In one example, a hybrid circuit interrupter may include a three-coil architecture, first coil circuitry, leakage detection circuitry, and a main processing circuit including a processor. The three-coil architecture may include a coil housing, three coils, and a plurality of coil assembly conductors. The coils may be disposed within the coil housing. The coil assembly conductors may be at least partially disposed within the coil housing. The first coil circuitry may be connected to the first coil and may generate first coil signals. The leakage detection circuitry may be connected to the other two coils and may generate a leakage signal. The processor may receive the first coil signals, receive the leakage signal, determine whether an arc fault exists based on the first coil signals, determine whether a ground fault exists based on the leakage signal, and generate a first trigger signal if a fault is determined to exist.

Method and system allowing more accurate detection and identification of unwanted arcing include novel processing of signal voltage representing recovered power-line current. In one implementation, arc-faults are detected based on numerical analysis where individual cycles of line voltage and current are observed and data collected during each cycle is processed to estimate likelihood of presence of arc-event within each individual cycle based on pre-defined number of arc-events occurring within pre-defined number of contiguous cycles. In another implementation, fast transient current spikes detection can be done by: computing difference values between consecutive line-current samples collected over a cycle, average of differences, and peak-to-peak value of line-current; comparing each difference value to average of difference; comparing each difference value to peak-to-peak value; and, based on calculation of composite of two comparisons, using thresholds to determine if arcing is present within processed cycle.

Arc Fault Circuit Interrupter (AFCI), Ground Fault Circuit Interrupter (GFCI) or AF/GF circuit breakers which may optionally have relatively small or compact bodies that have shaped neutral busbars and/or load terminals with an arm that extends through a window of a current transformer in a circuit breaker housing. The neutral busbar and/or load terminal can have a rigid or semi-rigid shaped body with a first segment that extends through the window of the current transformer and a second segment that extends behind the first segment about a printed circuit board. A plug-on, pigtail or bolt-on neutral can engage an electrical pad of the neutral busbar.

A circuit interrupting device including a line terminal, a wideband current sensor configured to measure a current flowing through the line terminal, a zero cross detection circuit configured to measure a voltage and frequency of the line terminal, and a microcontroller including an electronic processor. The microcontroller is configured to apply a digital filter to a line current measurement signal received from the wideband current sensor and estimate spectral density of the filtered line current measurement signal. The microcontroller is further configured to calculate an arcing characteristic based on the spectral density, determine whether an arc fault is present within the circuit interrupting device based on a comparison of the arcing characteristic to one or more thresholds, and activate an interrupting device when an arc fault is present.

In one example, an arc fault circuit interrupter (AFCI) is provided. The AFCI may include a plurality of current arc signature detection blocks configured to output a plurality of corresponding current arc signatures, and a processor. The processor may be configured to receive each of the plurality of current arc signature from each of plurality of current arc signature detection blocks, respectively, and generate a first trigger signal. The processor may be further configured to assess each of the current arc signatures, determine whether an arc fault exists based on the assessment, and generate the first trigger signal if an arc fault is determined to exist. A method for detecting an arc fault is also provided.

Arc Fault Circuit Interrupter (AFCI), Ground Fault Circuit Interrupter (GFCI) or AF/GF circuit breakers which may optionally have relatively small or compact bodies that have shaped neutral busbars and/or load terminals with an arm that extends through a window of a current transformer in a circuit breaker housing. The neutral busbar and/or load terminal can have a rigid or semi-rigid shaped body with a first segment that extends through the window of the current transformer and a second segment that extends behind the first segment about a printed circuit board. A plug-on, pigtail or bolt-on neutral can engage an electrical pad of the neutral busbar.

Arc Fault Circuit Interrupter (AFCI), Ground Fault Circuit Interrupter (GFCI) or AF/GF circuit breakers which may optionally have relatively small or compact bodies that have shaped neutral busbars and/or load terminals with an arm that extends through a window of a current transformer in a circuit breaker housing. The neutral busbar and/or load terminal can have a rigid or semi-rigid shaped body with a first segment that extends through the window of the current transformer and a second segment that extends behind the first segment about a printed circuit board. A plug-on, pigtail or bolt-on neutral can engage an electrical pad of the neutral busbar.

The line power and neutral conductors for a circuit interrupter such as a miniature circuit breaker, using ground fault sensing via a current transformer, are arranged as a rigid conductor formed from a flat plate and surrounding and holding an insulated flexible conductor when passing through the Ground Fault Interrupter current transformer. The rigid conductor can provide a shaped current path to maximize the effectiveness of the current transformer.

A circuit breaker with arc fault detection by accumulation of machine learning classifications is provided. The circuit breaker comprises a microcontroller including a processor, a memory and computer-readable software code which, when executed by the processor, causes the microcontroller to: sample analog signals representing one or more of the following: a RSSI signal, a voltage signal, and a current signal, perform multiple pre-processing steps on the analog signals to derive a data set, and input the data set into a machine learning classifier such that an output of the machine learning classifier is a value between 0 and 1 which represents a percent chance that the data set is from an electrical arc. Based on the value of the percent chance an accumulator value is either incremented or decremented and if the accumulator value passes an upper threshold level, the microcontroller sends a signal to trip open the circuit breaker.

A method for identifying a type of fault condition with a circuit breaker includes detecting by the circuit breaker a fault condition of a plurality of fault conditions, storing in a memory device a trip code representing a type of the detected fault condition, interrupting current flow through the branch circuit in response to detecting the fault condition, and receiving a reset of the circuit breaker. The trip code may then be displayed in response to a momentary press of a test button that is a short duration press, and activating an LED interface in the circuit breaker to indicate the trip code representing the type of the detected fault condition.