Patent Publication Number: US-2022223338-A1

Title: Transformer apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 63/135,255, filed on Jan. 8, 2021 and titled TRANSFORMER APPARATUS, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to a transformer apparatus for use in, for example, a medium-voltage or high-voltage electrical power distribution network. 
     BACKGROUND 
     A voltage transformer includes a first coil and a second coil that are coupled by a magnetic core. The voltage transformer may reduce the voltage at the input of the transformer so that the output of the transformer is suitable for a load. 
     SUMMARY 
     In one aspect, an assembly includes: a first switching apparatus configured to be electrically connected to a first segment of a transformer loop; a second switching apparatus configured to be electrically connected to a second segment of the transformer loop; and a transformer including: a first coil electrically connected to the first switching apparatus and the second switching apparatus; and a second coil electrically connected to an output that is configured to electrically connect to a load. 
     Implementations may include one or more of the following features. The assembly also may include an electronic control system configured to control a state of the first switching apparatus and a state of the second switching apparatus. The electronic control system may be further configured to: issue a command to a second electronic control system in a second assembly, where the command is sufficient to cause the second electronic control to change a state of a switching apparatus in the second assembly; and to receive a command from the second electronic control system, where the received command is sufficient to cause the electronic control to change a state of the first switching apparatus or the second switching apparatus. The electronic control system may be further configured to control any switching apparatus that is electrically connected to any segment of the transformer loop. The electronic control system may be further configured to communicate with a remote device that is separate from the assembly. 
     In some implementations, the assembly also includes a sensor system configured to sense electrical current in the first segment and electrical current in the second segment. The sensor system may include: a first current transformer configured to sense current flowing to the first switching apparatus; and a second current transformer configured to sense current flowing to the second switching apparatus. The assembly also may include an electronic control system that stores threshold current values and is coupled to the first switching apparatus, the second switching apparatus, and the sensor system; and the electronic control system may be configured to: open the first switching apparatus if the current flowing to the first switching apparatus exceeds the threshold; and to open the second switching apparatus if the current flowing to the second switching apparatus exceeds the threshold. 
     In some implementations, the assembly also includes a housing; and a tank inside the housing, and the electronic control includes an interface that is accessible from an exterior of the housing; and the tank encloses the first switching apparatus, the second switching apparatus, and the transformer. The tank may be at least partially filled with an insulating fluid. 
     The assembly may be a multi-phase transformer assembly configured for use with an N-phase electrical distribution system, and, in these implementations, N is an integer number greater than 1, the first switching apparatus is a gang-operated switching apparatus that includes N switches, and the second switching apparatus is a gang-operated switching apparatus that includes N switches. 
     In another aspect, a system includes a transformer loop configured to be electrically connected to a first electrical source and to a second electrical source; a first transformer assembly including: a first switching apparatus electrically connected to a first segment of the transformer loop; a second switching apparatus electrically connected to a second segment of the transformer loop; a first voltage transformer electrically connected to the first switching apparatus and to the second switching apparatus, where the first voltage transformer is further electrically connected to a first load; and a first electronic control system. The system also includes a second transformer assembly including: a third switching apparatus electrically connected to the second segment of the transformer loop; a fourth switching apparatus electrically connected to a third segment of the transformer loop; a second voltage transformer electrically connected to the third switching apparatus and to the fourth switching apparatus, where the second voltage transformer is further electrically connected to a second load; and a second electronic control system. 
     Implementations may include one or more of the following features. The first electronic control system may be coupled to the first switching apparatus and the second switching apparatus; the second electronic control system may be coupled to the third switching apparatus, and the fourth switching apparatus; and the first electronic control system and the second electronic control may be configured to communicate with each other. The first electronic control and the second electronic control also may be further configured to communicate with a remote station that is separate from the first transformer assembly and the second transformer assembly. 
     In another aspect, an electronic control system for a transformer assembly includes: a communications interface; an electronic processing module; and an electronic storage coupled to the electronic processing module, the electronic storage including instructions that, when executed, cause the electronic processing module to: process a command received from an external device, the command including information that identifies one of two switching apparatuses in a feed of the transformer assembly to transition from a first state to a second state; generate a command for an actuation apparatus associated with the identified one of the two switching apparatuses; and provide the command to the actuation apparatus to thereby change the state of the identified one of the two switching apparatuses and to thereby connect or disconnect the identified one of the two switching apparatuses from a transformer loop. 
     Implementations may include one or more of the following features. The external device may include a separate and distinct transformer assembly, and the instructions may cause the electronic processing module to process a command received from the separate and distinct transformer assembly. The electronic storage also may include instructions that, when executed, cause the electronic processing module to generate a command and provide the command to a communications interface of a separate and distinct transformer assembly. 
     In another aspect, a method of changing a transformer loop from a first source configuration to a second source configuration includes: identifying a first transformer assembly from among a plurality of transformer assemblies in the transformer loop, the first transformer assembly including a switching apparatus that is normally open in a first source configuration; identifying a second transformer assembly from among the plurality of transformer assemblies in the transformer loop, the second transformer assembly including a switching apparatus that is normally open in a second source configuration; commanding an electronic control system in the second transformer assembly to open the switching apparatus that is normally open in the second source configuration; and after the switching apparatus that is normally open in the second source configuration is open, commanding an electronic control system in the first transformer assembly to close the switching apparatus that is normally open in the first source configuration such that the source configuration is changed from the first source configuration to the second source configuration. 
     Implementations may include one or more of the following features. The first transformer assembly and the second transformer assembly may be different ones of the plurality of transformer assemblies. 
     In another aspect, a method of isolating a faulted transformer loop segment includes: receiving an indication of a current flowing to a first switching apparatus and a second switching apparatus of a first transformer assembly, where the first switching apparatus is electrically connected to a first segment of the transformer loop and the second switching apparatus is electrically connected to a second segment of the transformer loop; comparing the indication to a fault current threshold to determine whether the current flowing to the first switching apparatus or the second switching apparatus exceeds the fault current threshold; if the current flowing to the first switching apparatus exceeds the fault current threshold, commanding a motion control device associated with the first switching apparatus such that the first switching apparatus opens; and isolating the first segment of the transformer loop by commanding an electronic control system in a second transformer assembly to open a third switching apparatus, where the third switching apparatus is electrically connected to the first segment of the transformer loop and is in the second transformer assembly. 
