KR20070012786A - Method for implementing an earth leakage breaker and a device thereof - Google Patents

Abstract

The present invention relates to a method and apparatus (1) for protecting a user from leakage current while the user uses a product, such as a household appliance, or the like. The device 1 is provided with a differential switch 20 which is generally open and a differential current transformer 30 which generates a signal proportional to the leakage current, and the refinement unit 50 interfaced to the switch is provided with the signal. Is obtained and the switch 20 is closed until the acquired signal meets a dangerous condition having a magnitude greater than the limit value.

Description

METHOD AND SAFETY DEVICE FOR GROUND FAULT CIRCUIT}

The present invention relates to a method for protecting against leakage currents, and to an apparatus for implementing the same.

When using devices powered by a power network, and in direct contact with people, the risk of electric shock is always high, so a protective differential circuit breaker is required according to safety standards. In a single-phase system, an electrical device is powered by a public power network (i.e. main-main) via two lines (one "thermal" or "phase" and one "neutral"). It is common to receive a load). A public utility company grounds the neutral wire near the distribution cabin.

Injuries occur when they use a device powered by a power network near a bathtub or pool in a home. Water is the path of currents flowing from the "heat" line to the surface, such as leakage currents, or short circuits, which can cause electric shock if these leakage currents flow through the body. Standing on or touching a conductive surface, when a person touches the “heat” wire to the surface, it can also cause electric shock.

Commercial protection circuitry for this kind of dangerous event, the so-called Ground Fault Circuit Interrupter (GFCI), includes a differential current transformer in which the primary winding consists of thermal and neutral wires and the secondary winding is connected to an amplification stage. . When the current of the heat wire reaches the load and is returned to the ground through the neutral wire without a short circuit, there is no magnetizing force for inducing secondary current in the core of the transformer.

In contrast, when current leaks, a current is produced in the secondary winding that is proportional to the difference between the thermal current and the neutral current, and this signal is amplified and compared to the appropriate safety threshold, and if excessive, the relay (or Circuit breakers) disconnect the thermal and neutral wires from the load.

Since these devices provide total protection for the electrical system in the home, the sensitivity is limited to 30 kW, and small parasitic leakage currents flowing naturally in the system are not allowed.

Plugs connected to the power network supply for safety reasons when using electrical appliances or hand tools for installation of pipes or sanitary products in some conditions, ie in the presence of moisture or in the presence of water. It is desirable to use a more sensitive protection circuit that can be inserted into the. In such cases, devices sensitive to currents as low as 3 mA, or lower, can be implemented.

Hazardous current levels vary with various components, and standards for electrical medical devices with electrodes in contact with patients require a threshold of 3 kV for the protective circuit. Nevertheless, if the trip time of the protection circuit does not guarantee the interruption of the current before a dangerous event occurs, there may be a risk for currents of 1 mA or less.

This high sensitivity protection circuit can guarantee the safety of the operator, but this is where the circuit operates properly. In order to check whether the product currently used by the circuit is operating properly, a test button is provided in which the leakage current is slightly greater than the tested circuit sensitivity, thereby breaking the protection circuit. However, every time the home appliance is connected to the mains, the hassle of checking that the test button must be pressed and the circuit must be activated again after the interruption occurs is passed to the user.

Since the protection system does not rely on manual adjustments by the user, reliability can be maximized.

 Several solutions from existing technologies are disclosed.

Patent US 5,982,593 relates to a circuit breaker using a circuit breaker protection, which protection is provided by further using a test circuit for testing the safe operation of the protection circuit itself, while this test circuit is activated by a test-button .

Patent US 6,426,632 relates to a system for generating a current waveform for testing arch fault protection, which detects a secondary current of a differential transformer and compares the secondary current to a threshold stored in the microprocessor itself. The use of a microprocessor to do this is briefly described. If the detected current is greater than the threshold, the microprocessor transmits a signal that is blocked by the relay and disconnected from the mains.

However, no detailed description of how the microprocessor and related circuitry perform the above-described process is made, and no reference is made to any other process performed by the microprocessor.

