• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.4
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• pp.165-172
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• 2003

Low voltage circuit breakers are widely used in power distribution systems to interrupt fault current rapidly and to assure the reliability of the power supply. This paper is focused on understanding the interrupting capability, more specifically of the contacts and the arc runner, based on the shape of the contact system in the current molded case circuit breaker (hereafter MCCB). Moreover, in order to improve the interrupting capability of the circuit breaker, the estimation and analysis of the interrupting capability, based on the 3-D magnetic flux analysis, were developed. Furthermore, this paper also presents results of the estimation and analysis of the interrupting capability when applied to different model breakers. In addition, this paper analyzes the efficiency of the interrupting tests by forming false current paths consisting of a three-division cascade arc runner in the contact system. With regards to the interrupting test, there is a need to assure that the optimum design required to analyze the electromagnetic forces of the contact system generated by the current and flux density be present. Based on the results of this study, this paper presents both computational analysis and test results for the newly developed MCCB 460V/225A/50㎄ contact system.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.38-42
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• 2012

This paper describes electrical fire on residential environment such as apartment and detached house caused by defect of interior wiring. We carried out experimental study on short circuit characteristics by the interior wiring length. We were measured arc current, arc energy and interrupting time of earth leakage current circuit breaker(ELB), when an interior wiring break out short circuit in residential environment. From the experiment results, the longer of the interior wiring, the magnitude of arc current decreased and the interrupting time of ELB increased. When applied the A maker's ELB, the strength of arc current and interrupting time of ELB was 254 A and 245 ms respectively at 30 m interior wiring length. In 3 m interior wiring length, arc current and interrupting time was 716 A and 4.24 ms respectively. Arc energy was dependent on the magnitude of arc current and the interrupting time of ELB, the longer the interrupting time, arc energy increasing. In this paper, minimum arc energy was 277 J using C maker's ELB and 3 m interior wiring length(arc current 283 A, interrupting time of breaker 6.28 ms). Therefore in the residential environment, short circuit caused by defect of the interior wiring lead to electrical fire.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1257-1261
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• 2017

This paper focuses on understanding the interrupting capability of an arc contact system in a molded case circuit breaker (hereafter MCCB). We selected four types of MCCBs and analyzed the magnetic flux density distributions in the contact systems caused by the fault currents. We ascertained that the magnetic flux density profile varies according to the shape of the contact system and was asymmetric at both the ends of an arc, perpendicular to the arc column because of the magnetic grid installed in the contact system. The asymmetric difference creates a magnetic force that pushes the arc current outwards and provides an interrupting capability. We have introduced a simple analysis method for determining the interrupting capability of the contact system for an MCCB by the arc-driving magnetic flux density.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.147-150
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• 2003

Power demands are increased because of the growth of the economy and the improvement of a given condition life. For this reason, the fault current of the power system is largely increased and the fault current procedure for the proper interrupting capacity calculation of the existing or the new circuit breaker is essential. This paper is basis on collection of the case of foregin countries. It presented the new procedure of the fault current for the interrupting capacity of the circuit breaker. This procedure is applied to the future power system and calculates the fault current.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.77-79
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• 1996

The model interrupters of $SF_6$ gas electromagnetic contactor whose ratings are 7.2kV, 4.0kA have been designed and manufactured on the basis of theoretical and computational analysis for its development. The eddy current analysis, the magnetic field analysis and the calculation of the rotational force on arcs have been conducted using FLUX2D package. The short circuit current interrupting tests have been conducted for the model interrupters using the simplified synthetic testing facility in KERI. The results show that the model interrupters have sufficient interrupting capability and the new design concept is prefer for good interrupting performance.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.144-146
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• 2002

The latest development flow of MCCB(Molded Case Circuit Breaker) is largely separated from which are high capability of interrupting compact of size and multi-ability in functions. As follow of development of industrial system. MCCB which are including communication function and having a ultimate interrupting capability is required in electrical system. to attain an effective limitation of the peak let-through current and the let-through energy, the arc has to move rapidly off the contacts and has to increase the arc voltage which mainly effect to interrupt. In this paper. we made high performance circuit breaker which including current limiting unit which is attached to the main which is simulated by CAE tool that are repulsion force and mechanical dynamics after that we tested and finally selected optimized for circuit breaker.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.900-902
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• 1999

This paper deals with the interrupting characteristics of fuses element in different media of arc extinguisher. Aluminum hydro-oxide, boron nitride, silica and there size have been investigated here for their prospects as filling media in heavy current, high breaking capacity fuses. The result of these study are compared with those on silica sand at high current. This study demonstrates that silica sand is far superior filler in fuses for heavy current interrupting then the compound tested.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.330-332
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• 1997

In this paper, a development of the 7.2kV class $SF_6$ gas electromagnetic contactor which is used a rotary-arc principle in interrupting method is presented. A prototype contactor is made. In the interrupting small current permanent-magnet is used and in the interrupting high current the coil through which arc current itself flows is used. Successfully the prototype contactor carrys out the making, the braking and short time test.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.36-38
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• 2002

Low voltage circuit breakers which interrupt rapidly and raise the reliability of power supply are widly used in power distribution systems. In the paper, it was investigated how much Interrupting capability was improved by correcting the shape of the contact system in molded case circuit breaker(below MCCB), Prior to the interrupting testing, it was necessary for the optimum design to analyze magnetic forces on the contact system, generated by current and flux density. This paper presents both our compuational analysis and test results contact system in MCCB.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1593-1598
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• 1994

Recently rotary-arc, thermal expansion and their composite interrupters are widely used in the distribution power system because they have lots of advantages in making the larger interrupting capacity, the smaller size, the lighter weight and the less surge. A model interrupter of rotary-arc type, which has constant stroke and thermal expansion volume, was studied by varying the design parameters, i.e. the number of turns of the driving coil, the inner diameter of the moving contact, the gas pressure and the shape of the fixed contact for this project. Short cicuit current interrupting tests were conducted to the model interrupters by varying the requirements from 42% to 175% of the test voltage, interrupting current and transient recovery voltage for the test duty No.4 of 7.2kV 12.5kA single phase test. The pressure rise, minimum and maximum arcing times were analyzed for each model interrupter. All types of model interrupters showed good interrupting performances and sufficient design margins for the ratings.