Standby battery-meter socket adapter

An electrical system operable to supply power from at least one of a primary power source or a standby power source to one or more electrical loads. The electrical system is configured to be provided between an electricity meter and a meter socket. The electrical system includes a housing, a plurality of contacts configured to be coupled with the meter, the meter socket, and a transfer switch. The transfer switch includes a first switch configured to selectively connect the primary power source to the one or more electrical loads, a second switch configured to selectively connect the standby power source to the one or more electrical loads, and an electrical control logic.

BACKGROUND

The present disclosure generally relates to the field of building electrical systems and more specifically to building electrical systems including utility power sources and a standby power source. Secondary power systems are generally configured to provide backup power to electrical loads in the event of a utility power failure. The transfer between the utility power source and the standby power source is facilitated by an automatic transfer switch.

Presently, the transfer of the power supply from the utility source to the standby power source is carried out by a transfer switch that is positioned in a location between an existing utility meter housing and a distribution panel. The existing utility meter housing includes a meter socket that receives an electricity meter for measuring the amount of electricity consumed by the home or business. In typical installations, the transfer switch is mounted at or near either the utility meter housing or at or near the distribution panel. The installation of the transfer switch is a complicated process, often including isolation of the ground wires from the neutral wires within the distribution panel (breaker box), and relocation of the neutral-ground bonding point. Electrical codes require that all neutrals in a house or building electrical system be bonded to ground at the closest point to the service entrance disconnect. Accordingly, when installing a transfer switch into an existing house between the utility meter housing and the distribution panel, an electrician will have to isolate the ground wires and neutral wires in the electrical distribution panel to their individual terminal strips and connect them to the corresponding ground and neutral terminals within the transfer switch panel. Once complete, the electrician will then be required to relocate the neutral-ground bonding point from its previous location (within the distribution panel) to the transfer switch panel as this is now the closest panel to the service entrance disconnect. This can be a time consuming process. The time required to install a transfer switch between the utility meter housing and the distribution panel can be between 2 and 4 hours and requires trained electricians, which can be costly for the home or business owner.

In the building electrical system described above that includes a standby power source, the standby power source is often a standby generator that includes an internal combustion engine powered by a fuel source, such as natural gas or propane. The fuel source is provided from a fuel storage location or tank or from a utility source. Such standby power sources that utilize a standby generator require connections to the fuel source, which increases the time and cost for installation.

The system of the present disclosure solves the above-identified problems present at installation while providing a standby power source for powering electrical systems within a home or building. The system of the present disclosure addresses the desire to provide a standby power source while eliminating the cost and complexity of installation.

SUMMARY

One embodiment of the present disclosure includes an electrical system operable to supply power from at least one of a primary power source or a standby power source to one or more electrical loads. The electrical system is configured to be provided between an electricity meter and a meter socket. The electrical system includes a housing, a plurality of contacts configured to be coupled with the meter, the meter socket, and a transfer switch. The transfer switch includes a first switch configured to selectively connect the primary power source to the one or more electrical loads, a second switch configured to selectively connect the standby power source to the one or more electrical loads, and an electrical control logic.

Another exemplary embodiment of the present disclosure includes an electrical system operable to supply power from at least one of a first power source, a second power source, or a third power source to one or more electrical loads. The electrical system is configured to be provided between an electricity meter and a meter socket. The electrical system includes a housing, a plurality of contacts configured to be coupled with the meter, the meter socket, and a transfer switch. The transfer switch includes a first switch configured to selectively connect the first power source to the one or more electrical loads, a second switch configured to selectively connect the second power source to the one or more electrical loads, a third switch configured to selectively connect the third power source to the one or more electrical loads, and an electrical control logic.

Still another exemplary embodiment of the present disclosure includes a meter socket adapter configured to allow switching between a utility power supply and a secondary power supply to provide power to an electrical load. The meter socket adapter is configured to be mounted between an electricity meter and a meter housing. The meter socket adapter includes a transfer switch for selectively coupling the utility power supply or the secondary power supply to the electrical load and a load management controller comprising a transfer switch logic circuit.