Patent US 5,875,087 relates to a circuit breaker for controlling the flow of current from the main to the load. A microprocessor is used to compare the current flow with performance parameters stored or that may be stored within the microprocessor and to generate a control signal for a circuit breaker. The microprocessor performs tests as to whether it operates properly only on neighboring circuits, not collectively, on the protection system, and in addition, there is no calibration phase for the system.

Patent US Pat. No. 6,262,871 relates to an electronic circuit for automatic testing of GFCI, and the main feature of the present invention is that it must be associated with an already implemented GFCI, or it must include an essential component of the GFCI.

Periodically, an artificial leakage current is generated using a microcontroller, and the signal generated by the GFCI in between is irradiated. If the signal is normal, the test is terminated, otherwise the load controlled by the GFCI is disconnected from the main by breaking a second circuit breaker that is essentially added to the system.

The disadvantage of this solution is that there is excess circuit redundancy because it is complicated by the functionality already contained in the GFCI, i.e. automatic inefficient detection, and, in addition, access to form a reference node for voltage sampling. Is not always easy, on the other hand, leads to an increase in wiring and system costs. The GFCI circuit structure according to the present invention can be applied to conventional techniques. In the case of different circuit structures, the system according to the invention has to be completely redesigned.

Therefore, the prior art GFCI does not satisfy the following.

-No manual adjustment is required, it works automatically as a whole.

-It has high sensitivity against leakage current.

Small size and small enough to be inserted into any plug, socket or shunt element.

Include a self-test function for safe operation periodically during the initialization phase of powering up the GFCI or after powering up the load.

-Indicate the user's malfunction.

-After checking that the protection is adequate and efficient, the mains supply is allowed.

By calibrating the leakage current detection circuit, it is possible to operate independently from the implementation of such a detection circuit and compensate for its separation from it.

If a dangerous leakage current is detected, disconnect the load from the main and request a manual adjustment by the user to re-establish the power supply.

1 is a diagram illustrating a GFCI according to the present invention.

FIG. 2 is a detailed view of the GFCI of FIG. 1.

3 is a diagram illustrating an embodiment of the circuit of FIG. 2.

4 illustrates another embodiment of the circuit of FIG. 2.

The present invention is described for a product used at home, ie a hair dryer, but the present invention may be related to other applications, for example, to mount a reliable GFCI to a tool or a plant machine, or other electrical appliance. It is well understood by those of ordinary skill in the art.

In certain embodiments (but this does not limit the invention), the GFCI is integrated into the plug at the end of the feed-cable of the hair dryer. However, by integrating the GFCI of the present invention into a wall socket, a preferred solution can be obtained by inserting a plug of a hair dryer, or other household appliance device, into the socket.

Referring to Fig. 1, a block diagram of the GFCI 1 according to the present invention can be observed, where a single phase electrical power network, or main, is indicated by reference numeral 10, and a heat wire 12 and a neutral wire ( 14 is grounded to connect the network 10 to the individual contacts 22a and 22b of the relay 20. Other types of controlled switches (or circuit breakers), i.e. semiconductor devices, may be used. When the relay 20 is activated, the contacts 22a and 22b contact the two terminals 24a and 24b, the two leads 12a and 12b are routed and the hair dryer 16 Connected to the terminal.

Leads 12 and 14 include a leakage current detection circuit in the leads 12 and 14 themselves, in which case the differential current transformer 30 is implemented on a toroidal core using conventional techniques. do. The primary winding of the transformer consists of leads 12, 14, and with another winding on the ring, a secondary is realized. In order to detect a leakage direct current, a current probe can be used, for example an LEM product.

Using two leads 42, 44, a test generator circuit 40 forms a shunt for the leads 12, 14. The function of the circuit 40 is to artificially induce a precisely known current that flows into the conductors 42 and 44 and thus to the conductors 12 and 14, since the current is a differential element of the transformer 30, The current will be detected, resulting in a secondary signal having an amplitude proportional thereto.

