Patent Description:
Circuit interrupters, such as for example and without limitation, circuit breakers, are typically used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition, a short circuit, or another fault condition, such as an arc fault or a ground fault. Circuit breakers typically include separable contacts. The separable contacts may be operated either manually by way of an operator handle or automatically in response to a detected fault condition. Typically, such circuit breakers include an operating mechanism, which is designed to rapidly open and close the separable contacts, and a trip mechanism, such as a trip unit, which senses a number of fault conditions to trip the breaker automatically. Upon sensing a fault condition, the trip unit causes the operating mechanism to trip open the separable contacts.

Circuit breaker accessories such as shunt trip, spring release, and under voltage release devices can be operatively connected to a circuit breaker and used to open and close the separable contacts. A shunt trip assembly typically includes a conductive coil and armature operating mechanism that is coupled to the circuit breaker operating mechanism by a mechanical linkage such that movement in the shunt trip operating mechanism causes corresponding movement in the circuit breaker operating mechanism. The shunt trip assembly is additionally operatively coupled to a remote power source that is structured to energize the coil and actuate the shunt trip operating mechanism such that an operator at a remote location can open the circuit breaker separable contacts. An under voltage release device includes a conductive coil connected to a spring, wherein the coil requires a continuous power supply to maintain the spring in a position that keeps the separable contacts of circuit breaker closed and consequently trips the circuit breaker open when supply voltage to the under voltage release device drops below a threshold voltage. A spring release device comprises a coil and armature operating mechanism that causes a compressed spring to expand when the coil is energized by a voltage input and can remotely cause the operating mechanism of a circuit breaker to close the separable contacts by expanding the compressed spring.

In <CIT> there is disclosed a switch testing device intended to be used to test a switch which comprises an energy storage and an electromechanical drive which is fed at least by the energy storage when the switch is actuated. The switch testing device comprises an evaluation circuit which is designed to evaluate an electrical measurement variable detected on the energy storage device, the electromechanical drive or on a conductor connected to the energy storage device or the electromechanical drive for testing the switch.

In <CIT> there is disclosed a method to anticipate failure of a circuit breaker within a power system, which method comprises providing a coil signature element; measuring the analog coil voltage and analog coil current of the circuit breaker coil to determine a time characteristic baseline for the voltage across the circuit breaker coil, and the current flowing through the circuit breaker coil; measuring the analog coil voltage and coil current of the circuit breaker coil over time to determine an ongoing time characteristic for the voltage across the circuit breaker coil, and the current flowing through the circuit breaker coil; and analyzing any changes from said baseline in said ongoing time characteristic.

As with any electrical or mechanical components, the components of circuit breaker accessory devices such as shunt trip, spring release, and under voltage release devices can malfunction and/or wear down. Malfunctioning and wearing down of the accessory devices can in turn prevent the circuit breaker from operating properly. When a circuit breaker fails to operate properly, determining whether the issue lies within the components of the circuit breaker or the components of a connected accessory device can be time-consuming and inefficient.

There is thus room for improvement in diagnostics systems for circuit breaker accessory devices.

The present invention relates to an accessory device as it is defined in claim <NUM>.

Preferred embodiments of the accessory device are defined in the dependent claims.

A full understanding of the present invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:.

Directional phrases used herein, such as, for example, left, right, front, back, top, bottom and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.

As used herein, the singular form of "a", "an", and "the" include plural references unless the context clearly dictates otherwise.

As used herein, the statement that two or more parts or components are "coupled" shall mean that the parts are joined or operate together either directly or indirectly, i.e., through one or more intermediate parts or components, so long as a link occurs. As used herein, "directly coupled" means that two elements are directly in contact with each other. As used herein, "fixedly coupled" or "fixed" means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other. As used herein, "movably coupled" means that two components are coupled so as to allow at least one of the components to move in a manner such that the orientation of the at least one component relative to the other component changes.

As employed herein, the term "number" shall mean one or an integer greater than one (i.e., a plurality).

