Electrical transmission or interconnection systems – Plural supply circuits or sources – Substitute or emergency source
Reexamination Certificate
1999-08-19
2001-01-30
Paladini, Albert W. (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Substitute or emergency source
C361S020000
Reexamination Certificate
active
06181028
ABSTRACT:
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'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'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'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
Bagley John G.
Jonas Jeffrey J.
Kern Robert D.
Ruehlow Gerald C.
Wedel Francis X.
Deberadinis Robert
Generac Power Systems, Inc.
Jansson, Shupe Bridge & Munger, Ltd.
Paladini Albert W.
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