RESISTIVE LOAD BANK SYSTEMS

A load bank system is configured for providing a minimum load for a generator. The load bank system includes a resistive load bank, a relay, and a load bank controller. The resistive load bank is configured to provide a resistive load to a generator. The relay is configured to selectively engage the resistive load of the resistive load bank to the generator. The load bank controller is operable to control the relay such that the resistive load is engaged when a real load coupled to the generator is below a threshold load value. The load bank system may be arranged within a housing of the generator.

FIELD OF THE INVENTION

The present invention is directed to load bank systems, and in particular to load bank systems for generators.

BACKGROUND OF THE INVENTION

Generators are often driven by diesel engines. While a diesel engine provides an efficient driver for a generator, diesel engines are susceptible to wet stacking (i.e., when unburnt diesel fuel passes into the diesel exhaust system and produces an oily residue). Wet stacking happens when a diesel engine is running at a low percentage or proportion of its capacity. For example, a diesel engine coupled to a generator is susceptible to wet stacking when the generator it is driving has no load or only a minimal load coupled to it. When the generator is operating with no load or only a minimal load, the diesel engine is likely only idling, resulting in the risk of wet stacking because the diesel engine is not at a proper operating temperature (allowing unburnt fuel to escape into the diesel exhaust system). Diesel engines are most efficient when they are running at a sufficient percentage or proportion of their full capacity. When a diesel engine is running under a sufficient load, the diesel engine can run at an optimum operating temperature. To aid in the prevention of wet stacking of diesel engines coupled to generators, dummy loads or load banks can be applied to their generators. The load banks provide a load on the generator that is sufficient to prevent wet stacking of the generator's diesel engine.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a system for managing an operational environment of a diesel engine driven generator. A load bank system provides for the elimination or reduction of loading issues on diesel engine driven generators. The load bank system includes a resistive load bank that provides a dummy load for the generator to ensure that the diesel engine is run with a sufficient load to ensure that the diesel engine is running at an optimum operating temperature, such that the diesel engine avoids wet stacking conditions. The resistive load bank includes a plurality of resistors in a configurable arrangement. The load bank system includes a load bank controller for configuring the plurality of resistors such that the resistive load bank provides a desired load percentage regardless of the voltage output of the generator.

A load bank system for eliminating or reducing loading issues that lead to wet stacking in accordance with an embodiment of the present invention, comprises a resistive load bank, a load bank controller, and a relay. The resistive load bank provides a resistive load to a generator. The relay is for selectively engaging the resistive load of the resistive load bank to the generator. The load bank controller controls the relay such that the resistive load is engaged when a real load coupled to the generator is below a threshold load value.

In another embodiment of the present invention, a load bank system configured to provide a minimum load to a generator includes a reconfigurable resistive array, a relay, a voltage sensor, and a load bank controller. The reconfigurable resistive array provides a resistive load to a generator. The relay is for selectively engaging the resistive load of the resistive array to the generator. The voltage sensor is for sensing a voltage output of the generator. The load bank controller controls the relay such that the resistive load is engaged when a real load coupled to the generator is below a threshold load value. The load bank controller receives a voltage output value from the voltage sensor. The load bank controller selectively reconfigures the resistive array as defined by the output voltage value, such that the resistive load provided to the generator is a set percentage value regardless of the output voltage value.

In a further embodiment of the present invention, a load bank system is configured to selectively provide a minimum load to a generator. The generator is enclosed within a housing. A cooling system for cooling the generator is arranged within the housing. The cooling system outputs fan-forced air to cool the generator. The cooling air exits the housing via an exhaust vent in the housing. The load bank system is positioned upon the exhaust vent.

In an aspect of the present invention, the load bank system is alternatively positioned within the housing and adjacent to the exhaust vent. The cooling air exits the housing via the exhaust vent after passing through, and cooling, the load bank system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and the illustrative embodiments depicted therein, a load bank system provides for the elimination or reduction of loading issues on diesel engine driven generators, such as, for example, EPA Tier 4F certified or compliant diesel engine driven mobile generators. Exemplary load bank systems may be assembled or fitted to portable prime power skid generators or trailer-mounted diesel generators and provide selective engagement of resistive load banks to provide “dummy loads” to their respective generators when a real load is below a threshold load value. Alternatively, the load bank systems may be arranged within a housing of the generator.

