuous load rule, which is critical in assisting with the safe operations of circuit breaker types. For instance, a 20-amp circuit is only able to support devices with a total wattage not exceeding 1,920 watts, meaning that the 20-amp circuit should ideally not carry no more than 16 amps continuously.

Smart panels and other monitoring equipment that provide real-time data on load usage and capacity represent a remarkable advancement in the technologies utilized in modern electrical systems. Users can be notified of overload events which improves circuit management. A combination of good planning, periodic inspection, and advanced monitoring technology allows both individuals and organizations to achieve power system safety and efficiency while preventing overloading problems.

Frequently Asked Questions (FAQs)

Q: What is the importance of testing a circuit breaker?

A: Comprehensive testing guarantees effectiveness and safety with any electrical equipment. It validates that the breaker will trip appropriately during overloading or short-circuiting which negates possible damage to the electrical panel and other devices.

Q: What is the recommended frequency to conduct circuit breaker tests?

A: Circuit breaker tests depend on the type of breaker, the environment, and even usage. In most cases, low-voltage circuit breakers ought to be checked every year while high-voltage ones may need attention every six months. Consult the supplier’s guide or electrician for qualified advice.

Q: Which tools are necessary for thorough testing of a circuit breaker?

A: Test instruments include a circuit breaker analyzer, multimeter, contact resistance, and insulation resistance as well as a power supply unit and other designated tools for particular types of breakers for advanced diagnostics.

Q: What steps are taken when conducting a trip test on a circuit breaker?

A: To test a circuit breaker for its trip capability, an overload or a simulated short circuit is controlled by a circuit breaker analyzer. The test equipment monitors the time it takes for the trip break to occur and checks it against the manufacturer’s benchmarks. This checks if the circuit breaker functions adequately in a short-circuit situation.

Q: What are the most significant parameters noted while testing a circuit breaker?

A: Notable parameters include the times of trip, contact resistance, insulation resistance, and the functionality of the operating mechanism. For instantaneous low-voltage breakers, both instantaneous trip values and automatic overload protection are important, too. These measurements allow the verification of the proper operation of the breaker and the elimination of problems that can cause failures.

Q: Is it possible to test the circuit breaker without taking the breaker out of the electrical panel?

A: Basic functions like visual inspection may not require the breaker to be removed from the box; however, more elaborate tasks like trip testing do need the breaker to be taken out for accurate measurements to take place. For the other more comprehensive tests, the breaker must be detached from the panel. This guarantees safety, accuracy, and precision.

Q: What symptoms show that a circuit breaker needs to be tested or replaced?

A: If you notice that your circuit breaker is frequently tripping, it may need to be replaced. Other signs include: failing to reset, making strange sounds while functioning, visible burns or discoloration, or age over 20 years. It’s best practice to seek the guidance of a licensed professional to ensure accuracy. These issues can put you at an enhanced risk, so having professionals address these matters is crucial.

Q: In what aspects is acceptance testing different from routine maintenance testing of the circuit breakers?

A: Acceptance testing is done after the installation of new circuit breakers or following extensive repairs. This testing includes a complete series of verification tests to ascertain that the breaker meets all the required specifications, and is operational. In comparison to acceptance testing, routine maintenance testing is done after specific intervals to verify proper functioning and measure the decline in performance efficiency over some time.

Reference Sources

1. A Novel Approach to Modeling the Reverse Recovery Process of a thyristor for HVdc Circuit Breaker Testing

• Authors: Zhonghao Dongye Et AlBenson
• Published In: IEEE Transactions on Power Electronics, 2021

Summary:

• This paper describes a new technique that provides a novel approach to the reverse recovery process (RRP) modeling of a thyristor with a new trigonometric exponential (TE) model that is used in HVDC circuit breaker testing. The work focuses on the necessity of having a well-defined RRP model to avoid overvoltage problems that can endanger reliable operations.

Key Findings:

• The proposed TE model estimates the overvoltage with a relative error of 7.51%. The model also incorporates additional stray inductances which are usually more disregarded in existing methods, and results in better descriptions of the hard-switching process.
• The experimental data obtained from a 1 kV / 830 A IGBT circuit breaker shows that a negative peak voltage of -4.26 kV to the thyristor was recovered during the reverse recovery process.

Methodology:

• The authors investigated the physical phenomena associated with the RRP and considered splitting it into two parts for which analytical formulas are provided for the TE Model along with how to derive the model parameters from external circuit parameters and thyristor characteristics.(Dongye et al., 2021, pp. 1591–1601).

2. A Black-Box Arc Model Validated through Testing of a High-Voltage Circuit Breaker

• By: T. Ohtaka et al.
• Published by: IEEE Transactions On Power Delivery, 2018

Summary:

• The current paper presents a new black-box arc model validated by high-voltage circuit breaker testing. The goal of the model is to enhance the accuracy of the simulation of current and voltage waveforms during the interruption process.

Key Findings:

• The new model proved to be more accurate than four existing black box arc models.
• The arc parameters were altered to achieve the value of the arc voltage which bears the least difference between the measured and the computed value.

Methodology: 

• The authors applied an optimization method to derive arc parameters over the specified time interval and tested the model on a simplified circuit designed for the simulation of short-line faults(Ohtaka et al., 2018, pp. 1835- 1844).

3. Protection of Direct Current Shipboard Power Systems with a Solid State Circuit Breaker: Breaker Development, Relay Protection Coordination, Validation Examination

• By: L. Qi et al.
• Publication: IEEE Transactions on Industry Applications, 2020

Abstract:

• The development and examination of a solid-state DC circuit breaker (DCCB) for a shipboard power system is presented with emphasis on the protection coordination scheme and validation testing.

Primary Achievements:

• The prototype DCCB employing reverse blocking integrated gate commutated thyristor (RB-IGCT) technology was demonstrated to have excellent protective features under fault conditions.
• The experimental setup was able to interrupt the fault effectively and also reduced the fault energy in the system considerably.

Research Approach:

• A prototype with the rated parameters of 1 kV and 1.5 kA was built by the authors with a description of the protection coordination scheme and the experimental testing results(Qi et al., 2020, pp. 952–960).