Square D Company

Other

Schneider Electric USA, Inc.

David Joseph Dunne

Kevin John Malo

Steve M Meehleder

William Davison

Richard Allen Studer, Ii

Susan Jean Walker Colsch

Henry J Zylstra

Andy A Haun

Ryan James Moffitt

Robert A Kennedy

Charles D Bettis

Robert J Erger

Gary Michael Stumme

William C Davison

In a circuit breaker, a current transformer for fault powering trip unit electronics and sensing low currents and high currents includes a core with solid laminations and gapped laminations to sense a wide range of currents from locked-rotor currents to high, instantaneous short-circuit currents in a single current transformer. The current transformer can also fault power trip unit electronics without requiring an additional current transformer. The operating range of the circuit breaker is significantly enhanced compared to existing breakers that can sense only a limited range of current levels.

Circuit breaker-like apparatus with combination current transformer

A redundant trip activation scheme whereby at least one pre-trip condition must be satisfied before a trip signal is sent to a trip solenoid of a motor circuit protector. To provide a layer of protection against spurious or nuisance tripping caused by software errors or external events such as EMF effects, a trip module sets a trip variable upon detection of a trip signal. Instead of tripping the MCP, the trip module requires at least an additional trip signal to be detected. The next time a trip signal is detected, the trip module checks whether the trip variable has been set, and, if so, sends a trip signal to a trip circuit, causing the solenoid to be activated. To ensure that a trip actually occurs, the solenoid can be tripped from the microcontroller via the trip circuit or from an over-voltage protection circuit in the event of a system failure, which operates independently of the trip circuit.

Redundant trip activation

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.

Method and system of calibrating sensing components in a circuit breaker system

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.

Switch-to-trip point translation

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.

Method and system of fault powered supply voltage regulation

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.

Redundant instantaneous trip detection

A circuit breaker includes a breaker enclosure, a plurality of conductor connections, and a temperature sensor. The breaker enclosure contains internal components that include a trip unit. The plurality of conductor connections electrically couple the trip unit to a plurality of power conductors. The temperature sensor is located to sense heat radiated by the conductor connections and is positioned inside the enclosure.

Circuit breaker integral temperature monitoring for advance detection of defective power conductor connections

An assembly and method is provided for a tripping mechanism of an circuit breaker to limit the damage to a protected circuit breaker and other associated equipment such as enclosures, bus way, etc. from the high forces that result from high currents and prevent unwanted tripping of a circuit breaker due to rapidly decreasing currents. A trip system for a circuit breaker including a sensor to determine a rate of change in the current level. A positive detector is connected to the sensor to determine a positive current direction. A negative detector is connected to the sensor to determine a negative current direction. An electronic switch connected to the positive and negative sensors to activate the tripping mechanism of the circuit breaker. A power supply is connected to the tripping mechanism and electronic switch. Preferably a current delimiter applies a high voltage initially to an inductive device such as a tripping solenoid to effect a quick response but then limit the current to prevent damage to the tripping solenoid.

Quick responding instantaneous trip system

A zone selective interlocking system for electronic trip circuit breakers includes a plurality of downstream terminals, each downstream terminal connecting with at least one of a plurality of downstream electronic trip circuit breakers having input terminals. A restraint input circuit module, including a voltage comparator, is connected to the input terminals of each of the downstream electronic trip circuit breakers and the input terminals are shorted together providing a self-restraint signal for each downstream electronic trip circuit breaker at the occurrence of a downstream fault condition. The system also includes a plurality of upstream terminals, each upstream terminal connecting with at least one of a plurality of upstream electronic trip circuit breakers having input terminals. The restraint input circuit module is connected to the input terminals of each of the upstream electronic trip circuit breakers for receiving a signal indicative of the downstream fault condition and wherein the restraint input circuit module is self-sourcing. An output circuit module including an opto-isolator is connected to each of the upstream electronic trip circuit breakers and each of the downstream electronic trip circuit breakers for providing galvanic isolation between circuit breakers in a restrained mode and circuit breakers in an unrestrained mode.

Self-sourcing, isolated zone selective interlocking system for use with electronic trip circuit breakers

A circuit breaker and method for interrupting the flow of electric current in a line includes connecting separable contacts to a conductor in the circuit. An actuating device, actuated by an activating signal, is connected to the separable contacts to effect separation of the contacts wherein the flow of electric current in the circuit is interrupted. A current sensor, such as an iron core current transformer, senses the current in the circuit to provide a first sinusoidal signal. A bridge rectifier is connected to the current sensor wherein the first sinusoidal signal is converted to a rectified signal and power is derived from the rectified signal. An interface circuit connected to the rectifying network converts the rectified signal into a second sinusoidal signal for providing the activating signal to the actuating device at a predetermined magnitude of the first sinusoidal signal. The interface circuit includes generating a sign bit indicative of the polarity of the first sinusoidal signal. A switch, such as a complimentary metal-oxide silicon (CMOS) switch, generates a positive half-wave rectified signal and a negative half-wave rectified signal from the rectified signal and the sign bit. The negative half-wave rectified signal is inverted and the positive half-wave rectified signal and the inverted negative half-wave rectified signal are summed and level shifted relative to the magnitude of the first sinusoidal signal to generate a second sinusoidal signal in phase with the first sinusoidal signal.

Growing community of inventors

Cedar Rapids, IA, United States of America

David Joseph Dunne