     In some implementations, the method of isolating a faulted transformer loop segment also includes controlling an electronic control system in a third transformer assembly to close a fourth switching apparatus, the fourth switching apparatus being configured to be normally open prior to being closed. 
     Implementations of any of the techniques described herein may include an apparatus, a transformer assembly, a method, a system, a control system, or instructions stored on a computer-readable medium. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       DRAWING DESCRIPTION 
         FIG. 1A  is a perspective view of an example of a transformer apparatus. 
         FIG. 1B  is a block diagram of an example of an electrical circuit for the transformer apparatus of  FIG. 1A . 
         FIG. 2A  is a block diagram of an example of a system that includes a plurality of transformer apparatuses electrically connected to a transformer loop. 
         FIG. 2B  is a block diagram of an example of electrical components inside one of the transformer apparatuses of  FIG. 2A . 
         FIG. 2C  is a block diagram of an example of a vacuum fault interrupter. 
         FIG. 2D  is a block diagram of an example of a control system. 
         FIG. 3  is a flow chart of an example of a process for transferring between two sources in a transformer loop. 
         FIG. 4  is a flow chart of an example of a process for isolating a faulted segment of a transformer loop. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  is a perspective exterior view of a transformer apparatus (or transformer assembly)  140 . The transformer apparatus  140  may be used in medium-voltage (for example, 15 to 35 kiloVolts (kV)) and high-voltage (for example, greater than 45 kV) applications. The transformer apparatus  140  includes a housing  141 .  FIG. 1B  is a block diagram of an electrical circuit  172  that is inside the housing  141 . The transformer apparatus  140  also includes a control system  150 . The configuration of the control system  150  allows the transformer apparatus  140  be used alone or with other similarly configured transformer apparatuses to perform automatic source transfer and automatic isolation of line-side segments.  FIGS. 3 and 4  provide examples of processes for automatic source transfer and automatic line-side segment isolation, respectively. Moreover, the transformer apparatus  140  includes the control system  150  and the circuit  172  are in a single piece of equipment. 
     The electrical circuit  172  includes a first switching apparatus  110 A, a second switching apparatus  110 B, and a transformer  130 . The switching apparatuses  110 A and  110 B are any type of switching apparatus suitable for the voltages and currents at which the transformer apparatus  140  operates, and the switching apparatuses  110 A and  110 B are any type of trippable and/or openable device that utilizes a mechanical and/or electronic mechanism to separate current-carrying electrical contacts for the purpose of interrupting the flow of electricity. The switching apparatus  110 A and  110 B have a closed state in which current flows through switching apparatus and an open state in which current cannot flow through the switching apparatus. The switching apparatuses  110 A and  110 B may be, for example, vacuum fault interrupters, circuit breakers, circuit switchers, loadbreak switches, vacuum breakers, vacuum switches, gas-insulated breakers, contactors, reclosers, or any electronically trippable switching and/or interrupting device. Examples of gas-insulated breakers include, but are not limited to, sulfur hexafluoride (SF 6 ) insulated breakers and air-insulated breakers. Moreover, single-phase devices, multi-phase gang-operated devices, or a combination of single-phase and multi-phase devices may be used as the switching apparatus  110 A or  110 B. A gang-operated switching apparatus is configured to interrupt or switch more than one phase simultaneously. 
     The housing  141  is a three-dimensional body that is made of a rugged and durable material. For example, the housing  141  may be made of metal or a ruggedized polymer material. In the example shown in  FIG. 1A , the housing  141  is a parallelepiped that includes six walls. Two walls  141   a  and  141   b  are labeled in  FIG. 1A . The first switching apparatus  110 A is electrically connected to a first line-side input  119 A. The second switching apparatus  110 B is electrically connected to a second line-side input  119 B. The first line-side input  119 A and the second line-side input  119 B are on the high-voltage or medium-voltage side of the transformer apparatus  140 . The first line-side input  119 A is also referred to as the first feed  119 A or the incoming feed  119 A. The second line-side input  119 B is also referred to the second feed  119 B or the outgoing feed  119 B. The inputs  119 A and  119 B are the feed to the transformer apparatus  140 . The feed of the transformer apparatus  140  includes two switching apparatuses (the switching apparatuses  210 A and  210 B). 
     A single phase is shown in  FIGS. 1A and 1B . However, the transformer apparatus  140  may be implemented as a multi-phase device that includes an instance of the circuit  172  for each phase. For example, each phase of the transformer apparatus  140  may include two single-phase switching apparatuses and a transformer connected as shown in  FIG. 1B . In these implementations, a three-phase transformer apparatus may include three single-phase switching apparatuses on the first line-side input  119 A and three single-phase switching apparatuses on the second line-side input  119 B, with each phase including one of the single-phase switching apparatuses the input  119 A and one of the single-phase switching apparatus on the input  119 B. In another example of a three-phase implementation, each switching apparatus  110 A and  110 B is a gang-operated three-phase switching apparatus. In these implementations, the switching apparatus  110 A includes three gang-operated switches on the incoming feed  119 A and the switching apparatus  110 B includes three gang-operated switches on the outgoing feed  119 B. 
     The line-side inputs  119 A and  119 B extend through the wall  141   a  of the housing  141  and are accessible from the exterior of the housing  141 . The line-side inputs  119 A and  119 B are made of an electrically conductive material such as, for example, copper, brass, silver, and/or another metal. The transformer  130  is electrically connected to a load-side output  134 . The load-side output  134  also passes through the wall  141   a  of the housing  141  and is made of an electrically conductive material. 
     In operational use, the line-side inputs  119 A and  119 B are electrically connected to an electrical distribution system or a transformer loop that provides alternating current (AC) electrical power to the transformer apparatus  140 , and the load-side output  134  is electrically connected to a load that consumes electricity, transfers electricity, or otherwise uses electrical energy. 
