Abstract:
An emergency power station for traffic signal controllers having a general utility power supply, the emergency power station having a small footprint cabinet containing a fuel supply in a lowermost compartment, an engine and an electrical generator in a middle compartment, and a power station controller box in an uppermost compartment, the power station controller box having a power circuit connected to the utility power supply, the electrical power generator and the traffic signal controller, the power circuit including an activatable power switch selectively connecting the utility power supply or the power generator to the traffic signal controller, the power station controller box also including a control circuit with a power line monitor and a programmable timer system for sensing a power loss in the utility power supply, and, after a predetermined delay, activating the engine and switching the switch connecting the traffic signal controller to the power generator.

Description:
This application is a continuation-in-part of our application Ser. No. 09/065,231 filed Apr. 15, 1998, of the same title, now U.S. Pat. No. 6,094,130, issued Jul. 25, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to an emergency power station and in particular to a stand-by electrical power installation that is self-activated during a power outage. The stand-by power installation has particular application for traffic control signals where a power failure may have serious consequences. In such an environment, the power station is unattended and subject to the elements including potential vandalism. Therefore, a power station of this type must comprise a stand-alone unit that has a protective housing and occupies minimal space, particularly in the intended preferred use as an auxiliary power supply for traffic control signals. 
     In any traffic management system, it is often critical to maintain traffic control at certain intersections or locations in the event of a municipal power failure. Ordinarily, when a power failure occurs, a traffic officer may be dispatched to the location of the signal failure to maintain the orderly flow of traffic, until the municipal power is resumed, or, in the case of a back-up system, a portable power generator is brought to the scene and connected to the control signals. 
     In addition to the substantial use of man-power under emergency conditions that may be pervasive during a power outage, there is an unavoidable delay before orderly control can be established. During this time an accident may occur that may cause serious injury, or at least, further add to the congestion that inevitably results from the operational failure of traffic control signals. 
     The advantage of a permanent, on-site, back-up power station is evident. However, to solve the problem of delay in attending to the outage, the emergency power station must be intelligent and able to activate itself when the power outage occurs, and deactivate when the primary power is resumed. 
     SUMMARY OF THE INVENTION 
     The emergency power station of this invention is an intelligent auxiliary power supply for an outdoor installation where a prompt supply of emergency power is required for traffic intersection controller backup. 
     The emergency power station of this invention includes an internal combustion engine coupled to a generator mounted in a frame over a fuel tank. Mounted in the frame above the engine is a control box that includes the power switching circuitry and the control circuity for sensing a utility power failure, activating the operation of the engine and switching the connected traffic control signals from electrical connection with the primary power source of the municipal or utility power network to electrical connection with the auxiliary power generated by the engine and generator. 
     The emergency power station of this invention is self-contained in a tamper-proof cabinet with the components arranged in a vertical stack to minimize the effective footprint of the plant. 
     Additionally, the emergency power station includes a control system allowing manual testing in different modes of operation and a programmable timer system to allow a predetermined delay to occur prior to switching from utility power to generator power and/or back from generator power to utility power. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a typical traffic signal control system with the added emergency power station. 
     FIG. 2 is a perspective view of the emergency power station with cabinet panels removed showing an engine, a generator, a fuel tank and a power station controller box. 
     FIG. 3 is a partial front view of the power station controller box with the door of the box in an open position. 
     FIG. 4 is an electrical schematic of the generator control circuitry. 
     FIG. 5 is an electrical schematic of the power switch and control panel. 
     FIG. 6 is an electrical schematic of the engine control circuitry. 
     FIG. 7 is a perspective view of an alternate embodiment of the emergency power station with an improved air supply and exhaust system. 
     FIG. 8 is a front elevational view of the alternate embodiment of the emergency power station of FIG. 7 with the panel door removed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the perspective view of FIG. 1, the emergency power station for traffic control signals is designated generally by the reference numeral  10 , and shown with a typical traffic control signal  12 , a traffic signal controller in the form of a signal control box  14  and a utility meter pedestal  15 . The traffic control signal  12  is representative of one of multiple control signals at a street intersection and is shown mounted on a sidewalk  16  next to a street  18 . 
     The control box  14  is connected to the municipal or utility power source supplied to the utility pedestal  15  and regulates the timed operation of the intersection control lights  19  on a traffic control signal  12 , one of which is shown in FIG.  1 . Typically, the control box  14  includes a vandal-proof cabinet  20  with a locked access door  22  to restrict access to an internal control panel (not shown) to only authorized personnel. The signal control box  14  is electrically connected to the control signal  12  and other control signals serviced by the control box by underground wiring in a conduit  24  shown in dotted line. A meter  25  on the utility meter pedestal  15  records the power supplied to the signal control box  14  through the emergency power station  10  including any incidental power used in the power station  10 . 
