Electricity: power supply or regulation systems – Including a transformer or an inductor – Polyphase or plural transformers
Patent
1998-10-14
2000-05-23
Berhane, Adolf Denake
Electricity: power supply or regulation systems
Including a transformer or an inductor
Polyphase or plural transformers
H01F 3300
Patent
active
060669454
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a device for automatically adjusting an output voltage within a predetermined range even when an input voltage is increased or decreased beyond a predetermined range in an electric power saving device, such as an autotransformer, so that an abnormal voltage is not supplied to a load.
Japanese Patent Application No.1804/1995, which was filed prior to the present application by the same applicant, of which U.S. Pat. No. 5,654,627 is a U.S. counterpart is one of known conventional electric power saving apparatuses.
In a conventional electric power saving apparatus, as shown in FIG. 4, plural sets of exciting coils L3, L4, L7 and L8, which are wound on a single-phase core-type core (9) in a mutually connected series, are connected between the ends of plural sets of main coils L1, L2, L5 and L6 which are phase-wound on the core (9), in which the combinations of connection of the exciting coils L3, L4, L7 and L8 are controlled by thyristors (1, 2, 3, 4, 5, 6, 7, 8) connected with a voltage sensor (not shown) provided at the input ends of the main coils L2 and L6, whereby an output voltage is prevented from an unnecessary increase and decrease.
For example, a circuit, on which the exciting coils are combined to cause the voltage to output by dropping by 6V for an input voltage of 100V, is automatically changed to another circuit which has a lower-voltage rate of 3V and then 0V when the input voltage is decreased. On the other hand, the circuit will be automatically changed to another circuit which has a upper-voltage rate of 3V or 6V when the input voltage is too low. Therefore, the output voltage is prevented from unnecessarily increasing and decreasing so as to keep the effect on the load as little as possible.
However, conventional electric power saving transformers with automatic voltage changing device such as the aforementioned example are for single-phase current, and are restricted to autotransformers of single-phase three-wire or two-wire system, except for a power generator.
In the case of three-phase current, a simultaneous ON/OFF change of voltages of the three phases is desired. Since the three phases of alternating current are not at the same voltage level and simultaneous OFF is impossible for thyristors as electric switches, the control circuit is complex and difficult to manage compared with for single-phase current. Accordingly, manual voltage change has been performed conventionally instead of automatic voltage change in three-phase current.
SUMMARY OF THE INVENTION
To solve the aforementioned disadvantages, the present invention provides, as will be described in the following, a method and an apparatus having a function of automatically adjusting an output voltage within a predetermined range even when an input voltage is increased or decreased beyond a predetermined range of the voltage in an electric power saving device for three-phase current.
An electric power saving transformer for three-phase current with an automatic voltage transferring device, in an autotransformer of a three-phase three-wire system or a three-phase four-wire system, is characterized by phase-winding one set or plural sets of a main coils which are connected to input terminals on a three-phase core-type core; connecting plural sets of exciting coils mutually connected in series to wind the three-phase core-type core between the ends of the main coils by means of plural combinations of connection; connecting plural electric switches between the ends of the main coils and the exciting coils which are switched to ON/OFF based on the value detected by a voltage sensor connected to the input or output terminals; and connecting and disconnecting between the ends of the main coils and the exciting coils, by switching ON/OFF of the electric switches stepwise on the same value of voltages or currents between the phases in order to automatically change output voltage correspondingly to input voltage onto voltage transferring circuits in an uninterrupted manner.
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REFERENCES:
patent: 4535291 (1985-08-01), Lee et al.
patent: 5079687 (1992-01-01), Sakisaka et al.
patent: 5654627 (1997-08-01), Shimazu et al.
patent: 5714821 (1998-02-01), Dittman
Shimazu Chiyuki
Shimazu Kunio
Yabase Koji
Berhane Adolf Denake
Legend Power Ltd.
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