Abstract:
A high efficiency lighting system maintains normal lighting conditions by lighting fixtures requiring DC electrical power. A power control device receives AC electrical power from a public utility converts AC power to DC power and delivers low voltage DC electrical power to lighting fixtures. A standby battery is provided to maintain power during power outages. Optionally, a photovoltaic DC electrical power source may be connected to the power control device, to provide alternate DC electrical power. In a further embodiment, a gas driven cogenerator unit may supply DC electrical power.

Description:
This application is a continuation-in-part of application Ser. No. 08/606,219 filed Mar. 7, 1996, now U.S. Pat. No. 5,786,642 which is a continuation-in-part of application Ser. No. 08/328,574, filed Oct. 24, 1994, now U.S. Pat. No. 5,500,561 dated Mar. 19, 1996, which was a continuation of application Ser. No 08/129,375, filed Sep. 30, 1993, now U.S. Pat. No. 5,363,333, which is a continuation of application Ser. No. 07/944,796, filed Sep. 14, 1992, now abandoned, which is a continuation of application Ser. No. 07/638,637, filed Jan. 8, 1991 now abandoned. 

   BACKGROUND OF THE INVENTION 
   The field of the invention is high efficiency uninterruptable lighting systems. 
   Uninterruptable power supplies are well known accessories especially when applied to computer equipment to “ride out” brief power outages so that no data is lost or compromised. Some have more battery storage capability so that operation may be maintained for an extended outage. Some special lighting systems are also protected in a similar fashion by an uninterruptable power source for critical applications such as operating rooms in hospitals. In lieu of such systems, reduced amounts of auxiliary emergency lighting is provided for special areas by modular systems which are only engaged during power outages; these modules are often used in stairwells and consist of a housing enclosing a battery, charger, power sensor and one or two flood lamps. 
   These prior art systems do nothing to enhance lighting efficiency, and would not be considered as substitutes for conventional lighting. 
   OBJECTS OF THE INVENTION 
   It is an object of this invention to provide an uninterruptable lighting system that can be routinely substituted for conventional building or office lighting. 
   It is another object of this invention to provide high efficiency operation with lower operating cost than conventional incandescent and fluorescent lighting systems. 
   It is yet another object of this invention to provide long term uninterruptability (3 hours+) with small storage volumes. 
   It is an object of this invention to provide optimum battery management for long storage life, ultra low maintenance, and economical operation. 
   It is a further object of this invention to provide for economical connection to an alternate energy source such as a solar photovoltaic (PV) panel. 
   It is another object of this invention to provide a system with enhanced safety through low voltage operation between the power control unit and the lighting fixtures. 
   It is yet another object to achieve high power quality with low interference through very high power factor and low total harmonic distortion. 
   It is an object of this invention to provide for expansion of the lighting system through a modular approach to increase subsystem and component standardization to reduce cost. 
   SUMMARY OF THE INVENTION 
   In keeping with these objects and others, which may become apparent, the present invention includes a high efficiency lighting system for maintaining normal lighting conditions by lighting fixtures requiring DC electrical power. 
   The system includes a power control means for receiving AC electrical power from a grid source and delivering required low voltage DC electrical power to the lighting fixtures. The power control means converts the AC electrical power to DC electrical power. 
   A battery provides, on a standby basis, the required DC low voltage electrical power to the power control means. The battery is connected to the power control means so that the battery may be maintained in a fully charged condition by the power control means during normal supply of AC electrical power from the grid source. 
   The power control means delivers required DC electrical power from the battery to the lighting fixtures during an AC electrical power outage to maintain the power without interruption. 
   The power control means can be a plurality of multiple power control means, each connected to its own battery for maintaining the lighting in a building with multiple rooms. 
   An optional photovoltaic source of DC electrical power may be connected to the power control means for reducing the amount of electrical power taken from said grid source. 
   The battery provides, on a standby basis, DC low voltage electrical power to the power control means, which power control means maintains the battery in a fully charged condition by electrical power from an AC grid source. 
   In a version using AC power input only without an auxiliary battery or photovoltaic panel, the high efficiency lighting system for maintaining normal lighting conditions of lighting fixtures requiring DC electrical power, includes the power control means for receiving AC electrical power from a grid source and delivering required DC electrical power to the lighting fixtures, as well as a power control means converting AC electrical power to DC electrical power. 
   In a further embodiment for remote use, such as a remote campsite without access to conventional AC power, a high efficiency lighting system maintains normal lighting conditions of lighting fixtures requiring DC electrical power. The remote system includes a power control means for receiving DC electrical power from a photovoltaic panel and delivering required low voltage DC-electrical power to the remote lighting fixtures, and the power control means controls charging of a battery. 
   The battery also provides, on a standby basis, the required DC low voltage electrical power to the power control means. It is connected to the power control means while being maintained in a charged condition by the power control means, during daylight hours of input of power from the photovoltaic panel. 
   Moreover, the power control means delivers required DC electrical power from the battery to the lighting fixtures during periods of time when power from the photovoltaic panel is not available, such as at night times. 
   The present invention also provides A DC power supply system for DC loads requiring DC electrical power that includes power control means for receiving AC electrical power from a grid source and delivering required low voltage DC electrical power to said DC load. It converts the AC electrical power to DC electrical power. 
   In addition, one embodiment of the present invention includes a battery means that provides required DC low voltage electrical power on a standby basis to the power control means. 
   The battery means is connected to the power control means so as to permit the battery control means to maintain the battery in a fully charged condition during normal supply of AC electrical power from the AC grid source. 
   The power control means of the present invention delivers required DC electrical power from the battery means to a DC load during an AC electrical power outage so as to maintain normal operation of the DC load without interruption. 
   In addition, the present invention optionally provides a DC power supply system having a photovoltaic [PV] source of DC electrical power connected to the power control means in order to reduce the amount of electrical power taken from said grid source. 
