WO2005050690A1

WO2005050690A1 - Electric automatic switch

Info

Publication number: WO2005050690A1
Application number: PCT/SI2004/000038
Authority: WO
Inventors: Peter Flohr
Original assignee: Eti Elektroelement D.D.
Priority date: 2003-11-21
Filing date: 2004-11-19
Publication date: 2005-06-02
Also published as: DE10354505B4; DE10354505A1

Abstract

An electric automatic switch of a low-power loss and selective implementation with high breaking capacity for use especially as a miniature circuit breaker or main circuit breaker. The automatic switch has a universal actuation characteristic, which is practically not influenced even by considerable fluctuations of ambient temperature. The protect switch device in its actuation is resistant to switch-on peaks of bulbs, energy saving lamps and motors and is comparable as to its mode of selectivity to that of fuse-links.

Description

Electric Automatic Switch

The present invention relates to a low - power loss selective automatic switch intended for the protection of electric consumers and electric circuits with the characteristics of the characterizing clause of Claim 1.

For the protection of electric lines and for the protection of motors, protect switches are nowadays predominantly used, said switches replacing the conventional fuse-links of the past.

All protect switches of the present state of the art are based on series switching-on of a short-circuit trigger, over-current actuator and the arrangement of contacts thus corresponding to technical standards from the patent description No. 45892 of March 22, 1928.

All these constructions share an over-current actuator that uses electrical current to heat a fhermo-mechanical converter as early as normal use in order to trigger in case of failure, i.e. in case of an increased current, a protect switch device thus interrupting the electric circuit.

A common disadvantage of all these constructions lies in that the thermo-mechanical converter consumes also in normal operation approximately 1 % of the power needed for protection.

This stand-by operation is not necessary and is the cause for undesired mutual heating of protect switch devices and leads to unintentional switch-off as early as nominal current.

In order for the thermo-mechanical converter to carry out its function in a protect switch device without being influenced by fluctuating ambient temperatures, its operating temperature should considerably lie above the temperature zone, in which the protect switch device is used. Principally, the operating temperature could be increased, however higher heating power for the thermo-mechanical converter would be expected, whereas the latter would consume even more power loss in ordinary operation, i.e. practically always.

A further disadvantage of known products is in that protect switch devices automatically switch off also in case of undisturbed operation due to shorter circuit pulses when lamps or motors in electric devices are switched on.

Finally, the lack of selectivity between automatic switches was the reason to suggest solutions as published in DE 3840482 or DE 4118377 Al.

Protect switch devices with considerable technical complexity originated in practice from the above switches, the function of said switches depending as in e.g. DE 4118377 Al on line voltage.

The subject of the invention is therefore to conceive a low-loss selective automatic switch that can be used as a line or motor protect switch and also as a main circuit breaker. The technical characteristic for the manufacture should be comparable to that of known circuit breakers, its function should be independent on line voltage and auxiliary supply.

In order to solve this problem, the invention was subject to the consideration, from where to abolish the stand-by operation in automatic switches that is not required by any convention.

The invention does away with the heating of the thermo-mechanical converter in ordinary operation, therewith avoiding - i.e. practically always - the power loss, which unnecessarily heats the automatic switch and its environment. Instead of a thermo-mechanical converter as an over-current trigger a magnetic thermical converter is used in the invention, said converter being heated only in case of a failure and thus sensing its actuating function. The magnetic-thermic converter consists of two magnetic systems operating independently from each other with a thermo-bimetal.

In ordinary operation, i.e. with an automatic switch switched on, only an excitation coil of the magnetic-thermic converter is supplied by the operational current - the thermo-bimetal is short-circuited.

Only when the operational current exceeds the critical area, the first anchor of the double-anchor system activates at a predeteπnined current value and includes the thermo-bimetal in the main circuit in an uninterrupted manner.

The thermo-bimetal is now supplied by an over current and gets warmed and unlatches a switch latch, whereby the overloaded circuit is interrupted in a known way.

The operating temperature of the thermal bimetal is considerably higher than that in known arrangements, so that the delay time is short and the thermal influence on the neighbouring protect switch devices is omitted.

Due to high operating temperature of the thermo-bimetal even increased fluctuations of the ambient temperature do not exercise a negative influence on the actuating characteristic of the automatic switch.

The insensitivity of the automatic switch to switch-on pulses of series of bulbs, series of power saving lamps and motors is provided with an operating mode of the magneto-thermic actuator. Since the thermo-bimetal can actuate in a delayed manner only after the intake of a certain heat quantity, the selectivity to over-current exceeding 1000 A is given in this way comparable to that of the fuse-links.

At higher short-circuit currents the tube of the double-anchored system consisting of a ferromagnetic material is saturated, so that the immersion anchor when drawn over a striker pin pushes the contact bridge directly to the stable end position thus interrupting the electric circuit. The thermo-bimetal is simultaneously switched on without current and protected against damages.

Once the influence of the quick opening contacts in the high-current area and the cooperation with the deionic chambers intended for current limitation upon switch-off is known, this process needs no description.

The abolishment of the stand-by operation brings about also an increased economisation of the yearly power demand that is economically calculated. Thus the power loss of the automatic switch according to the innovation reduces in ordinary operation on ca. 1/3 compared to the protect switch devices of the state of the art.

A preferred embodiment of the invention is shown in figures and in patent subclaims. An embodiment and its mode of operation are evident from the figure. The figures show:

Fig. 1 magneto-thermic converter in ready-to-operate mode

Fig. 2 schematic diagram of the automatic switch

Fig. 3 U- formed thermo-bimetal

Fig. 4 contact bridge in triangle form

Fig. 5 current-time characteristic line of the automatic switch compared to known protect switch devices Constituent parts of the automatic switch that are of subordinated meaning for the understanding of the invention and are known are omitted from the schematic representation.