DETAILED DESCRIPTION

FIG.1illustrates a prior art electrical system5for a building (e.g., a home electrical system). Electrical system5includes an electric meter housing18that encloses a contact block that is electrically coupled to an off-site utility power source (not shown) and configured to provide power from the off-site utility source through an electricity meter20to a distribution panel11. Distribution panel11(e.g., a circuit breaker box, a fuse box, etc.) is configured to route electrical power to electrical loads (not specifically shown inFIG.1) in the building. Electrical system5also includes a standby generator13connected to a fuel source for providing electrical power to distribution panel11instead of (or potentially in addition to) the utility power provided through the meter housing18. For example, the standby generator13may be configured to provide power to distribution panel11through a transfer switch in the event of a utility power failure.

The electrical system5includes a meter socket adapter10that is positioned between the meter housing18and the distribution panel11. The meter socket adapter10is shown and described in U.S. Pat. No. 9,620,305 and is available from Briggs & Stratton Corporation under the Direct Power™ name. The adapter10includes an internal transfer switch controller and contacts to control the supply of power to the electric loads from either the utility or generator13. The meter socket adapter10is hard wired to the standby generator13through a cable12. The cable12can be a 25-foot, 50-foot or any other desired length cable that connects to the standby generator13or disconnect box in a known manner. The cable12enters into the outer housing14to provide power to a set of internal contacts that allows the transfer switch components of the meter socket adapter10to switch to power from the generator13when the utility-side power is interrupted. The outer housing14is preferably made of metal, such as steel or aluminum. However, other materials, such as a durable composite, are contemplated as being a viable alternative.

As can be seen inFIG.2, the meter socket adapter10is plugged into a meter socket formed as part of the conventional meter housing18. The meter housing18is conventionally mounted on the exterior of a home or on the interior of a building. The meter housing18typically receives an existing electricity meter20through the interaction between contact blades on the back surface of the electricity meter20and receiving jaws formed within the meter socket. The meter socket adapter10of the present disclosure is positioned between the meter housing18and the electricity meter20.

In addition to the transfer switch controller, the meter socket adapter10may also include load management controls contained inside the outer housing14. The load management controls communicate to load relays that are located in series with electric loads at the home or business. Wired or wireless communications can be used to activate the load relays to provide load shedding capabilities.

The load management controller contained within the outer housing14functions to selectively shed loads from the power distribution system and subsequently reconnect the loads to the power distribution system depending upon the amount of power drawn by the loads and the power available from the standby power source. The details of the load management control board can vary depending upon the particular power distribution system. The details of one exemplary load management controller and its method of operation are set forth in U.S. Pat. No. 8,415,830, the disclosure of which is incorporated herein by reference. However, other types of load management systems and methods of operation are contemplated as being within the scope of the present disclosure. The load management controller is contained within the housing such that both the transfer switch and the load management components required to selectively shed/reconnect loads within the home serviced by the generator can be installed as a single device contained within the housing.

FIG.3illustrates the meter socket adapter10securely mounted to the utility meter housing18. Typically, the utility meter housing18will be mounted to a wall of a building or home. The utility meter housing18can be mounted to either an exterior wall of a building or, in some instances, can be mounted inside a building. As discussed previously, the utility meter housing18typically receives the electricity meter20. However, when the meter socket adapter10is utilized, the electricity meter20is received within the meter socket adapter10while the meter socket adapter10is received within the meter socket of the meter housing18. A support bracket28is attached to a back surface30of the outer housing14. Although not required, the support bracket28is typically attached to the same wall that supports the meter housing18. The support bracket28provides support for the bottom end32of the meter socket adapter10. The support bracket28includes a pair of extending horizontal mounting portions34that can be securely attached to a wall surface. A pair of adjustment bolts allow the depth of the support bracket28to be adjusted depending upon the thickness of the meter housing18.

FIG.4illustrates an exemplary embodiment in accordance with the present disclosure in which the standby generator13shown inFIG.1is replaced by an alternate standby power source40. The standby power source40replaces the generator13and is connected to the meter socket adapter10by the same cable12shown inFIG.1. In the embodiment illustrated, the standby power source40includes a battery bank42and control module44. The battery bank42and control module44replace the standby generator and provides a source of electric power to operate the electric loads contained within the home or building46. The battery bank42is illustrated as having a capacity of between 20 kWh and 200 kWh. However, the size and capacity of the battery bank42can vary outside of this range depending upon the power requirements for the home or business including the standby power source40. In the embodiment shown inFIG.4, a supplemental generator48could be connected to the control module44to provide additional standby power. The generator48could be either a standby generator, such as shown by reference numeral13inFIG.1, or portable generator that is plugged into the control module44as will be described in greater detail below.

