Electrical transmission or interconnection systems – Switching systems – With operation facilitating feature
Patent
1997-01-13
1998-07-21
Shoop, Jr., William M.
Electrical transmission or interconnection systems
Switching systems
With operation facilitating feature
307112, 307125, 307127, 307139, H01H 930
Patent
active
057838763
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a switch with controlled rise and fall characteristics and power controller with controlled rise and fall characteristics the mentioned power controller comprising a triac or SCR (silicon controlled rectifier) switching element connected in series to the load, a control circuit connected to the gate and the power electrode of the aforementioned switching element.
There are known some certain electronic switching circuits with controlled rise and fall characteristics. Some known circuits are described in the book: Kiraly A., Elektronikai receptek I. (Electronic recepies I. Muszaki Kiado, Budapest). Such circuits developed for AC applications are well suited for applications belonging to the illumination techniques, where they are used in order to increase the lifetime of luminous body, to avoid sudden changes in illumination, to switch on or off the luminous body in a programmed or in a sensor controlled manner, to limit and control the luminous intensity or energy consumption controlling either manually or automatically the operation of other electrical loads like electrical heating appliances and motors.
A power controller having a relatively simple construction is described in the afore mentioned reference on page 34.
The power over an ohmic or inductive load is controlled via controlling the initial phase of the triac switching element, the necessary phase-shifting is created by a phase-shifting chain of serial RC-elements. The first resistor of the phase-shifting chain is fed by the AC mains, changing the resistance of the resistor the phase-shift of the current going through triac also varies. The impulse suitable for controlling the triac is formed by a diac connected in series with the lead coming from the gate of the triac.
A disadvantage of the known circuit is that it is unsuitable for achieving controlled rise and fall characteristics, it is suitable only for setting the power to a fixed value.
A circuit suitable slowly increasing the luminous intensity in an automated manner is given on page 70 of the afore mentioned reference. The controlling part of the circuit composed of a relatively big number of elements, such as transistors and integrated circuits, is fed from mains powersupply. A drawback of the solution is that it cannot be implemented in small size due to the presence of the transformer in the mains powersupply.
A switch with controlled rise and fall characteristics is presented on pages 73-75 of the referenced book. The triac of the switch is controlled via optoelectronic coupling between the LED of the control circuit and the photoresistor situated in the gate circuit. Also in this case the control circuit is supplemented with mains supply composing a transformer.
A time responsive switching circuit for use with a single phase alternating current motor comprising a triac in series with a start winding of the motor was disclosed in U.S. Pat. No. 4,366,426. In this circuitry the triac is used in the AC side of an diode bridge, and a low voltage SCR element is used in the control stage, at the DC side of said bridge. However this circuitry is constructed for driving an inductive start winding and not for turning on general loads, for instance incandescent lamps.
The known switches with controlled rise and fall characteristics, due to their relatively big space requirements and power consumption, are not suitable for being placed into hidden locations having bad cooling circumstances.
This is an object of the present invention to provide a switch with controlled rise and fall characteristics which effectively eliminates the disadvantages of the known solutions; the switch according to the invention does not require a separate power supply has small dimensions, and low heat dissipation, the switch according to the invention is suitable for use in a construction without a cooling surface formed in it, e.g. in the box of a sunk illumination switch on the wall together with the switch and power controlling potentiometer.
The invention is based on the idea that the
REFERENCES:
patent: 4366426 (1982-12-01), Turlej
patent: 4950963 (1990-08-01), Sievers
patent: 5539284 (1996-07-01), Stone
patent: 5606225 (1997-02-01), Hua
Kaplan Jonathan
Shoop Jr. William M.
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