TECHNICAL FIELD

This disclosure relates generally to power control systems and devices and, in particular, to circuit breaker devices and systems for protecting branch circuits from damage due to fault conditions.

BACKGROUND

Electrical circuit breakers are essential components in electrical distribution systems. In general, circuit breakers are disposed in a power distribution panel (e.g., circuit breaker panel) which divides a high-current power supply feed of a utility power supply system into a plurality of downstream branch circuits within a given building or home structure. Each circuit breaker is connected between the incoming high-current power supply feed and a corresponding one of the branch circuits to protect the branch circuit conductors and electrical loads on the branch circuit from being exposed to over-current conditions. There are several types of over-current conditions including overload conditions and fault conditions. An overload condition is defined as operation of equipment in excess of its normal, full-load rating, or a branch circuit in excess of its ampacity which, when the overload persists for a sufficient period of time, would cause damage or dangerous over-heating. Fault conditions comprise unintended or accidental load conditions that typically produce much higher over-current conditions than do overloads, depending on the impedance of the fault. A fault producing the maximum over-current condition is referred to as a short-circuit or a “bolted fault.”

Conventional circuit breakers are electromechanical in nature and have electrical contacts that are physically separated by either manual intervention of an operator lever or automatically upon the occurrence of a fault condition or prolonged over-current condition, in which cases the circuit breaker is deemed to be “tripped.” The separation of the electrical contacts of a circuit breaker can be performed electromagnetically or electromechanically, or by combination of both.

A significant problem with conventional circuit breakers is that they are slow to react to fault conditions due to their electromechanical construction. Conventional circuit breakers typically require at least several milliseconds to isolate a fault condition. The slow reaction time is undesirable since it raises the risk of hazardous fire, damage to electrical equipment, and arc-flashes, which can occur at the short-circuit location when a bolted fault is not isolated quickly enough. An arc-flash is an electrical explosion of the electrical conductors that create the short-circuit condition. The energy release in an arc-flash can produce temperatures exceeding 35,000° F. at the terminals, resulting in rapidly vaporizing metal conductors, blasting molten metal, as well as expanding plasma that is ejected outwards with extreme force. Therefore, arc-flashes are extremely hazardous to life, property and electrical equipment, particularly in industrial and residential environments where the risk of a gas leak is significant.

In addition to being slow at isolating faults, conventional circuit breakers exhibit large variations in both the time to trip and the current trip limit in response to a fault or prolonged over-current conditions. This variation is predominately due to the limitations of the electromechanical design of the circuit breaker device and the influence of physical factors such as mounting stresses and temperature variation. The variations in the time to trip and the current trip limit can themselves vary from device to device even when the devices are of the same type, have the same rating, and are from the same manufacturer.

Conventional circuit breakers provide high isolation capability once they have been tripped. However, their slow reaction times, lack of precision and high degree of variability are all very undesirable characteristics. Not only do the slow reaction times result in inadequate protection against the possibilities of arc-flashes, but the high degree of variability and lack of precision make coordination between multiple circuit breakers in a complex system almost impossible.

As a protection device, circuit breakers must be able to isolate a fault from the utility supply circuit even when the fault current greatly exceeds the circuit breaker trip current rating and, thereby, protect against being an internal single point of failure. The Ampere Interrupting Capacity (AIC) rating of a circuit breaker indicates the maximum fault current (in amperes) that the circuit breaker device will safely clear when a fault is applied at the load side of the circuit breaker device. The AIC rating of a circuit breaker device denotes the maximum fault current that can be interrupted by the circuit breaker device without failure of the circuit breaker device. The AIC rating demands an extremely high level of short-circuit protection and domestic circuit breakers are often rated at an AIC of 10,000 amperes or more.

Conventional circuit breakers do not implement functionality based on smart decision making for breaking or isolating utility power from a load, or otherwise monitoring or measuring power components such as voltage and/or current, and making intelligent decisions based on measurements and computations of the voltage and/or current. In contrast, conventional circuit breakers operate to protect against excessive load power demand (e.g., current overload, short-circuits) based on electromechanical components in which circuit breakers are tripped by magnetic forces or mechanical forces that are generated by expansion of a bi-metal element having metals with disparate thermal expansion parameters. The lack of intelligent tripping operations and the dependency on the brutal forces created in power distribution environment can result in excessive power conditions such as excessive arcing, slow trip response times, and dangerously high internal operational temperature. The dependency of conventional circuit breakers on mechanical components to effect tripping, such as hooks, springs etc., increases the potential for disasters with regard to fire hazards, device unreliability, and potential loss of human life and property. It is known that a common cause of electrical fires within a home or building is the result of unreliable and faulty electromechanical protection devices and circuit breakers. Accordingly, there is a desire and need in the circuit breaker and protection device industry to eliminate the use of conventional electromechanical/thermomagnetic circuit breaker/protection devices and implement a more reliable and efficient solution for protection devices.

SUMMARY

Embodiments of the disclosure include intelligent circuit breakers and systems and methods for implementing intelligent circuit breakers. For example, one embodiment includes a circuit breaker. The circuit breaker comprises an electromechanical switch, a current sensor, a voltage sensor, and a processor. The electromechanical switch is serially connected between a line input terminal and a load output terminal of the circuit breaker, and configured to be placed in one of (i) a switched-closed state and (ii) a switched-open state. The current sensor is configured to sense a magnitude of current flowing in the electrical path between the line input terminal and the load output terminal and generate a current sense signal. The voltage sensor is configured to sense a magnitude of voltage at a point on the electrical path between the line input terminal and the load output terminal and generate a voltage sense signal. The processor is configured to receive and process the current sense signal and the voltage sense signal to determine operational status information of the circuit breaker and determine power usage information of a load connected to the load output terminal.

Another embodiment includes a method which comprises: connecting a circuit breaker between a utility power source and a branch circuit comprising a load, wherein the circuit breaker comprises an electromechanical switch which is configured to be placed in one of (i) a switched-closed state to connect the utility power source to the branch circuit and (ii) a switched-open state to disconnect the utility power source from the branch circuit; sensing current flow through the circuit breaker and generating a current sense signal that is indicative of a magnitude of the sensed current flow through the circuit breaker; sensing a voltage at a point on an electrical path through the circuit breaker and generating a voltage sense signal that is indicative of a magnitude of the sensed voltage; and processing the current sense signal and the voltage sense signal to determine operational status information of the circuit breaker and determine power usage information of the load.

Another embodiment includes a system which comprises a circuit breaker distribution panel and a circuit breaker disposed within the circuit breaker distribution panel. The circuit breaker distribution panel comprises a bus bar coupled to a utility power source. The circuit breaker comprises a line input terminal coupled to the bus bar, a load output terminal connected to a branch circuit, an electromechanical switch, a current sensor, a voltage sensor, and a processor. The electromechanical switch is configured to be placed in one of (i) a switched-closed state to connect the utility power source to the branch circuit and (ii) a switched-open state to disconnect the utility power source from the branch circuit. The current sensor is configured to sense a magnitude of current flowing in an electrical path between the line input terminal and the load output terminal and generate a current sense signal. The voltage sensor is configured to sense a magnitude of voltage at a point on the electrical path between the line input terminal and the load output terminal and generate a voltage sense signal. The processor is configured to receive and process the current sense signal and the voltage sense signal to determine operational status information of the circuit breaker and determine power usage information of a load connected to the load output terminal.

Other embodiments will be described in the following detailed description of embodiments, which is to be read in conjunction with the accompanying figures.

