Conventional distribution transformers used in electric power distribution, e.g., on power lines, have an internal, built-in circuit breaker in a single assembly to protect the distribution transformer in some cases. To retrofit a distribution transformer by adding an internal circuit breaker is costly, and requires disruption of power to the customer for an unacceptable length of time. Moreover, the cost of unprotected distribution transformer is significantly less than a distribution transformer that has a built-in circuit breaker.
Another problem occurs when a power surge hits a distribution transformer having an internal circuit breaker as a solitary unit; it may be so powerful that both the distribution transformer and circuit breaker are destroyed. This increases the time and cost of replacement. Also, in some cases, when one component goes bad, the entire combination unit of distribution transformer and circuit breaker must be replaced.
A known distribution transformer system that utilizes a separate circuit breaker is disclosed in U.S. Pat. No. 3,183,362, which was assigned to System Analyzer Corp. and issued on May 11, 1965. However, this distribution transformer also included a series of switching contacts that are housed within the distribution transformer. When this distribution transformer fails or blows-up, complex repairs are required. It is not a simple matter of replacing a distribution transformer since there are contacts located within the distribution transformer that are actuated by the circuit breaker. Therefore, the circuit breaker as well as the distribution transformer are not stand-alone, replaceable units. Moreover, this is a one-of-a kind distribution transformer which makes it very difficult to maintain and replace.
Therefore, a need exists in the art for a cost-effective solution that can be quickly installed to provide current overload protection for the distribution transformer with limited down-time to customers during installation. Also, a need exists for a low cost alternative to the expensive combination unit of distribution transformer and circuit breaker.
The present invention is directed to overcome one or more of the problems as set forth above.
An aspect of the present invention includes a stand-alone circuit breaker in a box assembly that can quickly be installed immediately in series with an existing transformer, thereby providing suitable overload protection to the transformer. In use, the circuit breaker box assembly is mounted near the distribution transformer and connected in series between the transformer and the end-user (load) so that electricity flowing between the transformer and the end-user must pass through the circuit breaker box assembly. The circuit breaker assembly is directly connected to the transformer. When a current overload is detected, the circuit breaker will sever the connection to the end-user, thus protecting the transformer. When the problem has been corrected, the circuit breaker can be reset, restoring power to the end-user.
In one embodiment of the present invention, a single circuit breaker is provided that includes a circuit breaker mounted in a box, with the box having bushing assemblies installed thereto for wire connections. The circuit breaker may be implemented using a solenoid, a bimetallic strip, or both, as mere examples. The box is preferably sealable and at least partially filled with a non-conducting fluid such as mineral oil. The box may also include a fluid level sight gauge for viewing the level of the mineral oil or other fluid inside the box. The box may also include a fluid valve for conveniently filling or removing the fluid. Preferably, two sets of bushings are provided: one for the transformer side, and one for the load side. A circuit breaker is connected in series between the bushings so that current flowing between the transformer and the end-user must flow through the circuit breaker. When the circuit breaker allows electrical current to flow through, it is said to be in the closed position. When the circuit breaker does not allow current to flow through, it is said to be in the open or “tripped” position. In normal operation, the circuit breaker is in the closed position. If the current flowing through the circuit breaker is likely to cause the transformer to exceed acceptable parameters, the circuit breaker will trip and open the line, severing the electrical connection between the transformer and the load, thus preventing damage to the transformer. Once the circuit breaker has tripped, it activates an external trip signal such as a light, e.g., light-emitting diode (LED), mounted on the box. The trip signal serves to alert the technician to the fact that the circuit breaker inside the box has tripped, and must be reset to restore power to the end-user. The circuit breaker is externally resettable, i.e., it may be reset to a closed position without opening the box. The reset mechanism may be a mechanical handle that extends through an opening in the box that can be activated by using a hot-line stick.
Optionally, the box may include multiple circuit breakers, so that multiple loads may be independently connected to the transformer via the circuit breaker box assembly. In this embodiment, a unique set of bushings would be provided for connecting each circuit breaker to each individual load.
