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 interrupters 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 interrupters include an operating mechanism, which is designed to rapidly open the separable contacts, and a trip mechanism, such as a trip unit, which senses a number of fault conditions to trip the separable contacts open automatically. Upon sensing a fault condition, the trip unit trips the operating mechanism to a trip state, which moves the separable contacts to their open position.

When the separable contacts open during a trip, an arc will often form between the separable contacts. Arcing can be detrimental to the circuit interrupter itself and electrical components connected to it. Many techniques have been developed to minimize and extinguish arcing as quickly as possible. However, arcing cannot be completely avoided. Nevertheless, it is beneficial to minimize the effects of arcing during a trip or switching operations. In higher DC voltage applications, it is also a challenge to generate and maintain an arc voltage higher than the source voltage in order to interrupt the DC circuit.

There is room for improvement in circuit interrupters.

Attention is drawn to <CIT> describing a hybrid solid state/mechanical switch that is provided with a pair of mechanical contacts connected in parallel with a solid state switching device. These components are operated by a control circuit to achieve arcless current interruption under normal conditions. A circuit breaking device, which can be operated by a crowbar circuit, provides failure protection for the hybrid switch if excessive leakage current is detected in the solid state switching device or current continues to flow through the switch at a preselected time following the occurrence of a turn-off command signal.

Further attention is drawn to <CIT> describing a hybrid switch assembly for a circuit breaker assembly. The circuit breaker assembly includes a housing assembly and an operating mechanism. The housing assembly defines a power electronic switch assembly cavity. A hybrid switch assembly includes a number of conductor assemblies, each conductor assembly including a movable conductor, and a stationary conductor. Further, each movable conductor is structured to move between an open, first position, wherein each movable conductor is spaced from and not in electrical communication with an associated stationary conductor, and a closed, second position, wherein each movable conductor is coupled to and in electrical communication with an associated stationary conductor. A number of the conductor assemblies further include a power electronic switch assembly. Each power electronic switch assembly includes an isolation contact assembly. Each isolation contact assembly is selectively coupled to, and in electronic communication with, the stationary conductor and the movable conductor.

Attention is also drawn to <CIT> describing electrical distribution systems implementing micro-electromechanical system based switching devices. Exemplary aspects include a method in an electrical distribution system, the method including determining if there is a fault condition in a branch of the electrical distribution system, the branch having a plurality of micro electromechanical system (MEMS) switches, re-closing a MEMS switch of the plurality of MEMS switches, which is furthest upstream in the branch and determining if the fault condition is still present. Exemplary embodiments include an electrical distribution system, including an input port for receiving a source of power, a main distribution bus electrically coupled to the input port, a service disconnect MEMS switch disposed between and coupled to the input port and the main distribution bus and a plurality of electrical distribution branches electrically coupled to the main distribution bus.

Attention is further drawn to <CIT> describing an electronic controller of trip and fault indication for a low voltage circuit breaker.

These needs and others are met by embodiments of the disclosed concept in which a hybrid switch assembly for use with a circuit interrupter includes a solid state switching circuit that commutates current past separable contacts when the separable contacts are separated.

In accordance with the invention a hybrid switch assembly for use in a circuit interrupter comprises: an input; an output; separable contacts electrically connected between the input and the output; a solid state switching circuit electrically connected between the input and the output and in parallel with the separable contacts; and a fuse electrically connected in series with the solid state switching circuit, wherein the solid state switching circuit is structured to turn on and allow current to flow through it between the input and the output for a predetermined amount of time after the separable contacts separate.

In accordance with another aspect of the invention a circuit interrupter as set forth in claim <NUM> is provided.

A full understanding of the disclosed concept 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 employed herein, the statement that two or more parts are "coupled" together shall mean that the parts are joined together either directly or joined through one or more intermediate parts.