     The transformer apparatus  140  also includes the control system  150 . The control system  150  is coupled to the circuit  172  and controls the components of the circuit  172 . For example, the control system  150  is configured to control a state of the switching apparatuses  110 A and  110 B. The control system  150  includes an interface  153  that is accessible from the exterior of the housing  141 . The interface  153  includes a data interface or data connection  156  that allows the control system  150  to communicate with a remote device. For example, the control system  150  may communicate with another transformer apparatus and/or with a remote monitoring station through the data connection  156 . Furthermore, the interface  153  may include controls (for example, a keypad or transceiver that accepts input from a remote control) that allow an operator of the transformer apparatus  140  to control the various components of the circuit  172  or another transformer apparatus without accessing the interior of the housing  141  or the interior of the other transformer apparatus. 
     The housing  141  may have other shapes, and the configuration and arrangement of the line-side inputs  119 A and  119 B, the interface  153 , the interface  156 , and the load-side output  134  may be other than shown in the example of  FIG. 1A . 
       FIG. 2A  is a block diagram of a system  200 . The system  200  includes transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4  that are electrically connected to a transformer loop  204 . The transformer loop  204  is also electrically connected to electrical sources  202 _A and  202 _B, which are part of an alternating current (AC) electrical power distribution system  201 . The transformer loop  204  includes a first segment  205 _ 1 , a second segment  205 _ 2 , a third segment  205 _ 3 , a fourth segment  205 _ 4 , and a fifth segment  205 _ 5 . The configuration of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4  allows automatic isolation of faulted segments and automatic transfer between the source  202 _A and the source  202 _B. 
     The power distribution system  201  may be, for example, an electrical grid, a utility system, an electrical system, or a multi-phase electrical network that distributes electrical power to industrial, residential, and/or commercial entities. The power distribution system  201  may be a sub-system of a larger power system. For example, the power distribution system  201  may be a utility substation. The power distribution system  201  may have a system level voltage of, for example, at least 1 kilovolt (kV), 25 kV,  27 , kV, 29 kV, between 15 kV and 35 kV, up to 34.5 kV, up to 38 kV, up to 69 kV, or 69 kV or higher and a fundamental frequency of, for example, 50 or 60 Hertz (Hz). The transformer loop  204  is any device that distributes electricity and may include, for example, transmission lines, electrical cables, and/or electrical wires. The transformer loop  204  operates at the system voltage. In other words, if the nominal operating voltage of the power distribution system  201  is 15 kV, the nominal voltage on the transformer loop  204  is also 15 kV. 
     The transformer apparatus  240 _ 1  includes vacuum fault interrupters  210 A_ 1 ,  210 B_ 1  and a transformer  230 _ 1 . The vacuum fault interrupters  210 A_ 1  and  210 B_ 1  are electrically connected to an input of the transformer  230 _ 1 , and the output of the transformer  230 _ 1  is electrically connected to a load  203 _ 1 . The transformer  230 _ 1  may be a voltage transformer that reduces the system voltage to an operating voltage that is suitable for the load  203 _ 1 . The transformer apparatuses  240 _ 2 ,  240 _ 3 ,  240 _ 4  are configured in a similar manner. In the example shown, the transformer apparatus  204 _ 2  includes vacuum fault interrupters  210 A_ 2 ,  210 B_ 2  and a transformer  230 _ 2 , the transformer apparatus  204 _ 3  includes vacuum fault interrupters  210 A_ 3 ,  210 B_ 3  and a transformer  230 _ 3 , and the transformer apparatus  240 _ 4  includes vacuum fault interrupters  210 A_ 4 ,  210 B_ 4  and a transformer  230 _ 4 . The output of each transformer  230 _ 2 ,  230 _ 3 ,  230 _ 4  is electrically connected to a respective load  203 _ 2 ,  203 _ 3 ,  203 _ 4 . 
     The first segment  205 _ 1  of the transformer loop  204  electrically connects the electrical source  202 _A and the vacuum fault interrupter  210 A_ 1 . The second segment  205 _ 2  is electrically connected to the vacuum fault interrupter  210 B_ 1  and the vacuum fault interrupter  210 A_ 2 . The third segment  205 _ 3  is electrically connected to the vacuum fault interrupter  210 B_ 2  and to the vacuum fault interrupter  210 A_ 3 . The fourth segment  205 _ 4  is electrically connected to the vacuum fault interrupter  210 B_ 3  and the vacuum fault interrupter  210 A_ 4 . The fifth segment  205 _ 5  is electrically connected to the vacuum fault interrupter  210 B_ 4  and the electrical source  202 _B. 
     Aspects of the transformer apparatus  240 _ 1  are discussed below. The transformer apparatuses  240 _ 2 ,  240 _ 3 , and  240 _ 4  are configured in a similar manner. 
       FIG. 2B  is a block diagram that shows additional details of the transformer apparatus  240 _ 1 . The vacuum fault interrupter  210 A_ 1  and the vacuum fault interrupter  210 B_ 1  are electrically connected to a first coil  231 _ 1  of the transformer  230 _ 1 . The transformer  230 _ 1  also includes a second coil  232 _ 1  and a magnetic core  233 _ 1  that magnetically couples the first coil  231 _ 1  and the second coil  232 _ 1 . The second coil  232 _ 1  is electrically connected to the load  203 _ 1 . 
       FIG. 2C  is a side cross-sectional block diagram of the vacuum fault interrupter  210 A_ 1 . The vacuum fault interrupter  210 A_ 1  includes a housing  215 A_ 1  that encloses a stationary contact  213 A_ 1  and a movable contact  214 A_ 1  in an evacuated space. The stationary contact  213 A_ 1  is at an end of a stationary rod  211 A_ 1 . The movable contact  214 A_ 1  is at an end of a movable rod  212 A_ 1 . The stationary rod  211 A_ 1  extends through the housing  215 A_ 1  and is accessible from an exterior of the housing  215 A_ 1 . The movable rod  212 A_ 1  also extends through the housing  215 A_ 1  and is accessible from the exterior of the housing  215 A_ 1 . In the example shown, the movable rod  212 A_ 1  and the stationary rod  211 A_ 1  extend through opposite sides of the housing  215 A_ 1 . However, other implementations and configurations of the vacuum fault interrupter  210 A_ 1  are possible. Moreover, the vacuum fault interrupter  210 A_ 1  may include other components that are known in the art. For example, the bellows may surround the movable operating rod  212 A_ 1 , and the vacuum fault interrupter  210 A_ 1  may include end caps. 