     The emergency power station  10  has a similar vandal-proof and rodent resistant cabinet  26  with a front access door  28  having a lock  30  to restrict access to authorized personnel. The emergency power station  10  is designed to be housed in a tall protective cabinet to maintain a relatively small footprint, since it is preferred that it occupy minimal space on a sidewalk or street island where it is intended to be located. Preferably, the power station  10  is electrically connected to the control box  14  and utility pedestal  15  by cables in underground conduit  24  and  31  shown in dotted line. Any above ground connection should be made using a protective grounded casing or conduit to prevent any uncontrolled discharge in the event of an accidental collision by a vehicle. 
     Referring also to FIG. 2, the emergency power station  10  is shown with front and side panels  32 ,  34  of the cabinet  26  removed to reveal the vertical, tiered arrangement of the components necessary to provide the small footprint required for intended use. The emergency power station has a frame  36  formed of box tube welded to provide three compartments  38 ,  40  and  42 . The lowermost compartment  38  contains a rectangular fuel tank  44  with a fuel fill spout  43  and vent cap  46 , a fuel gauge  48  for visual inspection of the fuel supply and a ½″ threaded port  45  for a 120-V tank heater  49 , shown in dotted line. The fuel fill spout  43  and vent cap  46  are located at the front of the cabinet  26  for convenient access when the cabinet door  28  is opened. The fuel tank  44  has tabs  51  bolted to the bottom cross members  53  of the frame  36 . Locating the fuel tank at the bottom of the cabinet prevents a fuel spill from contaminating the other components and causing a potential fire. 
     Above the fuel tank is the compartment  40  that contains the thermal engine  50 , engine battery  52  and auxiliary components related to engine operation. The engine is preferably a diesel engine, which uses the less volatile and safer diesel fuel instead of gasoline for operation. The diesel engine  50  shown, is a compact, Power Tech Model 1DL8000 with an integral oil pan  56 . The engine  50  can develop 8 KW of power from a mechanically coupled generator  58 . Depending on the power requirements of the installation, a larger or smaller engine/generator combination can be utilized. Additionally, other engine types can be substituted. For example, a natural gas engine with a natural gas or propane cylinder in the lowermost compartment is suitable for certain installations. 
     The engine battery  52  is located in front of the coupled diesel engine  50  for convenient removal and positioned to one side of the cabinet to allow clear access to the fill spout  43 . The battery  52  is a conventional heavy duty, twelve-volt vehicle battery that provides the electrical power to start the engine and the basic d.c. power for the engine operating circuits. The generator  58  has a control panel  60  with a start switch  62  for manually starting the engine during testing or periodic service operations. The generator control panel  60  is an integral component of the engine/generator combination and includes a meter  64  for recording the hours of engine operation. The engine  50  has a cooling system with a radiator  66  situated at the side of the frame  36  and aligned with a protective grate  68  on the side panel  34  of the cabinet  26  for passing air into the cabinet, as shown in FIG.  1 . Exhaust from the engine is discharged through a critical grade exhaust silencer  70  in the upper compartment  42  and through a vent pipe  72  with a hinged vent cap  74  at the top of the cabinet  26 . 
     The upper compartment  42  of the frame  36  contains the power station controller box  76  with a door panel  78  providing the mount for the basic operating controls  80  for setting the mode of operation of the system. The power station controller box  76  is shown in FIG. 3 with the door panel  78  opened to show the internal components that control the switching from line power to emergency generator power. 
     The front of the door panel  78  has a red panel light  82  signaling that the load is connected to the emergency power station, and a green panel light  84  signaling that the load is connected to the normal line supply. Additionally, the front of the door panel has a voltmeter  86  and a voltmeter selector switch  88  for selecting polarity and voltage depending on the installation hookup. The selector switch  88  has an “off” position for deactivating the voltmeter  86 . A generator control switch  90  has three static positions including “off”, “off”, for automatic activation of the emergency power, and “test” for manual activation where the engine and system can be tested by a service operator. Twisting the switch  90  to a spring-loaded forth position and holding, will start the engine in the manner of an ignition switch. When released the switch returns to “test” with the engine running. 