First, the embodiment of Fig. 1 will be explained.

The magneto-thermic converter consists of two magnetic systems operating on the contact bridge (16) independently from each other and induce in redundancy with the bimetal (12) the actuation of the automatic switch upon disturbed operation over a bolt (8).

Both magnetic systems are connected to a double-anchor actuator and are excited by a common current coil (11).

In operating mode the current flows from a clamp (17) through the current coil (11) and a main switch part (15), a contact bridge (16) to a main switch part (21) and from there to a clamp (23). The thermo-bimetal (12) is short-circuited. The magnet circle for the double-anchor magnet consists of an anchor (1), a magnet yoke (5) and (6) and of a tube (4). The anchor (1) is arranged by force and rotatably in the magnet yoke (5) and acts in disturbed operation with its leg (20) in counter-clockwise direction on the contact bridge (16) and opens the contact point on the main contact part (15).

The air gap (la) of the anchor equals 0, the thermo-bimetal (12) is switched on via burnt-down piece (13) and the connection (14) to the main circuit and flown through by over-current. The thermo-bimetal bends and releases the switch latch via the bolt (8) in a delayed manner.

The tripping value of the bend anchor magnet can be preselected via an adjustment device (9, 10). The anchor (2) and the core (3) form the magnet circle for the immersion anchor. In cases of high short-circuit currents the anchor (2) strikes via a striker pin (22) directly on the contact bridge (16) and opens the current circuit without delay. The air gap (2a) of the anchor equals 0 and the thermal bimetal is protected against overload. The tube (4) and the magnet yoke (5) and (6) in this case are magnetically saturated and the magnet circle acts as an air coil.

The arrangement of contact points with stationary contacts (13, 15, 21) on the contact bridge (16) and the impingement position of both anchors with respect to the point of contact of the contact pressure spring (18) assures that upon each switching off the burnt- down piece (13) takes over the switching; the burnt- down piece is therefore equipped with a burning proof contact cover (19).

Figure 2 represents three possible contact settings.

The closed contact is indicative of normal operation and short-circuited bimetal.

The middle contact setting represents the position in malfunctioning operation and delayed activation - the thermo-bimetal was switched to the main circuit without interruptions.

The open contact shows the situation in "OFF" position, which can be achieved by means of the anchor (2) or through manual actuation via the switch latch.

Fig. 3 and 4 show the component parts thermo-bimetal (12) and contact bridge (16) in their second dimension to explain their operating mode in Fig. 1.

Fig. 5 shows the current-time characteristic of the electric automatic switch compared to known protect switch devices that could be substituted by those of the invention. Short actuation time of the short-circuit proof thermal bimetal abolishes the adjustment of the latter.

According to the invention the operating current in switched-on mode flows only tlirough the current coil and the main switch parts, the impedance of the protect switch device and its power loss are therefore extremely low - it is possible to conceive a low-loss "cool" automatic switch to be used in a closed distribution box, said distribution box experiencing no influence on its actuation by the fluctuating ambient temperature.

Claims

1. Electric automatic switch especially for use as a line protect switch, main circuit breaker or motor protect switch with electric triggering and manual actuation, contact arrangement and device for arc extinguishing for current limitation and means for the fitting and manufacture of an electric connection, characterized in that a short- circuited thermo-bimetal (12) in normal operation switches to the main circuit only in case of disturbed operation without interruptions and that in this case the magneto- thermic converter acts as a command for the actuation over a bolt (8).

2. Electric automatic switch according to claim 1 with a magneto-thermic converter consisting of a combination of a thermo-bimetal (12) and a magnet actuator with an anchor (1) and of a second magnet actuator with an anchor (2) excited by a common current coil (11).

3. Electric automatic switch according to claims 1 and 2 with a magneto-thermic converter, of which two magnet actuators are conceived as a double-anchor magnet system, whereby one magnet actuator is intended as a fold anchor system with an adjustment device (9, 10) and the U-shaped thermo-bimetal (12) is connected in a form-locking way with its 1st foot point with a stationary main switch piece (15) and with its 2nd foot point via a connection (14) with a stationary burnt-off piece (13) and the second magnet actuator according to the immersion principle consists of an anchor (2), a core (3), a tube (4), a magnet yoke (5) and (6) and a binding spring (7).

4. Electric automatic switch according to claims 1, 2 and 3 with a contact arrangement, of which the moving part is conceived as a contact bridge (16) in the form of a triangle and of the total of its three contact positions two are conceived as main switch pieces (15, 21) and a burnt-off piece (13) with a contact cover (19).

5. Electric automatic switch according to claims 1 to 4 with a contact arrangement, of which contact bridges (16) in interrupted operation are actuated in a delayed manner independently from each other by an anchor (1) via a leg (20), an anchor (2) via a striker pin (22) and by a switch latch.

6. Electric automatic switch according to claims 1 to 5 with a triangle-shaped contact bridge (16), which is pushed in normal operation centrally from the contact pressure spring (18) to the three stationary contacts (13, 15, 21), whereby the contacts (13) and (21) form a rotary axis for the contact bridge (16), so that in case of interrupted operation first the contact (15) is opened by the anchor (1) via the leg (20) lying closest to the contact (15).

7. Electric automatic switch according to one of the claims 1 to 6 with a contact arrangement, the contact bridge (16) of which is pushed only in case of a short circuit exclusively from the anchor (2) via the lifter (22) to a stable end position.