Abstract: A self-contained branch circuit monitor 2 is has a small form factor configured to fit in the limited space available in a load center 1, in association with a branch circuit breaker 10A occupying a branch location slot 45 in the load center 1. A flexible printed circuit board 4 is wrapped around an outside circumference of a toroidal sensor coil 6 of a current transformer. A current monitoring circuit 15 is formed on the flexible printed circuit board. The monitoring circuit is electrically connected to leads 7, 9 from the sensor coil and is powered by current 17 induced in the sensor coil from current 5 in the branch circuit wire. A branch circuit wire 3A is threaded through the current transformer's center. A transmitter 22 is part of the flexible printed circuit board, to transfer the monitored current data to other locations.

Abstract: An optical waveguide sheet 50 is fastened to an inward facing access door 4 of the load center 2. When the door is closed, the optical waveguide sheet is positioned so that one portion is juxtaposed with the circuit breaker 10A in the load center, to enable the optical waveguide sheet to receive an optical signal 70A characterizing current in the circuit breaker. The optical waveguide sheet 50 is further positioned so that another portion is juxtaposed with an optical window 48 of an aggregator. The optical waveguide sheet is configured to internally reflect the optical signal 70A within its body and to conduct the internally reflected optical signal from the circuit breaker to the optical window of the aggregator. The aggregator may provide information characterizing current usage to an alarm, a measurement device, the smart grid, or a storage device for later use.

Abstract: A self-contained branch circuit monitor 2 is has a small form factor configured to fit in the limited space available in a load center 1, in association with a branch circuit breaker 10A occupying a branch location slot 45 in the load center 1. A flexible printed circuit board 4 is wrapped around an outside circumference of a toroidal sensor coil 6 of a current transformer. A current monitoring circuit 15 is formed on the flexible printed circuit board. The monitoring circuit is electrically connected to leads 7, 9 from the sensor coil and is powered by current 17 induced in the sensor coil from current 5 in the branch circuit wire. A branch circuit wire 3A is threaded through the current transformer's center. A transmitter 22 is part of the flexible printed circuit board, to transfer the monitored current data to other locations.

Abstract: An optical waveguide sheet 50 is fastened to an inward facing access door 4 of the load center 2. When the door is closed, the optical waveguide sheet is positioned so that one portion is juxtaposed with the circuit breaker 10A in the load center, to enable the optical waveguide sheet to receive an optical signal 70A characterizing current in the circuit breaker. The optical waveguide sheet 50 is further positioned so that another portion is juxtaposed with an optical window 48 of an aggregator. The optical waveguide sheet is configured to internally reflect the optical signal 70A within its body and to conduct the internally reflected optical signal from the circuit breaker to the optical window of the aggregator. The aggregator may provide information characterizing current usage to an alarm, a measurement device, the smart grid, or a storage device for later use.

Abstract: A circuit breaker system for providing thermal protection to a conductor conducting current from a power source to a load. While the power source is connected to the load, a microcontroller is powered by the current passing through the conductor to thermally model the temperature of the conductor. If the microcontroller determines that the temperature of the conductor has risen to an undesirable or unsafe level, the circuit breaker disconnects the power source from the load and the current no longer passes through the conductor. With no current passing through the conductor, the microcontroller no longer receives power from the conductor. Instead, the microcontroller continues to model the temperature of the conductor as the conductor cools to an ambient temperature by receiving power from an energy storage device. Accordingly, the microcontroller continuously models the temperature of the conductor until the temperature of the conductor cools to the ambient temperature.

Abstract: A circuit breaker system for providing thermal protection to a conductor conducting current from a power source to a load. While the power source is connected to the load, a microcontroller is powered by the current passing through the conductor to thermally model the temperature of the conductor. If the microcontroller determines that the temperature of the conductor has risen to an undesirable or unsafe level, the circuit breaker disconnects the power source from the load and the current no longer passes through the conductor. With no current passing through the conductor, the microcontroller no longer receives power from the conductor. Instead, the microcontroller continues to model the temperature of the conductor as the conductor cools to an ambient temperature by receiving power from an energy storage device. Accordingly, the microcontroller continuously models the temperature of the conductor until the temperature of the conductor cools to the ambient temperature.

Abstract: A method and system to detect currents in the saturation region of a current transformer for a circuit breaker is disclosed. An example method is sensing a fault condition with a current transformer in a circuit breaker. The characteristic curve of the current transformer in a saturation mode is determined based on peak current. A current is received on the transformer. A secondary current is output from the transformer. It is determined whether the secondary current is indicative of a fault current in the saturation mode of the transformer. The breaker is tripped if the secondary current is indicative of a fault current.