As employed herein, the term "processor" shall mean a programmable analog and/or digital device that can store, retrieve and process data; a controller; a control circuit; a computer; a workstation; a personal computer; a microprocessor; a microcontroller; a microcomputer; a central processing unit; a mainframe computer; a mini-computer; a server; a networked processor; or any suitable processing device or apparatus.

<FIG> shows a schematic depiction of a smart accessory <NUM> structured to be operatively coupled to a protective relay or trip unit <NUM> of a circuit breaker according to an exemplary embodiment of the present invention. For economy of disclosure, the protective relay or trip unit <NUM> will be referred to hereinafter as the trip unit <NUM>, but it will be appreciated that the trip unit <NUM> can instead or additionally comprise a protective relay without departing from the scope of the present invention. The trip unit <NUM> trips open the separable contacts of the associated circuit breaker (not pictured) upon detection of a fault condition. Accessory <NUM> can be, for example and without limitation, a shunt trip, spring release, or under voltage release device structured to be used with the circuit breaker associated with the trip unit <NUM>.

Accessory <NUM> comprises a power section <NUM> and a control section <NUM>, the power section <NUM> and the control section <NUM> each containing electrical circuitry and being in electrical communication with and operatively coupled to one another. The control section <NUM> further comprises a processor <NUM>, which performs diagnostic functions for the accessory <NUM> as described in more detail herein with respect to <FIG> and <FIG>. In addition, circuit breaker accessory devices such as accessory <NUM> are often powered by external power sources, and the power section <NUM> is in direct electrical communication with an external power source <NUM>, while the control section <NUM> is in direct electrical communication with a communication bus <NUM> that enables communication between the accessory <NUM> and any other entity connected to the bus <NUM>.

Non-limiting examples of entities that can be connected to the bus <NUM> include the trip unit <NUM> (including the supervisory intelligence of the trip unit or protective relay) and a diagnostic interface <NUM> through which a user can receive information provided by the accessory <NUM> about the state of the accessory <NUM>. It will be appreciated that the schematic depiction of the accessory <NUM>, the trip unit <NUM>, and the diagnostic interface <NUM> in <FIG> is meant to be illustrative and is not intended to be limiting on the scope of the present invention. For example, the diagnostic interface <NUM> is depicted as being a separate component from the trip unit <NUM>, but both the diagnostic interface <NUM> and the trip unit <NUM> can be included in the same physical structure housing the associated circuit breaker without departing from the scope of the present invention.

For economy of disclosure, the power section <NUM> and the control section <NUM> are depicted in a simplified manner in <FIG>, as are the elements of the power section <NUM> schematically shown in <FIG>, and it will be appreciated that the elements of the power section <NUM> shown in <FIG> are illustrative and not intended to limit the scope of the present invention. In particular, a current sensor <NUM> and a voltage sensor <NUM> are included in the power section <NUM> so that the control section <NUM> can monitor the current and voltage being supplied by the external power source <NUM> to the accessory <NUM>, but the specific implementations of the current sensor <NUM> and voltage sensor <NUM> shown in <FIG> are illustrative in nature and intended to be non-limiting. For example, the current sensor <NUM> is depicted as being in series between the power source and an input terminal of an inductor L1 (which also represents an actuator <NUM> of the accessory <NUM> as described with respect to <FIG> herein), but the current sensor <NUM> can be placed elsewhere in the power section <NUM> and more than one current sensor can be included in the power section <NUM> without departing from the scope of the present invention. In another example, the voltage sensor <NUM> is depicted as being in parallel with the series-connected actuator <NUM> (inductor L1) and MOSFET Q1, but the voltage provided by the external power source <NUM> can be measured using elements other than a MOSFET in series with the actuator <NUM> without departing from the scope of the present invention.