   The DC power supply system of the present invention optionally further provides a cogeneration source of DC electrical power connected to the power control means to reduce the amount of electrical power taken from a grid source. 
   Further, the present invention alternatively provides a DC power supply for DC loads requiring DC electrical power. The DC power supply includes a separate power control means for receiving AC electrical power from a grid source. The DC power supply delivers required low voltage DC electrical power to a DC load. The power control means converts the AC electrical power to DC electrical power. 
   In addition, in an alternate embodiment, the DC power supply system for DC loads requiring DC electrical power includes a power control means for receiving DC electrical power from a DC power source and for delivering required low voltage DC electrical power to the DC load. The power control means is also directed toward the function of controlling charging of a battery means. 
   In this battery-charging embodiment, the present invention&#39;s battery means provides the required DC low voltage electrical power on a standby basis to the power control means. 
   Also, in this battery-charging embodiment, the battery means is connected to the power control means so as to maintain the power control means in a charged condition during hours of input from the DC power source. 
   Furthermore, in this battery-charging embodiment, the power control means delivers required DC electrical power from the battery means to the DC load during times when power from the DC power supply is not available. 
   The DC power supply system of the present invention further provides an optional embodiment wherein the DC power source is a cogeneration unit. 
   Alternatively, in a different embodiment of the present invention, the DC power supply system has a DC power source that is at least one photovoltaic panel. 
   In yet another embodiment of the present invention, the DC power supply system furnishes power to a DC load that is a household appliance. The household appliance may alternatively be a microwave oven, a heater, or any other household electrical device. 
   Furthermore, in further embodiments with or without access to conventional AC power, a DC generator (e.g.—powered by a natural gas engine) is used either as a primary source of electrical power or as a cogeneration companion to normal AC grid power. Thus the power control means can be supplied power for use by a high efficiency lighting system in much the same manner as DC electrical power is received from a photovoltaic panel. 
   It can be appreciated that any compatible DC load can be serviced by the power control means of this high efficiency lighting system in addition to DC ballasted fluorescent lighting or instead of the latter lighting load. These other DC loads can be supplied with standby power from a storage battery as well. Some examples of DC loads include household appliances, microwave ovens, and heaters. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can best be understood in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a block diagram of basic uninterruptable lighting system; 
       FIG. 2  is a physical block diagram of basic uninterruptable lighting system; 
       FIG. 3  is a wiring layout of a single lighting module; 
       FIG. 4  is a wiring layout of a four module system; 
       FIG. 5  is a block diagram of lighting system with a PV panel; 
       FIG. 6  is a front view of power control unit; 
       FIG. 7  is a wiring diagram and specs for two lamp ballast; 
       FIG. 8  is a wiring diagram and specs for single lamp ballast; 
       FIG. 9  is a front view of battery enclosure; and 
       FIG. 10  is a block diagram of power control unit. 
       FIG. 11  is a: block diagram of an alternate lighting system using natural gas cogeneration. 
       FIG. 12  is a block diagram of a customer side, power management system and illustrating its interface with existing electric utility power lines of the customer facility. 
       FIG. 13  is a schematic diagram of an alternate power management system. 
       FIG. 14  illustrates the invention with regard to incorporation of the linear voltage regulator and control interface as one means for controlling the charge level of the storage battery. 
       FIG. 15  illustrates the use of circuit breaker means and looping of a DC lighting circuit as well as auxiliary DC equipment and an inverter associated with a simplified illustration of the electric distribution box. 
       FIG. 16  illustrates a converter fed by a DC supply from a rectifier and providing an output to storage battery means illustrated as having a filter capacitor in electrical parallel therewith. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a block diagram of the major components of an uninterruptable lighting system of this invention. It may be installed anywhere conventional building lighting is required. Unlike emergency lighting, this is a full service, high quality lighting product. It functions with standard fixtures and lamps, without compromise in output quality and with no flicker in the event of a power failure. This permits normal building activities to continue for several hours using battery storage without disruption of work activity due to loss of lighting. The key subsystem that ties the entire system together is the power control unit  1  which normally uses AC grid power to supply the lighting energy and keep the battery  2  charged. The lighting fixtures  3  are fluorescent tubes using electronic ballasts which have a low voltage (nominal 26.6 volts) DC input supplied by line  5  from power control unit (PCU)  1 . During a power outage, the DC line  5  is supplied by battery  2 . 
     FIG. 2  shows a physical block diagram showing the AC electric service panel  6  with a three wire cable system supplying either 120 or 220 VAC to PCU  1 . Battery case  7  contains two group  24 / 27  deep discharge lead acid storage batteries wired in series and through a 30 amp fuse to the PCU  1 . The wiring to all lighting fixtures  3  is at a nominal 26.6 volts DC. In the preferred embodiment, each PCU can power ten two tube 48 inch T8 fluorescent fixtures or  20  single tube fixtures. 
     FIG. 3  shows a wiring layout for three offices as controlled by a single PCU  1 . A closet area  17  is used to house battery  2 . The AC line  4  leads to PCU I, which is placed in the ceiling cavity. The DC wiring  5  to the lighting fixtures is also in the ceiling cavity. 
   The 220 VAC input power to the PCU is 725 watts for an AC rms of approximately 3 amps. The equivalent  120  VAC unit will be about 6 amps. Because the PCU is power factor corrected to 0.99, a 20 amp circuit breaker and number 12 wire can support a maximum of 3 PCU&#39;s from a 120 volt line and 6 units from a 220 volt line for a total DC power output of about 2100 watts and 4200 watts respectively. 
     FIG. 4  shows a wiring layout serving  8  small offices and four larger ones. This involves the use of four separate uninterruptable lighting systems using four PCU&#39;s  1  and four battery modules  2  located in four central closets  17 . The four PCU&#39;s are supplied from a single 220 VAC circuit breaker in power panel  6  via AC cable  4  as distributed from distribution box  20 . Each of the lighting systems supplies  10  two lamp fixtures  3 . 