<FIG> is a schematic diagram of a circuit interrupter <NUM> (e.g., without limitation, a circuit breaker) in accordance with an example embodiment of the disclosed concept. The circuit interrupter <NUM> is structured to be electrically connected between a power source <NUM> and a load <NUM> via LINE and NEUTRAL conductors <NUM>,<NUM>. The circuit interrupter <NUM> is structured to trip open or switch open to interrupt current flowing between the power source <NUM> and load <NUM> in the case of a fault condition (e.g., without limitation, an overcurrent condition) to protect the load <NUM>, circuitry associated with the load <NUM>, as well as the power source <NUM>.

The circuit interrupter <NUM> includes a hybrid switch assembly <NUM>, an operating mechanism <NUM>, and an electronic trip unit <NUM>. The electronic trip unit <NUM> is structured to monitor power flowing through the circuit interrupter <NUM> via a current sensor <NUM> and/or other sensors and to detect fault conditions based on the power flowing through the circuit interrupter <NUM>. In response to detecting a fault condition, the electronic trip unit <NUM> is structured to output a signal to initiate a trip. The operating mechanism <NUM> is structured to cause the hybrid switch assembly <NUM> to open to interrupt current flowing through the circuit interrupter <NUM> in response to the signal from the electronic trip unit <NUM>. For example and without limitation, the operating mechanism <NUM> is structured to cause separable contacts <NUM> (shown in <FIG>) to open by, for example and without limitation, moving a movable arm to cause the separable contacts <NUM> to separate.

The hybrid switch assembly <NUM> includes separable contacts <NUM> (shown in <FIG>) and a solid state switching circuit <NUM> (shown in <FIG>). The separable contacts <NUM> are structured to physically separate when a trip or switch action is initiated. The solid state switching circuit <NUM> includes solid state switching elements (e.g., without limitation, insulated-gate bipolar transistors (IGBTs)) that are structured to turn-on and turn-off (i.e., open and close) to allow current to selectively commutate past the separable contacts <NUM> while they are separated. For example, the solid state switching circuit <NUM> is structured to allow current to commutate past the separable contacts <NUM> for a limited amount of time after the separable contacts <NUM> are separated, in the case of a trip or switching action, or for a limited amount of time before the separable contacts <NUM> are closed, in the case of closing the separable contacts <NUM>. Commutating current past the separable contacts <NUM> reduces the arcing and its detrimental effects. It allows the solid state switching circuit <NUM> to interrupter a DC circuit. Example embodiments of the hybrid switch assembly <NUM> will be described in more detail hereinafter.

<FIG> is a diagram of the circuit interrupter <NUM> in accordance with an example embodiment of the disclosed concept. As shown in <FIG>, a moveable arm <NUM> that is attached to one of the separable contacts <NUM>. Moving the moveable arm <NUM> causes the separable contacts <NUM> to open or close. Also shown in <FIG> is a clinch joint <NUM> which is used in the hybrid switch assembly <NUM> and will be described in more detail with respect to <FIG>.

<FIG> is a schematic diagram of the hybrid switch assembly <NUM> in accordance with an example embodiment of the disclosed concept. The hybrid switch assembly <NUM> includes the separable contacts <NUM>, the clinch joint <NUM>, a current limiting inductor <NUM>, a fuse <NUM>, the solid state switching circuit <NUM>, and a trigger switch <NUM>.

When the separable contacts <NUM> are closed, current flows through the LINE conductor <NUM>, the separable contacts <NUM>, the movable arm <NUM> to the load <NUM>. When the separable contacts <NUM> are closed, the solid state switching circuit <NUM> is turned off a current is unable to flow through it. When the separable contacts <NUM> begin to open, the movable arm <NUM> interacts with the trigger switch <NUM>, which causes the solid state switching circuit <NUM> to turn on. When the solid state switching circuit <NUM> turns on, current is able to flow through it. In this state, current flows through the LINE conductor <NUM>, the solid state switching circuit <NUM>, and the moveable arm <NUM> at the point where it contacts the clinch joint <NUM>. In this manner, current is able to commutate past the separable contacts <NUM>. As the moveable arm <NUM> continues to move upward and further separate the separable contacts <NUM>, in the direction shown by arrow <NUM>, the moveable arm <NUM> separates from the clinch joint <NUM> (as shown for example in <FIG>). When the moveable arm <NUM> separates from the clinch joint <NUM>, the LINE connection between the power source <NUM> and the load <NUM> is broken and current cannot flow between the power source <NUM> and the load <NUM>. In the progression of moving the moveable arm <NUM> to separate the separable contacts <NUM>, the separable contacts <NUM> are opened, then current is allowed to commutate past the separable contacts <NUM> via the solid state switching circuit <NUM> for a limited time, and then the isolation is achieved when the moveable arm <NUM> loses contact with the clinch joint <NUM>. This progression is able to reduce the effects of arcing.