The signal is obtained (or sampled) by a logic refinement unit in which the secondary winding 32 is interfaced through an amplification step, and the logic refinement unit 50 also relays a test generator circuit 40 and a relay. Interfaced to (20), the test generator circuit 40 and the relay 20 may transmit control signals or activation signals via connections 36 and 38, respectively. The unit 50 also includes one or more arithmetic modules for performing binary operations, RAM, ROM, and A / D converters (all of which are not shown in the figures).

With reference to FIG. 2, a more detailed schematic of the GFCI 1 according to the present invention is provided, with parts corresponding to those of FIG. 1 being retained with reference numerals.

In particular, the single phase power network 10 is connected to the conductors 12, 14 extending through the two fuses 11 to the individual contacts 22a, 22b of the relay 20, and the coils of the relay 20 ( When 21 is activated, the contacts 22a and 22b contact the two terminals 24a and 24b from which the two leads 12a and 12b are routed and the hair dryer 16 Connected to the terminal.

The components of this embodiment of the present invention are preferably embedded into the supply plug 55 of the hair dryer 16, which is indicated by the dashed line in FIG. 2.

Referring to FIG. 2, the leads 41, 42 are connected to the test generator circuit 40, and the leads 45 form a shunt of the leads 12, 14 of the power network 10.

 A drop resistive-capacitive network 46 appearing within the area indicated by the dashed line is connected to the conductor 45 and commutated directly to the power network 10 via the conductor 44. (Iii) can extend to the bridge 47. The output of the bridge 47 is filtered by the electrolytic capacitor 48 and the level is determined by the zener 49, which in this embodiment is 30V. The voltage is the first power supply value of the GFCI. The positive terminal of capacitor 48 is connected via conductor 200 to the emitters of the two PNP transistors 60 and 70, while the negative terminal constitutes ground for the GFCI circuit 1. The conductive wire 100 is connected to the conductive wire 100, and the conductive wire 100 is also referred to as ground 100. A resistor 61 is provided between the emitter and the base of the transistor 60, which is connected via the limiting resistor 62 to the collector of the NPN transistor 80. The NPN transistor 60 has an emitter connected to the ground 100 and has a base connected to an output pin of the logic unit 50 through a bias resistor 63 and a lead 38. As such a unit, for example a microcontroller Motorola MC908Q2 can be used. Of the cathode of the freewheeling diode 64, the anode of which is connected to ground 100, the bias resistor 65 of the base of the transistor 70, and the coil 21 of the relay 20; A terminal is connected to the collector of the transistor 60. Another terminal of the coil 21 is directed to the parallel normalization zener 92 and the filtering capacitor 91, the negative terminal connected to the ground 100 and the positive terminal connected to the conductor 110, the logic unit A positive second supply voltage (5.1 V in this case) is provided to both the 50 and the operational amplifier 90 (e.g., LPV321). The current of the transistor 70 by the collector extends through the limiting resistor 71 to the lead 110, which is supplied to the Miller capacitor 72.

The output 90u of the amplifier 90 is connected to both the input pin of the unit 50 and the molded feedback resistors 74, 75, and 76, and the two preceding resistors connected in series are the inverses of the amplifier 90. While connected to the input pin, the third resistor connects the common node of resistors 74 and 75 to a resistive divider forming a shunt of the second supply voltage of 5.1V.

The divider is formed by two equivalent resistors 76, 77 connected in series so that the divider is connected to the common node of the terminal of the resistor 76. Two bypass capacitors 78, 79 are provided in parallel with resistors 76, 77, respectively.

To the inverting, non-inverting input of amplifier 90, a series coupling of resistor 82 and decoupling capacitor 83, and resistor 84 are directly connected. The elements of this group sense the voltage across the load resistor 85, which is connected in series to the two leads 32a, 32b extending from the secondary winding 32 of the transformer 30. A terminal of the load resistor 85 is connected to the divider output formed by resistors 76 and 77.