     FIG. 5  shows an uninterruptable lighting system including a PV panel  25 . 
   As shown in  FIG. 6 , a front view of PCU  1 , it is simply wired to two terminals. This simple system configuration permits high security lighting using an AC line, battery back-up, and PV shared contribution. A system with the PCU alone attached to the AC line is a viable lighting system that can pay for itself by providing high efficiency DC lighting. By adding the battery subsystem, the user achieves uninterruptable lighting. By using a system without a battery but with AC input and a PV panel, the power savings of the PV contribution is achieved with the balance supplied by the AC input. In an area remote from the AC grid, a system using a PCU attached to a large PV panel and a larger battery can supply totally solar lighting. The PCU is sufficiently flexible to support all of these configurations of lighting systems. It can also supply other DC loads besides lighting, such as for example, household appliances, microwave ovens, heaters and the like. Furthermore, it can also alternately accept external DC power from many varied sources such as wind generators or engine powered generators. 
     FIG. 6  shows a front view of PCU  1  with finned heat sink  28  and terminal strip  29 . 
     FIGS. 7 and 8  show the wiring diagrams and specifications for the two lamp and one lamp DC ballasts respectively (designated as NB2756/2 and NB2727M respectively). 
     FIG. 9  shows a front view of the battery case with hinged lid  36  and latches  37 . It is a thermoplastic case rated only for sealed type lead acid batteries. 
     FIG. 10  shows a block diagram of the PCU  1 . The AC input is rectified by DC Rectifier Means  50  such as a bridge circuit. The Power Factor Correction Means  51  is used to achieve a high power factor (0.99) at the AC input. The Control Means  53  and Voltage Regulator means  52  interact through circuits such as pulse width modulation and DC to DC switching power supply topologies to provide the nominal 26.6 volts to the lighting ballasts or other suitable DC loads  57  through the power junction means  55 . Other voltages are also possible, such as 13.3, 26.6, 39.9 etc. 
   The Battery Undervoltage Cut-Off  56  disconnects the battery  2  in situations of depletion to prevent “over sulfation” or chemical and physical damage to the storage battery. The PV Voltage Regulator and Suppressor  54  is a power conditioner block to suppress voltage transients (such as from lightning strikes in the vicinity) and also to prevent over charging of the storage battery from the PV panel  25 . 
   An embodiment of control means  53  determines if the utility power drawn is above a manually pre-set threshold or a threshold derived from an automatic setpoint circuit. If the utility power drawn exceeds this threshold voltage regulator means  52  output voltage will be set such that power junction means  55  will be biased accordingly such that power to DC loads  57  will be drawn from storage battery  2  and/or PV source  25  through its PV voltage and suppressor  54 . In this manner. AC cower peaks from the utility are reduced as are monthly utility charges if a peak power surcharge is assigned. The power sharing-between PV source  25  and battery  2  is regulated by the output voltage of PV source  25  as modified by PV voltage regulator and suppressor  54 . The interaction of voltage output at suppressor  54  with that of battery  2  voltage via biasing within power function means  54  determines the level of power sharing between these DC secondary sources. The latter action also describes the sharing of power between PV panel  25  and battery  2  during periods of utility power outage. 
     FIG. 11  is an alternate embodiment for a loadside powered lighting system including natural gas in a cogeneration component. AC power  50  is normally converted to DC power by DC power converter  51  and control means  52 . However, a cogenerator in the form of a DC gas generator  53  receives natural gas from a natural gas source  54 , and sends DC power to building lighting system  55 , such as electronic ballasted fluorescent lighting. This system provides a flatter and more predictable power demand for electric utility customers at building lighting system  55 , since it supplants peak power from electric utility generating sources. This results in reduced demand charges, since gas offers a lower cost per unit of energy consumed, compared to conventional AC power from a public utility. 
   The cogeneration system can run continuously for lighting load  55 , without having to be sent back to AC line power  50 , which avoids the need for costly AC synchronization methods and sine wave purity, as is needed when sending excess-electricity back to a public utility. 
   DC gas generator  53  directly couples to building lighting system  55  through a diode isolator that allows either AC or DC power to operate building lighting system  55 . 
   Referring now to  FIG. 12  of the drawings, it will be seen that a customer side, power management system formed in accordance with the present invention may be easily inter-connected with the existing electric power wiring of the customer facility to monitor the load requirements of the customer. To facilitate an understanding of the invention,  FIG. 12  shows three phase power wiring (i.e., wires labeled L 1 , L 2  and L 3  representing each phase) and a neutral (i.e., N) wire coming from the utility and being received by the customer facility. The three phase wires, L 1 , L 2  and L 3  and the neutral wire N are received by a main distribution panel  202  of the customer facility. The main distribution panel  202  distributes the power throughout the facility, and in many cases provides power to a lighting distribution panel  204 , which, as its name implies, distributes power to the various lighting circuits of the facility. That is, the main distribution panel  202  conventionally distributes the three phase power wiring of the electrical utility throughout the consumer facility and in so doing distributes power to the various loads served by the customer facility. There are three types of very common AC electrical loads which may be required to be satisfied by the AC electrical power generated at the public or electrical facility and emanating from the illustrated consumer facility and they are a Lighting Load Semi-Random Punctuated Loads, and Semi-Random Longer Cycle Loads. Thus, the three phase power wiring L 1 , L 2  and L 3  and the neutral wiring N connects from the public utility side of the main distribution panel  202  and issues therefrom as AC electrical conductors on the customer side of this panel into connection with the composite of loads which are required to be satisfied by the power emanating from the electrical utility. Normally, the main distribution panel  202  and the lighting distribution panel  204  are interconnected by one or more power lines  206 , including a neutral line  208 , but for purposes of this invention, the interconnecting lines between the main distribution panel and the lighting distribution panel are interrupted, as illustrated by the broken lines in FIG.  12 . It will be understood that the interruptions of the lines between the main distribution panel  202  and the lighting distribution panel  204  with introduction of the inverter  110  are necessary only if the Lighting Load is not capable of being powered solely by direct current, as distinct from a situation where the Lighting Load may be powered in whole or in part, by AC power. To the extent it is not so capable, the inverter  110  must be employed to supply AC power, all in the event that there could be failure of the electrical facility to deliver any AC at all. 