Abstract: A time-synchronized trip implementation for a motor circuit protector (MCP) having a reconfigurable microcontroller. The microcontroller causes a power supply to, be charged for an initial time period during a charging mode. An onboard comparator is configured for a predetermined self-protection level of the MCP, and fault currents that exceed the comparator's threshold will directly drive a solenoid to trip the MCP. The microcontroller reconfigures the comparator's threshold to both measure and charge the power supply toward a stored energy trip voltage, which will charge quickly when high fault currents are present. As a result, self-protection is not compromised. After the trip voltage is reached, the microcontroller reconfigures the onboard comparator's threshold for self-protection trip levels. When a trip event occurs in this mode, stored energy trip activation occurs.

Abstract: An automatic temperature compensation method that automatically adjusts trip point thresholds of a motor circuit protector in response to changes in temperature. The relationship between two curves is exploited to match temperature sensor readings from a temperature sensor circuit with burden resistor percentage values derived from a burden resistor circuit. A temperature inflection point is determined from the intersection of (1) the temperature sensor curve plotting the voltage output of the temperature sensor versus temperature and (2) the burden resistance curve plotting burden resistance versus temperature. A temperature value along the temperature sensor curve is transformed into the corresponding burden resistance on the burden resistance curve. The burden resistance is expressed as a percentage variance from a burden resistance at an ambient temperature.

Abstract: A method and system to calibrate a motor circuit protection device is disclosed. An example method calibrates a signal chain of a circuit breaker. The signal chain includes a current transformer, a burden resistor, a stored energy circuit and a controller. The circuit breaker includes a memory coupled to the controller. A calibration instruction routine is written in a first location of the memory. A test current is injected in the circuit breaker signal chain. The test current peak of the test current in the circuit breaker signal chain is measured. Data indicative of the test current peak is stored in a second location of the memory. The test current peak data is read from the second location of the memory. The test current peak data is compared with nominal current data related to the signal chain remotely from the circuit breaker. A calibration factor is determined based on the comparison.

Abstract: A translation technique for translating mechanical button positions of a circuit breaker to trip point settings stored in a memory of the circuit breaker. A turn of a mechanical button turns a potentiometer button, whose output is converted to scaled voltages and converted to corresponding digital values. These digital values are checked against a range of thresholds (minimum/maximum) corresponding to mechanical orientation positions of the mechanical button. Once the mechanical orientation position is determined by scaling and converting the potentiometer output, a trip curve lookup table stored in memory is accessed to determine which trip point setting should be set for the circuit breaker based upon the button position. The circuit breaker's trip curve settings can be changed easily via the mechanical button. They can also be changed easily by modifying the trip curve lookup table without having to recalibrate the circuit breaker or the switch settings.

Abstract: A method and system for supply voltage regulation in a motor circuit protector (MCP) that includes a current transformer coupled to a rectifier and a stored energy circuit. A solenoid is actuated by that circuit when a sufficient voltage is present. A controller having a configurable input is coupled to the stored energy circuit. Upon startup of the motor circuit protector, the controller causes the stored energy circuit to be charged to a startup voltage level via secondary current from the current transformer. The controller periodically interrupts the charging to measure the secondary current to detect fault levels. During startup, the configurable input is set to a comparator input for rapid current measurements. During run mode, the configurable input is set to an A/D input for accurate measurements. The controller measures the voltage of the stored energy circuit while charging it to a power level sufficient to actuate the solenoid.

Abstract: A motor circuit protector that trips in accordance with an instantaneous trip curve that is split into three protection regions, a self-protection region, an in-rush avoidance region, and a locked-rotor avoidance region. Software modules for detecting whether primary current exceeds each region are run in parallel or simultaneously, providing redundant instantaneous trip detection, and these redundant protection regions remain active throughout the startup and steady-state modes of operation of the motor circuit protector. This redundancy provides improved time current trip performance for a wide variety of short circuit conditions and improved system safety properties are realized. The current threshold for the self-protection region can be adjusted toward the in-rush avoidance region once steady-state operation is achieved. In startup mode, only the self-protection region may be detected, but can remain active during steady-state mode.