The following components of the test generator circuit 40 are grouped within the area indicated by the dashed lines. The high precision test resistor 86 connects the lead 12 to the positive pole of the triac 88 via the lead 42, and the negative pole of the triac 88 to the lead 14 via the lead 44. It is. Resistor 86 creates a shunt of leads 12 at a downstream node of transformer 30 such that current flowing through resistors 86 passes through leads 44, 14, but not of transformer 30. It does not flow through the toroidal core, but turns to the network 10. In practice, the lead 44 contacts the upstream lead 12 of the transformer 30. Since the current flowing to the resistor 86 needs to be detected by the transformer 30, other positions for the leads are also possible. Instead of forming a shunt of the lead 12 through the upstream lead 41 of the transformer 30, another compensating resistor 87 is provided in parallel with the resistor 86. Between the gate of the triac 88 and the cathode, a resistor 89 is provided. The series-connected resistor 101 and diode 104 and the series-connected resistor 103 and diode 102 whose anodes are adjusted in the gate direction are connected to the gate. The diodes 104 and 103 are not in parallel. The collector of an NPN transistor 105 having an emitter connected to ground 100 is connected to a resistor 103 and is connected by an output pin of the unit 50 to a base biased by a resistor 106. Inflows in turn. The output pin is connected to the anode of diode 104, which is connected in series with resistor 101.

Two pins of the logic unit 50 power two series resistors 111 and 113 and LED diodes 112 and 114. By driving the LED diode, the logic unit 50 may provide a visual alert or signal to a user of the GFCI 1. To highlight the alert, the LED diode 112 is green and the LED diode 114 is red. Acoustic alarms such as buzzers, or similar devices may also be considered.

Square voltage with network frequency, forming a divider with two resistors 28, 29 connected in series with one end connected to ground 100 and the other end connected in series with drop resistor 46 Is supplied to the pins of the unit 50, and the unit 50 uses the internal timing (20 ms for 50 ms and 16,66 ms for 60 ms main) by calculating the number of linear periods. Another source of computation of internal timing may be a square waveform signal recovered from the clock of unit 50 and scaled down appropriately by the coefficients.

 The calculation step of the GFCI 1 in the condition that the user safely uses the hair dryer 16 is now described from the initialization when the user connects the plug 55 to the socket.

Phase Ⅰ

The user inserts the plug 55 into the associated socket. The normally open relay 20 is not activated such that the hair-dryer 16 is not connected to the power network 10 and thus does not operate. Through the diode bridge 47, the capacitor 48 is charged and when the blocking voltage of the zener 49 is reached, the voltage across the terminals of the capacitors is fixed. Transistor 60 is shut off. This is because the transistor 80 is also blocked because the unit 50 does not bias the base of the transistor 80 without being biased by the transistor 80 and through the resistor 63. Instead, the transistor 70 becomes saturated because of the current path to the base current passing through the resistor 65, the coil 21 of the relay 20, and the zener 92. The base current is too low to activate the relay 20. The saturation of the transistor 70 supplies power to the Zener 92 having a voltage filtered by the capacitor 91 through the resistor 71 and to the operational amplifier 90 and the logic unit 50. Supply power.

STEP II

Since no current flows into the hair dryer 16, and therefore no current flows into the primary winding of the transformer 30 and into the secondary winding, as a result, any voltage across the resistor 85. Also does not exist. Therefore, the voltage at the output 90u of the amplifier 90 maintains a fixed value (about 1/2 of its supply voltage) set by the dividers formed by the resistors 77a and 77b. Through an internal A / D converter (which is 8 bits in this embodiment), the unit 50 uses a sequential acquisition (or sampling) of the output 90u voltage of the amplifier 90 and an internal arithmetic module 65536. Perform an average bet of (2 ¹⁶ ) samples, which requires less than 1 second execution time. The averaged value will be 127 with a deviation of ± 3 bits taking into account the tolerance, ie 1/2 of the full size. This value is obtained when the divider formed by resistors 76, 77 outputs a nominal voltage equal to one half of the supply voltage. If the obtained value is outside this range, step II is repeated from the beginning, otherwise proceed to the next step III. In this step, the LED diodes 122 and 114 are both turned on.