The clinch joint <NUM> is a conductive member that is structured to contact the moveable arm <NUM> while the moveable arm <NUM> is disposed between prongs of the clinch joint <NUM>. The clinch joint <NUM> is electrically connected to an output of the solid state switching circuit <NUM> such that when the moveable arm <NUM> contacts the clinch joint <NUM>, there is an electrical path past the separable contacts <NUM> via the solid state switching circuit <NUM>. When the moveable arm <NUM> loses contact with the clinch joint <NUM>, that electrical path is broken.

The current limiting inductor <NUM> is electrically connected <NUM> in series with the LINE conductor <NUM>. In some example embodiments of the disclosed concept, the current limiting inductor <NUM> is electrically connected on the LINE side of the separable contacts <NUM> and the solid state switching circuit <NUM>. The current limiting inductor <NUM> is structured to limit the current as well as the rate of rise of the current flowing through the circuit interrupter <NUM> during a short circuit fault. In some example embodiments, the current limiting inductor <NUM> is used in medium and high voltage applications.

In some example embodiments, the fuse <NUM> is electrically connected between the solid state switching circuit <NUM> and the clinch joint <NUM>. However, it will be appreciated by those having ordinary skill in the art that the fuse <NUM> may be located elsewhere such as, for example and without limitation, between the current limiting inductor <NUM> and the solid state switching circuit <NUM>. The fuse <NUM> is structured to provide additional circuit protection. Namely, the fuse <NUM> is structured to provide galvanic isolation in the case of a short circuit in the solid state switching circuit <NUM>. That is, if components in the solid state switching circuit <NUM> fail and current flows through the solid state switching circuit <NUM> even when it is turned off, the current will become high and cause the fuse <NUM> to blow and provide galvanic isolation to prevent current from continuing to flow through the solid state switching circuit <NUM>. The protection provided by the fuse <NUM> is beneficial because the solid state switching circuit <NUM> includes solid state elements that are generally not intended to have current flowing through them between the power source <NUM> and the load <NUM> under normal operating conditions. Current flowing through the solid state switching circuit <NUM> under normal operating conditions is too high for the components and can damage the components of the solid state switching circuit <NUM> and create heat that can potentially cause a fire or other damage to the circuit interrupter <NUM>. The components of the solid state switching circuit <NUM> are only intended to have high current flowing through them during the limited time between when the moveable arm <NUM> interacts with the trigger switch <NUM> and when the moveable arm <NUM> loses contact with the clinch joint <NUM>. This limited amount of time will not damage the components of the solid state switching circuit <NUM>. The fuse <NUM> provides protection against a failure in the solid state switching circuit <NUM> that causes current to flow through it longer than intended.

<FIG> is another schematic diagram of the hybrid switch assembly <NUM> in accordance with an example embodiment of the disclosed concept. <FIG> shows some circuit components of a switching circuit <NUM>' of the solid state switching circuit <NUM> in accordance with an example embodiment of the disclosed concept. As shown in <FIG>, the switching circuit <NUM>' includes two voltage dependent resistors <NUM> each connected in parallel with a pair of series connected IGBTs <NUM>. The IGBTs <NUM> can be turned on or off under control of additional circuitry included in the solid state switching circuit <NUM>, some examples of which will be described in more detail hereinafter. The example embodiment shown in <FIG> shows one example of an arrangement of solid state elements that may be included in the solid state switching circuit <NUM>. Modules of the pair of voltage dependent resistors <NUM> and parallel connected IGBT <NUM> can be connected both in series and in parallel with each other to either increase the solid state switching circuit <NUM> voltage rating or current rating. However, it will be appreciated by those having ordinary skill in the art that other components in other arrangement may be employed without departing from the scope of the disclosed concept.