   The power management system includes a power transducer  210 . The power transducer  210  has associated with it one or more voltage or current sensors  212 , each sensor being coupled to a respective power line phase. The power transducer  210  measures in real time the power consumed by the customer facility from the electric utility, and provides an output signal corresponding to this measurement. The output signal provided by the power transducer  210  is proportional in magnitude to the power consumed by the customer facility. For example, the output signal may be in terms of voltage, and have a range of from 1 to +10 or −10 volts, which would correspond to a power consumption of from 0 to 100 kilowatts. A suitable power transducer  210 , which may be used for the power management system of the present invention, is Part No. PCB-20 manufactured by Rochester Instrument Systems, Inc. 
   The output signal from the power transducer  210  is preferably provided to an integrator circuit  214 . The integrator circuit  214  averages the real time power measurement made by the power transducer. The integrator circuit  214  simulates the operation of a similar integration circuit, which the utility uses to average the peak power demands of its customers. 
   The integrator circuit  214  may be formed in various ways, including using an operational amplifier  216  with a feedback capacitor  218  and an input resistor  220 , as shown in FIG.  12 . The values of capacitor  218  and resistor  220  are selected to provide a desired integration time. The integrator circuit  214  shown in  FIG. 12  provides a negative gain; accordingly, if such a circuit is used, it may be coupled to the 0 to −10 V output of the power transducer to provide a positive output voltage signal which varies in response to changes in power drawn from the utility and sensed by the sensor  212 . 
   The power management system further includes a comparator circuit, which in a preferred form is a differential amplifier circuit  220 . The output of the integrator circuit  214  is provided to a first input of the differential amplifier circuit  220 . A second input of the differential amplifier circuit  220  is connected to a switching circuit  222 , which is functionally depicted in  FIG. 12  as a single pole, double throw switch  222   a.    
   More specifically, the “wiper” arm  224  of the switching circuit is connected to the second input of the differential amplifier circuit  220 , one pole  226  of the switching circuit is connected to an automatically adjustable set point circuit  228 , and the other pole  230  of the switching circuit is connected to a manually adjustable set point circuit  232 . 
   The automatically and manually adjustable set point circuits  228 ,  232  provide at threshold signal, which may be in the form of a voltage, through the switching circuit  222  to the second input of the differential amplifier circuit  220 . The threshold signal represents the power level at which a secondary source of DC power, such as a storage battery  234 , forming part of the power management system is to take over in supplying power to one or more various loads in the customer&#39;s facility, as will be described. 
   Various manually adjustable set point circuits are envisioned to be used in the present invention. One example of such is a potentiometer  236  connected between positive and negative voltages or a voltage V 1  and ground, with its wiper arm connected to the pole  230  of the switching circuit  222 . Such a circuit would provide a threshold voltage to the differential amplifier circuit  220 . The set point circuit  232  would be adjusted after an analysis of the customer&#39;s energy consumption profile. The threshold would be set so that any stochastic or recurrent (i.e., non-random, time of day) peaks in the customer&#39;s daily power demand would be supplied in full or proportionally by the secondary DC power source of the power management system, as illustrated by FIG.  13 . 
   The automatically adjustable set point circuit  228  will periodically derive and store the maximum value of the actual peak power demands over predetermined time intervals, for example, daily or monthly, and provide a threshold which is based on a “moving average” computed by the circuit. This threshold signal is provided to the input of the differential amplifier circuit  220  through the switching circuit  222 . The automatic set point circuit  228  will automatically adjust the threshold signal in accordance with the moving average of the customer&#39;s peak power requirements, which it calculates algorithmically. An example of such a circuit is disclosed in U.S. Pat. No. 4,731,547, which issued to Phillip Alenduff et al., the disclosure of which is incorporated herein by reference. 
   As its name implies, the comparator (or more preferably the differential amplifier) circuit  220  will compare the threshold signal provided by either set point circuit  228 , 232 , which is selected by the switching circuit  222  with the output signal from the integrator circuit  214 , which output signal represents the power being drawn from the utility averaged over the predetermined integration period. IF the output signal from the integrator circuit  214  is greater in magnitude than the threshold signal, i.e., indicating that excessive or peak power is being consumed, the differential amplifier circuit  220  will sense this and provide a proportional output signal, which is compatible with that required to control an AC-to-DC converter or switching mode type power supply  238  forming part of the power management system, as will be described. 
   One form of a differential amplifier circuit  220  which is suitable for use in the present invention is an operational amplifier  240  having a feedback resistor  242  and an input resistor  244 , with the threshold signal being provided to the inverting input of the operational amplifier  240  through the input resistor  244 , and the output signal from the integrator circuit  214  being provided to one side of a second input resistor  243  whose other side is connected to the non-inverting input of the operational amplifier and to another resistor  245  to ground. When the values of the first input and feedback resistors  244 ,  242  equal those of the second input and the ground resistors  243 ,  245  respectively, the output signal from the differential amplifier circuit  220  will be a voltage level equal to the difference between the voltage levels of the integrator circuit&#39;s output signal and the threshold signal, multiplied by the ratio between the values of the feedback and first input resistors  242 ,  244 . Accordingly, the output signal from the differential amplifier circuit  220  is preferably a voltage level which varies proportionally with the difference between the output signal from the integrator circuit  214  and the set point threshold signal level. 
