Temperature Sensitivity of Residential Molded Case Circuit Breakers

Aronstein, J.

doi:10.1109/access.2019.2906198

Cited by 7 publications

(3 citation statements)

References 3 publications

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“…The temperature coefficient of the 15A T-M breaker is −0.034 A/Deg. F, which is within the range of other brands previously tested for [12]. The temperature coefficient for the 15 A H-M breaker is nil.…”

Section: Brand 14 Breakers: Temperature Coefficientsupporting

confidence: 70%

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Faulty Residential Circuit Breakers—A Persistent Fire Safety Problem

Aronstein

2023

IEEE Open J. Ind. Applicat.

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Circuit breakers for residential branch circuits must trip at or below 135% of rated current. A breaker that fails that requirement is defective. Samples of two brands, purchased from retail sources, are tested for that basic calibration. Both brands were tested 4 years ago. Previous samples of one brand were 50% defective, and new samples manufactured in 2021 are 28% defective. The second brand, previously defect-free, is again defect-free. The test results, past and present, imply that some manufacturers are calibrating breakers to trip too close to the allowable upper current limit, and are checking calibration by testing at higher current. The standard calibration test at 200% of rated current is shown to be incapable of indicating whether or not a breaker will trip properly, as required by the applicable standard, at 135% of rated current. A third brand tested came on the market recently. Its thermal-magnetic breakers trip correctly, but the brand's hydraulic-magnetic breakers are erratic, with 38% of the samples malfunctioning. The malfunctions are attributed to thermal distortion that causes mechanical binding of the triggering mechanism. Some breaker brands with a high defect rate have been in the distribution chain for many years and are permanently installed in homes. The increased risk of fire and injury for the occupants of these dwellings is significant. The long-standing history of this problem and the fire safety consequences are discussed.INDEX TERMS Circuit breaker, electrical fires, electrical safety, failure, fire, quality control, residential, risk, test data, test method, test results, testing.

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Section: Brand 14 Breakers: Temperature Coefficientsupporting

confidence: 70%

“…T-M breakers are temperature sensitive. That diminishes circuit protection when they are operating in low ambient temperature and increases the chance of nuisance tripping when operating in high ambient temperature [12]. H-M breakers are not expected to be temperature sensitive.…”

Section: Brand 14 Breakers: Temperature Coefficientmentioning

confidence: 99%

Faulty Residential Circuit Breakers—A Persistent Fire Safety Problem

Aronstein

2023

IEEE Open J. Ind. Applicat.

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“…The intelligent air circuit breaker (ACB) and molded case circuit breaker (MCCB) (used as master protection switch and slave protection switch, respectively) [2][3][4][5][6][7][8][9][10] were commercialized (e.g., ABB Emax 2 series and Tmax T series). Although miniature circuit breakers (MCBs) are required to protect most of the terminal electrical equipment in the power grid [11], the commercialization of an intelligent MCB is constrained by its operating principle.…”

Section: Introductionmentioning

confidence: 99%

An electrothermal current prediction method for overload protection of miniature circuit breakers

Lyu¹,

Zong²

2020

Turk J Elec Eng & Comp Sci

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Traditional miniature circuit breakers (MCBs) cannot meet the requirement for the intelligence of distributing apparatuses in a smart grid. The intellectualization of MCBs is restricted due to the lack of appropriate current measurement methods. Thus, an electrothermal current prediction method is proposed based on the derived relationship between root-mean-square (RMS) current and steady-state temperature rise. A fast acquisition algorithm is used to obtain the required temperature rise before thermal equilibrium to highly reduce the total time consumption. The presented prediction method is found immunized against the ambient temperature. The theory is validated with experiments using a thermostat. The tested steady-state accuracy and transient performance could meet the overload protection requirements without being affected by the environmental temperature.

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