FIG.5provides a system diagram of a standby power source40constructed in accordance with the present disclosure. In the embodiment shown inFIG.5, a supply of utility voltage50is received at the meter box18as is conventional. The utility power supply50may refer to electricity received from an electrical grid provided by a utility company. The meter box18, in turn, is connected to a home or small business to power electric loads within the home, as shown by reference numeral51. As described previously, the standby power source includes the meter socket adapter10that is directly connected to the meter box18through the inlet line53. The meter socket adapter10includes a transfer switch52that is movable between first and second positions as will be described below. As shown inFIG.5, a direct connection54allows power from the meter box18to travel through the meter20. The opposite power connection56from the meter20flows through the transfer switch52and back to the meter box18when the transfer switch52is in the position shown inFIG.5. The position of the transfer switch52inFIG.5is the position when utility power is present or when the system desires to have the utility power drive the loads51contained within the house. The power from the utility flows through the meter box18and to the loads51in the home.

If the transfer switch52is moved to a second position in which the switch is in contact with the secondary internal terminal58, the power connection from the utility is interrupted such that the supply of power from the utility no longer flows through the power meter20and to the loads51.

As shown inFIG.5, the control module44includes a system controller60, a power inverter circuit62, a battery charging circuit64and a power management controller66. Although each of these control circuits are shown within a common control module44, it should be understood that one or more of the individual controls60,62,64or66could be either removed from the control module44and located elsewhere in the system or eliminated. The operation of each of the separate controls will be described in greater detail below.

In the embodiment shown inFIG.5, a battery bank42is connected to the control module44. The battery bank42preferably includes a series of individual batteries linked together either in a series or parallel configuration, or both. In one embodiment of the present disclosure, the battery bank42is a 96 kWh battery pack which is able to power the electric loads51within a home for between 8-12 hours of full operation. The individual batteries within the battery bank42can be various types of batteries, such as but not limited to lithium ion battery packs. Further, it is contemplated that the number and size of the individual batteries that make up the battery bank42could be initially selected or later modified by the homeowner depending upon the back-up power needs for the home. As an illustrative example, if the homeowner decides that the current size of the battery bank42is not sufficient for the home or if the power demands of the home have changed since installation, the homeowner can add additional batteries to the battery bank42to increase both the output power and the standby supply time.

The control module44includes a power inverter circuit62that is able to convert the DC output voltage from the battery bank42to an AC output. The AC output from the power inverter circuit62is supplied to the terminal58in the meter socket adapter10through the output line68. When the transfer switch52is switched to the secondary position and is thus in contact with the terminal58, the inverter output voltage on line68is supplied to the meter box through the output line70. The secondary power supplied from the battery bank42is then directed to the house loads51such that the house loads51can be run from the stored power supply from the battery bank42. The system controller60is used to monitor the charge on the battery bank42and control operating parameters of the power inverter circuit62in a well-known, conventional manner.

When the utility power supply is interrupted or absent, stored electric power from the battery bank42is supplied to power the house loads51as discussed above. However, it should be understood that the supply of electric power from the battery bank42is limited. Thus, after the utility power supply returns, the transfer switch52is moved back to the position shown inFIG.5such that utility power is supplied to the house loads51.

At this time, the battery charging circuit64determines the stored charge on the battery bank42and functions to recharge the series of batteries contained within the battery bank42. The battery charging circuit64can typically utilize the utility power supply50to recharge the battery bank42. The system shown inFIG.5can also include other alternate charging sources. In the embodiment shown inFIG.5, a photovoltaic system72is connected to the control module44such that the battery charging circuit64can utilize the photovoltaic system72to recharge the battery bank42. As described previously, the system can also include a generator48that can either supplement the power supplied from the battery bank42or can be used to recharge the battery bank42as desired. The generator48can be a standby generator or a gas-powered backup generator depending upon the requirements of the homeowner. The generator48can be operated by the homeowner to either recharge the battery bank42when the utility power supply is no longer present or can be utilized to provide power directly to the house loads51in combination with the battery bank42. The use of a generator48allows for the secondary power source40shown in the present disclosure to provide power to the house loads51for an extended period of time should the utility power supply50be interrupted for a period longer than can be supplied by the battery bank42.