     The stationary contact  213 A_ 1 , the stationary rod  211 A_ 1 , the movable contact  214 A_ 1 , and the movable rod  212 A_ 1  are made of an electrically conductive material such as, for example, brass, copper, silver, or another metallic material. When the stationary contact  213 A_ 1  is in contact with the movable contact  214 A_ 1 , the vacuum fault interrupter  210 A_ 1  is in the closed state and electrical current flows through the vacuum interrupter  210 A_ 1  and to the transformer  230 A_ 1 . When the stationary contact  213 A_ 1  is separated from the movable contact  214 A_ 1  (such as shown in  FIG. 2C ), the vacuum fault interrupter  210 A_ 1  is in the open state and current does not flow through the vacuum fault interrupter  210 A_ 1 . 
     The state of the vacuum fault interrupter  210 A_ 1  is controlled by actuating a motion control mechanism  216 A  1 . The motion control mechanism  216 A  1  includes one or more components that are configured to drive the movable operating rod  212 A_ 1 . For example, the motion control mechanism  216 A_ 1  may include a motor, gear assembly, shaft, rod, or a combination of such devices. The motion control mechanism  216 A  1  also includes a communications interface  218 A_ 1 , for example, a transceiver, that communicates with a control system that is separate from the vacuum fault interrupter  210 A_ 1 . For example, to change the state of the vacuum fault interrupter  210 A_ 1 , an electronic processor of a control system (such as a control system  250 _ 1 ) issues a command to the communications interface  218 A_ 1  such that one or more components of the motion control mechanism  216 A_ 1  drives the movable operating rod  212 A_ 1  in the Z direction or −Z direction along a linear path  217 A_ 1 . The vacuum fault interrupters  210 B_ 1 ,  210 A_ 2 ,  210 B_ 2 ,  210 A_ 3 ,  210 B_ 3 ,  210 A_ 4 , and  210 B_ 4  may be configured in the same way or similar to the vacuum fault interrupter  210 A_ 1 . 
     Returning to  FIG. 2B , the transformer apparatus  240 _ 1  also includes sensors  270 A_ 1  and  270 B_ 1 . Each of the sensors  270 A_ 1  and  270 B_ 1  is any type of device configured to measure current through a conductor and to provide an indication of the measured current. The indication of the measured current may be a numerical value that directly represents the measured current or a measured value (for example, a voltage value) from which the current may be derived. Examples of sensors that may be used as the sensor  270 A_ 1  and/or  270 B_ 1  include, without limitation, cored current sensors, coreless current sensors, and a shunt resistor with an isolation analog-to-digital converter (such as a power operational amplifier). Examples of cored current sensors include, without limitation, iron core current transformers (CTs) or air core CTs (that is, a Rogowski coil). A Hall sensor is an example of a coreless current sensor, and other coreless current sensors may be used as the sensor  270 A_ 1  or the sensor  270 B_ 1 . Additionally, low-energy analog (LEA) current sensors may be used. 
     Furthermore, the sensors  270 A_ 1  and/or  270 B_ 1  may be voltage sensors. The voltage sensor is any device configured to measure voltage across a circuit or at a particular point or node relative to ground or another reference potential. For example, when implemented as a voltage sensor, the sensor  270 A_ 1  and/or  270 B_ 1  may be a direct/instrument transformer. An example of a direct/instrument transformer is a potential transformer that converts high or medium voltage (for example, 15 kVac) to lower voltage (for example, 120Vac). In another example of a voltage sensor, the sensors  270 A_ 1  and  270 B_ 1  may be implemented as an indirect instrument transformer. The indirect instrument transformer provides an indication of measured voltage across a resistive or capacitive element, as amplified by an electronic amplifier. The current is determined by accounting for the size of the resistive or capacitive element and the amount of amplification. 
     The sensor  270 A_ 1  is positioned to sense the current or voltage in the stationary rod  211 A_ 1  of the vacuum fault interrupter  210 A_ 1 . The sensor  270 B_ 1  senses the current or voltage in the stationary rod of the switching apparatus  210 B_ 1 . Together, the sensors  270 A_ 1  and  270 B_ 1 , the vacuum fault interrupters  210 A_ 1  and  210 B_ 1 , and the transformer  230 _ 1  form a circuit  272 _ 1  that operates at the system voltage of the transformer loop  204 . The circuit  272 _ 1  is a high-voltage or medium-voltage circuit, depending on the system voltage of the transformer loop  204 . 
     The transformer apparatus  240 _ 1  includes a housing  241 _ 1 . The housing  241 _ 1  is a three-dimensional body that encloses a tank  242 _ 1 . The tank  242 _ 1  is also a three-dimensional and substantially hollow body that defines an interior space. The components of the circuit  272 _ 1  are within the interior space of the tank  242 _ 1 . In addition to containing the various components of the circuit  272 _ 1 , the interior space of the tank  242 _ 1  also may be filled with an insulating material or an insulating fluid, such as, for example, oil. 
     The transformer apparatus  240 _ 1  also includes the control system  250 _ 1 . The control system  250 _ 1  controls the state of the vacuum fault interrupters  210 A_ 1  and  210 B_ 1  via the respective motion control mechanisms  216 A_ 1  and  216 B_ 1 . The control system  250 _ 1  is also coupled to the sensors  270 A_ 1  and  270 B_ 2 . The control system  250 _ 1  may control the state of the switching apparatuses  210 A_ 1  and  210 B_ 1  based on the amount of current flowing in the stationary rod of the vacuum fault interrupters  210 A_ 1  and  210 B_ 1 . The control system  250 _ 1  is accessible from an exterior of the tank  242 _ 1 . Furthermore, all or a portion of the control system  250 _ 1  may be accessible from the exterior of the housing  241 _ 1 . 
