Abstract:
A transfer mechanism is provided for transferring the supply of power between a generator and utility source. The transfer mechanism includes a monitoring system for monitoring the power supplied by the utility source. The monitoring system starts the generator in response to a power outage from the utility source and stops the generator in response to the restoration of power from the utility source. A power relay has a utility input connectable to the utility source, a generator input connectable to the generator, an output connectable to a load, and a movable contact for selectively interconnecting one of the inputs to the output in response to the generation of power by the generator.

Description:
FIELD OF THE INVENTION 
     This invention relates to stand-by generators, in particular, to a transfer mechanism for transferring the supply of power between a utility source and a stand-by generator. 
     BACKGROUND OF THE INVENTION 
     As is known, virtually all facilities which utilize electric power receive such power from a utility company. Typically, such utility companies have an excellent record of providing uninterrupted or infrequently interrupted power at proper voltage levels and line frequency. However, due to the increasing demands for power, power outages have become more frequent. While such outages usually last for a only a short duration, an extended power outage may cause more than simple aggravation for customers of the utility company. By way of example, for a residential customer, any power outage renders a home owner&#39;s sump pump inoperable. If a power outage occurs during a rain storm, it is quite possible that the failure of the sump pump to operate will result in the flooding of a home owner&#39;s basement. 
     In order to overcome these occasional disruptions in service, various customers, including home owners, have equipped their facilities with stand-by power systems. These stand-by power systems include internal combustion engines which drive electrical generators. If the commercial power from the utility company fails, the internal combustion engine is automatically started causing the electrical generator to generate power. When the power generated by the generator reaches the voltage and frequency desired by the customer, a manually operated transfer switch transfers the load imposed by the customer from the commercial power lines to the generator. 
     Typically, the transfer mechanism incorporates a switch which isolates the power supplied by the utility company and the generator. In a residential application, a home owner manually flips a switch between the utility source and the generator in order to provide power to the electrical system of the home. However, due to a potential time delay before the home owner can flip the switch, a significant amount of damage may be sustained by a home owner before power is supplied to the electrical system of the home. For example, an extended power outage may result in foodstuffs spoiling within a refrigerator or melting within a freezer. Therefore, it is highly desirable to provide a transfer mechanism which automatically transfers power from the utility company to the generator whenever the generator is activated. 
     Further, prior art transfer mechanisms require a home owner to transfer the entire electrical system of the home onto the generator. Such an arrangement does not allow a home owner the ability to decide which circuits of a home&#39;s electrical system to be powered. As such, it is also desirable to provide a transfer mechanism which allows various branch circuits of a home to be brought on line separately, rather than at once, to allow for loads with large starting requirements to be brought up to speed before bringing the other circuit branches of the home on line thereby insuring that adequate power is provided by the generator to start such loads. 
     Therefore, it is a primary object and feature of the present invention to provide a transfer mechanism for transferring power between a utility source and a stand-by generator. 
     It is a further object and feature of the present invention to provide a transfer mechanism which automatically transfers power from the utility source to the generator in response to a power outage. 
     It is a still further object and feature of the present invention to provide a transfer mechanism for transferring power between a utility source and a generator which allows for the bringing of individual circuit branches of a home electrical system on line separately. 
     It is a still further object and feature of the present invention to provide a transfer mechanism which is simple to install and inexpensive to manufacture. 
     SUMMARY OF THE INVENTION 
     An improvement in a transfer mechanism for transferring the supply of power to a load between a generator which generates power when started, and a utility source is provided. The transfer mechanism monitors the power supplied by the utility source and starts the generator in response to a power outage from the utility source. The improvement comprises a relay having a utility input operatively connected to the utility source, a generator input and a coil operatively connected to the generator, and an output operatively connected to the load. The inputs are selectively connected to the output in response to the application of power to the coil by the generator. 