The control module44further includes a power management controller66. The power management controller66can be included either in the control module44or within the meter socket adapter10. In each case, the power management controller66can send signals to load management modules that are associated with high power consuming loads within the home. In this manner, the power management controller66can selectively shed high power consuming loads either when the battery bank42is becoming depleted or as desired to extend the time at which the battery bank42can power the house loads51. In this manner, the control module44is able to shed loads as desired to extend the period of time that the battery bank42can supply and power the house loads51.

As described above, the battery bank42can be used to supply power to house loads51during times in which the utility power supply50is not available, such as during storms, power outages or at other times when the utility power supply is interrupted. In addition, the battery bank42can be utilized at other times that are controlled either by the homeowner or by the utility. As an illustrative example, during times at which the demand for power faced by the utility is high, the utility can send control signals out to the control module44that cause the transfer switch52to switch to the secondary power supply from the battery bank42. In this manner, the utility can increase capacity by utilizing the stored power on the battery banks42of individual homeowners. Such control could be utilized to avoid brown outs.

In another contemplated embodiment, the battery bank42can be connected to the house loads51during times at which energy is at the peak cost. In this manner, the homeowner would be able to reduce power consumption from the utility at times when the cost of power from the utility is at a peak value. Switching would not only reduce the power consumption for the homeowner but would also be a benefit to the utility by reducing peak loads.

FIG.6provides a diagram of a system100in accordance with an exemplary embodiment with a standby power source40. The system100is similar to the system ofFIG.5with the exception of the different features shown in the diagram and described herein. System100includes a shutoff switch102, which allows emergency responders (e.g. firefighters, police, etc.) to cut utility power to the house. The shutoff switch102may be used, for example, to cut power to the house load51when a gas leak is detected in the house in order to prevent fires. The shutoff switch102is intended to remain closed during the normal operation of the system100.

Rather than a single transfer switch52, system100includes a first or utility switch104and a second or standby power switch106. The utility switch104may close or open to connect or disconnect the utility power supply50to or from the house load51. The standby power switch106may close or open to connect or disconnect the standby power source40to or from the house load51. System100may optionally include an additional standby generator110. Generator switch108may close or open to connect or disconnect the standby generator110to or from the house load51. The standby generator may be, for example, a gas-powered generator, and may be used when the utility power supply50is unavailable and the standby power source40has no power available (e.g., when battery bank42has no remaining charge).

The arrangement of the system100provides for several configurations depending on the particular power use situation. In a first configuration, the utility switch104and the standby power switch106are both closed. In one situation the utility power supply50provides power to the house load51and also to the battery bank42via control module44. The battery bank42may then be charged by the utility power supply50. This may be useful to charge the battery bank42when the standby power source40does not include a photovoltaic system72or a generator48, or if either are not available, for example, if no sunlight is available for the photovoltaic system72or if the generator48is out of fuel or fuel prices for the generator48are more expensive than from the utility power supply50. In another situation, the battery bank42may be selectively charged by the utility power supply50(e.g. by closing the standby power switch106) during off-peak hours, when electrical power from the grid is typically less expensive.

In a second situation, the first and second switches104,106are both closed so that the standby power source40and the utility power supply50may supply power to the house load51. For example, the standby power source40may provide half of the power needed by the house load51and the utility power supply50may supply the other half. This may be useful when power from the utility power supply50is more expensive than the power available from the standby power source40, but the standby power source40does not have sufficient capacity to power the whole house for an extended period of time. The standby power source40may provide its maximum amount of power and the utility power supply50may supply the remainder needed by the house load51. Power supplied from the standby power source40may come from the battery bank42or may come directly from the photovoltaic system72. For example, if the battery bank42is fully charged, power from the photovoltaic system may be delivered directly to the house load51rather than to the battery bank42.