       FIG. 2D  is a block diagram that shows the control system  250 _ 1  in more detail. The control system  250 _ 1  includes an electronic processing module  251 _ 1 , an electronic storage  252 _ 1 , and an input/output (I/O) interface  253 _ 1 . In some implementations, the electronic processing module  251 _ 1 , the electronic storage  252 _ 1 , and the I/O interface  253 _ 1  are implemented as a microcontroller. The electronic processing module  251 _ 1  includes one or more electronic processors. The electronic processors of the module  251 _ 1  may be any type of electronic processor, may be multiple types of processors, and may or may not include a general purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a field-programmable gate array (FPGA), Complex Programmable Logic Device (CPLD), a digital signal processor (DSP), a microcontroller unit (MCU) and/or an application-specific integrated circuit (ASIC). 
     The electronic storage  252 _ 1  is any type of electronic memory, machine-readable memory, or computer-readable memory that is capable of storing data and instructions, which may be in the form of computer programs or software, and the electronic storage  252 _ 1  may include multiple types of memory. For example, the electronic storage  252 _ 1  may include volatile and/or non-volatile components. The electronic storage  252 _ 1  and the processing module  251 _ 1  are coupled such that the processing module  251 _ 1  is able to read data from and write data to the electronic storage  252 _ 1 . 
     The electronic storage  252 _ 1  stores data and information related to the operation of the vacuum fault interrupters  210 A_ 1  and  210 B_ 1  in a switch control module  254 _ 1 . The switch control module  254 _ 1  may, for example, store one or more fault current limits, a transformer loop over-current limit, and/or a transformer loop over-voltage limit. The switch control module  254 _ 1  also stores executable instructions in the form of a computer program, procedures, or functions that cause the processing module  251 _ 1  to perform actions related to the operation of the vacuum fault interrupter  210 A_ 1  and/or the vacuum fault interrupter  210 B_ 1 . For example, the switch control module  254 _ 1  may store instructions that compare an indication from the sensor  270 A_ 1  or the sensor  270 B_ 1  to a pre-defined fault current limit that is stored on the electronic storage  252 _ 1 . 
     The switch control module  254 _ 1  also stores instructions for controlling the state of the vacuum fault interrupters  210 A_ 1  and  210 B_ 1 . For example, the switch control module  254 _ 1  may store instructions that cause the electronic processing module  251 _ 1  to issue a command to a motion control device  216 A_ 1  such that the vacuum fault interrupter  210 A_ 1  opens when the current sensed by the sensor  270 A_ 1  exceeds the pre-defined fault current limit. Similarly, the switch control module  254 _ 1  also stores instructions that cause the electronic processing module  251 _ 1  to issue a command to the motion control device  216 B  1  that causes the vacuum fault interrupter  210 B_ 1  to open when the current sensed by the sensor  270 B_ 1  exceeds the pre-defined fault current limit. Additionally, the switch control module  254 _ 1  stores instructions that cause the control system  250 _ 1  to command the motion control mechanism  216 A_ 1  or  216 B_ 1  to open or close the respective vacuum fault interrupter  210 A_ 1  or  210 B_ 1  in response to receiving a trigger or other signal from any of the control systems  250 _ 2 ,  250 _ 3 , and  250 _ 4  and/or from a remote device  257 . The trigger or other signal may be, for example, an electrical signal that has a voltage that is sufficient to activate the mechanism  216 A_ 1  or  216 B_ 1 . 
     The electronic storage  252 _ 1  also stores information about the configuration of the system  200 . For example, during typical and ordinary operation of the system  200 , one of the vacuum fault interrupters  210 A_ 1 ,  210 B_ 1 ,  210 A_ 2 ,  210 B_ 2 ,  210 A_ 3 ,  210 B_ 3 ,  210 A_ 4 ,  210 B_ 4  is configured to be in the open state (or normally open). All of the other vacuum fault interrupters are in the closed state. The electronic storage  252 _ 1  may store information that indicates which vacuum fault interrupter is in the normally open configuration. In some implementations, information about the configuration of the various vacuum fault interrupters and the various transformer apparatuses is provided to the control system  250 _ 1  during operation via the I/O interface  253 . 
     The control system  250 _ 1  also includes the I/O interface  253 _ 1 , which is any interface that allows a human operator, an external device, and/or an autonomous process to interact with the control system  250 _ 1 . The I/O interface  253 _ 1  allows the control system  250 _ 1  to communicate with components in the transformer apparatus  240 _ 1  and the circuit  272 _ 1 . The VO interface  253 _ 1  also allows the control system  250 _ 1  to communicate with other components in the transformer apparatus  240  such as the sensors  270 A_ 1  and  270 B_ 1 , and the motion control mechanisms  216 A  1  and  216 B  1 . 
     The I/O interface  253 _ 1  may include, for example, audio input and/or output (such as speakers and/or a microphone), visual output (such as lights, light emitting diodes (LED)), serial or parallel port, a Universal Serial Bus (USB) connection, and/or any type of network interface, such as, for example, Ethernet. The I/O interface  253 _ 1  also may allow communication without physical contact through, for example, an IEEE 802.11, Bluetooth, cellular, optical, or a near-field communication (NFC) connection. The I/O interface  253 _ 1  also may include a transceiver of any kind. For example, the I/O interface  253 _ 1  may include an optical transceiver, an electronic transceiver, or a combination of such devices. The control system  250 _ 1  may be operated, configured, modified, and/or updated through the I/O interface  253 _ 1 . 
     The I/O interface  253 _ 1  also enables the control system  250 _ 1  to communicate with the remote device  257  via a communication path  298 _ 1 . The remote device  257  includes an electronic controller  290 , which may include an electronic processor and an electronic storage. The remote device  257  is any type of apparatus, system, or device that is separate from the transformer apparatus  240 _ 1 . For example, the remote device  257  may be a control system similar to the control system  250 _ 1  that is in another transformer apparatus. The remote device  257  may be a computer-based work station, a smart phone, tablet, or a laptop computer in a remote monitoring station that connects to the control system  250 _ 1  via a services protocol, or a remote control that connects to the control system  250 _ 1  via a radio-frequency signal or an infrared signal. The I/O interface  253 _ 1  and the remote device  257  may communicate via any type of communication path. For example, the communication path  298 _ 1  may be a physical cable that connects the I/O interface  253 _ 1  and to the remote device  257 , or the communication path  298 _ 1  may be a wireless connection that does not utilize a physical cable. In implementations in which the path  298 _ 1  is a physical cable, the cable is any cable suitable for the type of connection on the I/O interface  253 _ 1  and the remote device  257 . For example, the cable may be an electrical cable, an Ethernet or other type of network cable, or a fiber optic cable. 
