Power systems for telecommunication sites exist. The power systems utilize a rectified commercial alternating current (AC) power line as primary power for a load at a site. The power systems utilize an internal battery bank as backup power for the load at the site in case the commercial AC power fails. The commercial AC power line maintains the battery bank at a constant “float” voltage until the commercial AC power fails. For example, a lead acid battery bank is arranged on a load bus such that the lead acid battery bank is maintained at a constant float voltage until the commercial AC power fails. Subsequent to the commercial AC power failing, the lead acid battery bank provides power for the load at the site.
While the lead acid battery bank is capable of providing backup power for a load at a site, lead acid battery banks alone are not capable of being the primary power source for the load at the site. This is because the lead acid batteries have only about 400 charge/recharge cycles on average of useable life. Thus, if lead acid batteries were employed as the primary source for the load, the lead acid batteries would need to be replaced with new lead acid batteries after only about 400 cycles. Replacing the lead acid batteries at the site after every 400 cycles would be cost prohibitive. Moreover, these power systems are not suitable for use with other alternate power sources (e.g., solar power, wind power, geothermal power, etc.) to recharge the lead acid batteries. For example, the power systems are not suitable for use with an inconsistent power output of the alternate power sources as compared to a consistent power output of the commercial AC power.
This summary is provided to introduce simplified concepts for a telecommunication power system and methods, which is further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.
A telecommunication power system and methods are provided to utilize batteries as primary power for loads at telecommunication sites in conjunction with utilizing alternate power sources as secondary power for the loads at the telecommunication sites. In one example, a telecommunications power system comprises a battery recharge bus connected (e.g., electrically connected) to a load bus via a plurality of contactor control paths. The power system may comprise a plurality of battery strings arranged to be primary power sources for at least one load. Each battery string of the plurality of battery strings may be connected to a respective contactor control path of the plurality of contactor control paths.
The power system may further comprise a load control circuit connected to the plurality of battery strings. The load control circuit may be arranged to switch each battery string of the plurality of battery strings on to the load bus or on to the battery recharge bus. A plurality of power sources may be connected to the load control circuit, and arranged to switch each power source of the plurality of power sources on to the battery recharge bus.
The power system may further comprise a site controller communicatively coupled with the plurality of contactor control paths and the load control circuit. The site controller may be arranged to control configurations of the plurality of contactor control paths and control the load control circuit.
In another example, a method of powering a load may comprise providing primary power to a load via a first battery string connected to a first contactor control path having a closed circuit with a load bus, configuring a second contactor control path to have a closed circuit with the load bus, and switching to a second battery string connected to the second control path such that the second battery string provides the primary power to the load instead of the first battery string. The method may include configuring the first contactor control path such that the first contactor control path has a closed circuit with the battery recharge bus, and switching the first battery string off of the load bus and on to the battery recharge bus to be recharged by at least one of a plurality of secondary power sources.
In another example, a method of installing a power system in a telecommunications site may comprise installing a battery recharge bus in the telecommunications site, connecting the battery recharge bus to a load bus via a plurality of contactor control paths, and connecting a battery string of a plurality of battery strings to a respective contactor control path of the plurality of contactor control paths.
The detailed description is described with reference to the accompanying figures. The use of the same reference numbers in different figures indicates similar or identical items.
This disclosure is directed to a telecommunication power system and methods of using and installing such a system. The power system utilizes batteries as primary power in conjunction with alternate power sources as secondary power for the loads at telecommunication sites. The batteries may include lithium iron phosphate batteries, lithium-ion batteries, lithium-ion polymer batteries, nickel-metal hydride batteries, nickel-cadmium batteries, thin film batteries, potassium-ion batteries, or any other rechargeable batteries having a high level of cycleability as compared to a low cycleability of lead-acid batteries. For example, lead-acid batteries may have a low cycleability of at most about 400 cycles of expected life as compared to lithium-ion batteries having a high cycleability of at least about 5,000 cycles to at most about 20,000 cycles of useable life. As used herein, the term “cycles” is a quantity of discharge/recharge events of a battery before the useable life of the battery expires, and a “high level of cycleability” means at least about 5,000 cycles of expected life.