     On the back of the door panel  78 , as shown in FIG. 3, the described components are similarly numbered. Also mounted on the back or inside of the door panel  78  is a switch controller  94 , which includes a programmable procession that allows a delay to be programmed from the cut-off of line voltage to the activation of emergency power and/or delaying the switch from emergency power back to normal line power. 
     This provides the option of delaying the change to emergency power where interruption of power may be temporary, avoiding an unnecessary start of the engine. Similarly, this prevents a or premature shut down where the return of line power is momentary. A timer control  92  also provides a real time clock for programming periodic startup of the engine at pre-determined intervals to insure systems are at ready. Also mounted on the door panel  78  are the switch controller  94  and a switch plate  96  with three toggle switches  98 ,  100 ,  102  and one push button switch  104 . The toggle switch  98  sets the exercise mode with load or without load. The toggle switch  100  sets the transfer mode with load or without load. The toggle switch  102  sets the inhibit transfer to normal as “on” or “off”. The push button switch  104  effects the re-transfer to normal immediately on pushing. 
     In this manner, various options are available for testing and operation and depend on whether an operator is present. For example, pre-programmed periodic testing may be designed simply to exercise the engine without interfering with the normal line connection to the load. In such instance switch  98  would be set to exercise without load and switch  100  might also be set to transfer without load if the transfer protocol is to be tested without effecting an actual transfer. The inhibit transfer to normal may be set to “on” where resumption of line power is erratic. The push button switch  104  is used when an operator is confident that the line power has resumed and further interruption is unlikely, allowing a programmed delay in returning to line power to be overridden. 
     The controller box  76  in the emergency power station contains the transfer switch unit  106  which is mounted next to the battery charging unit  108 . The transfer switch unit  106  includes a 100 AMP, two pole, power transfer switch  109  from ASCO and the auxiliary components needed to reversibly switch the load from line power to emergency power. Emergency power is generated by the activated engine and generator under control of the switch controller  94 . The transfer switch unit  106  and the switch controller  94  are electrically interconnected by wires in a number of wire harnesses  110  with a bank of circuit breakers  112  interposed to protect the control circuitry from momentary overloads, and to allow disconnecting of protected loads for testing, servicing or replacement. Adjacent the bank of circuit breakers is a terminal rail  114  for routing the wiring, and an electrical outlet  115  for tapping power at the power station for use with auxiliary equipment. 
     The battery charging unit  108  includes a charge regulation circuit and a meter  116  with a switch  118  for activating the charging unit  108 , meter  116  and indicator lights  120  for signaling that the charging unit is on. The battery charging unit  108  insures that the battery  52  maintains a full charge whether emergency power is activated or not. Power for charging is drawn from the municipal or utility line, or from the emergency generator  58  after starting the engine. 
     The electric circuit diagrams of FIGS. 4-6 detail the circuitry of the. power system. Referring to FIG. 4, the generator  58  is schematically illustrated with output leads L 1 , L 2  and N, which is grounded neutral. The output leads connect to the power transfer switch unit  106  for supplying power to a load such as the traffic signal  12  of FIG. 1 in the event of a line failure. The generator start contacts  113  are connected through the terminal rail  114  to the terminals  124  of the switch controller  94  shown in the wiring diagrams of FIGS. 5 and 6. The four position generator control switch  90  is interposed between the terminal rail  114  and the terminals  124  of the switch controller. The terminal rail  114  also connects the battery charger  108  to the battery  52  under protection of a diode  126 . 
     Referring to FIG. 5, the transfer switch unit  106  is a component manufactured by ASCO, and is rated at 100 amps and is connected to the switch controller  94  by the harness  110  and the generator control switch by lines  128 . The switch controller  94  is also manufactured by ASCO and includes the terminals  124  connecting the load indicator lights  82  and  84  on the door panel  78  of FIG.  2  and the toggle switches  98 ,  100  and  102  and push button switch  104  on the switch plate  96 . 
     Referring to the power circuit schematic of FIG. 6, the transfer switch unit  106  connects to the utility power by lines  130  and to the load, for example the traffic signals, by lines  132 . The circuit breakers  114  (CBI-CB 4 ) protect the auxiliary components including the battery charging unit  108 , the electronic timer control  92 , the voltmeter  86  and a block heater  134  that maintains the engine  50  in condition for a cold start. The generator  58  has integral pole breakers  136  protecting the connection with the transfer switch unit  106 . 
     The transfer switch unit  106  has a switch coil  140  that operates under control of internal circuitry in the switch controller  94  that senses power or the absence thereof in the utility line  132 . Depending on the settings of the delay switches, the switch controller  94  immediately, or after a set delay, activates the switch coil  140  to switch the power switch  109  transferring the power supply from utility power to emergency power or vice versa. 