An aspect of the present invention includes a circuit breaker assembly. This circuit breaker assembly includes a housing having a plurality of openings, a plurality of first bushings mounted through the openings in the housing for receiving electrical power from a distribution transformer, a circuit breaker, having a plurality of input terminals and a plurality of output terminals, wherein the circuit breaker is located inside the housing, a plurality of first electrical connectors electrically connected in one-to-one correspondence between the plurality of first bushings and the plurality of input terminals, a plurality of second bushings mounted through the openings in the housing for providing electrical power from the circuit breaker, and a plurality of second electrical connectors electrically connected in one-to-one correspondence between the plurality of second bushings and the plurality of output terminals.
Another aspect of the present invention includes a circuit breaker assembly. This circuit breaker assembly includes a housing having a plurality of openings, a plurality of first bushings mounted through the openings in the housing for receiving electrical power from a distribution transformer, a plurality of circuit breakers, each having a plurality of input terminals and a plurality of output terminals, wherein the plurality of circuit breakers are located inside the housing, a plurality of first electrical connectors electrically connected in one-to-one correspondence between the plurality of first bushings and the plurality of input terminals, a plurality of second bushings mounted through the openings in the housing for providing electrical power through the plurality of circuit breakers, and a plurality of second electrical connectors electrically connected in one-to-one correspondence between the plurality of second bushings and the plurality of output terminals.
Still another aspect of the present invention includes an electrical power distribution system. This electrical power distribution system includes a distribution transformer, having a primary and a secondary, wherein the primary is capable of being electrically connected to a plurality of high voltage lines and the secondary includes a plurality of low voltage electrical conductors extending therefrom, a housing having a plurality of openings, a plurality of first bushings mounted through the openings in the container that are electrically connected to the plurality of low voltage electrical conductors, a plurality of circuit breakers, each having a plurality of input terminals and a plurality of output terminals, wherein the plurality of circuit breakers are located inside the housing, a plurality of first electrical connectors electrically connected in one-to-one correspondence between the plurality of first bushings and the plurality of input terminals, a plurality of second bushings mounted through the openings in the container for providing electrical power through the plurality of circuit breakers, and a plurality of second electrical connectors electrically connected in one-to-one correspondence between the plurality of second bushings and the plurality of output terminals.
Yet another aspect of the present invention includes a method of protecting a distribution transformer. This method includes mounting an external, stand-alone circuit breaker assembly in proximity to a distribution transformer, electrically connecting the stand-alone circuit breaker assembly to the distribution transformer in series, and electrically connecting the stand-alone circuit breaker assembly to an end-user such that an electrical path is created flowing from the distribution transformer, through the circuit breaker assembly to the end-user, wherein the stand-alone circuit breaker assembly includes a housing having a plurality of openings, a plurality of first bushings mounted through the openings in the housing for receiving electrical power from the distribution transformer, at least one circuit breaker, each circuit breaker having a plurality of input terminals and a plurality of output terminals, wherein the at least one circuit breaker is located inside the housing, a plurality of first electrical connectors electrically connected in one-to-one correspondence between the plurality of first bushings and the plurality of input terminals, a plurality of second bushings mounted through the openings in the housing for providing electrical power through the at least one circuit breaker, and a plurality of second electrical connectors electrically connected in one-to-one correspondence between the plurality of second bushings and the plurality of output terminals.
These are merely some of the innumerable aspects of the present invention and should not be deemed an all-inclusive listing of the innumerable aspects associated with the present invention. These and other aspects will become apparent to those skilled in the art in light of the following disclosure and accompanying drawings.
For a better understanding of the present invention, reference may be made to the accompanying drawings in which:
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. Additionally, the present invention contemplates that one or more of the various features of the present invention may be utilized alone or in combination with one or more of the other features of the present invention.
The tank case 10 is preferably filled with a non-conducting tank fluid, e.g., mineral oil. However, the tank case 10 does not absolutely need a non-conducting tank fluid and can simply be filled with air or vacuum. The tank fluid serves as a heat sink to prevent overheating of the device, and also provides arc-suppression to prevent arcing inside the tank. The tank fluid may also provide anti-corrosive benefits.
The tank case 10 includes a fluid valve 12 for filling or draining of the tank fluid from the tank case 10. The tank case 10 further includes a fluid level sight gauge 17 which allows the operator to view the fluid level in the tank case 10. The tank case 10 further includes a pressure release valve (PRV) 18 to expel non-conducting tank fluid from the tank case 10 in the event that the fluid pressure in the tank case 10 becomes too high.