FIG. 1illustrates a load bank system120that includes a resistive load bank122that absorbs energy from a diesel generator assembly110and allows the generator110to work under a loaded condition (even when there is no load or only a minimal load coupled to the generator110) that is sufficient to prevent wet stacking when a variable real load102is too low to prevent wet stacking. Wet stacking can occur when the diesel engine is run below an optimal operating temperature. Optionally, the generator110is a portable generator (e.g., arranged or fitted to a skid or trailer). As illustrated inFIG. 1, the load bank system120and a real load102are both coupled to the power output116of the generator110. While the circuit is simplified inFIG. 1, the load bank120and the real load102are arranged in a parallel circuit with the generator110. Optionally, the generator110has a variable output voltage, e.g., 120V, 240V, and 480V.

When the generator110is running without a real load102attached to its power output116(or when the attached real load102is a minimal load below a threshold (i.e., below 30%)), the load bank system120selectively provides a 30-40% load on the generator110that will keep the generator's engine exhaust and cooling system temperatures in an optimum operating range. The cooling system of the generator110includes fan-forced air cooling. The load bank system120includes a resistive load bank122and an associated controller124fitted to a diesel generator assembly110(seeFIG. 3A).FIG. 1illustrates an exemplary resistive load bank122and controller124coupled together.

FIGS. 3A and 3Billustrate an exemplary load bank system120positioned over cooling air exhaust vents302of an exemplary generator110(e.g., a diesel engine driven generator) for passive cooling of the load bank system120. The generator's fan-forced cooling air exits the generator110via the exhaust vents302. The load bank system120ofFIG. 3Bincludes a resistive load bank122and a load bank controller124.FIG. 3Cis an interior view of an exemplary arrangement of resistors126in the resistive load bank122.FIG. 3Dis an underside view of the load bank system120, illustrating the arrangement of resistors126in the resistive load bank122.FIG. 3Eillustrates the load bank controller124with an outer cover removed to reveal interior components (e.g., circuit breakers/fuses and wiring terminals).FIG. 3Aillustrates the generator110optionally fitted with diesel particulate filters (DPFs)304in the diesel engine exhaust system. The DPFs304aid in further reducing emissions from the diesel engine by removing soot and ash from the exhaust gases of the diesel engine.

Positioning the load bank system120, such that the resistive load bank122is positioned over the cooling-air exhaust vents302of the generator's cooling system, allows the cooling air as it exits the generator110to be used to passively cool the resistors126of the resistive load bank122(without any adaption or change in the generator's cooling system). As illustrated inFIGS. 3A, 3B, and 3F, the resistive load bank122positions an arrangement of resistors126above the exhaust vents302for cooling.FIGS. 4A, 4B, 4C, and 4Dillustrate an alternative load bank system420that includes an alternative resistive load bank422with a different arrangement of resistors126as compared to the resistive load bank122(illustrated inFIGS. 3C and 3F). As illustrated inFIGS. 3B, 3D, 4C, and 4D, the housing of the resistive load bank122,422does not include a bottom panel and only a minimal mesh top panel, such that the cooling air exiting the exhaust vent302can freely pass through the resistive load bank122,422to cool the resistors126. Embodiments of the load bank system120,420are thus able to utilize cooling air exhaust vent cooling from an associated generator110in a variety of weather environments. An exemplary resistive load bank122,422includes a plurality of resistors126that is arranged to allow for passive cooling from the generator's vented cooling air.

