FI60328C - ELEKTRISK ANORDNING MED FOERBAETTRAD ISOLATION - Google Patents

Description

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Patent mo Helat (51) Kv.lk?/lnt.CI.3 H 02 H 3/16 FINLAND — FINLAND (21) PaMnttihaktmut - Patantamekning 752950 (22) Hak «ml * pilvl - AnaBknlngadag 22.10.75 (23) Alkupllvt— GlMghutadag 22.10.75 (41) Tullut (ulklMkal - Blhrtt offumllg 25.0¾. 76

National Board of Patents and Registration .... w,. ,. _,,. .

. . . Λ. (44) Date of NthUvlkilpsnon and kuL | utkalaun. - Q,

Patent- och registerstyrelsen Anrtkan utlagd oeh utl.skrlft * n public · ™) 31.08.81 (32) (33) (31) Requested «Tuoikwis — Begird prlorltet 2¾.10.7¾ 21.11.7¾ France-France (FR) 7 ^ 35731 , 7 ^ 38286 1 (71) Thomson-Brandt, 173, Bl. Haussmann, 75008 Paris,; LCC-CICE-Compagnie Europeenne des Composants Electroniques, 128, rue de Paris, 93 Montreuil-sous-Bois, France-France (FR) '(72) Daniel Fleuret, Auxonne, Paul Thevenet, Nevers, France-France (FR) ( 7¾) Oy Kolster Ah

(5¾) Electrical equipment with improved insulation - Elektrisk anordning med för- I

bättrad isolation;

The invention relates to an electrical device supplied by an alternating current network and having a combined supply circuit, i.e. it comprises partly means through which a direct current flows and partly means means connected to the alternating current network.

These devices have a relatively complex electrical circuit with a manually accessible control element, e.g. a programming element, used e.g. in washing machines.

Electrical distribution circuits in which one conductor may accidentally come into contact with users, especially electrical distribution circuits in living rooms, are now protected by highly sensitive differential isolators which trip in the event that the current between the conductor and ground exceeds a value which could cause serious electrical injury. about 30 milliamperes.

Such separators are formed mainly of a transformer, the primary side of which is windings through which a current is proportional to the current flowing through each conductor of the network, so that the resulting magnetic field through the transducer core is exactly zero as long as there is no conductor. and leakage between the ground. In the event of a leak, an imbalance between the current flowing through the two conductors is created, so that a magnetic field proportional to this imbalance develops in the heart. The secondary winding under the influence of this differential field then generates a voltage which triggers the separator. The sensitivity of such a separator, and thus its efficiency, requires that the field generated by each conductor be proportional to the current flowing through it, that is, that the heart is not saturated.

Devices that require an electric motor running at variable power, e.g., washing machines, generally use a single motor supplied with direct current or reverse AC. This type of motor is very suitable for speed control over a wide range, and still maintains acceptable efficiency. In the conventional technique, this current is rectified by a direct current bridge formed of diodes and then adjusted on the basis of the indications given by the programming device. Such a device thus has a relatively complex electrical network through which a rectified current passes.

An insulation fault in this network causes the transformer in the isolator to become improper due to saturation of the core of this isolator. The isolator does not trip in the event of a fault in the DC circuit, nor does it trip in the event of any other fault occurring at any point in the circuit protected by the isolator.

To overcome this disadvantage, an isolation transformer can be placed between the mains and the DC circuits, or a detector indicating a DC fault may be installed in the device, whereby this detector switches the isolator to de-energize all circuits located after this isolator.

The use of wedding methods is complicated, heavy, expensive and inconvenient.

Another method is based on the use of double insulation in the various components through which such a rectified current passes or may have to pass. This double insulation (i.e. class II insulation) is mainly based on the fact that the mass is insulated and thus the electrical contact between the person and any equipment or component where this rectified current can flow is prevented.

For this reason, the body of the electric motors is insulated from the body of the machine, and the mechanical transmission between them is effected by means of an insulating joint, a gear or a belt.

3 60328

One component that can hardly be equipped with double insulation is a programming device, which by definition must be manually accessible. If this is not the case, it has been found that the protection of the differential separator can certainly not be realized.