<FIG> is a schematic diagram of the solid state switching circuit <NUM> in accordance with an example embodiment of the disclosed concept. The solid state switching circuit <NUM> includes a power supply circuit <NUM>, a trigger circuit <NUM>, a gate driver circuit <NUM>, and a main circuit <NUM>.

The solid state switching circuit <NUM> is structured to be powered by current flowing through the circuit interrupter <NUM>. In particular, the solid state switching circuit <NUM> is structured to be powered from arcing caused when the separable contacts <NUM> separate. The power supply circuit <NUM> is structured to use power from the arc to power the various components of the solid state switching circuit <NUM>. Namely, the power supply circuit <NUM> is structured to convert power from the arc for use by the components of the solid state switching circuit <NUM>. For example, the power supply circuit <NUM> is structured to convert power from the arc to various DC voltages suitable for use by the components of the solid state switching circuit <NUM>.

The trigger circuit <NUM> is structured to receive an output of the trigger switch <NUM>. In response to receiving the output of the trigger switch <NUM>, the trigger circuit <NUM> is structured to cause the solid state switching circuit <NUM> to turn on (e.g., allow current to flow through it).

The gate driver circuit <NUM> is structured to control the solid state switching elements of the solid state switching circuit <NUM> to turn on and turn off upon receiving a trigger signal from the trigger circuit <NUM>. The gate driver circuit <NUM> is structured to generate the control signals to control the state of the solid state switching elements.

The main circuit <NUM> includes a switching circuit <NUM>, a snubber circuit <NUM>, a bridge circuit <NUM>, and a metal oxide varistor (MOV) circuit <NUM>. The switching circuit <NUM> includes the solid state switching elements (e.g., IGBTs) that turn on to allow current to flow through the solid state switching circuit <NUM> or turn off the prevent current from flowing through the solid state switching circuit <NUM>. The snubber circuit <NUM> is structured to absorb energy and suppress voltage spikes due to turning on or turning off the solid state switching elements. The bridge circuit <NUM> is structured to rectify received current to DC current. This allows the solid state switching circuit <NUM> to achieve bidirectional switching performance with fewer power switching components (e.g., IGBTs). Meanwhile, power from the arc will be rectified so that the current provided by the solid state switching circuit <NUM> to the power supply circuit <NUM> is DC current. The MOV circuit <NUM> is structured to absorb energy and clamp voltage.

In some example embodiments, the input of the main circuit <NUM> is electrically connected to the LINE conductor <NUM>. The output of the main circuit <NUM> is electrically connected to the clinch joint <NUM>. This configuration allows the main circuit <NUM> to receive power from the arc and provide the commutated current that has bypassed the separable contacts <NUM>. The MOV circuit <NUM>, the bridge circuit <NUM>, the snubber circuit <NUM>, and the switching circuit <NUM> are sequentially arranged from the input to the output of the main circuit <NUM>. Some example embodiments of the power supply circuit <NUM>, the trigger circuit <NUM>, the gate driver circuit <NUM>, and the main circuit <NUM> will be described hereinafter with reference to <FIG>.

<FIG> is a circuit diagram of the power supply circuit <NUM> in accordance with an example embodiment of the disclosed concept. The power circuit <NUM> includes two inputs <NUM> and <NUM>, a capacitive divider <NUM>, a resistive divider <NUM>, a first output <NUM>, a second output <NUM>, and a neutral output <NUM>. The inputs <NUM> and <NUM> are electrically connected to the main circuit <NUM> outputs <NUM> and <NUM> (shown in <FIG>) and are structured to receive power from the arc. During the arc, the voltage at the inputs <NUM> and <NUM> may be, for example, <NUM>-900V. The resistive divider <NUM> reduces the output voltage. The power supply circuit <NUM> also include diodes arranged to clamp the output voltage. At the first output <NUM>, the power supply circuit <NUM> outputs a first DC voltage (e.g., without limitation, 30V) and at the second output <NUM>, the power supply circuit <NUM> outputs a second DC voltage (e.g., without limitation <NUM>. The neutral output <NUM> serves as a neutral reference. The power output at the first and second outputs <NUM>,<NUM> may be used by other components in the solid state switching circuit <NUM>.