     The control system  250 _ 1  also includes a power source  258 _ 1 . The power source  258 _ 1  provides power to the control system  250 _ 1 . The power source  258 _ 1  may be, for example, a battery, a solar cell, or any other type of power source. In some implementations, the control system  250 _ 1  is configured to receive electrical power from a power grid or electrical source that is external to the control system  250 _ 1 . In these implementations, the power source  258 _ 1  is a back-up power source that is only used when the external power source is unavailable or operating in a reduced manner. 
     Returning to  FIG. 2A , the transformer apparatuses  240 _ 2 ,  240 _ 3 , and  240 _ 4  are configured in a similar manner as the transformer apparatus  240 _ 1 . For example, the transformer apparatuses  240 _ 2 ,  240 _ 3 ,  240 _ 4  include respective control systems  250 _ 2 ,  250 _ 3 ,  250 _ 4 . The control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 ,  250 _ 4  are coupled to the remote station  257  via respective communication paths  298 _ 1 ,  298 _ 2 ,  298 _ 3 ,  298 _ 4 . The communication paths  298 _ 1 ,  298 _ 2 ,  298 _ 3 ,  298 _ 4  are any type of path capable of carrying data and information. For example, the communication paths  298 _ 1 ,  298 _ 2 ,  298 _ 3 ,  298 _ 4  may be any type of wired or wireless connection. Any of the control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 ,  250 _ 4  is able to communicate with any of the other control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 ,  250 _ 4  via a data bus  299 . The data bus  299  is any type of wired or wireless connection that is capable of carrying data or information. 
     The configurations shown in  FIGS. 2A, 2B, 2C, and 2D  are provided as examples, and other implementations are possible. For example, the system  200  may include more than four or fewer than four transformer apparatuses. 
       FIG. 3  is a flowchart of a process  300 . The process  300  is an example of a process for transferring between two sources in a transformer loop or changing the source configuration of the transformer loop. The process  300  is discussed with respect to the system  200  and the transformer loop  204  ( FIG. 2A ). In the example discussed below, all or part of the process  300  is performed by an electronic processor in the control system  290  of the remote device  257 . However, other implementations are possible. For example, all or part of the process  300  may be performed by any one of the control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 , or  250 _ 4 . 
     During typical and ordinary operation of the system  200 , the transformer loop  204  has one open point. The open point is a vacuum fault interrupter that remains open (or is normally open). The other vacuum fault interrupters are in the closed state. The transformer loop  204  has more than one possible source configuration, and each source configuration is defined by which one of the vacuum fault interrupters  210 A_ 1 ,  210 B_ 1 ,  210 A_ 2 ,  210 B_ 2 ,  210 A_ 3 ,  210 B_ 3 ,  210 A_ 4 ,  210 B_ 4  is configured to be normally open. The location of the open point determines how the transformers  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4  are connected to the sources  202 _A and  202 _B. For example, if the vacuum fault interrupter  210 A_ 1  is configured to be normally opened, all of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4  are electrically connected to the source  202 _B. If the vacuum fault interrupter  210 B_ 2  is configured to be normally opened, the transformer apparatuses  240 _ 1  and  240 _ 2  are electrically connected to the source  202 _A and the transformer apparatuses  240 _ 3  and  240 _ 4  are electrically connected to the source  202 _B. 
     Information that defines the various source configurations of the transformer loop  204  may be stored on the control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 ,  250 _ 4  and/or at the control system  290  on the remote device  257 . For example, the lookup table or database may indicate which source each of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 ,  240 _ 4  is connected to when a specific one of the vacuum fault interrupters  210 A_ 1 ,  210 B_ 1 ,  210 A_ 2 ,  210 B_ 2 ,  210 A_ 3 ,  210 B_ 3 ,  210 A_ 4 ,  210 B_ 4  is the normally open point. In some implementations, information about the source configurations is provided by an operator of the system  200 . 
     A command is received to change to a different source configuration of the transformer loop  204  ( 310 ). The command may be received at the remote device  257  or via any of the I/O interfaces  253 _ 1 ,  253 _ 2 ,  253 _ 3 ,  253 _ 4 . An updated open point of the transformer loop  204  is identified ( 320 ). The updated open point is the open point that will provide the source configuration specified by the command. For example, data that identifies which one of the vacuum fault interrupters  210 A_ 1 ,  210 B_ 1 ,  210 A_ 2 ,  210 B_ 2 ,  210 A_ 3 ,  210 B_ 3 ,  210 A_ 4 ,  210 B_ 4  is to become the open point may be included in the command signal. In some implementations, the command signal specifies which transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 ,  240 _ 4  should be electrically connected to the source  202 _A and which should be electrically connected to the source  202 _B. In these implementations, the updated open point is determined based on information related to the various possible source configurations that is stored on the remote device  257 . 
     The transformer apparatus that includes the updated open point is identified ( 330 ). For example, the remote station  257  may store a look-up table or database that includes data that specifies which vacuum fault interrupters are included in each of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 ,  240 _ 4 . In these implementations, the transformer apparatus that includes the updated open point is identified from the database or look-up table. In other implementations, the command includes information that indicates which of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 ,  240 _ 4  include the updated open point. 
     The control system of the identified transformer apparatus is controlled such that the vacuum fault interrupter associated with the updated open point is transitioned from the closed state to the open state ( 340 ). After the transition from the closed state to the open state is complete, the vacuum fault interrupter associated with the updated open point and the vacuum fault interrupter associated with the open point for the previous source configuration are both in the open state. The transformers between these two open vacuum fault interrupters are disconnected from the transformer loop  204  and temporarily do not receive electrical power from the source  202 _A or the source  202 _B. 