Phase III

The amplifier 90 output voltage 90u is sampled while the unit 50 stores the average value obtained in step II and calculates the average value obtained in step II for another 65536 time. The average value obtained should only allow a maximum of one bit error and equal to the previous value. If not, the system performs step II again. This ensures that the second supply voltage is fixed and ensures that the A / D converter operates properly. The average value calculated in this step is stored inside the unit 50 and is assumed to be a means of zero-reference value for the A / D converter. LED diodes 112 and 114 remain on.

Phase IV

The unit 50 enters into a routine mode for obtaining the output voltage 90u of the amplifier 90 and the difference between the output voltage 90u of the sampled amplifier 90 and the zero-reference value stored in step III. The absolute value of the value is calculated. The maximum value is stored from all of these processed values, and then after a delay of some network 10 cycles, the unit 50 indicates that the maximum value is less than 2, i.e., only the least bits of the A / D Verify that the change was made during the change. This ensures that the noise of the system is so weak that it does not interfere with the operation of the GFCI, and if this condition is not met, the unit 50 performs step I again. During this step, the LED diodes 112 and 114 both shine.

Step Ⅴ

Unit 50 is biased with positive voltage lead 36, transistor 105 is biased by resistor 106, and is saturated. Through a diode 104 and a resistor 101 connected in series, during the positive half-wave of the network 10 voltage, the gate of the triac 88 is positively biased on the lead 12 ( positively biased). Instead, a diode 102, a resistor 103, and a transistor 105 are included in the path to the bias current of the triac 88 during negative half-wave. In both cases, current flows through the resistor 89 and the triac 88 is activated.

STEP VI

The active state of the triac 88 is maintained for two periods of the network 10 voltage, and when the triac 88 with a very accurate value is activated, a differential-current flow is generated for the transformer 30 to detect. The transformer induces a current in the secondary winding 32, thereby generating a voltage across the resistor 85. The AC voltage is amplified by the operational amplifier 90 and provided at its output 90u.

The unit 50 samples this voltage signal in the previous steps, converts it to a digital value using an internal A / D converter, and stores the maximum of these. Thereafter, the unit 50 verifies whether the maximum value is included between the upper limit reference value and the lower limit reference value previously stored in the ROM of the unit 50. To ensure circuitry for detecting differential currents, it operates collectively and has acceptable sensitivity. If the sampled maximum value is too low, the green diode LED 112 glows for a short time, and the system again performs step II. If the sampled maximum value is too high, the red diode 114 glows and the system resumes step II. If the sampled maximum value is appropriate, it is stored as a test-value provided by GFCI 1, and the next step Ⅶ begins.

Step Ⅶ

The unit 50 is biased by the positive voltage lead 38, the transistor 80 is biased by the resistor 63, and saturates. Current current is connected from the first 30V supply to ground 100 through resistors 61 and 62, saturating transistor 60 and powering the coil 21 of relay 20 from the first supply. do. In the coil 21, current can flow to a size sufficient to activate the relay 20 connecting the hair-dryer 16 to the network 10 and thus become available. At the same time, the unit 50 turns on the green diode 112 and permanently turns off the switch on the red diode 114.

Step Ⅷ

After activating the relay 20 and thereby powering the hair dryer 16 from the network 10, as in the previous step, the unit 50 is connected to the output voltage 90u of the operational amplifier 90. ) Continue to be monitored. In particular, after converting the output voltage 90u into a digital number using an A / D converter, the unit 50 subtracts the zero-reference value from its maximum value, and then the module (or absolute value). Calculate and obtain the maximum value of the actual pouring current. If this maximum value is greater than the reference value, in this case, at the end of step VI, the test-value is stored for at least 10 consecutive times, ie for 10 acquisitions (performed at about 0.1 Hz), and the unit 50 removes the voltage from the resistor 38, so that the relay 20 is disconnected and the hair dryer 16 is disconnected from the network 10. By illuminating the red LED diode 114, the logic unit 50 signals for a critical condition. In a dangerous state, the GFCI 1 is locked, thus preventing any further activation, and only after being switched off and on again. In this case, this requires the user to disconnect the plug 55 from the wall socket, remove the problem that the GFCI is blocked, and connect the plug 55 again. At this point, the GFCI 1 will start operating again from step I.