Still referring to <FIG>, the actuating mechanism of the shunt trip, spring release, and under voltage release devices that an accessory <NUM> can comprise often includes a solenoid and plunger arrangement, such as the actuator <NUM> shown in <FIG>. Referring to <FIG>, which show a cross-sectional view of a solenoid <NUM> and a plunger <NUM>, the solenoid <NUM> comprises a coil of conductive wire wound around a bobbin and enclosed by a magnetic frame (none of these components being numbered), with the ends of the coil structured to be electrically connected to a power source such as the external power source <NUM>. The plunger <NUM> is produced from ferromagnetic material and is mechanically coupled to the solenoid <NUM>. When power is provided to the solenoid <NUM> and current flows through the coil, a magnetic field is generated and actuates the plunger <NUM> to move in the direction denoted by the arrow <NUM>.

A load <NUM> can be coupled to the plunger <NUM>, such that the plunger <NUM> either acts as a pull-type plunger (shown in <FIG>) or a push-type plunger (shown in <FIG>) when actuated. For example, a solenoid <NUM> used in an under voltage release device is generally coupled to a pull-type plunger <NUM> as shown in <FIG>, while a solenoid <NUM> used in a shunt trip or spring release device is generally coupled to a push-type plunger <NUM> as shown in <FIG>. However, whether the type of plunger <NUM> coupled to a solenoid <NUM> included in an accessory device <NUM> is a pull-type or push-type is not intended to limit the scope of the present invention. In addition, an optional spring is sometimes coupled to the solenoid frame as well (as shown in <FIG>), particularly in under voltage release devices. In the context of circuit breaker accessory devices, if the accessory <NUM> is a shunt trip or under voltage release device, the load <NUM> coupled to the plunger <NUM> is generally a component that actuates the circuit breaker operating mechanism to open the separable contacts, and if the accessory <NUM> is a spring release device, the load <NUM> coupled to the plunger <NUM> is generally a component that actuates the circuit breaker operating mechanism to close the separable contacts.

The accessory <NUM> can only function properly to actuate the circuit breaker operating mechanism if sufficient power is provided to the actuator <NUM>. The actuator <NUM> of the accessory <NUM> is depicted in <FIG> as comprising a solenoid <NUM> and a plunger <NUM> for economy of disclosure, as several types of circuit breaker accessory devices use a solenoid <NUM> and plunger <NUM> as actuators, however, it will be appreciated that other types of actuators can be used in place of a solenoid <NUM> and plunger <NUM> without departing from the scope of the present invention.

Referring to <FIG>, when more than one accessory <NUM> is connected to a circuit breaker, it is ideal to connect each accessory <NUM> to its own designated external power source <NUM>. In practice, it is not always possible to provide each accessory <NUM> with its own external power source <NUM>, and multiple accessories <NUM> need to be connected to the same external power source <NUM>, as shown in <FIG>. For each accessory <NUM> to actuate reliably, the external power source <NUM> must be able to supply a minimum amount of current to each of the solenoids <NUM> of the accessories <NUM> connected to the external power source <NUM> on demand. In operation, the external power source <NUM> may only be able to supply sufficient power for fewer solenoids <NUM> at one time than are connected to the external power source <NUM>. Even when each accessory <NUM> is connected to its own designated external power source <NUM> as shown in <FIG>, a user may inadvertently connect the accessory <NUM> to an external power source <NUM> that is under-rated for the power consumption requirements of the accessory solenoid <NUM> (or other power-consuming components of the connected accessory <NUM>), or a wiring error may exist and lower the output of the external power source <NUM> to the accessory <NUM>. It is therefore an object of the present disclosure to provide a diagnostic mechanism that can alert a user in real time that the power provided by the external power source <NUM> to an accessory <NUM> is insufficient, regardless of whether the accessory <NUM> is connected to its own external power source <NUM> or is connected to a common external power source <NUM> shared by other accessories <NUM>.

Certain types of accessories <NUM> require a constant power supply. Non-limiting examples of such accessories <NUM> include under voltage release devices, or shunt trip and spring release devices that are activated based on communication commands. Referring to <FIG>, in accordance with an exemplary embodiment of the present invention, the processor <NUM> (shown in <FIG>) in the control section <NUM> of each accessory <NUM> executes an applied power diagnostic <NUM>, represented by the flow chart shown in <FIG>, to determine if the external power source <NUM> is meeting the power consumption demands of the accessory <NUM>. It will be appreciated that the processor <NUM> must constantly execute the applied power diagnostic <NUM> when power is being applied to the accessory <NUM>.