     The vacuum fault interrupter associated with the previous open point is closed and the source configuration change is complete ( 350 ). To close the previous open point, the control system  290  first identifies the previous open point. The previous open point is the open point of the source configuration that existed when the command in ( 310 ) is received. The identity of the previous open point may be stored in an electronic storage and/or provided with the command. For example, in some implementations, the operator or automated process that initiates the command to change the source configuration in ( 310 ) also provides the location of the open point in the existing source configuration. In these implementations, the vacuum fault interrupter that is the previous open point is identified from the command itself. In other implementations, the location of the open point at the time of receiving the command in ( 310 ) is stored at the remote device  257  or on one or more of the control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 ,  250 _ 4 . In these implementations, the vacuum fault interrupter associated with the previous open point is identified by being retrieved from the electronic storage. After identifying the previous open point, the transformer apparatus that includes the previous open point is identified, and a command is issued to the control system in that transformer apparatus. The command causes the control system to issue a command to close the previous open point. 
     Two examples of the process  300  are provided below. In a first example, the initial source configuration has the vacuum fault interrupter  210 B_ 3  as normally open, the transformers  240 _ 1 ,  240 _ 2 ,  240 _ 3  are electrically connected to the source  202 _A, and the transformer  240 _ 4  is electrically connected to the source  202 _B. The command is provided to the remote device  257 . The command specifies that the source configuration is to change such that the transformer  240 _ 1  is electrically connected to the source  202 _A and the transformers  240 _ 2 ,  240 _ 3 ,  240 _ 4  are electrically connected to the source  202 _B. The remote device  257  determines that the updated open point to achieve the requested source configuration is the vacuum fault interrupter  210 A_ 2 . Next, the remote device  257  identifies the transformer  240 _ 2  as including the vacuum fault interrupter  210 A_ 2 . The remote device  257  triggers the control system  250 _ 2  to open the vacuum fault interrupter  210 A_ 2 . For example, the remote device  257  may send an electrical signal that is sufficient to cause the control system  250 _ 2  to operate in a specified manner. Because the vacuum fault interrupter  210 B_ 3  is already opened, opening the vacuum fault interrupter  210 A_ 2  disconnects the transformers between these two points. In this example, the transformer  230 _ 2  and the transformer  230 _ 3  are disconnected from the transformer loop  204 . Although the transformers  230 _ 2  and  230 _ 3  are temporarily disconnected from the transformer loop  204 , the total disconnection time is relatively short, for example, about 2.5 s. 
     The remote device  257  or the control system  250 _ 2  then triggers the control system  250 _ 3  to close the previous open point, which in this example is the vacuum fault interrupter  210 B_ 3 . After the vacuum fault interrupter  210 B_ 3  is closed, the transformers  230 _ 2  and  230 _ 3  are again electrically connected to the transformer loop  204  and the source configuration has been changed as requested by the command. Specifically, in this example, after the source configuration is changed as requested, the transformer apparatus  240 _ 1  is electrically connected to the source  202 _A and the transformer apparatuses  240 _ 2 ,  240 _ 3 , and  240 _ 4  are electrically connected to the source  202 _B. The entire process of changing from one source configuration to another source configuration when the control systems in two different transformer apparatuses are commanded may take about, for example, 5 s. 
     In a second example, the current source configuration has the vacuum fault interrupter  210 A_ 3  as the open point (that is, the vacuum fault interrupter  210 A_ 3  is configured as normally open), the transformer apparatuses  240 _ 1  and  240 _ 2  are electrically connected to the source  202 _A, and the transformer apparatuses  240 _ 3  and  240 _ 4  are electrically connected to the source  202 _B. The command specifies that the source configuration is to change such that the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3  are electrically connected to the source  202 _A, and the transformer apparatus  240 _ 4  is electrically connected to the source  202 _B. The remote device  257  determines that the updated open point is the vacuum fault interrupter  210 B_ 3 . The remote device  257  determines that the transformer apparatus  240 _ 3  includes the vacuum fault interrupters  210 A_ 3  and  210 B_ 3 . The remote device  257  triggers the control system  250 _ 3  to first open the vacuum fault interrupter  210 A_ 3  and to then close the vacuum fault interrupter  210 B_ 3  after the vacuum fault interrupter  210 A_ 3  is in the open state. The source configuration change is complete after the vacuum fault interrupter  210 B_ 3  is closed. After the vacuum fault interrupter  210 A_ 3  is opened and before the vacuum fault interrupter  210 B_ 3  is closed, the transformer  230 _ 3  is disconnected from the transformer loop  204 . The disconnection time may be, for example, about 2.5 s and the total time to transfer sources may be, for example, about 5 s. 
       FIG. 4  is a flow chart of a process  400 . The process  400  is an example of a process for isolating a faulted segment of a transformer loop. The process  400  is discussed with respect to the system  200  and the transformer loop  204 . The process  400  may be stored as a collection of executable instructions on the control system  250 _ 1 ,  250 _ 2 ,  250 _ 3 , and/or  250 _ 4 , and/or the control system  290 . 
     A fault is detected in a segment of the transformer loop  204  ( 410 ). The fault may be caused, for example, by a lightning strike, a malfunction in the transformer loop  204 , or an incursion of debris or water into the transformer loop  204  that causes a short circuit. The fault causes a large amount of current to flow in the faulted segment, and the fault may be detected by a sensor that is adjacent to the faulted segment. For example, if the segment  205 _ 2  has a fault, a large amount of current flows in the segment  205 _ 2 . The sensor  270 B_ 1  senses the current and provides an indication of the amount of sensed current to the control system  250 _ 1 , which compares the indication of the sensed current to a stored threshold current value. If the indication shows that the amount of sensed current is above the threshold current value, a fault is declared in the segment  205 _ 2 . 