   As will be described in greater detail, many AC-to-DC power supplies adjust their output voltage levels in proportionment to the voltage applied to their control signal input, and operate on positive control signal voltages, for example, 0 volts to 10 volts for an output adjustment of from 125 volts to 110 volts. To prevent negative voltage swings in the output signal from the differential amplifier circuit  220 , such as when the level of the output signal of the integrator circuit is below the set point threshold signal level, one can provide a positive supply voltage to the appropriate supply terminal of the operational amplifier  240 , and ground the negative supply terminal. Alternatively, one may connect a diode (not shown) having its anode connected to ground and its cathode connected to the output of the operational amplifier  240  to clamp the differential amplifier&#39;s output signal to 0 volts when the output signal from the integrator circuit  14  is less than the set point threshold signal level. 
   Instead of using the differential amplifier circuit  220 , which provides a continuously variable output signal which is proportional to the difference between the threshold signal and the integrator circuit&#39;s output signal, a simple comparator, such as in the form of an operational amplifier, may be used. The integrator&#39;s output signal and the threshold signal are provided to the two inputs of the comparator, and the comparator&#39;s output signal is provided to the control input of the AC-to-DC converter  238 . When the integrator circuit&#39;s output signal is greater than the threshold signal, the output signal of the comparator will be in a first state to signal the AC-to-DC converter  238  to provide a first output voltage level. When the integrator circuit&#39;s output signal is less than or equal to the threshold signal, the output signal of the comparator will be in a second state to signal the AC-to-DC converter  238  to provide a second output voltage level. 
   As mentioned previously, the power management system of the present invention includes an AC-to-DC converter circuit  238 . Preferably, the converter circuit  238  is a power supply of the switching type, which is known to have good regulation and high efficiency. The power line  206  and neutral line  208  from the main distribution panel  202 , which originally were provided to the lighting distribution panel  204 , are now provided to the AC inputs of the switching power supply  238 . The output signal from the comparator or differential amplifier circuit  220  is provided to the control input of the power supply. The switching power supply  238  will convert the AC power provided to it into a DC voltage and current to run a particular load or loads at the customer facility, such as a fluorescent lighting load  246 , as illustrated by  FIG. 12. A  suitable AC-to-DC switching power supply  238  which may be used in the power management system of the present invention is Part No. 2678644 manufactured by Technl Power Corp., a Penril Company, located in Connecticut. For greater power handling requirements, several power supplies may be connected in parallel, all being controlled by the comparator or differential amplifier circuit  220 . With whichever AC-to-DC converter  238  that is used, the comparator or differential amplifier circuit  220  is designed to provide the compatible control signal to vary the converter output as required. 
   The output voltage of the switching DC power supply  238  is adjustable proportionally to the control signal it receives. For example, the power supply  238  may be selected or designed such that control voltage provided to the control input of the power supply of from 0 to 10 volts will inversely adjust the output DC voltage of the power supply from 125 to 110 volts. As will be described in greater detail, the control of the output voltage of the AC-to-CD power supply  238  is an important aspect of the power management system, as it will allow the lighting or other load to be driven by power from the electric utility or from the secondary DC source, such as the storage battery  234 , situated at the customer facility. 
   The DC output voltage from the AC-to-DC power supply  238  is provided to a power isolation and distribution circuit  48  and to a second source of DC power, which, in the preferred form of the invention, is a storage battery  234 . More specifically, the positive terminal of the power supply  238  is provided to the input of the power isolation and distribution circuit  248 , one output of the power isolation and distribution circuit is provided to the power line  206  connected to the lighting distribution panel  204 , and another output of the power isolation and distribution circuit is provided to the positive terminal of the storage battery  234 . The negative output of the power supply  238  is provided to the negative output of the storage battery  234  and to the neutral line  208  connected to the lighting distribution panel  4 . Connected in this manner, the AC-to-DC power supply  238  will not only provide DC power to the lighting or other load  246  of the customer, but will also charge the storage battery at times of low power demand. 
   In a preferred form of the present invention, the power isolation and distribution circuit  248  basically consists of a series of three interconnected diodes  250 ,  252 ,  254 . The first diode  250  has its anode connected to the positive output terminal of the power supply  238 , and its cathode connected to the positive terminal of the storage battery  234 . The second diode  252  has its anode connected to the positive terminal of the storage battery  234 , and its cathode connected to the first output of the power isolation and distribution circuit  248 , which output is connected to the power line  206  provided to the lighting distribution panel  204 . The third diode  254  has its anode connected to the positive output terminal of the power supply  238 , and has its cathode connected to the cathode of the second diode  252  and to the first output of the power isolation and distribution circuit  248 . 
   The diodes of the power isolation and distribution circuit provide isolation between the storage battery  234  and the AC-to-DC power supply  238 , and provide a larger “dead band” or buffer region to allow the storage battery to be switched into the circuit, to supply power to the lighting of other load  246 , or isolated from the circuit. The diodes  250 - 254  used in the power isolation and distribution circuit are preferably high power, silicon diodes. 
   The power isolation and distribution circuit  248 , power supply  238  and storage battery  234  work in the following manner. Assuming the storage battery is 124 volts DC, and the output of the AC-to-DC power supply is 125 volts DC, for example, then the first and third diodes  250 ,  254  are forward biased so that the potential at the first and second outputs of the power proportioning circuit is 124.3 volts each, assuming diode drops of 0.7 volts. The second diode  252  is essentially back biased and not turned on. The DC power supply  238  is supplying current to the lighting or other load  246  as well as to the storage battery  234  to charge the battery. This condition occurs during times when there is no peak power demand. 