In a third situation, the first and second switches104,106are also both closed. Power may be provided to the house load51from either the standby power source40or the utility power supply50. The standby power source40may also provide power back to the grid. This may be useful when power from the utility power supply is expensive and the house load51is low. Power from the battery bank42or from the photovoltaic system72may be sold back to the electric company for payment or to receive a credit on the homeowner's electric bill. For example, the photovoltaic system72may produce more power than the house load51requires. The house load51may be powered entirely by the photovoltaic system72and the excess power can be fed back to the grid. In another example, the house load51may be powered entirely by the battery bank42and the battery bank42may feed additional power back to the grid. The battery bank42may have been charged at off-peak hours when electrical power from the grid was less expensive, and may feed power back to the grid at peak hours when electricity is more expensive. Thus the homeowner can essentially purchase less expensive electricity from the grid to charge the battery bank42and then sell the electricity back to the grid when electricity is more expensive.

In another configuration, the standby power switch106is closed while the utility switch104is open. In the situation where the utility power supply50is unavailable (e.g. during a power outage), the house load may be powered only by the standby power source40. The utility switch104may be opened to prevent the standby power source40from feeding power back to the grid. This allows all of the power from standby power source40to be fed only to the house load51so that all of the power stored by the battery bank42or generated by the generator48or the photovoltaic system72can be used by the homeowner.

In another configuration, the standby power switch106is open while the utility switch104is closed. The house load51may be powered only by the utility power supply50. The standby power source40may be disconnected from both the house load51and the utility power supply50. For example, in a situation where the battery bank42is fully or near fully discharged, the standby power switch106may open to disconnect the standby power source40. The battery bank42may then be charged by the photovoltaic system72or the generator48. This may be useful when power from the utility power supply is expensive, but power from the photovoltaic system72is available.

In some embodiments, the transfer switch controller or another controller within meter socket adapter10may be configured to receive inputs and automatically control the positions of the switches102,104,108,106based on the inputs. The inputs may include, for example, the price of fuel, the price of utility power from the utility power supply50, the availability of utility power, the level of charge of the battery bank42, the remaining fuel in the generator48or the standby generator110, user preferences for using stored battery charge when available or conserving charge for utility power outages, user preferences for using green energy from the photovoltaic system72. For example, if the controller determines that the cost of utility power falls below a predetermined threshold, the controller can close switches104and106such that the battery bank42may be charged by the utility power supply50. If the controller determines that the cost of utility power exceeds a second predetermined threshold, the controller can open switch104and can power the house load51via the standby power source40.

The utility switch104and the generator switch108cooperatively form transfer switch103. Transfer switch103may be configured such that the utility switch104and the generator switch108cannot be closed at the same time. This would prevent the house load51from being connected to both the utility power supply50and the standby generator110at the same time. The logic sequence controlling the switching of the house load51from receiving power from the utility power supply50to receiving power from the standby generator110is shown inFIGS.8-16. During an emergency, the shutoff switch102may be opened to disconnect the house load from the utility power supply50. Opening the shutoff switch102may also cause the standby power switch106and the generator switch108to open. With shutoff switch102, standby power switch106, and generator switch108open, no power can reach the house load51. In some embodiments, the transfer switch103may be set such that the generator switch108is closed and the utility switch104is open. An emergency stop on the standby generator110may be engaged to prevent the generator from supplying power. With shutoff switch102and standby power switch106open and the emergency stop engaged, no power can reach the house load51. In some embodiments, the shutoff switch102is located between the meter box18and the house load61, and opening the shutoff switch102prevents power from any source from reaching the house load51.FIG.7provides a diagram of a system200in accordance with an exemplary embodiment with a standby power source40. The system200is substantially similar to system100with the exception of the different features shown in the diagram and described herein. System200does not include a separate standby power switch106. Instead, a backup power switch208may be configured to connect and disconnect the standby power source and, optionally, the standby generator. Utility switch104and standby power switch208cooperatively form a transfer switch203. Transfer switch203may operate similarly to transfer switch103. For example, transfer switch203may prevent both the utility power supply50and the standby power source40(or the standby generator110) from supplying power to the house load51simultaneously. The standby power switch208and the generator switch108may collectively be referred to as secondary power switches.