     It is contemplated to provide a circuit breaker to interconnect the generator to the generator input of the relay. The circuit breaker includes a first setting which isolates the generator input from the generator and a second setting which protects the relay against an overload by the generator. The relay may include a movable contact which is movable between a first position which interconnects the utility input and the output and a second position which connects the generator input and the output. In response to the application of power to the coil, the movable contact moves into the second position. 
     The relay may also include a time delay switch interconnecting the generator and the coil of the relay. The time delay switch delays application of power through the coil so as to delay movement of the movable contact to the second position. The relay may also include a second utility input operatively connected to the utility source, a second generator input and a second coil operatively connected to a generator, and a second output operatively connected to the second load. The second inputs are selectively connected to the second output in response to application of power to the second coil by the generator. 
     In accordance with a still further aspect of the present invention, a transfer mechanism is provided for transferring a supply of power between a generator and a utility source. The transfer mechanism includes a monitoring system for monitoring the power supplied by the utility source. The monitoring system starts the generator in response to a power outage from the utility source and stops the generator in response to the restoration of the power from the utility source. An electromagnetic switch is also provided. The electromagnetic switch includes a utility input connectable to the utility source, a generator input connectable to the generator, an output connected to a load, and a movable contact for selectively interconnecting one of the inputs to the output in response to the generation of power by the generator. 
     A generator circuit breaker interconnects the generator to the generator intput of the electromagnetic switch. The generator circuit breaker has a first setting which isolates the generator input from the generator and a second setting which protects the electromagnetic switch from an overload by a generator. The movable contact is movable between a first position interconnecting the utility input and the output and a second position interconnecting a generator input and output. A selection structure is provided for moving the contact between the first and second positions. The selection structure includes the coil operatively connected to the generator. The coil urges the movable contact to the second position in response to the generation of power by the coil. When a generator is stopped, the selection structure urges the movable contact to the first position. A time delay switch interconnects the generator and the coil of the electromagnetic switch. The time delay switch delays the supply of power to the generator to the load at the starting of the generator by the monitoring system. 
     It is contemplated to provide a utility circuit breaker to interconnect the utility source to the utility input of the electromagnetic switch. The utility circuit breaker has a first setting which isolates the utility input from the utility source and a second setting which protects the electromagnetic switch against the overload from the utility source. A second electromagnetic switch may also be provided. The second electromagnetic switch includes a second utility input connectable to the utility source, a generator input connectable to the generator, an output connected to a second load, and a movable contact for selectively interconnecting one of the second inputs to the output in response to the generation of power by the generator. 
     In accordance with a still further aspect of the present invention, a transfer mechanism is provided for transferring the supply of power between a generator which generates power when started and a utility source. The transfer mechanism includes a monitoring system for monitoring the power supplied by the utility source. The monitoring system starts the generator in response to a power outage from the utility source and stops the generator in response to the restoration of power from the utility source. A plurality of relays are also provided. Each relay includes a utility input; a generator input; an output connectable to a corresponding load; a movable contact movable between a first position interconnecting the utility input and the output and a second position interconnecting the generator input and the output; and a coil connectable to the generator. The coil urges the movable contact into the second position in response to the generation of power by the generator. A plurality of generator circuit breakers and utility circuit breakers are also provided. Each generator circuit breaker interconnects the generator to the generator input of a corresponding relay. Each utility circuit breaker interconnects the utility source to the utility input of a corresponding relay. 
     A plurality of time delay switches interconnect the generator and the coil of a corresponding relay so as to delay the power from the generator to each load when the generator is started. Each time delay switch delays the supply of power to each load for a predetermined period of time such that power is supplied to each load in a predetermined sequential order. 
     Each relay may also include a biasing structure for biasing the movable contact towards the first position. Further, at least one of the relays may be include a second utility input; a second generator input; a second output connectable to a corresponding load; a second movable contact movable between a first position interconnecting the second utility input and the second output and a second position interconnecting the second generator input and the second output; and a second coil connectable to the generator. The second coil urges the second movable contact into the second position in response to the generation of power by the generator. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings furnished herewith illustrate a preferred construction of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description of the illustrated embodiment. 