Referring now to
Referring again to
There is a first electrical conductor 52 that is electrically connected to a first terminal 54 of the circuit breaker 13, a second electrical conductor 56 that is electrically connected to a second terminal 58 of the circuit breaker 13 and a third electrical conductor 60 that is electrically connected to a third terminal 62 of the circuit breaker 13.
On the output side of the circuit breaker 13, there is a fourth electrical conductor 72 that is electrically connected to a fourth terminal 70 of the circuit breaker 13, a fifth electrical conductor 74 that is electrically connected to a fifth terminal 76 of the circuit breaker 13 and a sixth electrical conductor 78 that is electrically connected to a sixth terminal 80 of the circuit breaker 13.
The fourth electrical conductor 72 is electrically connected to a first output bushing 82, the fifth electrical conductor 74 is electrically connected to a second output bushing 84 and the sixth electrical conductor 78 is electrically connected to a third output bushing 86. Electrically connected thereto and extending from the first output bushing 82, the second output bushing 84 and the third output bushing 86 are a first output line 88, a second output line 90 and third output line 92, respectively.
Referring again to
Referring again to
An illustrative, but nonlimiting, example of an oil-filled transformer having a heater and thermostat for regulating temperature is found in U.S. Pat. No. 4,192,174, issued on Mar. 11, 1980 to Lobermann et al., which is incorporated herein by reference in its entirety.
As shown in
A first alternative embodiment of a dual circuit breaker system, as shown in
The tank case 110 is preferably filled with a non-conducting tank fluid, e.g., mineral oil. However, the tank case 110 does not absolutely need a non-conducting tank fluid and can simply be filled with air or vacuum. The tank fluid serves as a heat sink to prevent overheating of the device, and also provides arc-suppression to prevent arcing inside the tank case 110. The tank fluid may also provide anti-corrosive benefits.
As shown in
Referring now to
Referring again to
On the input side of a first circuit breaker 113, there is a first electrical conductor 173 that is electrically connected to a first terminal 166 of the first circuit breaker 113, a second electrical conductor 174 that is electrically connected to a second terminal 167 of the first circuit breaker 113 and a third electrical conductor 175 that is electrically connected to a third terminal 168 of the first circuit breaker 113.
On the input side of a second circuit breaker 104, there is a fourth electrical conductor 176 that is electrically connected to a fourth terminal 169 of the second circuit breaker 104, a fifth electrical conductor 177 that is electrically connected to a fifth terminal 170 of the second circuit breaker 104 and a sixth electrical conductor 178 that is electrically connected to a sixth terminal 171 of the second circuit breaker 104.
On the output side of the first circuit breaker 113, there is a seventh electrical conductor 156 that is electrically connected to a fourth terminal 161 of the first circuit breaker 113, an eighth electrical conductor 154 that is electrically connected to a fifth terminal 160 of the first circuit breaker 113 and a ninth electrical conductor 152 that is electrically connected to a sixth terminal 159 of the first circuit breaker 113. The seventh electrical conductor 156 is electrically connected to a first output bushing 150, the eighth electrical conductor 154 is electrically connected to a second output bushing 148, and the ninth electrical conductor 152 is electrically connected to a third output bushing 146.
On the output side of the second circuit breaker 104, there is a tenth electrical conductor 157 that is electrically connected to a fourth terminal 164 of the second circuit breaker 104, an eleventh electrical conductor 155 that is electrically connected to a fifth terminal 163 of the second circuit breaker 104 and a twelfth electrical conductor 153 that is electrically connected to a sixth terminal 162 of the second circuit breaker 104. The tenth electrical conductor 157 is electrically connected to a fourth output bushing 151, the eleventh electrical conductor 155 is electrically connected to a fifth output bushing 149, and the twelfth electrical conductor 153 is electrically connected to a sixth output bushing 147.
As shown in
As shown in
Referring again to
Optionally, a heater 111, utilized in conjunction with a temperature controller 271, e.g., thermostat, can be used to maintain oil temperature so the response time of the breaker is not influenced by fluctuations in ambient temperature. An illustrative, but nonlimiting, example of an oil-filled transformer having a heater and thermostat for regulating temperature is found in U.S. Pat. No. 4,192,174, issued on Mar. 11, 1980 to Lobermann et al., which is incorporated herein by reference in its entirety.
As shown in
Also shown in
Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “have,” “having,” “includes,” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required.” Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims that follow.