<FIG> is a circuit diagram of the trigger circuit <NUM> in accordance with an example embodiment of the disclosed concept. The trigger circuit <NUM> includes an input <NUM> that is electrically connected to the trigger switch <NUM> and is structured to receive the output of the trigger switch <NUM>. The trigger circuit <NUM> also includes a power input <NUM> which is structured to receive power from the power supply circuit <NUM> (e.g., <NUM>. 8V) to power components of the trigger circuit <NUM>. The trigger circuit <NUM> further includes an output <NUM> that is electrically connected to the gate driver circuit <NUM>. The trigger circuit <NUM> is structured to output a signal via the output <NUM> to cause the gate driver circuit <NUM> to control the solid state switching elements in the solid state switching circuit <NUM> to turn on and turn off.

The trigger circuit <NUM> is structured to control the timing of turning on the solid state switching circuit <NUM> and the amount of time the solid state switching circuit <NUM> is turned on. In response to the trigger switch <NUM> being actuated by the moveable arm <NUM>, a signal is received at the input <NUM> of the trigger circuit <NUM>. In response to receiving the signal, the trigger circuit <NUM> does not immediately output a signal, but rather delays outputting the signal by a predetermined time. To create the predetermined delay, the trigger circuit <NUM> includes first and second RC circuits <NUM>,<NUM>, which cause a predetermined delay between when the trigger circuit <NUM> receives a signal at its input <NUM> and outputs a signal at its output <NUM>. Once the trigger circuit <NUM> begins outputting the signal at its output, it outputs the signal for a predetermined amount of time. To facilitate outputting the signal for the predetermined amount of time, the trigger circuit <NUM> includes a monostable multi-vibrator <NUM>.

<FIG> is a circuit diagram of a trigger circuit 130A in accordance with another example embodiment of the disclosed concept. The trigger circuit 130A has functions of controllable double pulse, controllable delay time, and controllable predetermined solid state switching circuit <NUM> on time in accordance with an example embodiment of the disclosed concept. The trigger circuit 130A includes an input 131A that is electrically connected to the trigger switch <NUM> and is structured to receive the output of the trigger switch <NUM>. The trigger circuit 130A also includes a power input 133A which is structured to receive power from the power supply circuit <NUM> (e.g., <NUM>. 8V) to power components of the trigger circuit 130A. The trigger circuit 130A further includes an output 132A that is electrically connected to the gate driver circuit <NUM>. The trigger circuit 130A is structured to output a signal via the output 132A to cause the gate driver circuit <NUM> to control the solid state switching elements in the solid state switching circuit <NUM> to turn on and turn off.

The trigger circuit 130A is structured to control the timing of first turning-on the solid state switching circuit <NUM>, the amount of time the solid state switching circuit stays on, and the timing of second turn-on the solid state switching circuit <NUM>, and the amount of time the solid state switching circuit stays on. All these parameters can be adjusted by adjusting the potentiometers in the trigger circuit 130A which can generate different RC circuit combinations. In response to the trigger switch <NUM> being actuated by the movable arm <NUM>, a signal is received at the input 131A of the trigger circuit 130A. In response to receiving the signal, the trigger circuit 130A does not immediately output a signal, but rather delays outputting the signal by a predetermined time. To create the predetermined delay, the trigger circuit 130A includes first and second RC circuits, which are controllable by the two potentiometers, and cause a predetermined delay between when the trigger circuit 130A receives a signal at its input 131A and outputs a signal at its output 132A. Once the trigger circuit begins outputting the signal at its output 132A, it outputs the signal for a predetermined amount of time. To facilitate outputting the signal for the predetermined amount of time, the trigger circuit 130A includes a mono-stable multi-vibrator which can be controllable for the amount of solid state switch on time. Once the trigger circuit 130A finishes outputting the first output signal, it will output a second signal for a predetermined amount of time with predetermined delay time to prevent re-ignition. To generate the second signal for the predetermined amount of time, the trigger circuit 130A includes a second mono-stable multi-vibrator which can be controllable for the amount of solid state switch on time and has a controllable input delay by another RC with potentiometer.