     In the drawings: 
     FIG. 1 is an isometric view of an enclosure for a housing transfer mechanism in accordance with the present invention; 
     FIG. 2 is a front elevational view, with its cover removed, of the enclosure of FIG. 1; 
     FIG. 3 is a wiring diagram of the transfer mechanism of the present invention; 
     FIG. 4 is a schematic diagram of a first embodiment of the transfer mechanism of the present invention; and 
     FIG. 5 is a schematic view of a second embodiment of the transfer mechanism of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 2 and 3, a transfer mechanism in accordance with the present invention is generally designated by the reference numeral  10 . It is contemplated that the transfer mechanism  10  be mounted within a housing  12 , FIGS. 1 and 2. Housing  12  includes a cabinet  14 . Cabinet  14  defines a pair of sidewalls  16  and  18 , a top wall  20  extending between upper ends of sidewalls  16  and  18 , a bottom wall (not shown) extending between and interconnecting the lower ends of sidewalls  16  and  18 , and a rear panel  22 . Upper and lower mounting flanges  24  and  26  project from opposite ends of rear panel  22  of cabinet  14  and include apertures  28  therein for allowing cabinet  14  to be mounted on a wall within the interior of a building via screws or the like. 
     Housing  12  further includes a cover  30  defined by a pair of sidewalls  32 , a top wall  34  extending between the upper ends of sidewalls  32 , a bottom wall (not shown) extending between and interconnecting the lower ends of sidewalls  32 , and a front panel  36 . The front panel  36  of cover  30  includes an opening  38  therein so as to allow for a plurality of circuit breakers project therethrough, as hereinafter described. Cover  30  may be positioned on cabinet  14  to limit access to transfer mechanism  10  contained therein. 
     Referring to FIG. 4, transfer mechanism  10  is interposed between a utility source  42  and a stand-by generator  44 . As is conventional, utility source  42  is interconnected to ground  46  through line  48  and supplies ±120 volts across lines  50  and  52 . Lines  50  and  52  are connected to a main circuit breaker  54  within a main distribution panel located in the interior of a building. As is conventional, two bus bars  56  and  58  are connected to main circuit breaker  54 . A plurality of single pole circuit breakers  60  and  62  are interconnected to bus bar  58 . Similarly, a plurality of single pole circuit breakers  64  and  66  are interconnected to bus bar  56 . Circuit breakers  60 ,  62 ,  64  and  66  are operatively connected to corresponding individual branch circuits within the building which requires 120 volt service, in a manner hereinafter described. A double pole circuit breaker  68  may be attached to both bus bars  56  and  58 . Circuit breaker  68  is operatively connected to a corresponding individual branch circuit which requires 240 volt service, in a manner hereinafter described. 
     As best seen in FIGS. 3-4, circuit breakers  60  and  64  are interconnected to normally closed contacts  70  and  76 , respectively, of a first double pole, double throw power relay  77  through corresponding lines  78  and  84 , respectively. Circuit breakers  62  and  66  are interconnected to normally closed contacts  72  and  74 , respectively, of a second double pole, double throw power relay  79  through lines  80  and  82 , respectively. Double pole circuit breaker  68  is interconnected to normally closed contacts  88  and  90  of a third double pole, double throw power relay  92  through corresponding lines  94  and  96 , respectively. Referring to FIGS. 2 and 3, it is contemplated to mount a terminal block  86  to rear panel  22  of cabinet  14  in order to facilitate the connecting of the circuit breakers to the power relays. 
     As is conventional, circuit breakers  60 ,  62 ,  64 ,  66 , and  68  may be toggled between off-positions wherein the corresponding power relays  77 ,  79  and  92  are isolated from utility source  42  and on-positions wherein the corresponding power relays  77 ,  79  and  92  are protected from the potential overload by utility source  42 . 