Each of the resistors126includes resistive materials in a desired arrangement. For example, the resistors126may be implemented as exemplary nickel chromium wire-wound resistors. As discussed herein, the resistive load bank122includes a variable number of resistors126arranged in a grid pattern that allows for individual mechanical supports and individual air cooling. As illustrated inFIG. 3C, the resistive load bank122includes an exemplary forty-eight (48) resistors126. Alternatively, as illustrated inFIGS. 4A-4C, the resistive load bank122includes an exemplary twelve (12) resistors126. As also illustrated inFIGS. 3C and 4A-4C, each of the resistors126is supported by mica insulators. For example, each resistor126may be supported by an arrangement of mica insulators on each side (of the resistor126). The mica insulators provide a high-temperature tolerant insulation for the resistors126. The mica insulators are an improvement over conventional ceramic supports, which are susceptible to breakdown, especially from vibrations on trailer-mounted load banks. Thus, the resistors126of the resistive load bank122,422may be arranged and cooled such that the resistors126are prevented from overheating (e.g., the resistors126will be kept from heating to a point where they are visibly “red-hot” and susceptible to deformation and damage from overheating).

The alternative load bank system420, illustrated inFIGS. 4A, 4B, 4C, and 4D, includes an alternative resistive load bank422comprising a different arrangement of resistors126(as compared to the resistive load bank122). A load bank controller424is also illustrated coupled to the side of the resistive load bank422. Functionally, the load bank controller424is the same as the load bank controller124. However, as compared to the load bank system120, the load bank controller424has different dimensions and is arranged along a different side of the resistive load bank422. As illustrated inFIG. 4A, the alternative load bank system420is arranged on the cooling-air exhaust vents302of the generator110in a similar fashion as illustrated inFIGS. 3A and 3B.FIG. 4Bis an underside view of the resistive load bank422illustrating mounting arrangements, as well as a bottom side view of the arrangement of resistors126.FIG. 4Cillustrates the load bank controller424with an outer cover removed to reveal interior components (e.g., circuit breakers/fuses and wiring terminals).

As illustrated inFIG. 1, the only control link between the generator110and the load bank controller124is a control signal114(also known as a “load signal”) output by the generator controller112and received by the load bank controller124. As discussed herein, the load bank controller124will engage and disengage the resistive load bank122from the generator110based upon whether or not the load signal114has been received. The control signal or load signal114may be implemented as a 12 VDC customer supplied load demand signal that is output by the generator controller112. The generator controller112monitors the generator's load output and outputs the load signal114in response to a determined percentage of load capacity. As illustrated inFIG. 1, a relay128in the resistive load bank122engages or disengages the resistive load bank122from the power output116of the generator110. Optionally, the relay128may be a part of the load bank controller124,424. As also discussed herein, the load bank controller124, after a delay period (e.g., a 5-minute delay), engages the resistive load bank122. The delay period provides operational stability for the generator110and avoids nuisance starting and stopping of the load bank system120.

The load bank system120utilizes a single resistive value for the resistive load bank122as opposed to multiple, selective, resistive banks that may be selectively engaged to set a desired load value. In other words, engaging the resistive load bank122provides a set resistive value to the output of the generator110to apply a set load (e.g., a 30-40% load) on the generator110. Thus, the load bank controller124of the load bank system120, once activated, will energize the relay128to apply a resistive load, via the resistors126of the resistive load bank122(also known as a dummy load), to the output of the generator110. The resistive load bank122provides an exemplary 40% load to the generator110. Optionally, the resistive load bank122provides an exemplary 30% load to the generator110. Other configurations are also possible such that the resistive load bank122will provide a resistive load of between 30-50% (in addition to any real load102). Optionally, as discussed herein, the resistive load bank122includes reconfigurable circuits for arranging the resistive load bank122to provide a desired load for a variety of voltage outputs and conditions (seeFIG. 2).

The load bank controller124of the load bank system120will apply the resistive load bank122to the generator110upon receiving the load signal114from the diesel generator controller112. Upon receiving the load signal114, the load bank controller124will delay five minutes before engaging the relay128to apply the resistive load bank122to the generator110. The generator controller112outputs the load signal114if a real load102coupled to the generator110is determined to be less than 30% of the generator's load capacity (as determined by the generator controller112). The load bank system120provides a dummy load of approximately 30-40% load, e.g., a 30% load or a 40% load, or some other selected load value. When the generator110is running without the real load102attached (or with a real load102that is zero or below a threshold load value), attaching the load bank system120(providing a 30-40% load) will keep the generator exhaust and cooling system temperatures in an optimum operating range.