     In operation, the emergency power station  10  of this invention is designed for placement at a remote site for automatic start-up upon failure of the utility power. Because power interruption may be temporary, the power station of this invention includes the delay circuit that is programmable to set a desired time delay before start-up in the event of a momentary power failure. The set time delay can also be applied. to the power station shut-down phase, so that a momentary utility power resumption will not cut the emergency power generation. 
     The unique vertical design of the power station provides a small footprint allowing the power station to be installed on a sidewalk or traffic island. 
     Referring now to FIG. 7, an alternate embodiment of the emergency power station is shown and designated generally by the reference numeral  150 . The emergency power station  150  includes the same components as the emergency power station  10  of FIG.  1 . However, the emergency power station  150  of FIG. 7 includes an improved air supply and exhaust system in a compact unit that reduces the height while maintaining the same essential footprint as the embodiment of FIG.  1 . The emergency power station  150  includes an external cabinet  152  having a front panel door  154  with an identical back door  156  for access to the internal compartment  158  of the cabinet  152 . 
     The cabinet  152  houses the diesel generator engine  160 , the engine and generator control components  162  in a top sub-compartment  164  above a bottom compartment  166  as shown in FIG.  8 . The sub-compartments  164  and  166  are separated by a shelf  168 . In the bottom compartment  166  is a transfer panel  170  and a double wall fuel tank  172 . In operation, the emergency power station  150  operates in a manner similar to the emergency power station  10  previously described. 
     To improve the all-weather functioning of the emergency power station  150 , the cabinet  152  has a sloped canopy  174  with overhanging front and rear angled eaves  178 . The front and rear eaves  178 , as shown in the broken away portion include an opening  180  with a L-shaped screen  182  having vertical and lower horizontal segments (not visible) to allow air intake under the eaves  178 . The opening  180  under the eaves  178  supplies the combustion process air and engine cooling air for the diesel generator engine  160 . 
     The diesel generator engine  160  has a typical air intake for internal combustion of fuel supplied from the fuel tank  172 . As shown schematically in FIG. 8, arrows depict air flow with the air entering under the eaves and directed at the diesel generator engine  160 . The majority of the air flows over the engine  160  and through a radiator  186  with an overflow bottle  187 , forced by a push fan  188  behind the radiator as shown in dotted line. The radiator  186  contains a liquid coolant circulated to the engine  160  and is equipped with an overflow bottle  189 . 
     Coupled to one side  190  of the cabinet  152  is an exhaust housing  192 . The exhaust housing  192  is preferably provided with a separate casing  194  attached to the cabinet  152  that extends from the front to back of the cabinet  152 . The exhaust housing  192  includes a double-walled exhaust compartment  196  into which forced air enters through an interconnecting passage  198  from the upper compartment  164  of the cabinet  152 . Within the exhaust compartment  196  is an horizontally positioned cylindrical exhaust muffler  200  connected at one end to an engine exhaust pipe  202  and at the other end to a discharge pipe  204 . The discharge pipe  204  includes a flap  206  at its discharged end  208  for discharging exhaust gases into the top of the compartment  196  to mix with the forced air from the upper compartment  164  of the cabinet  152 . The mixed gases then pass through a covering screen  210  at the top of the exhaust housing  192 . The covering screen  210  extends the depth of the housing  192  allowing the mixture of forced air and engine exhaust to pass to the atmosphere as shown. In this manner the exhausted engine gases at the top screen  210  of the housing  192  are substantially reduced in temperature with the exhaust compartment  196  functioning as a heat exchanger for the muffler  200  and exhaust pipe  204 . 
     Although the upper compartment  164  is not hermetically sealed from the lower compartment  166 , the panel door  154  includes a louvered and screened vent plate  212  to supplement air flow through the cabinet  152 . Additionally, as shown in FIG. 7, the doors  154  have a top and bottom locking mechanism  214  to restrict access to the internal components of the cabinet  152 . 
     The design of the air supply and exhaust system allows for a well ventilated cabinet with adequate air supply for operation of the engine. In addition, the air supply and exhaust system of the alternate embodiment is operable in inclement conditions including deep snow with exhausted gases reduced in temperature to prevent inadvertent injury by contact with hot combustion gases or heated structural components. 
     While, in the foregoing, embodiments of the present invention have been set forth in considerable detail for the purposes of making a complete disclosure of the invention, it may be apparent to those of skill in the art that numerous changes may be made in such detail without departing from the spirit and principles of the invention.