     A first switching apparatus adjacent to the faulted segment is opened ( 420 ). Continuing with the example above, the control system  250 _ 1  has declared that fault current is flowing in the segment  205 _ 2 . The fault current was sensed by the sensor  270 B_ 2 , which is associated with the vacuum fault interrupter  210 B_ 1 . Thus, the control system  250 _ 1  commands the motion control mechanism  216 B_ 1  to open the vacuum fault interrupter  210 B_ 1 . The vacuum fault interrupter  210 B_ 1  may be opened within for example, about 16 milliseconds (ms) plus the time for two cycles of the fundamental frequency of the distribution system  201 . For a system operating at a 60 Hz fundamental frequency, it may take about 50 ms after the occurrence of the fault for the vacuum fault interrupter  210 B_ 1  to be opened. 
     Next, the faulted segment is isolated. As shown in  FIG. 2A , the various segments  205 _ 1 ,  205 _ 2 ,  205 _ 3 ,  205 _ 4 ,  205 _ 5  are between one transformer apparatus and a separate device. Thus, isolating a faulted segment includes triggering a control system in the separate device. 
     A command is issued to a control system in a separate transformer apparatus ( 430 ), and the control system in the separate transformer apparatus opens a second switching apparatus adjacent to the faulted segment ( 440 ). Continuing with the example above, after opening the vacuum fault interrupter  210 B_ 1 , the control system  250 _ 1  communicates with the control system  250 _ 2 . The control system  250 _ 1  provides a signal, information, or command that triggers the control system  250 _ 2  to open the vacuum fault interrupter  210 A_ 2 . The faulted segment  205 _ 2  is now isolated. The faulted segment  205 _ 2  may be isolated within, for example, about 66 ms plus two cycles of the fundamental frequency. For a system with a fundamental frequency of 60 Hz, the faulted segment  205 _ 2  may be isolated in about 98 ms. 
     During typical and ordinary operation of the transformer loop  204 , one of the vacuum fault interrupters is configured as a normally open interrupter. After the faulted segment is isolated, more than one of the vacuum fault interrupters are open and the transformer apparatus or apparatuses between the normally open vacuum fault interrupter and the isolated segment are disconnected from the transformer loop  204 . In situations where only one segment in the transformer loop  204  has a fault (such as the example above), closing the normally open vacuum fault interrupter allows electrical power to be restored to all of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4  while the faulted segment remains isolated. Continuing the example above in which the vacuum fault interrupter  210 A_ 3  is normally open, after the faulted segment  205 _ 2  is isolated, the transformer apparatus  240 _ 1  continues to receive electrical power from the source  202 _A, and the transformer apparatuses  240 _ 3  and  240 _ 4  receive electrical power from the source  202 _B. However, the transformer apparatus  240 _ 2  does not receive electrical power from either the source  202 _A or the source  202 _B because the vacuum fault interrupters  210 A_ 2  and  210 A_ 3  are open. 
     The normally opened switching apparatus is closed ( 450 ). The control system  250 _ 2  determines which vacuum fault interrupter is the normally open vacuum fault interrupter. For example, the control system  250 _ 2  may determine this from information stored on the control system  250 _ 2 . Continuing the above example, the vacuum fault interrupter  210 A_ 3  is identified as the normally open vacuum fault interrupter. The control system  250 _ 2  commands the control system  250 _ 3  to close the vacuum fault interrupter  210 A_ 3 . After closing the vacuum fault interrupter  210 A_ 3 , the transformer  240 _ 2  is electrically connected to the source  202 _B. Each of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4  are connected to one of the sources  202 _A and  202 _B, and the system  200  is able to continue operation while the faulted segment  205 _ 2  is repaired or replaced. Electrical power may be restored to the transformer  240 _ 2  in about 3 seconds (s), about 2.5 s, or between 2.5 s and 3 s after the initial fault occurred. Accordingly, within a relatively short amount of time after the fault event, the faulted segment  205 _ 2  is isolated and power is restored to all of the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4 . 
     In the above example, the control system  250 _ 1  commands the control system  250 _ 2  to open the vacuum fault interrupter  210 A_ 2 , and the control system  250 _ 2  commands the control system  250 _ 3  to close the vacuum fault interrupter  210 A_ 3 . However, other implementations are possible. For example, the control system  250 _ 1  may command the control system  250 _ 2  to open the vacuum fault interrupter  210 A_ 2 , and also may command the control system  250 _ 3  to close the vacuum fault interrupter  210 A_ 3 . In other words, any of the control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 ,  250 _ 4  may command any of the other command systems, and the process  400  may be performed by one of the control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 , and  250 _ 4  or by more than one of the control systems  250 _ 1 ,  250 _ 2 ,  250 _ 3 ,  250 _ 4 . Moreover, the process  400  may be performed by the control system  290  of the remote device  257 . In these implementations, the control system  290  triggers the control systems in the respective transformer apparatuses to control the state of the various vacuum fault interrupters. 
     Furthermore, the transformer apparatuses  240 _ 1 ,  240 _ 2 ,  240 _ 3 , and  240 _ 4  are shown and discussed as including vacuum fault interrupters as the switching apparatuses. However, the system  200  may be implemented with other types of switching apparatuses, and the processes  300  and  400  may be performed on systems that include other types of switching apparatuses. For example, in other implementations, the switching apparatuses  210 A_ 1 ,  210 A_ 2 ,  210 B_ 1 ,  210 B_ 2 ,  210 C_ 1 ,  210 C_ 2 ,  210 D_ 1 , and  210 D_ 2  may be implemented as any type of trippable and/or openable device that utilizes a mechanical and/or electronic mechanism to separate current-carrying electrical contacts for the purpose of interrupting the flow of electricity, including, for example, circuit breakers, circuit switchers, loadbreak switches, vacuum breakers, vacuum switches, gas-insulated breakers, contactors, reclosers, or any electronically trippable switching and/or interrupting device. Examples of gas-insulated breakers include but are not limited to sulfur hexafluoride (SF 6 ) insulated breakers and air-insulated breakers. Moreover, the switching apparatuses  210 A_ 1 ,  210 A_ 2 ,  210 B_ 1 ,  210 B_ 2 ,  210 C_ 1 ,  210 C_ 2 ,  210 D_ 1 , and  210 D_ 2  may be gang-operated multi-phase devices. 
     These and other implementations are within the scope of the claims.