FIGS.8-13illustrate a control logic process that prevents the one power source from connecting to the house load51until the other power source has been disconnected.FIG.8shows a schematic diagram of transfer switch control logic800in utility mode, i.e., when the house load51is being powered by the utility power supply50. Transfer switch control logic800may be implemented by a control circuit within the transfer switch controller of the meter socket adapter10or another controller within the meter socket adapter10. The control circuit may take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, microcontrollers, etc.), telecommunication circuits, hybrid circuits, and any other type of “circuit.” In this regard, the control circuit may include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, relays, and so on). The control circuit may also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. The control circuit may include one or more memory devices for storing instructions that are executable by the processor(s) of the controller. The controller may determine whether various relay contacts are open or closed and may send signals causing various relay contacts to open or close based on the transfer switch control logic800. Relay contacts may be provided as the sole contact in a relay or as one of multiple contacts in a relay.

The hardware and data processing components used to implement the various processes, operations, illustrative logics, logical blocks, modules and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or, any conventional processor, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, the one or more processors may be shared by multiple circuits. Alternatively or additionally, the one or more processors may be structured to perform or otherwise execute certain operations independent of one or more co-processors. In other example embodiments, two or more processors may be coupled via a bus to enable independent, parallel, pipelined, or multi-threaded instruction execution. All such variations are intended to fall within the scope of the present disclosure.

The memory device (e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory device may be communicably connected to the processor to provide computer code or instructions to the processor for executing at least some of the processes described herein. Moreover, the memory device may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory device may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.

The transfer switch control logic800as implemented by the controller controls the operation of the transfer switch103,203so as to prevent multiple power sources from simultaneously reaching the house load51. Transfer switch control logic800includes an interlock module810, a load bus voltage detection module820, a transfer signal module830, a signal cutoff module840, and a signal voltage source850. The signal voltage source850may send a signal to close the utility switch104or the generator switch108when the appropriate relay contacts are positioned to transmit the signal. The load bus voltage detection module820includes four detection relay contacts822,824,826,828that remain open and prevent a signal voltage from traveling therethrough when a voltage is detected from the utility power supply50or a backup power source (e.g., the standby generator110, the standby power source40). In some embodiments, the relay contacts are provided as two relays each with two sets of contacts (e.g., contacts822and826are provided in a double pole double throw relay and contacts824and828are provided in a second relay. In other embodiments, each relay contact is provided in its own relay for a total of four relays. While the system remains in utility mode, the switches in the signal cutoff module840remain in a blocked position such that the voltage from the signal voltage source850does not cause either of the switches104,108to close or open.

Next,FIG.9shows a schematic diagram of transfer switch control logic800after a transfer signal has been received to switch the house load51to receiving power from the standby generator110. The transfer signal may be, for example, a signal delivered by a manual switch on the meter socket adapter10or by a signal sent by the control module44, the transfer switch controller, or some other controller coupled to the system. The controller may be configured to determine which power source to connect to the house load51based on various inputs. For example, if the controller detects no incoming power from the utility power supply50, the controller can generate a transfer signal to switch the transfer switch103,203from the utility power supply50to the backup power source. If the controller detects that the fuel level of the standby generator110or the battery charge of the battery bank42falls below a predetermined threshold and that there is incoming power from the utility power supply50, the controller can generate a transfer signal to switch the transfer switch103,203from the standby generator110or standby power source40to the utility power supply50.

The controller may also receive cost inputs and may compare the costs of various power sources to determine whether to switch from the utility power supply50to the backup power source. For example, the controller may receive a rate schedule for power from the utility power supply50that includes higher rates during the day than at night. The controller may also receive an input indicating the cost of fuel for the standby generator110and may calculate a cost per kilowatt-hour generated. When the cost of power from the utility power supply50exceeds the cost of power from the standby generator110, the controller can generate a transfer signal to switch the transfer switch103,203from the utility power supply50to the standby generator. The controller may also receive inputs relating to user preferences. For example, a user may enter a green energy preference indicating that power from the photovoltaic system72should be used whenever it is available. If the controller detects that the battery bank has been charged by the photovoltaic system72, the controller can generate a transfer signal to switch the transfer switch103,203from the utility power supply50to the standby power supply40. In another example, the controller may receive a preference for backup power when power from the utility power supply50exceeds an input cost. When the cost of power from the utility power supply50exceeds the input cost, the controller can generate a transfer signal to switch the transfer switch103,203from the utility power supply50to the standby power supply40.