Whenever the generator controller112determines that a combined real load102and dummy load (provided by the resistive load bank122) are above a 75% load capacity of the generator110, the generator controller112will immediately stop transmitting the load signal114, such that the load bank controller124will immediately disengage the resistive load bank122from the generator110. However, should the real load102fall to a load value of less than 30% of load capacity, the generator controller112will transmit the load signal114and the load bank controller124will reengage the resistive load bank122(after a five-minute delay by the load bank controller124) and stay engaged until the combined load again exceeds 75% load capacity. This automatic operational state will continue until the load bank system120is turned off.

As illustrated inFIG. 2, in an alternative embodiment, the load bank controller124includes an “auto-sense” feature that senses the output voltage of the generator110and selects an arrangement for the resistive load bank122that produces the desired 30-40% load. As illustrated inFIG. 2, a sensor202monitors the voltage level of the power output116from the generator110and supplies a voltage signal to an auto-sense module204. Based upon the sensed voltage of the power output116from the generator110, the auto-sense module204selects a circuit arrangement for the resistors126of the resistive load bank122. Thus, the load bank system120adapts to the supplied voltage output from the generator110to supply a consistent load percentage. Whether the output voltage from the generator110is, for example, 110V, 240V, or 480V, the resistive load bank122will be adapted to provide the desired 30-40% load.

FIG. 5illustrates an exemplary generator system500that includes a generator510arranged within a housing501. A cooling system includes an air intake and fan arrangement504that draws in cooling air506to air cool the generator510, and with an exhaust vent302for venting the cooling air from the housing501.FIG. 5illustrates a load bank system120arranged upon the housing501and over the exhaust vent302. As illustrated inFIG. 5, the cooling air506, in exiting the housing501via the exhaust vent302, passes through and cools the load bank120.

FIG. 6illustrates an alternative generator system600that includes a generator510and a load bank120within a housing601. As compared to the housing501for the generator system500ofFIG. 5, the housing601of the alternative generator system600is configured to retain the load bank120within the housing601. As illustrated inFIG. 6, the load bank120is positioned against (or adjacent to) the exhaust vent302, such that the cooling air506(from the air intake and fan arrangement504) in leaving the housing601, passes through and cools the load bank120before exiting the housing601via the exhaust vent302.

Additional hardware of the cooling system has been omitted fromFIGS. 5 and 6for the sake of clarity. For example, additional hardware to force the cooling air506through and around the generator510and to guide the cooling air506to the exhaust vent302has been omitted. The diesel engine exhaust system (including optional diesel particulate filter) is also omitted.

FIGS. 7A and 7Billustrate the placement of an exemplary load bank120within the housing601of the alternative generator system600ofFIG. 6. As illustrated inFIGS. 7A and 7B, the load bank120is positioned immediately below the exhaust vent302of the housing601.FIGS. 7A and 7Bprovide different perspective views of the load bank120with respect to the exhaust vent302.FIGS. 8A and 8Bprovide additional views of the load bank120positioned within the housing601. InFIGS. 8A and 8B, a side panel of the housing601ofFIGS. 7A and 7Bhas been removed to provide another set of views of the orientation of the load bank120with respect to the housing601and the exhaust vent302.

Thus, the exemplary embodiments discussed herein provide for the elimination or reduction of loading issues for diesel engine driven generators, such that their diesel engine drivers are prevented from operating under loading conditions that promote wet stacking. An exemplary load bank system includes a resistive load bank that is selected to provide a desired resistive load for an associated generator, such that the diesel engine driving the generator will be able to operate within a desired operational temperature range regardless of whether or not a real load is applied to the generator. A load bank controller of the load bank system engages the resistive load bank when a load on the generator is below a threshold load value. Alternative embodiments provide for the positioning of the load bank system either within a housing of the generator or upon the generator housing. Thus, the load bank system is either positioned adjacent to and before the exhaust vent, or adjacent to and above the exhaust vent.