At step <NUM> of diagnostic <NUM>, the external power source <NUM> applies power to the accessory <NUM>. At step <NUM>, the processor <NUM> determines if the accessory <NUM> has actuated a trip in the associated circuit breaker, the trip either constituting an opening of the separable contacts (for example and without limitation, in the case of the accessory <NUM> being a shunt trip or under voltage release device), or a closing of the separable contacts (for example and without limitation, in the case of the accessory <NUM> being a spring release device). If the processor <NUM> determines at step <NUM> that the accessory <NUM> has actuated a trip, that particular diagnostic cycle ends at step <NUM> (and returns to step <NUM> if power is still being applied to the accessory <NUM> as explained above). If, however, the processor <NUM> determines at step <NUM> that the accessory <NUM> has not actuated a trip, the diagnostic proceeds to step <NUM>.

At step <NUM>, the processor <NUM> determines, based on the voltage sensed by the voltage sensor <NUM> (shown in <FIG>) whether the external power source <NUM> is under-rated for meeting the power requirements of the accessory <NUM>, i.e. whether the external power source <NUM> producing power of a lesser magnitude than is required by the accessory <NUM> to actuate the operating mechanism of the associated circuit breaker. If the processor <NUM> determines that the external power source <NUM> is indeed supplying less power than the accessory <NUM> requires, the processor <NUM> triggers an alarm at step <NUM> indicating to the user that the external power source <NUM> is insufficient for meeting the needs of the accessory <NUM>. The alarm can comprise, for example and without limitation, a sound notification such as a beep, a visual notification such as a toggled sticker display or an illuminated LED, or a notification sent to a remote device via wireless communication. It will be appreciated that the trip unit <NUM> can be programmed with software to have wireless communication (or other communication) capability, and that a trip unit <NUM> so programmed transmits a notification to the remote device after receiving a message from the processor <NUM> on the bus <NUM> indicating that an alarm condition exists. If, however, the processor <NUM> determines that the power supplied by the external power source <NUM> is of sufficient magnitude to meet the power requirements of the accessory <NUM>, then the diagnostic <NUM> proceeds to step <NUM> to commence execution of a trigger time diagnostic <NUM>, as depicted by the flow chart shown in <FIG>.

Referring to <FIG> and <FIG>, in order for the external power source <NUM> to sufficiently meet the power requirements of the accessory <NUM>, the duration of the power signal provided by the power source <NUM> must be long enough to overlap with the response time of the accessory <NUM> actuator. <FIG> and <FIG> show graphs of a power signal <NUM> provided by the external power source <NUM> and the signal <NUM> of the power produced in the accessory <NUM> actuator after receiving power from the external power source <NUM>. Logic <NUM> and logic <NUM> on the y-axis of the graphs shown in <FIG> and <FIG> represent the accessory <NUM> being OFF and ON, respectively. The duration of the power signal <NUM> supplied by the external power source <NUM> shown in <FIG> is too short to enable the accessory power signal <NUM> to reach logic <NUM> and turn the accessory <NUM> actuator ON, while the duration of the power signal <NUM> supplied by the external power source <NUM> shown in <FIG> is sufficiently long that the accessory power signal <NUM> reaches logic <NUM> and causes the accessory <NUM> actuator to turn ON and actuate the operating mechanism of the associated circuit breaker. The trigger time diagnostic <NUM> executed by the processor <NUM> in accordance with an exemplary embodiment of the present invention and depicted by the flow chart shown in <FIG> determines whether the power signal <NUM> supplied by the external power source <NUM> is sufficient to turn the accessory ON as shown in <FIG> or insufficient as shown in <FIG>.

