Electric resistance heating devices – Heating devices – Tank or container type liquid heater
Reexamination Certificate
2000-10-16
2001-05-29
Walberg, Teresa (Department: 3742)
Electric resistance heating devices
Heating devices
Tank or container type liquid heater
C392S500000, C392S449000
Reexamination Certificate
active
06240249
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to electrical apparatus and, in a preferred embodiment thereof, more particularly relates to an electric water heater which incorporates therein apparatus that substantially simplifies the conversion of the water heater between single phase and three phase operation thereof.
Electric water heaters are typically manufactured for use with either a single or three phase electric power supply, and may normally be later converted from single to three phase operation or vice versa. The manufactured electric water heaters are often shipped to warehouses or other holding areas to await delivery to a purchaser. It is often the case that a purchaser needs an electric water heater having a given heating capacity and, for example, being operable with single phase electrical power. If the warehouse has a water heater with the desired heating capacity but manufactured to be operated with three phase electrical power the water heater must be converted at the warehouse to single phase operation (or converted from single to three phase operation as the case may be) before the water heater is delivered to the purchaser.
Modern electric water heaters are often manufactured with multiple immersion type electrical resistance type heating elements, each having an associated thermostat. The thermostats are typically connected through fuse holders to the load side of a terminal structure via what may be a large number of individual wires. AS an example, for an electric water heater having nine heating elements there would typically be 18 individual wires operatively connected to the load side of the terminal structure. When it becomes necessary to change the water heater from one phase operation to another phase operation it is conventionally necessary to individually relocate most or all of these wires on the terminal structure in accordance with a phase conversion wiring diagram provided with the water heater.
As might be imagined, this is a laborious, time-consuming task that must be carefully performed if the phase-converted water heater is to function properly. This laborious phase conversion task, of course, is not limited to electrical water heaters, but is necessary in a wide variety of other electrical devices that may be rewired to convert the phase of their electrical operation. A need thus exists to provide simplified phase conversion apparatus for an electrical device such as an electric water heater. It is to this need that the present invention is directed.
SUMMARY OF THE INVENTION
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, electrical apparatus, representatively an electric water heater, is provided with a phase conversion system that substantially simplifies the changeover of the water heater from single to three phase operation and vice versa.
The electrical apparatus includes an electrical structure, representatively electrical heating elements in the water heater, which is operable utilizing either single or three phase electrical power, and a terminal structure having a line side portion operative to selectively receive either single or three phase electrical power from a source thereof, and a load side portion having first and second electrical connectors associated therewith.
Power receiving circuitry is coupled to the electrical structure and as a third electrical connector releasably mateable with either selected one of the first and second electrical connectors. To facilitate phase conversion of the electrical apparatus, routing circuitry is interconnected s between the line side portion of the terminal structure and the first and second electrical connectors and is operative, without altering the power receiving circuitry, to (1) route single phase electrical power to the electrical structure, via the power receiving circuitry, when the third electrical connector is operatively mated with the first electrical connector and single phase electrical power is being supplied to the line side portion of the terminal structure, and (2) route three phase electrical power to the electrical structure, via the power receiving circuitry, when the third electrical connector is operatively mated with the second electrical connector and three phase electrical power is being supplied to the line side portion of the terminal structure.
In the illustrated preferred water heater embodiment of the electrical apparatus, the first and second electrical connectors are multi pin connector sockets, and the third electrical connector is a screw-in multi-pin connector plug which is connected by a series of electrical leads to a fuse apparatus which is operatively coupled to the electrical resistance heating elements through controlling thermostats. By simply disconnecting the connector plug from one of the connector sockets and reconnecting it to the other connector socket, the electrical phase operation of the associated heating elements may be conveniently and quickly changed without the necessity of laboriously relocating each of the fuse apparatus leads on the terminal structure.
According to another feature of the invention, the terminal structure includes a housing on which the first and second electrical connectors are carried, and first, second and third replaceable line lug members removably carried by the housing and interconnected to the first and second electrical connectors by the routing circuitry, each line lug member being configured to removably receive an end portion of an electrical power supply lead. Thus, when a phase conversion entails an increase or reduction in the amperage load in the converted system, the same terminal structure may be utilized by simply replacing its line lugs with other line lugs sized to accommodate the differently sized electrical power supply leads required.
REFERENCES:
patent: 4365228 (1982-12-01), Rowley
patent: 5437003 (1995-07-01), Blanco
patent: 5687052 (1997-11-01), Bennett
patent: 5886422 (1999-03-01), Mills
Henderson David L.
Powell Timothy E.
Campbell Thor
Konneker & Smith P.C.
Rheem Manufacturing Company
Walberg Teresa
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