   If, for example, the output of the AC-to-DC power supply decreases to 123 volts, then the first and third diodes  250 ,  254  of the power isolation and distribution circuit are back biased, and the second diode  252  is forward biased. Under such conditions, the storage battery  234  contributes power to the lighting or other load. This condition occurs during peak power demands. The amount of power contributed by the battery  234  to the load is substantially equal to the amount of power drawn from the utility by the customer, which exceeds the set point threshold, up to the limit of the load. 
   For example, assume that the customer demand is 750 K watts, the set point threshold is set at 800 K watts, and the lighting load controlled by the power management system of the present invention is 100 K watts. Since the customer demand is below the peak set point threshold, the lighting load of the customer will be entirely powered by the utility through the AC-to-DC converter, and the storage battery  234  is being recharged under these conditions. This can be considered a first mode of operation of the power management system. 
   Assume now that the customer&#39;s demand has increased to 850 K watts, which is 50 K watts over the 800 K watt set point threshold set in the management system. Under such conditions, the lighting load controlled by the system will draw 50 K watts of power from the utility through the AC-to-DC converter  238  and 50 K watts of power from the storage battery. Thus, there is a proportional sharing of power to the load from the utility and the storage battery to provide power to the lighting or other load. This can be considered a second mode of operation of the system. 
   If customer demand increased to 1000 K watts, which is 200 K watts above the threshold, the lighting load will be powered entirely from the storage battery and not by the utility. This is a third “uninterrupatable” mode of operation of the system. 
   Preferably, the storage battery  234  is formed from a series connection of ten, 12 volt DC batteries. One form of battery, which is suitable for use, is a sealed, maintenance free lead acid Absolyte™ series of batteries manufactured by GNB, Inc. 
   The operation of the power management system will now be described. A stochastic or recurrent peak power demand is detected by the power transducer  110 . The voltage level of the output signal from the power transducer will increase, and this increase in voltage level will be averaged over a predetermined integration period by the integrator circuit  214 . The output signal of the integrator circuit will accordingly also increase in magnitude. If the output signal level of the integrator circuit  214  is greater than the threshold signal level of either set point circuit  228 ,  232  connected to the system, the comparator or differential amplifier circuit  220  will sense this and provide an appropriate output signal to the AC-to-DC power supply  238  to reduce the power supply output voltage to below the potential of the storage battery  234 . Since the battery potential is greater than the power supply voltage, power from the battery  234  will be supplied to the load. 
   If electric power demand from the utility decreases, a corresponding decrease in the magnitude of the output signals from the power transducer  210  and the integrator circuit  214  will follow. If the output signal from the integrator circuit falls to or below the threshold level set by the set point circuits  228 , 232 , the comparator or differential amplifier circuit  220  will sense this and will provide the appropriate signal to the control input of the switching power supply  238  to increase the output voltage level of the power supply. If the supply&#39;s output voltage level is greater than the present or “spot” potential of the storage battery  234 , the load will again be fully served by the power supply, and current will also flow to the battery until the battery is fully charged. In this mode, no current will flow from the battery to the load. 
   Another form of the power management system is shown schematically in FIG.  13 . The power transducer  210  is connected to one or more of the customer&#39;s utility power lines., as shown in  FIG. 12 , and has its output connected to the non-inverting input of an operational amplifier  260  configured as a non-inverting buffer amplifier. The output of the buffer amplifier  260  is connected to one side of a differential amplifier circuit including an operational amplifier  240 , a first input resistor  243  connected between the buffer amplifier output and the non-inverting input of the operational amplifier  240 , and another resistor  245  connected between the non-inverting input of the operational amplifier and ground. The differential amplifier includes another input resistor  244  connected to the inverting input of the operational amplifier  240 , a feedback resistor  242  connected between the output and inverting input of the operational amplifier and a feedback capacitor  262  connected in parallel with the feed back resistor. The input resistors  243 ,  244  are preferably equal in value, as are the feedback resistor  242  and grounded resistor  245 , as in the previous embodiment. The feedback capacitor  262  is provided to slow the response time of the differential amplifier. 
   A manual set point threshold circuit includes a potentiometer  236  having its opposite legs connected between a positive voltage and ground and its wiper provided to the non-inverting input of an operational amplifier  264  configured as a non-inverting buffer amplifier. The output of the buffer amplifier  264  is provided to the other input resistor  244  of the differential amplifier. 
   The output of the differential amplifier is provided to a voltage-to-current converter. The voltage-to-current converter includes an NPN transistor  266 , a base resistor  268  connected between the output of the differential amplifier and the base of the transistor  266 , and an emitter resistor  270  and series connected diode  272  which together are connected between the emitter of the transistor and ground. The collector of the transistor  266  is connected to one end of a fixed resistor  274  and one end and the wiper of a multi-turn potentiometer  276 , whose other end is connected to ground. The remaining end of the fixed resistor  274  is connected to the adjust input of a series regulator  278 , such as Part No. TL783C manufactured by Texas Instruments and to one end of another fixed resistor  280  whose other end is connected to the output (OUT) of the regulator  278 . 
   As in the previous embodiment, the power management system includes an AC-to-DC converter comprising the regulator  278  mentioned previously, a full wave rectifier circuit consisting of two diodes  282 ,  284  and a conventional pi filter consisting of two by-pass capacitors  290 ,  292  and a series choke or inductor  294 , the filter circuit being connected to the output of the rectifier circuit. The output of the filter circuit is connected to one leg of a fixed resistor  296 , whose other leg is connected to the input (IN) of the regulator  278  and to the base of a PNP transistor  298  through a base resistor  100 . The emitter of the transistor  298  is connected to the output of the filter circuit, and the collector is connected to the base of an NPN power transistor  102 . A suitable power transistor  102 , which may be used, is Part No. TIPL762 manufactured by Texas Instruments. Of course, the power transistor is selected in accordance with the power requirements of the system. The collector of the power transistor  102  is connected to the emitter of its driving transistor  298  and to the output of the filter, and the emitter of the transistor  102  is connected to the output of the regulator  278 . Transistor  298  and  102  and their associated components form a current booster circuit. 