     Generator  44  is interconnected to ground  100  through line  102 , and supplies ±120 volts across lines  104  and  106 . Lines  104  and  106  are connected to corresponding bus bars  108  and  110 , respectively, which are mounted to rear panel  22  of cabinet  14 . A plurality of single pole circuit breakers  114  and  116  are interconnected to bus bar  108 . Similarly, a plurality of single pole circuit breakers  118  and  120  are interconnected to bus bar  110 . Circuit breakers  114 ,  116 ,  118 , and  120  are operatively connected to corresponding individual branch circuits within the building which require 120 volt service, in a manner hereinafter described. A double-pole circuit breaker  122  is interconnected to both bus bars  108  and  110  and is operatively connected to a corresponding individual branch circuit within the building which requires 240 volt service, in a manner hereinafter described. 
     Circuit breakers  114  and  118  are interconnected to normally opened contacts  124  and  126 , respectively, of power relay  77  by corresponding lines  128  and  130 , respectively. Circuit breakers  116  and  120  are interconnected to normally open contacts  132  and  134 , respectively, of power relay  79  through corresponding lines  136  and  138 , respectively. Double-pole circuit breaker  122  is interconnected to normally open contacts  140  and  142  of relay  92  through corresponding lines  144  and  146 , respectively. 
     As is conventional, circuit breakers  114 ,  116 ,  118 ,  120  and  122  may toggle between off-positions wherein the corresponding power relays  77 ,  79  and  92  are isolated from generator  44  and on-positions wherein the corresponding power relays  77 ,  79  and  92  are protected from potential overload by generator  44 . 
     Power relay  92  includes a magnetic coil K 1  having terminals A and B. Terminal A of power relay  92  is interconnected to normally open contact  140  by line  150 . Terminal B of power relay  92  is interconnected to normally open contact  142  by line  152 . Similarly, power relays  77  and  79  include corresponding magnetic coils K 3  and K 2 , respectively, having terminals A and B. Terminal A of power relay  79  is interconnected to normally open contact  132  by line  154 . Terminal B of power relay  79  is interconnected to normally opened contact  134  by line  156 . Likewise, terminal A of power relay  77  is interconnected to normally open contact  124  by line  158  and terminal B of power relay  77  is interconnected to normally open contact  126  by line  160 . 
     The common terminals  162  and  164  of power relay  77  are connected by lines  166  and  168 , respectively, to corresponding individual branch circuits within the building which require 120 volt service. Common terminals  170  and  172  are interconnected by lines  174  and  176 , respectively, to corresponding individual branch circuits within the building which also require 120 volt service. Common terminals  178  and  180  of power relay  92  are interconnected by lines  182  and  184 , respectively, to a corresponding branch circuit within the building which requires 240 volt service. Referring to FIGS. 2 and 3, it is contemplated to mount a terminal block  186  on rear panel  22  of cabinet  14  in order to facilitate connecting of the common terminals of the power relays to various loads. 
     Under normal operating circumstances, main circuit breaker  54  and circuit breakers  60 ,  62 ,  64 ,  66  and  68  are toggled to their on-positions. Movable contacts  190  and  192  of power relay  77  are engaged with normally closed contacts  70  and  76 , respectively; movable contacts  194  and  196  of power relay  79  are engaged with normally closed contacts  72  and  74 , respectively; and movable contacts  198  and  200  of power relay  92  are engaged with normally closed contacts  88  and  90 , respectively. As described, utility source  42  provides power on lines  50  and  52  to corresponding loads. 
     As best seen in FIG. 4, monitoring circuit  188  is operatively connected to the utility source  42  and generator  44 . As is conventional, monitoring circuit  188  monitors the power supplied by the utility source  44 . In response to a power outage from the utility source  42 , monitoring circuit  188  starts the internal combustion engine of the generator  44 . As heretofore described, a starting of the internal combustion motor causes the electrical generator of generator  44  to generate electrical power across lines  104  and  106 . 