Referring to <FIG>, at step <NUM> of the trigger time diagnostic <NUM>, the external power source <NUM> applies power to the accessory <NUM>. As stated with respect to the applied power diagnostic <NUM> shown in <FIG>, it will be appreciated that the processor <NUM> must constantly execute the trigger time diagnostic <NUM> when power is being applied to the accessory <NUM>. At step <NUM>, the processor <NUM> determines if the accessory <NUM> has actuated a trip in the associated circuit breaker (as previously described with respect to step <NUM> of the applied power diagnostic <NUM>), the trip either constituting an opening of the separable contacts or a closing of the separable contacts. If the processor <NUM> determines at step <NUM> that the accessory <NUM> has actuated a trip, that particular diagnostic cycle ends at step <NUM>. If, however, the processor <NUM> determines at step <NUM> that the accessory <NUM> has failed to actuate a trip, the diagnostic proceeds to step <NUM>.

At step <NUM>, the processor <NUM> determines whether the duration of the power signal provided by the external power source <NUM> to the accessory <NUM> is sufficient to actuate the accessory <NUM>. If the processor <NUM> determines that the duration of the power signal provided by the external power source <NUM> is too short to actuate the accessory <NUM> (as depicted in <FIG>), then the processor <NUM> triggers an alarm at step <NUM> indicating to the user that the duration of the power signal provided by the external power source <NUM> to the accessory <NUM> is insufficient for actuating the accessory <NUM>. Similarly to the alarm described with respect to step <NUM> of the applied power diagnostic <NUM>, the alarm can comprise, for example and without limitation, a sound notification such as a beep, a visual notification such as a toggled sticker display or an illuminated LED, or a notification sent to a remote device via wireless communication. If, however, the processor <NUM> determines that the power signal provided by the external power source <NUM> is of sufficient duration to enable actuation of the accessory <NUM> (as depicted in <FIG>), then the diagnostic <NUM> proceeds to step <NUM> to execute the applied power diagnostic <NUM> previously described with respect to <FIG>.

Including the self-diagnostic functionality in the accessory <NUM> with regard to applied power enables the accessory <NUM> to immediately alert a user of the associated circuit breaker if the power requirements of the accessory <NUM> are not being met. This functionality presents several advantages. First, it alerts the user that there is an issue with the accessory <NUM>, as opposed to the circuit breaker. Second, it alerts the user that an accessory <NUM> malfunction originates with the external power source <NUM> and/or the wiring between the external power source <NUM> and the accessory <NUM> rather than the actuating components of the accessory <NUM>. Third, the continuous evaluation of the sufficiency of the applied power alerts the user of any applied power issues in a timely manner, and can help ensure that any power source issues are addressed at commissioning of an accessory <NUM> and/or the associated circuit breaker, rather than after the circuit breaker has been placed into service.

Claim 1:
An accessory device (<NUM>) for use with a circuit breaker, the circuit breaker including separable contacts and an operating mechanism structured to open or close the separable contacts, the accessory device being separate from the operating mechanism and being structured to be operatively coupled to the circuit breaker so as to be able to actuate the operating mechanism, the accessory device (<NUM>) comprising:
a power section (<NUM>) structured to be electrically connected to a power source (<NUM>), the power section comprising:
an actuator (<NUM>) structured to actuate the operating mechanism of the circuit breaker;
a current sensor (<NUM>) structured to sense a current provided by the power source (<NUM>) to the accessory device (<NUM>); and
a voltage sensor (<NUM>) structured to sense a voltage provided by the power source (<NUM>) to the accessory device (<NUM>); and
a control section (<NUM>) electrically and operatively connected to the power section (<NUM>), the control section comprising a processor (<NUM>),
wherein the power section (<NUM>) and the control section (<NUM>) are not components of the operating mechanism;
wherein the processor (<NUM>) is configured to monitor a power provided by the power source (<NUM>) to the accessory device (<NUM>) based on information received from the current sensor (<NUM>) and based on information received from the voltage sensor (<NUM>),
wherein the processor (<NUM>) is configured to determine whether the power provided by the power source (<NUM>) to the accessory device (<NUM>) is sufficient to enable the accessory device to actuate the operating mechanism of the circuit breaker.