Abstract: A method and system to calibrate a motor circuit protection device is disclosed. An example method calibrates a signal chain of a circuit breaker. The signal chain includes a current transformer, a burden resistor, a stored energy circuit and a controller. The circuit breaker includes a memory coupled to the controller. A calibration instruction routine is written in a first location of the memory. A test current is injected in the circuit breaker signal chain. The test current peak of the test current in the circuit breaker signal chain is measured. Data indicative of the test current peak is stored in a second location of the memory. The test current peak data is read from the second location of the memory. The test current peak data is compared with nominal current data related to the signal chain remotely from the circuit breaker. A calibration factor is determined based on the comparison.

Abstract: A method and system for supply voltage regulation in a motor circuit protector (MCP) that includes a current transformer coupled to a rectifier and a stored energy circuit. A solenoid is actuated by that circuit when a sufficient voltage is present. A controller having a configurable input is coupled to the stored energy circuit. Upon startup of the motor circuit protector, the controller causes the stored energy circuit to be charged to a startup voltage level via secondary current from the current transformer. The controller periodically interrupts the charging to measure the secondary current to detect fault levels. During startup, the configurable input is set to a comparator input for rapid current measurements. During run mode, the configurable input is set to an A/D input for accurate measurements. The controller measures the voltage of the stored energy circuit while charging it to a power level sufficient to actuate the solenoid.

Abstract: A motor circuit protector that trips in accordance with an instantaneous trip curve that is split into three protection regions, a self-protection region, an in-rush avoidance region, and a locked-rotor avoidance region. Software modules for detecting whether primary current exceeds each region are run in parallel or simultaneously, providing redundant instantaneous trip detection, and these redundant protection regions remain active throughout the startup and steady-state modes of operation of the motor circuit protector. This redundancy provides improved time current trip performance for a wide variety of short circuit conditions and improved system safety properties are realized. The current threshold for the self-protection region can be adjusted toward the in-rush avoidance region once steady-state operation is achieved. In startup mode, only the self-protection region may be detected, but can remain active during steady-state mode.

Abstract: An automatic temperature compensation method that automatically adjusts trip point thresholds of a motor circuit protector in response to changes in temperature. The relationship between two curves is exploited to match temperature sensor readings from a temperature sensor circuit with burden resistor percentage values derived from a burden resistor circuit. A temperature inflection point is determined from the intersection of (1) the temperature sensor curve plotting the voltage output of the temperature sensor versus temperature and (2) the burden resistance curve plotting burden resistance versus temperature. A temperature value along the temperature sensor curve is transformed into the corresponding burden resistance on the burden resistance curve. The burden resistance is expressed as a percentage variance from a burden resistance at an ambient temperature.

Abstract: A method and system to detect currents in the saturation region of a current transformer for a circuit breaker is disclosed. An example method is sensing a fault condition with a current transformer in a circuit breaker. The characteristic curve of the current transformer in a saturation mode is determined based on peak current. A current is received on the transformer. A secondary current is output from the transformer. It is determined whether the secondary current is indicative of a fault current in the saturation mode of the transformer. The breaker is tripped if the secondary current is indicative of a fault current.

Abstract: A translation technique for translating mechanical button positions of a circuit breaker to trip point settings stored in a memory of the circuit breaker. A turn of a mechanical button turns a potentiometer button, whose output is converted to scaled voltages and converted to corresponding digital values. These digital values are checked against a range of thresholds (minimum/maximum) corresponding to mechanical orientation positions of the mechanical button. Once the mechanical orientation position is determined by scaling and converting the potentiometer output, a trip curve lookup table stored in memory is accessed to determine which trip point setting should be set for the circuit breaker based upon the button position. The circuit breaker's trip curve settings can be changed easily via the mechanical button. They can also be changed easily by modifying the trip curve lookup table without having to recalibrate the circuit breaker or the switch settings.

Abstract: A time-synchronized trip implementation for a motor circuit protector (MCP) having a reconfigurable microcontroller. The microcontroller causes a power supply to, be charged for an initial time period during a charging mode. An onboard comparator is configured for a predetermined self-protection level of the MCP, and fault currents that exceed the comparator's threshold will directly drive a solenoid to trip the MCP. The microcontroller reconfigures the comparator's threshold to both measure and charge the power supply toward a stored energy trip voltage, which will charge quickly when high fault currents are present. As a result, self-protection is not compromised. After the trip voltage is reached, the microcontroller reconfigures the onboard comparator's threshold for self-protection trip levels. When a trip event occurs in this mode, stored energy trip activation occurs.