The telecommunication sites may be remote sites, off-grid cell sites (e.g., sites not connected to the public electrical grid), wireless sites, cellular cites, outside plant sites, co-locate sites, central office sites, or any other site. The sites may be configured to utilize non-renewable energy and/or renewable energy. For example, the sites may be configured to utilize fuel cells, generators (e.g., backup generators), commercially available alternating current (AC) power, solar power (e.g., photovoltaics), wind power (e.g., windmills and/or wind turbines), geothermal power, or the like.
In some of the power system implementations, a battery recharge bus may be connected to a load bus via a plurality of contactor control paths. In some of the power system implementations, each battery string of a plurality of battery strings may be connected to a respective contactor control path of the plurality of contactor control paths. For example, the power system may include three or more battery strings, a first battery string connected to a first contactor control path being used as a primary voltage source, a second battery string connected to a second contactor control path ready to be used as the primary voltage source, and a third battery string connected to a third contactor control path ready to be recharged.
In some of the power system implementations, a load control circuit may be connected to the plurality of battery strings and arranged to switch each battery string on to the load bus or on to the battery recharge bus. The load control circuit may be a voltage control circuit, for example, as described in U.S. patent application Ser. No. 13/664,193, titled “Voltage Control Using Field-Effect Transistors,” the contents of which are incorporated by reference herein in its entirety.
In some of the power system implementations, a site controller (e.g., a site control board) may be arranged to control configurations of the plurality of contactor control paths and control the load control circuit disposed at the site. The site controller may be arranged at the site to receive control signals to control each piece of telecommunication equipment, power device(s), and/or controller(s) disposed at the site. The site controller may be a programmable site controller arranged to manage the switching operations via input/output ports and predefined parameters. The site controller may be a central control board, for example, as described in U.S. patent application Ser. No. 13/094,631, titled “Telecommunication Wireless Control System,” the contents of which are incorporated by reference herein in its entirety.
Traditional telecommunication power systems for remote cell sites have utilized rectified commercial alternating current (AC) power as primary power and an internal battery bank (e.g., lead acid battery strings) as backup power in case of failure of the rectified AC power. The traditional power systems cycle multiple backup battery strings to increase a usable life of the battery strings, charge capacity, and reliability. For example, traditional power systems rely on the constancy of the rectified commercial AC power to recharge the backup battery strings. Because of the reliance of traditional power systems and methods reliance on the rectified commercial AC power to cycle the backup battery stings, the traditional power systems are not capable of managing alternate energy sources (e.g., wind power, solar power, geothermal power, etc.). This is because of the inconsistent power output of the alternate energy sources when compared to the consistent power output of the commercial AC power. Therefore, the traditional power systems are unable to utilize the alternate energy sources to cycle the backup battery strings.
For example, traditional power systems utilize battery stings (e.g., lead acid battery strings) having a low cycleability of at most about 400 cycles. Because of the low cycleability of the lead acid battery strings, the traditional power systems cannot afford to cycle through the lead acid battery strings, and thus do not continuously cycle the lead acid battery strings. Because the traditional power systems cannot continuously cycle the lead acid battery strings, the traditional power systems only cycle the lead acid battery strings when the commercial AC power fails. Having the ability to utilize the inconsistent power output of the alternate energy sources in conjunction with having the ability to continuously cycle battery strings will allow for optimization of a telecommunication site's power consumption and reduce costs.
Because traditional telecommunication power systems do not continuously cycle the lead acid battery strings as primary power, the traditional telecommunication power systems do not employ a battery recharge bus connected to a load bus via a plurality of contactor control paths. Also because traditional telecommunication power systems do not continuously cycle the lead acid battery strings as primary power, the traditional telecommunication power systems do not employ a load control circuit connected to the plurality of battery strings arranged to switch each battery string on to the load bus or on to the battery recharge bus. Further, because traditional telecommunication power systems do not continuously cycle the lead acid battery strings as primary power, traditional telecommunication power systems also do not employ a site controller arranged to control configurations of the plurality of contactor control paths and control the load control circuit disposed at the site.
Accordingly, this disclosure describes systems and methods for utilizing battery strings as primary power, in conjunction with alternate power sources as secondary power, for powering loads at telecommunication sites while making use of the lowest cost energy available, which may result in a reduction of power consumption costs.