During step VII, ie, while power is supplied to the hair dryer 16, as in Steps V and VI, a test is performed periodically to ensure that the GFCI 1 is operating correctly. In this embodiment, during the test, i.e. during the operation described in steps V and VI, an appropriate maximum value at the arithmetic output 90u, i.e., the reference value, that is required for the relay 20 not to be cut off. This doubles, ensuring user safety.

As mentioned above, it is clear that another advantage of the present invention is that the operating threshold of the GFCI 1 is easy to be set, i.e., by changing the value of the test-resistance 86. The threshold previously stored in the unit 50 for comparison is not a fixed value and is actually the result of a specified current that must be detected by the GFCI (1) in the initialization phase, which is the result of the GFCI (1) for the GFCI (1). Ensure a check for too low operating thresholds. In this case, the supply load is isolated.

Another advantage of the present invention is that it is easy to add another kind of passive protection. Examples are short-circuit protection, or arch-fault protection.

A short circuit condition occurs when the leads 12a, 12b of FIG. 2 are contacted, even temporarily, or when the load reaches a very low impedance value, for example, when the user contacts the leads 12a, 12b. At this point, a high current can flow through the leads 12a, 12b, which can cause fatalities. The fuse 11 of FIG. 2 does not guarantee a quick shutdown response.

This difficulty can be overcome by implementing embodiments of the present invention (see FIG. 3).

In this embodiment, protection against leakage current may be added by inserting the current transformer 300 on the lead 14.

Insertion of transformer 300 may be performed on lead 12 or downstream of relay 20. The primary winding of such a transformer 300 is the lead 14 itself, and the secondary side is a secondary winding equipped with a center tap implemented using the second winding 330. The center-tab is connected to a terminal of a resistor 111a having a very low value (a few ohms), and at the other terminal, the two diodes 310, which are connected to the terminals of the secondary winding of the transformer 300, The anode of 311 is connected.

In FIG. 2, the resistor 111 was directly connected to the LED diode 112, and is now connected to the node where the cathodes of the diodes 310 and 312 meet, and the conductor 320 is the secondary winding of the transformer 300. The center-tab of 330 is connected to the LED diode 112, and a resistor 111b having a relatively high value (about 10 kohm) is attached in parallel to the LED diode. Thus, in the secondary winding 330 of the current transformer 300, the voltage is rectified by the diodes 310 and 311, and thus a field proportional to the current flowing in the conductor 14 across the resistor 111a. A signal will be provided. The operation of the circuit is as follows.

The pin of the unit 50 (referred to herein as A0), to which the resistor 11 is connected, is used as an output pin during initialization to connect the red LED diode 112 through the resistor 111 and the resistor 111a. Drive it. However, the resistor 111b does not affect the operation of the LED diode 112. At the end of the initialization phase, the red LED diode 112 is turned off and the A0 pin of the unit 50 becomes a pseudo input, which is an appropriate indication of the program contained in the unit 50.

Thereafter, the A0 pin can sample the voltage provided to it through an A / D converter, and as a result, the current transformer 300 can be used to indirectly measure the current drawn from the load. If a current above a predetermined threshold flows into the conductor 14, in a manner similar to the method described above, the unit 50 is assured that the switch (relay) 20 is disconnected, thereby protecting against leakage. Guaranteed.

A second embodiment of the device according to the invention is shown in FIG. 4, in which it is similar in many respects to the first embodiment, and new reference numerals have been added to indicate new parts.

A current transformer 3001 with an insertion that can be performed on lead 12b, on lead 12b, or upstream of switch (relay) 20 is connected to the load and the primary winding of transformer 3001 Implemented by this lead 12b, the secondary side is implemented by the secondary winding 3301.