When the transfer signal is received, the transfer relay contacts832and834in the transfer signal module switch from a utility position to generator position. A signal from the signal voltage source850can travel through the second signal cutoff relay contact844, the transfer relay contact832and the connector880to the utility switch104, causing the utility switch104to open and disconnecting the house load51from the utility power supply50. In this configuration, the signal from the signal voltage source850would be able to reach the generator switch108if not for the relay contacts in the load bus voltage detection module820

Next,FIG.10shows a schematic diagram of transfer switch control logic800after the utility switch104opens. Opening of the utility switch104sends a signal causing the first interlock relay contact812and the first signal cutoff relay contact842to switch positions. The first interlock relay contact812changes to a generator mode position and the first signal cutoff relay contact842changes to a cutoff position. Because the second signal cutoff relay contact844is still in its original position, the signal from the signal voltage source850is still able to travel through the transfer signal module830, but is still unable to travel through the open relay contacts in the load bus voltage detection module820.

Next,FIG.11shows a schematic diagram of transfer switch control logic800after the voltage is cut off to the load bus voltage detection module820. The detection relay contacts822,824,826,828close in response to the load bus detection module detecting no voltage. A signal from the signal voltage source850may then travel through the second signal cutoff relay contact844, the transfer relay contact832, the detection relay contacts826,828, the connector881, and the first interlock relay contact812, causing the generator switch108to close and connecting the house load51to the standby generator110. The standby generator110may then supply power to the house load51.

Next,FIG.12shows a schematic diagram of transfer switch control logic800after the generator switch108closes. Closing of the generator switch108causes the second interlock relay contact814and the second signal cutoff relay contact844to switch positions. The second signal cutoff relay contact844switches to a position that, in combination with the position of the first signal cutoff relay contact842, grounds the signal voltage source850such that a signal does not reach either of the switches104,108. The second interlock relay contact814switches to a position disconnecting the utility switch104from the connector882and the rest of the control logic circuit.

Next,FIG.13shows a schematic diagram of transfer switch control logic800after power begins to flow from the generator to the house load51. The power flowing to the house load51causes the detection relay contacts822,824,826,828to detect a voltage, causing them to reopen. The relay contacts822,824,826,828remain open while the voltage is present, thus preventing a signal from reaching the first switch104. The house load51is now receiving power only from the standby generator110. The transfer switch control logic800, as shown inFIGS.8-13, ensures that the standby generator110and the utility power supply50cannot be connected to the house load51at the same time by preventing either source from connecting until no voltage is detected in the load bus. In some embodiments, the transfer switch control logic800may be used to prevent additional power sources (e.g. standby power source40) from connecting to the house load51at the same time as the utility power supply50.

FIG.14shows a schematic diagram of a transfer signal detection circuit1400. When a transfer signal is generated, for example, by a manual switch on the meter socket adapter10or by a signal sent by the control module44or some other controller coupled to the system, a transfer signal detector1402detects a voltage. The transfer signal detector may then cause the transfer relay contacts832,834to change from a utility mode position to a generator mode position, as described in reference toFIG.9.

FIG.15shows a schematic diagram of a load bus detection circuit1500. The load bus detection circuit includes two voltage detectors1502and1504. When power being delivered to the house load51by either the utility power supply50or the standby generator110, the voltage detectors1502,1504may detect a voltage in the load bus, causing the detection relay contacts822,824,826,828in the transfer switch control logic800to remain open, as described in reference toFIG.8. When no voltage is detected by the voltage detectors1502,1504, the detection relay contacts822,824,826,828are allowed to close, as described in reference toFIG.11, allowing a signal to be sent to close the utility switch104or the generator switch108to connect the utility power supply50or the standby generator110.

FIG.16shows a schematic diagram of a switch detection circuit1600, including a generator switch detector1602and a utility switch detector1604. When the generator switch108is closed or opened the generator switch detector1602detects or stops detecting a voltage and causes the second interlock relay contact814and the second signal cutoff relay contact844to switch positions, as described in reference toFIG.12. When the utility switch104is closed or opened the utility switch detector1604detects or stops detecting a voltage and causes the second interlock relay contact814and the second signal cutoff relay contact844to switch positions, as described in reference toFIG.12.