A lead acid battery string may include a quantity of twenty four lead acid battery cells, each cell being about 2 Volts (V). The lead acid battery string may have a total string voltage of about 55V. Configurations of lithium iron phosphate battery strings may include lithium iron phosphate battery cells being at least about 3V to at most about 4V, and the lithium iron phosphate battery cells being arranged as 6V cell packs, 7V cell packs, 12V cell packs, and/or 14V cell packs to have a total voltage of at least about 48V direct current (DC) voltage to at most about 54 VDC voltage to operate telecommunication equipment or loads.
The renewable energy 112 may comprise solar power 112(1) (e.g., photovoltaics), wind power 112(2) (e.g., windmills and/or wind turbines), and/or geothermal power 112(N). While
The backup generator 114 may be arranged to provide AC power to the rectifier AC power system 110 when the commercial power fails. For example, the backup generator 114 may be arranged to provide power during a power outage caused by weather.
The load control circuit 118 may be a soft load control circuit for physically switching one or more of the plurality of battery strings 106 and/or the alternate power sources 108 on to the battery recharge bus 116 and/or a load bus. While
The controller 120 may be a programmable site controller for controlling the power system 104. The controller 120 may be communicatively coupled with the power system 104 via a simple network management protocol (SNMP). For example, the controller 120 may be communicatively coupled with the rectifier AC power system 110 via SNMP. Moreover, the controller 120 may be arranged to be communicatively coupled with various types of rectifier AC power systems in use at existing sites.
For example, each contactor control path of the plurality of contactor control paths 206(1), 206(2), 206(3), and 206(N) may include a first contactor 208(1) connected to the load bus 204 and a second contactor 208(2) connected to the first contactor 208(1) and connected to the battery recharge bus 116. The first and second contactors 208(1) and 208(2) may comprise load control circuitry, relays, contactors, or the like to control the flow of power. The first contactor 208(1) may be in an open or closed state, and the second contactor 208(2) may be in an open or closed state. Each battery string 106(1), 106(2), 106(3), and 106(N) of the plurality of battery strings may be connected between the first contactor 208(1) and the second contactor 208(2) of each contactor control path of the plurality of contactor control paths 206(1), 206(2), 206(3), and 206(N). Thus, the negative terminal of each battery string 106(1), 106(2), 106(3), and 106(N) can be connected to either the battery recharge bus 116 or the load bus 204 depending on an open or closed state of the first contactor 208(1) and an open or closed state of the second contactor 208(2).
While
Similarly,
For example, because the contactor control path 206(2) has a closed configuration with the battery recharge bus 116, the battery recharge bus 116 may be supplying power to the battery string 106(2). Similarly, because the contactor control path 206(3) has a closed configuration with the battery recharge bus 116 and the load bus 204, the battery recharge bus 116 may be supplying power to the loads 124(1)-124(N).
The controller 120 may perform cycling, discharging, recharging, and/or parking of each of the battery strings 106(1)-106(N) in order to optimize a useable life of the battery strings 106(1)-106(N). Moreover, the controller 120 may perform cycling, discharging, recharging, and/or parking of each of the battery strings 106(1)-106(N) in order to optimize a useable life of the battery strings 106(1)-106(N) while maintaining a constant voltage on the load bus 204. For example, the controller 120 may cycle, discharge, recharge, and/or park any of the battery strings 106(1)-106(N) to maintain a constant voltage of at least about −48 VDC to most about −54 VDC on the load bus 204. The controller 120 may implement any of the cycling, discharging, recharging, and/or parking of any of the battery strings 106(1)-106(N) based on specific events detected by monitoring circuits.
For example, an event may comprise an online battery string dropping below a predetermined voltage threshold. For this event, the controller 120 may establish configurations of the contactor control paths 206(1)-206(N) and control the load control circuit 118 to bring a second fully charged battery string that was previously parked in open-circuit mode on to the load bus 204. For example, the controller 120 may determine the voltage of the online battery string 106(1), providing the primary voltage for the loads 124(1)-124(N), has dropped below the predetermined voltage threshold. The controller 120 may then proceed to establish a closed configuration of the contactor control path 206(3) and switch the open state of the switch 210(3) to a closed state of the switch 210(3) to bring the battery string 106(3), previously charged and parked in open circuit mode, on to the load bus 204.
In one example, the predetermined voltage threshold may be set to about 40V. In another example, the predetermined voltage threshold may be set to about 46V. The predetermined voltage threshold may be set based at least in part on the application of the site 102 and/or a preference of a user.