   The power management system shown in  FIG. 13  further includes an isolation and distribution circuit consisting of three interconnected first, second and third diodes  250 ,  252 ,  254  as in the previously described embodiment illustrated by FIG.  12 . The output of the regulator  278  is connected to the anodes of first and third diodes  250 ,  254 . The anode of the second diode  252  and cathode of the third diode  254  are connected to the positive terminal of a storage battery  234  used in the power management system, and the cathodes of the second and third diodes  252 ,  254  are connected to the load  246  which is powered by the system. 
   The power management system shown in  FIG. 13  operates in the following manner. When the power drawn from the utility is such that the output level of the transducer  210  is below the set point threshold level, the transistor  266  of the voltage-to-current converter is non-conducting. This effectively increases the resistance of the lower leg of a resistor divider network defined by resistor  280 , comprising the upper leg, and the combination of resistors  274  and the parallel combination of the multi-turn potentiometer  276  and the resistance of the voltage-to-current converter, which comprise the network&#39;s lower leg. Under such conditions, the voltage at the anode of the first diode  250  will be greater than the voltage at the anode of the second diode  252 , which is the voltage of the storage battery  234 . The first diode  250  will be turned on and the second diode  252  will be back biased so that power from the utility through the AC-to-DC converter, i.e., the full wave rectifier circuit, the filter and the current booster circuit, will be provided to the load  246 . 
   When the transducer  210  of the power management system senses an increase in utility power drawn by the customer, the output signal from the buffer amplifier  260  will exceed the magnitude of the output signal of the threshold signal&#39;s buffer amplifier  264 . In response, the differential amplifier will provide a positive voltage output signal, which will cause the transistor  266  of the voltage-to-current converter to conduct current. This effectively lowers the resistance of the lower leg of the resistor divider network, which in turn decreases the voltage on the anode of the first diode  250 . If the voltage on the anode of the first diode  250  decreases to a point where the second diode  252  is forward biased, current will flow from the storage battery  234  to the load. As now less power is drawn from the utility, the output voltage from the power transducer  210  will decrease, which affects the output voltage of the differential amplifier and the current drawn through the collector of the voltage-to-current converter transistor  266 . This will change the voltage on the anode of the first diode  250  to a point where there is a proportional sharing of power from the storage battery and from the utility. Thus, the power management system acts as a servo system with feedback and has a self-leveling capability. 
   As can be seen from the above description, the power management system can be easily implemented in a customer facility with little or no rewiring. Because the main distribution panel  202  is usually connected to a second, lighting distribution panel  204 , the interconnection between the two can be broken and connected to the power management system. Also, fluorescent lighting, which may represent approximately 40% of the total load for some utility customers, is a particularly attractive load to work in conjunction with the power management system. The lighting load remains fairly constant throughout the day and, therefore, the power management system parameters may be easily optimized for operating such a load. In addition, many of the electronic ballasts currently, and increasingly, used in fluorescent lighting will function on either direct current (DC) or alternating current (AC). If fluorescent lighting, either electronically ballasted or magnetically ballasted, is to be controlled by the system and powered by AC, this may be accomplished by using an inverter  110  interconnected between the output of the power isolation and distribution circuit  248  (and the negative terminal of the AC-to-DC converter  0 . 38 ) and the lighting distribution panel  204 , as shown by dashed lines in FIG.  12 . Accordingly, fluorescent and other lighting is perfectly suited for operation with the power management system. 
   With reference to  FIG. 14  note that the circuit shown largely parallels  FIG. 13  wherein rectification is effected by the diodes  282  and  284 . They feed the TEE circuit  294 ,  290 ,  292  of the voltage regulator section (so labeled) operating in conjunction with the control interface (so labeled) to output DC at the junction A. Thus, an important objective is realized, namely, that the charge level of the storage battery means SB to service an intrinsic DC load means such as  346  in  FIG. 14  or the electronically (DC) ballasted fluorescent lighting circuit FL in  FIG. 15  is maintained at the desired level. Note that the three modes of operation as disclosed in Applicant&#39;s U.S. Pat. No. 5,500,561 obtain. 
   When AC input is present, the voltage regulator function illustrated in  FIG. 14  is one means for maintaining the charge level of the storage battery means SB. contained within the module M and which is connected to the junctions J 1  and J 2 . The lighting load  346  is, of course, an intrinsic DC load means such as the looped LIGHTS circuits FL looped between the ground buss GB and the circuit breakers B 5  and B 6  which are connected to the neutral buss NB as in FIG.  15 . The photo-voltaic panel means PV and the inverter means INV are shown in FIG.  14 . It will also be understood that although the electric distribution box is not illustrated fully in  FIG. 14 , this is done for 0.5 simplicity to avoid overcrowding of the Figure. 
     FIG. 15  shows the electric distribution box EDB in simplified and uncluttered form and is principally directed to illustrating the concept of ganged circuit breakers and of looping of an intrinsic DC load means as well the use of a load source means. The box EDB is outlined and the ground buss GB, the neutral buss NB and the power buss P 2  are all designated. The DC ballasted fluorescent lighting intrinsic DC load means FL comprises an example of a distributor box DBD emanating from the box EDB. Each looping WDBD 54  and WDBD 56  is between the neutral buss NB (−DC) through the circuit breaker means B 5  and B 6  to the ground buss GB (+DC). Four electrical outlet means E 01 , E 02 , E 03  and E 04  are illustrated, all identical, with the two wirings W 20  connected with the power buss P 2  through the respective circuit breaker means B 1  and B 3 . Similarly, the two wirings W 22  are connected with the neutral buss NB through the respective circuit breaker mans B 2  and B 4 . The circuit breakers B 1  and B 2  “belong” to an AC path and a DC path, respectively, and the circuit breakers B 3  and B 4  similarly “belong”. 