<FIG> is a circuit diagram of the gate driver circuit <NUM> in accordance with an example embodiment of the disclosed concept. The gate driver circuit <NUM> includes an input <NUM> and an output <NUM>. The gate driver circuit <NUM> also includes a neutral output <NUM> which is used as a reference. The gate driver circuit <NUM> is structured to receive the output of the trigger circuit <NUM> at the input <NUM>. The gate driver circuit <NUM> is structured to isolate the input <NUM> from the output <NUM> and output a signal suitable for controlling solid state switching elements (e.g., IGBTs) at the output <NUM> based on the signal received at the input <NUM>.

<FIG> is a circuit diagram of the main circuit <NUM> in accordance with an example embodiment of the disclosed concept. The main circuit <NUM> includes the switching circuit <NUM>, the snubber circuit <NUM>, the bridge circuit <NUM>, and the MOV circuit <NUM>. The main circuit <NUM> also includes a line side input <NUM>, a load side output <NUM>, and control inputs <NUM>,<NUM>. The main circuit <NUM> also provides power to the power supply circuit <NUM> inputs <NUM> and <NUM> at outputs <NUM> and <NUM>.

The main circuit <NUM> is structured to electrically connect to the LINE conductor <NUM> via inductor <NUM> on the line side of the circuit interrupter <NUM> at the line side inputs <NUM>. The main circuit <NUM> is structured to electrically connect to the clinch joint <NUM> via fuse <NUM> at the load side output <NUM>. The main circuit <NUM> is structured to electrically connect to the outputs of the gate driver circuit <NUM> at the control inputs <NUM>,<NUM>.

The MOV circuit <NUM> is structured to absorb energy and clamp voltage. In the example embodiment shown in <FIG>, the MOV circuit <NUM> includes a number of MOVs electrically connected between the input <NUM> and the output <NUM> of the main circuit <NUM>. The output of the MOV circuit <NUM> is electrically connected to an input of the bridge circuit <NUM>. The bridge circuit includes a number of diodes arranged in a bridge and is structured to rectify the output of the MOV circuit <NUM>. The output of the bridge circuit <NUM> is electrically connected to an input of the snubber circuit <NUM>. The snubber circuit <NUM> is arranged as a snubber and is structured to absorb energy and suppress voltage spikes.

The switching circuit <NUM> includes a number of solid state switching elements <NUM> such as IGBTs. The switching circuit <NUM> is structured to receive control signals via the control inputs <NUM>,<NUM>. The control signals cause the solid state switching elements <NUM> to turn on or turn off. For example, the control signals are received at gates of the solid state switching elements <NUM>, which causes the solid state switching elements to turn on or turn off. When the solid state switching elements <NUM> are turned off, the solid state switching circuit <NUM> is turned off and current cannot flow through it. When the solid state switching elements <NUM> are turned on, the solid state switching circuit <NUM> is turned on and current can flow through it.

Via the trigger circuit <NUM>, the timing of turning on and off of the solid state switching circuit <NUM> can be precisely controlled. That is, the trigger circuit <NUM> creates a predetermined delay time after the trigger switch <NUM> is actuated before outputting a signal and outputs the signal for a predetermined amount of time. The output of the trigger circuit <NUM> causes the solid state switching elements <NUM> to selectively turn on, remain on for the predetermined amount of time, and then turn off. The result is that the solid state switching circuit <NUM> commutates current past the separable contacts <NUM> in a controlled manner and then turns off. The controlled manner of turning on and turning off of the solid state switching circuit <NUM> provides reliable results and limits the potential to damage of solid state switching circuit <NUM> or other components of the circuit interrupter <NUM> or the circuit it protects.