In another example, an event may comprise a battery string being connected or switched to the battery recharge bus 116 for recharging. For this event, the controller 120 may determine what alternate power sources 108 (e.g., second energy sources) are available for recharging. For example, the controller 120 may determine if the solar power 112(1) and/or wind power 112(2) present a threshold voltage. If the controller 120 determines the solar power 112(1) and/or wind power 112(2) are available (i.e., present a threshold voltage), the controller 120 controls the load control circuit 118 to connect the solar power 112(1) and/or wind power 112(2) to the battery recharge bus 116. For example, the controller 120 may control the load control circuit 118 to switch the open state of the switch 210(6) and/or the switch 210(N) to a closed state of the switch 210(6) and/or the switch 210(N) to connect the solar array system 112(1) and/or the wind turbine 112(2) to the battery recharge bus 116.
Further, in the event that a battery string is being connected or switched to the battery recharge bus 116 for recharging, the controller 120 may determine that the solar power 112(1) and/or wind power 112(2) do not present the threshold voltage. For example, the controller 120 may determine the secondary power sources (e.g., the renewable power sources 112) are not available. If the controller 120 determines that the solar power 112(1) and/or wind power 112(2) are not available (i.e., do not present the threshold voltage), the controller 120 may determine if conditions permit parking the battery string until one or more of the secondary sources become available and/or until an off-peak time of day to access rectified AC commercial power at a lower cost.
The conditions may be, voltage levels of each of the battery strings 106(1)-106(N), a quantity of the battery strings 106(1)-106(N) that are recharged (i.e., a quantity of additional or extra recharged battery strings), and/or an availability of rectified AC power (e.g., availability of commercial power and/or availability of backup generator power), for example. If the controller 120 determines conditions permit parking the battery string, the controller 120 may keep the battery string off of the recharge bus 116 and off of the load bus 204. For example, if the controller 120 determines conditions permit parking the battery string, the controller 120 may configure a contactor control path associated with the battery string to have an open configuration with the load bus 204 and the battery recharge bus 116, and control the control circuit 118 to open the switch associated with the battery string.
However, if the controller 120 determines conditions permit charging the battery string with the rectifier AC power system 110, the controller 120 may control the load control circuit 118 to connect the rectifier AC power system 110 to the recharge bus 116. For example, the controller 120 may control the load control circuit 118 to switch an open state of the switch 210(5) to the closed state of the switch 210(5) to connect the rectifier AC power system 110 to the battery recharge bus 116.
Further, if the controller 120 determines conditions permit charging the battery string with one or more of the renewable power sources 112, the controller 120 may control the load control circuit 118 to connect one or more of the renewable power sources 112 to the recharge bus 116. For example, the controller 120 may control the load control circuit 118 to switch the open state of the switch 210(6) and/or the switch 210(N) to a closed state of the switch 210(6) and/or the switch 210(N) to connect the solar array system 112(1) and/or the wind turbine system 112(2) to the battery recharge bus 116. Moreover, the controller 120 may manage the application of the rectified AC power system 110 and the renewable power sources 112 according to a charging algorithm designed to provide ideal charging conditions for the battery string. For example, the controller 120 may utilize the rectified AC power system 110 to apply constant power (e.g., constant Watts) to the battery string and then utilize the renewable power sources 112 to apply constant current for the last 10 amps to achieve 100% state-of-charge. The controller 120 may apply constant power to the battery string and then switch to apply constant current to the battery string based on monitored values of voltages and temperatures of the battery string and the charging algorithm for the battery string.
Subsequent to charging the battery string, the controller 120 may control the load control circuit 118 to remove the rectified AC power system 110 and/or the renewable power sources 112 from the recharge bus 116. Further, subsequent to charging the battery string, the controller 120 may control the load control circuit 118 to remove the newly charged battery string from the recharge bus 116. The controller 120 may park the newly charged battery string in an open circuit mode (e.g., battery strings 106(3) and 106(N)).
In another example, an event may comprise a battery string being parked in open circuit mode after charging the battery. For this event, the monitoring circuit arranged with the battery string measures a voltage of the battery string after a specified amount of time. For example, the monitoring circuit arranged with the parked battery string may measure a voltage of at least about 45V to at most about 60V about every 4 hours. The monitoring circuit may also measure a temperature of the parked battery string after the specified amount of time. Moreover, the monitoring circuit may measure the voltage and or temperature at each cell of the battery string.