It is an object of the invention to provide a supply circuit for a device provided with a programming element or the like, and a circuit element for rectified current, in which a fault in the rectifying current-carrying part of this circuit does not affect the operation of the differential isolator.

According to one feature of the invention, this result is achieved in that the members carrying the rectified current are double insulated, while the members connected to the alternating current network are simply insulated, the connections between the two types being made by connecting members in the part of the circuit where the rectified current flows, the current through the connecting members as a whole becomes smaller than a predetermined maximum level.

Experience has shown that the sensitivity of a differential separator operating at a current of 30 milliamperes is not significantly affected by the current of 5 milliamperes flowing from the rectifying circuit to the mass. In practice, resistors (or capacitances) such that their equivalent resistance (or capacitance) is greater than 10,000 ohms (or less than 100,000 picofarads in the case of capacitances) are used as connection components when the mains voltage is 220 volts.

Other features of the invention will now be described with reference to some embodiments of circuits according to the invention applied to washing machines, shown in the accompanying schematic figures.

Figure 1 shows a circuit according to the invention in which resistances are used as connecting components.

Figure 2 shows the connection circuit between the programming device and the supply circuit, in which the connection component is a capacitor.

Figure 3 shows a circuit according to the invention in which capacitors are used as connecting components.

In these formulas, the symbol "mass" means, as usual, a connection to a common neutral conductor, which in turn is isolated from the mass of the body.

4 60328

According to Fig. 1, a bipolar switch 11 connects the mains voltage to its rectifier bridge 12. The rectified current filtered to some extent by the capacitor 13 is connected to the collector of the switching transistor 14. The voltage shared and stabilized by the resistor 13 and the zener diode 16 supplies a cut-off control circuit formed by the multivibrator 17, which may or may not be independent of the mains frequency, and which acts on the single position lever 18. This voltage is also used in the comparator 22 as a reference source . This comparator further receives a first voltage proportional to the average voltage at the terminals of the motor 23 obtained by the resistors 24 and 23 and the capacitor 26, and a second voltage proportional to the intensity of the current flowing through the motor and obtained by the resistor 27.

The result of the comparison of the reference voltage and the pole voltage converted by the current flowing through the motor is used to adjust the magnitude of the pulses of the single-position lever 18 to match the motor's power demand, thereby restoring the motor's power through a fast-acting diode 28.

The pulses of the thus adjusted single-position lever 18 are applied to the base of the transistor 29, and this transistor further conducts them to the primary winding of the transformer 31, which transmits these pulses to the base of the switching transistor 14 via the matching resistor 32. feed the motor 23 *

As an alternative to the circuit diagram described above, transistors 14 and 29 can be connected to a Darlington circuit, in which case a transformer 31 can be used.

All the controls are connected to a programming device 33 * which in particular includes a main switch 11. The limit controls are provided by switches 34, 33, 36, 37 and 38 separately from the second conductor of the network via respective resistances 41 * 42, 43 * 44 and 43, the other end of which is connected to the mass through their respective capacitances shown in the circuit diagram. The mass shown in the drawing is in fact a common pole isolated from the body of the machine when the above-mentioned double insulation class is used.

The switch 34 controls the operation of the multivibrator 17 and thus the starting and stopping of the motor 23.

Switches 33 and 37, through transistors 46 and 47 and shear resistors 48 and 49, act on a voltage divider formed of resistors 24 and 25 and capacitance 26, which generates a voltage proportional to the average voltage of the motor. These switches 55 and 57 convert the instructions given to comparator 22 which affect motor speed.

The circuit breaker 56 and its resistance 45 affect the reference voltage obtained from the voltage divider formed by the resistors 19 and 21. Closing this switch also affects engine speed.

The switch 58 and its resistance 45 act on the base of the transistor 51, which controls the operation of the electromechanical relay 52 to change the direction of travel of the motor.

Figure 2 shows a control element 55 to which the network supplies alternating current, which in turn supplies a rectifier bridge 12 via a bipolar switch. The circuit has circuit breakers, one of which is shown at 55, which affect the operation of the supply circuit according to the programming device. To this end, the switch 55 is connected to the transistor 46 via a capacitor 61, a resistor 62 and a diode 64. The input of this diode 64 is connected to a common insulated conductor (shown in the figure as "mass") via a second diode 65 which is polarized in reverse, while the output of this diode 64 is connected to a common insulated conductor via a second capacitor 65.