   The DC power sources are illustrated as the DC generator and the photo-voltaic panel means PV which, after regulation at the regulator  440 , passes through the isolating diode D 2  to the junction A to which the positive side of the DC generator DCPS is connected through the isolating diode D 1 . The junction A is connected to the ground buss GB through the circuit breaker B 8  whereas the AC input from the inverter  450  is connected to the neutral buss NB by means of the wiring W 50  and to the circuit breaker B 7  through the wiring W 52 . The looping of the intrinsic DC load means effectively doubles the current carrying capacities of the associated wirings whereas the ganging of the AC and DC paths as to circuit breaker means allows the dual voltage aspect to be carried out with increased safety. 
   To reiterate some of the above, the modular concept of this invention is very important in that it involves the provision of separate entities which are the storage battery means SB and the filter capacitor means FC. The storage battery means SB has a very large battery equivalent capacitance consistent with an excellent AC path to ground and the filter capacitor means FC has a very small capacitance consistent with a limited AC path to ground and being sized in capacitance wherein the capacitive reactance xc is low enough to pass sufficient current to keep both the worst case fault currents well below any shock hazards and to allow sufficient current flow to trip the relevant circuit breaker(s) in the event of an appliance short circuit. As noted, the capacitance of the filter capacitor FC should be in the order of 50 microfarads. 
     FIG. 16  is directed to a circuit, which embodies a switching type converter of very high efficiency and is a preferred form of converter because this type of DC-to-DC power supply represents high efficiency contemporaneously possible.  FIG. 16  illustrates input mechanisms, some of which are not designated by reference characters but which are designated as to function, and also illustrates output mechanisms, none of which are designated by reference characters but which are designated as to function. In all such cases, the meanings should be clear and the additional descriptive material detailing the mechanisms and reference characters are believed to be unnecessary. 
   The block enclosed in dashed lines and designated by the reference character  501  is a typical full wave rectifier bridge circuit (i.e., the opposite of an inverter) feeding the capacitor  505  at the junction  501 ′ and whose purpose is to reduce the rectified ripple component of the circuit  501  and to provide filtered DC input voltage, present between the junction  501 ′ and the conductor  501   v  to the converter means. 
   The converter circuit shown, downstream of and as fed by filtered DC from the rectifier circuit  501  has junctions  521 ′ and  521 ″ within the section  521  between which the resistor/capacitor pair  521   r  and  521   c  are connected and which pair provide the further junction  521 ′″. The junction  521 ′″ is connected to the conductor  521   v  which supplies the pulse width modulator  503  with positive voltage Vcc, and this junction feeds the diode  521   d   1  having junctions with the parallel resistor/capacitor pair which are connected between the diode  521   d   2  and the junction  521 ″. 
   The converter employs a pulse width modulator PWM, indicated at  503 , controlling the switching transistor circuit  508  to impress transient voltage spikes present on the conductor  508   v  through the primary of the transformer  506  to cycle current to the primary windings L 1  and L 2  of the transformer  506  whereby “ac is generated as an intermediate process in the flow of energy” as is defined in the above definition of “converter”. The secondary side of the transformer  506  is represented by the windings L 3  and L 4 . 
   The circuit  509  is an optical isolation link between the pulse width modulator  503  and the control means  522  on the secondary side of the transformer  506  which allows control voltage on the conductor  509   v  emanating from the pulse width modulator  503  on the primary side of the transformer  506  to provide an input to the control means  522  on the secondary side to influence the pulse width modulator PWM  503  without current leakage back from the secondary circuit. Typically, the frequency of conversion effected by the transformer  506  will be 20,000-100,000 Hz, which dictates the need for the special capacitor  517  to absorb these transients, the capacitance of the capacitor  517  being typically about 1 microfarad when used. 
   A secondary winding L 4  drives the circuit  514  which, similarly t6 the rectifier  501  plus the filtering of the capacitor  505 , provides a DC output, in this case the proper DC input to the control means  522  at the conductor  514   v . The control means  522  has an output conductor  522   o  connected to the optical link  510  for controlling the three modes of operation of voltage control in accord with the principles of my prior applications. That is to say, when the optical isolator  510  link is “on”, modes which permit DC current to flow from the photovoltaic means  520  are operative, i.e., either or both DC power input from the means  520  alone and partial or shared DC power input from the means  520 . When the optical isolator  510  link is “off”, the remaining mode, DC power input solely from another source (i.e., no photovoltaic input) is effected. 
   The modes are controlled by the DC voltage prevailing across the junctions J 1  and J 2  (or the presence of a rechargeable DC mechanism such as a storage battery means connected to these junctions) in which case, mode  1 , DC power input to the rechargeable DC mechanism alone, mode  2 , shared DC power input, and mode  3  no DC power input to the rechargeable DC mechanism are the order of the day. That is to say, when the conductors  523  and  524  are connected to one of the DC sources illustrated in  FIG. 16 , or to a DC power source such as DCPS in  FIG. 15 , the system will be fully operative for the purposes intended. 
   Stated another way, the DC voltage applied to the storage means will depend upon the feedback influenced by the resistors  336 ,  342 ,  343 ,  344 ,  345 ,  368 ,  370 ,  374  and  376  in  FIG. 14  or by the resistors including  511 ,  512 ,  513  and  515  in FIG.  16 . 
   This is true even if the system according to this invention is operated on the barest of input. For example, in locations where either AC or DC power is available only part of the time, or is available on site only from mechanism thereat, some configuration disclosed in the drawing Figures herein will be effective to provide DC power supply to the storage battery means. This, therefore, constitutes a universal power system. 
   Other modifications may be made to the present invention without departing from the scope of the invention, as noted in the appended claims.