The monitoring circuit may send the values of the measured voltages and/or temperatures to the controller 120. The controller 120 may compare the received values with predetermined values. For example, the controller 120 may compare the received values with a predetermined value for each cell. The predetermined value for the voltage may be about 2.8V and the predetermined value for the temperature may be about 25 degrees Celsius (C). Subsequent to the measured voltage value falling below the predetermined voltage threshold, the controller 120 may configure a configuration of one or more of the contactor control paths 206(1)-206(N) and control the load control circuit 118 to bring the parked battery string back on to the battery recharge bus 116 for recharging.
The controller 120 may also configure a configuration of one or more of the contactor control paths 206(1)-206(N) and control the load control circuit 118 to connect one or more of the alternate power sources 108 to the battery recharge bus 116. The controller 120 may apply the connected one or more alternate power sources 108 to recharge the battery string. For example, the controller 120 may apply voltage provided by the solar array system 112(1) and/or the wind turbine system 112(2) to achieve 100% state-of-charge. The controller 120 may determine the battery string to be at 100% state-of-charge by comparing the received voltage and/or temperatures with the predetermined values.
The controller 120 may then control the load control circuit 118 to remove the connected one or more alternate power sources 108 from the battery recharge bus 116. The controller 120 may also then control the load control circuit 118 to remove the fully charged battery string from the battery recharge bus 116 and park the battery string in an open circuit mode.
In another example, an event may comprise one of the renewable power sources 112 reaching a voltage threshold of the load bus 204. For this event, the controller 120 may determine if a voltage of the solar array system 112(1), wind turbine system 112(2), geothermal system 112(N), or other renewable power source 112 reaches or exceeds the voltage threshold of the load bus 204.
In one example, the voltage threshold of the load bus 204 may be set to about 40V. In another example, the voltage threshold of the load bus 204 may be set to about 46V. If the controller 120 determines a voltage of one of the renewable power sources 112 reaches or exceeds the voltage threshold of the load bus 204, the controller 120 controls the load control circuit 118 to connect the renewable power source 112 to the load bus 204. For example, if the controller 120 determines a voltage of the solar power 112(1) and/or wind power 112(2) meets or exceeds the voltage threshold of the load bus 204 the controller 120 may connect the solar power 112(1) and/or wind power 112(2) to the load bus 204. For example, the controller 120 may configure a configuration of one or more of the contactor control paths 206(1)-206(N) and control the load control circuit 118 to bring the solar power 112(1) and/or wind power 112(2) on to the load bus 204 to provide power to the load(s) 124(1)-124(N).
Further, the controller 120 may configure a configuration of one or more of the contactor control paths 206(1)-206(N) and control the load control circuit 118 to provide power to the load(s) 124(1)-124(N), and simultaneously recharge one or more of the battery strings 106(1)-106(N). Subsequent to the controller 120 determining a voltage of the renewable power source 112 is below the voltage threshold of the load bus 204, the controller 120 may configure a configuration of one or more of the contactor control paths 206(1)-206(N) and control the load control circuit 118 to disconnect or remove the renewable power source 112 from the load bus 204. Subsequent to the removal of the renewable power source 112 from the load bus 204, the battery string may resume providing primary power to the load bus 204.
Process 300 also includes operation 304, which represents a controller (e.g., controller 120) configuring a second contactor control path (e.g., contactor control path 206(3)), connected to a second battery string (e.g., battery string 106(3)), such that the second contactor control path has a closed circuit with the load bus. In one example, for instance, the controller 120 may be triggered to perform operation 304 based on one or more events. For example, the controller 120 may be triggered to perform operation 304 based on the event that the first battery string (e.g., online battery string) drops below a predetermined voltage threshold (e.g., at least about 40V to at most 46V).
Process 300 may also include operation 306, which represents the controller switching the second battery string on to the load bus such that the second battery string provides the primary power to the load instead of the first battery string. The switching may comprise switching a switch (e.g., switch 210(3)) of a load control circuit (e.g., load control circuit 118) connected to the first and second battery strings to bring the second battery string on to the load bus. For example, the controller may control the load control circuit, connected to the first and second battery strings, to switch the open state of the switch to a closed state of the switch to bring the second battery string, previously charged and parked in open circuit mode, on to the load bus.