The circuit described above operates as follows: Both half-waves of the mains current pass through capacitor 61 and resistor 62, then one passes through diode 65 and the other through diode 64 and capacitor 65. , which is balanced with respect to mass by means of diodes 65 and 64. This voltage 66 is adapted as the voltage to be connected to the transistor 46 by suitably selecting the magnitude of the resistance 62.

Figure 5 shows in combination a device input circuit using a capacitor connection between the programming device and the rest of the circuit, as described above.

The various circuit breakers 54 to 58, when closed, connect a rectified voltage circuit to the various members of the circuit so as to convert the operating conditions of that circuit. To this end, switches 54 to 38 are connected to respective capacitors 141, 151, 11, 171 and 1 to 1, which are connected to series resistances 142, 152, 162, 172 and 1 to 2, which in turn are connected to a common insulated conductor by two diodes 145, 144, (155, 6 60328 154 - 163, 164 - 173 »174 - 183» 184) arranged in parallel and polarized, the filter capacitor 145, 133 »165, 175» 185) being located at the diode 144 (154, 164, 174 and 184). ) and a common insulated conductor. When switches 34-38 are closed, they connect to the circuit points 146, 156, 166, 176 and 186 the corresponding rectified voltages which, according to the instructions of the programming device, convert the operating conditions of the supply circuit in the same way as described above in the case of resistors.

In various embodiments of the circuit, the system has been found to operate satisfactorily when the values of capacitances 141, 151, 161, 171, 181 are 10,000 to 100,000 picofarads.

According to an important feature of the invention, the elements of this circuit through which the rectified current passes are provided with class II insulation, as described above. The only elements insulated according to class I are those which are connected directly to the alternating current network and which are located inside the closed space of the programming device indicated by the number 33 in the figures.

According to another feature of the invention, the electrical connections between the mains-operated programming device and the rest of the rectified current-through circuit are made through sufficiently high resistances 41 to 45 or sufficiently small capacitances 141, 151, 161, 171, 181 so that no direct current the tripping sensitivity of the differential isolator protected by the network is not affected by the interference. As mentioned above, the equivalent resistance of these five resistances is greater than 10,000 ohms and the corresponding equivalent of these five capacitances is less than 100,000 picofarads, and thus Class I.

The circuits thus described can be used to provide reversal and varying speeds within a wide motor range by using a DC motor supplied with a direct current that does not contain prohibited harmonics in the network, so that the combination poses no risk of interference with the protective isolator.

Claims (5)

7 Claims: 6 0 3 2 8 1. In addition to the power supply, the electrical apparatus with the same power supply, dvs. double-stranded, medically de-energized organs and angelic solids, colors of electrical discharges from the body of the body, a characteristic of the body of the body of the body of the body of the body of the body, sin helhet blir raindre än en förutbestämd maximinivä. An electrical device supplied by an AC mains with a combined supply circuit, i.e. comprising partly means through which a rectified current passes and partly means means connected to an alternating current network, characterized in that the means through which the direct current flows pass are double insulated, while the members connected to the AC network are simply insulated, the connections between the two types of members being made through connecting members whose properties are such that if a ground leak occurs in the part of the circuit where the rectified current flows, the current through the connecting members is less than a predetermined maximum. 2. Apparat enligt patentkravet 1, kännetecknad därav, att copplingsorganen utgöres av motständ. Device according to Claim 1, characterized in that the connecting elements consist of resistors. 3. Apparat enligt patentkravet 2, kännetecknad därav, at a maximum equivalent resistance of up to 10,000 ohms. Device according to Claim 2, characterized in that the equivalent resistance of the resistors is higher than 10,000 ohms. 4. Apparat enligt patentkravet 1, kännetecknad därav, att copplingsorganen utgöres av condensatorer. Device according to Claim 1, characterized in that the connecting elements consist of capacitors. Device according to Claim 4, characterized in that the equivalent capacitance of the capacitors is from 10,000 to 100,000 pF, 5. Apparat enligt patentkravet 4 »kännetecknad därav, a capacitor with an equivalent capacitance up to 10,000 and 100,000 pF.