<FIG> is a flowchart of a method of opening contacts in accordance with an example embodiment of the disclosed concept. The method of <FIG> may be implemented, for example in the circuit interrupter <NUM> described herein. The method begins at <NUM> where the main separable contacts <NUM> of the circuit interrupter <NUM> are opened. At <NUM>, the solid state switching circuit <NUM> is powered. For example, the solid state switching circuit <NUM> receives power from the arc created by opening the separable contacts <NUM>. At <NUM>, the solid state switching circuit <NUM> is triggered. For example, the trigger switch <NUM> is actuated by movement of the moveable arm <NUM>, which results in a trigger signal being output to the solid state switching circuit <NUM>. As a result of receiving the trigger signal, the solid state switching circuit <NUM> turns on and commutates current past the separable contacts <NUM> at <NUM>. As previously described, the solid state switching circuit <NUM> may turn on a predetermined delay time after receiving the trigger signal.

After a predetermined amount of time, the solid state switching circuit <NUM> turns off at <NUM>, which results in the circuit being interrupted at <NUM>. The method concludes with the line and load side of the circuit interrupter <NUM> becoming isolated at <NUM>. For example, isolation occurs when the moveable arm <NUM> loses contact with the clinch joint <NUM>. In accordance with the method of <FIG>, current may be commutated past the separable contacts <NUM> in a controlled manner.

<FIG> is a flowchart of a method of closing contacts in accordance with an example embodiment of the disclosed concept. The method of <FIG> may be employed when closing contacts in a circuit interrupter such as the circuit interrupter <NUM> described herein. The method of <FIG> utilizes the hybrid switching assembly <NUM> to minimize the effects of arcing when closing contacts.

The method begins at <NUM> where isolation between the line and load side of the circuit interrupter <NUM> is ended. The isolation may be ended when, for example, the moveable arm <NUM> comes into contact with the clinch joint <NUM>, creating a leakage current path via the solid state switching circuit <NUM> between the line and load sides of the circuit interrupter <NUM>. The method continues at <NUM> where the solid state switching circuit <NUM> is powered. The solid state switching circuit <NUM> may receive power from a line side voltage.

At <NUM>, the solid state switching circuit <NUM> is triggered, for example by the moveable arm <NUM> actuating the trigger switch <NUM>. At <NUM>, the separable contacts <NUM> are closed. At <NUM>, the current is commutated past the solid state switching circuit <NUM>. The solid state switching circuit <NUM> then turns off at <NUM> and current flows through the separable contacts <NUM>. Using the hybrid switching assembly <NUM> when closing the separable contacts <NUM> reduces arcing contact erosion.

Claim 1:
A hybrid switch assembly (<NUM>) for use in a circuit interrupter (<NUM>), the hybrid switch assembly (<NUM>) comprising:
an input;
an output;
separable contacts (<NUM>) electrically connected between the input and the output;
a solid state switching circuit (<NUM>) electrically connected between the input and the output and in parallel with the separable contacts (<NUM>); and
a fuse (<NUM>) electrically connected in series with the solid state switching circuit (<NUM>),
characterised by:
a moveable arm (<NUM>) structured to move to separate the separable contacts (<NUM>);
a trigger switch (<NUM>) disposed in a path of the moveable arm (<NUM>) and structured to be actuated when the moveable arm (<NUM>) moves to separate the separable contacts (<NUM>);
wherein the solid state switching circuit (<NUM>) is structured to turn on and allow current to flow through it between the input and the output for a predetermined amount of time after the separable contacts (<NUM>) separate, and
wherein the solid state switching circuit (<NUM>) includes a trigger circuit (<NUM>) structured to cause the solid state switching circuit (<NUM>) to turn on, and wherein the trigger circuit (<NUM>) is structured to wait a predetermined delay after the trigger switch (<NUM>) is actuated before causing the solid state switching circuit (<NUM>) to turn on.