Operation 306 may be followed by operation 308, which may represent configuring the first contactor control path such that the first contactor control path has a closed circuit with a battery recharge bus. For example, a battery recharge bus may be coupled with the load bus via the first and second contactor control paths, and the controller may configure the first contactor control path to have a closed circuit with the battery recharge bus and an open circuit with the load bus. Operation 308 may also include switching the first battery string off of the load bus and on to the battery recharge bus to be recharged by at least one of a plurality of secondary power sources (e.g., renewable power sources 112). For example, the controller may control the load control circuit, connected to the first and second battery strings, to switch an open state of a switch (e.g., switch 210(1)) to the closed state of the switch to bring the first battery string, previously providing primary power to the load, on to the recharge bus for recharging by at least one of the plurality of secondary power sources.
Process 300 may include operation 310, which represents determining if one or more of the plurality of secondary power sources are available to recharge the first battery string. For example, the controller may determine if the solar power and/or wind power present a threshold voltage. If one or more of the secondary power sources are available, the controller may switch one or more of the secondary power sources on to the recharge bus to recharge the first battery string. Or, if one or more secondary power sources are not available, the controller may determining if conditions provide for switching the first battery string off of the recharge bus and off of the load bus. For example, the controller may determine voltage levels of each of the battery strings, a quantity of the battery strings that are recharged (i.e., a quantity of additional or extra recharged battery strings), and/or an availability of rectified AC power (e.g., availability of commercial power and/or availability of backup generator power).
Process 300 may be completed at operation 312, which represents the controller configuring the first contactor to keep the first battery string off of the recharge bus and off of the load bus until one or more secondary power sources become available, or configuring the first contactor to keep the first battery string off of the recharge bus and off of the load bus until a cost of rectified alternating current (AC) power is below a threshold.
Process 400 begins at operation 402, which represents installing a battery recharge bus (e.g., battery recharge bus 116) in the telecommunications site. For example, a technician may arrange a battery recharge bus with a chassis, a cabinet, a housing, a battery distribution feeder bay (BDFB), or the like arranged in the telecommunication site.
Process 400 includes operation 404, which represents connecting the battery recharge bus to a load bus (e.g., load bus 204) via a plurality of contactor control paths (e.g., contactor control paths 206(1)-206(N). The load bus may be arranged to distribute power to at least one load (e.g., load(s) 124(1)-124(N)) at the telecommunications site. For example, a technician may arrange a plurality of contactor control paths with a chassis, a cabinet, a housing, a battery distribution feeder bay (BDFB), or the like arranged in the telecommunication site and connect the plurality of contactor control paths with the battery recharge bus and the load bus. Further, the plurality of contactor control paths may be fixed in a battery management panel (e.g., a 3 rack unit (RU), 19 inch mount). Moreover, a technician may simply install the battery management panel in to a rack arranged in the telecommunication site.
Operation 404 may be followed by operation 406, which represents connecting a battery string of a plurality of battery strings (e.g., 106(1)-106(N)) to a respective contactor control path of the plurality of contactor control paths. Process 400 may include operation 408, which represents connecting a first contactor (e.g., first contactor 208(1)) of each of the plurality of contactor control paths to the load bus, and connecting a second contactor (e.g., second contactor 208(2)) of each of the plurality of contactor control paths to the battery recharge bus.
Process 400 may include operation 410, which represents connecting a battery string of a plurality of battery strings between the first contactor and the second contactor of each contactor control path of the plurality of contactor control paths.
Process 400 may continue with operation 412, which represents connecting a load control circuit (e.g., load control circuit 118) to the plurality of battery strings. The load control circuit may be arranged to switch each battery string of the plurality of battery strings on to the load bus or on to the battery recharge bus. Operation 412 may be followed by operation 414, which represents connecting a plurality of power sources (e.g., alternate power sources 108) to the load control circuit. The plurality of power sources may be arranged to be secondary power sources for the at least one load, and the load control circuit may be arranged to switch each power source of the plurality of power sources on to the battery recharge bus.
Process 400 may be completed at operation 416, which represents communicatively coupling a controller (e.g., controller 120) with the plurality of contactor control paths and the load control circuit. The controller may be arranged to control configurations of the plurality of contactor control paths and control the load control circuit.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as example forms of implementing the claims.