     With circuit breakers  114  and  118  toggled to their on-positions, current flows through magnetic coil K 3  of power relay  77  such that the magnetic coil K 3  becomes magnetized and attracts movable contacts  190  and  192  within power relay  77 , As a result, movable contacts  190  and  192  disengage from normally closed contacts  70  and  76 , respectively, and close against corresponding normally open contacts  124  and  126 , respectively, so as to operatively connect corresponding loads to generator  44 . 
     With circuit breakers  116  and  120  toggled to their on-positions, current flows through magnetic coil K 2  of power relay  79  such that the magnetic coil K 2  becomes magnetized and attracts movable contacts  194  and  196  within power relay  79 . As a result, movable contacts  194  and  196  disengage from normally closed contacts  72  and  74 , respectively, and close against corresponding normally open contacts  132  and  134 , respectively, so as to operatively connect corresponding loads to generator  44 . 
     With circuit breaker  122  toggled to its on-position, current flows through magnetic coil K 1  of power relay  92  such that the magnetic coil K 1  becomes magnetized and attracts movable contacts  198  and  200  within power relay  92 . As a result, movable contacts  198  and  200  disengage from normally closed contacts  88  and  90 , respectively, and close against corresponding normally open contacts  140  and  142 , respectively, so as to operatively connect a corresponding load to generator  44 . 
     In response to the restoration of power from utility source  42 , monitoring circuit  188  stops the internal combustion engine of the generator  44 . By stopping the internal combustion engine, the electrical generator of generator  44  no longer generates power across lines  104  and  106  and current ceases to flow through magnetic coils K 1 , K 2  and K 3  of power relays  92 ,  79  and  77 , respectively. As a result, movable contacts  190  and  192  of power relay  77  disengage from normally open contacts  124  and  126 , respectively, and reclose against corresponding normally closed contacts  70  and  76 , respectively, so as to operatively connect corresponding loads to utility source  42 . 
     Similarly, movable contacts  194  and  196  disengage from normally open contacts  132  and  134 , respectively, and reclose against corresponding normally closed contacts  72  and  74 , respectively, so as to operatively connect corresponding loads to utility source  42 . In addition, movable contacts  198  and  200  disengage from normally open contacts  140  and  142 , respectively, and reclose against corresponding normally closed contacts  88  and  90 , respectively, so as to operatively connect a corresponding load to utility source  42 . Thereafter, monitoring system  188  continues to monitor the power supplied by the utility source  44  and repeats the above-described process if a power outage from utility source  42  is detected. 
     Referring to FIG. 5, an alternate embodiment of the transfer mechanism is shown. The alternate embodiment of the transfer mechanism is generally designated by the reference numeral  202 . Transfer mechanism  202  is identical in structure to transfer mechanism  10  with the exception of time delay switches  204 ,  206  and  208  as hereinafter described. As such, common reference characters will be utilized. 
     In order to sequentially bring the various loads on line with generator  44 , a first time delay switch  204  is positioned between magnetic coil K 1  of power relay  92  and normally open contact  140 ; a second time delay switch  206  is positioned between magnetic coil K 2  of power relay  79  and normally open contact  134 ; and a third time delay switch  208  is positioned between magnetic coil K 3  of power relay  77  and normally open contact  126 . As generator  44  is started as heretofore described, time delay switches  204 ,  206  and  208  are normally open so as to prevent the flow of current through magnetic coils K 1 , K 2  and K 3 , respectively. Thereafter, time delay switches  204 ,  206  and  208  are sequentially closed over a predetermined time period in order to allow for the flow of current through corresponding magnetic coils K 1 , K 2  and K 3 , respectively. As current flows through each magnetic coil K 1 , K 2  and K 3 , various loads are operatively connected to generator  44  in the matter heretofore described with respect to transfer switch  10 . 
     Further, in the second embodiment, it can be appreciated to utilize DC control relays in place of power relays  77 ,  79  and  92  and driving them directly using staggered delays. 
     Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.