A resistor 1111a having a very low value (a few ohms) connects the terminals of the secondary winding 3301. In FIG. 2, the resistor 111 connected to the LED diode 112 is connected to the resistor 1111a in this embodiment, which supplies power to the anode of the LED diode 112. The cathode is connected to the collector of transistor 370, the emitter is connected to ground 100, the base is biased by a divider formed by two resistors 346 and 344, and the Power is supplied by the collector. In parallel to the transistor 370, a capacitor 340 is provided, while the collector of the transistor 370 is connected to the output 90u of the operational amplifier 90 via a resistor 342.

An assembly consisting of a resistor 342 and a capacitor 340 forms a low-pass filter on voltage at the output 90u of the amplifier 90 such that the DC voltage at the collector of the transistor 370 is increased to the secondary. It is kept equal to one half of the supply voltage.

The operation of the circuit is as follows.

In the initialization phase, while transistor 370 is saturated, transistor 70 is saturated, relay 20 is not active, and LED diode 112 is turned on, so that pin of unit 50 is turned on. A0 is used as the output pin and drives the red LED diode 112 through the resistor 111 and the resistor 1111a. At the end of the initialization phase, the red LED diode 112 is turned off and pin A0 of the unit 50 becomes an analogical input due to proper program instructions.

Due to the blocking of the transistor 70, at the same time, the transistor 370 is cut off and the relay 20 is activated. In the collector of transistor 370, there will be a DC component of the output 90u voltage of amplifier 90, and the DC voltage generated at transformer 3001 and applied to the signal across resistor 1111a is A /. Sampled through the D converter, and consequently, the unit 50 can indirectly measure the current absorbed by the load.

Reading the voltage at pin A0 is performed in the same way as reading the output 90u voltage of amplifier 90, with the absolute value of the difference between the voltage at pin A0 and the zero-reference voltage being ROM of unit 50. It is compared with a reference value stored at, and if larger, the relay 20 is cut off and the load 16 is disconnected.

Claims (35)

In the method for protection against leakage current generated in the supply of the load 16 connected to the electrical network 10, the method Generating and detecting a pre-established test leakage current, thereby verifying the efficiency and calibration for the detection of the leakage current, Detecting an actual leakage current and generating a signal proportional to the actual leakage current, Acquiring the proportional signal and disconnecting the load 16 from the electrical network 10 when a dangerous condition is reached in which the magnitude of the acquisition signal is greater than a limit value; Method for protecting against a leakage current comprising a. The method of claim 1, wherein verifying the efficiency and calibration is performed prior to connecting the load (16) to the network (10). 3. The method of claim 2, wherein verifying the efficiency and calibration comprises generating a test leakage current, generating a corresponding signal proportional to the leakage current, and verifying that the signal is within a predetermined range. A method for protection against leakage currents, characterized in that performed. The method according to any one of claims 1 to 3, wherein the proportional signal is obtained one or more times without generating a test leakage current before connecting the load 16 to the network 10. A method for protection against leakage current, characterized in that a zero-reference value of a proportional signal is obtained. 5. The method of claim 4, further comprising performing an average bet operation to obtain a more reliable estimate of the zero reference value. 5. The limiting method according to claim 4, wherein the limit is obtained by taking the absolute value of the difference between the signal 90u and the zero-reference value obtained after generating the test leakage current, with no load connected from the network 10. A method for protection against leakage currents characterized in that a value is obtained. 7. The method of any one of claims 1 to 6, further comprising periodically verifying periodic detection of leakage current by generating a test current after the load 16 is connected to the network 10. Characterized by a method for protecting against a leakage current. 8. The method of claim 7, further comprising disconnecting the load 16 from the network 10 during the periodic detection phase of the periodic detection of leakage current, wherein the magnitude of the obtained signal 90u is greater than that of the obtained signal 90u. The maximum value of the coefficient is the limit value and the magnitude of the obtained signal 90u after generating a test leakage current while the connection of the load 16 is disconnected from the network 10 and the limit value. A method for protection against leakage currents, characterized in that greater than the sum. The method of claim 1, wherein the detection of the leakage current is performed using a differential transformer 30, wherein the primary winding of the differential transformer 30 supplies power to the load 16. And a secondary winding, for generating said signal proportional to the leakage current. 10. The method of claim 9, wherein disconnecting the load 16 is performed by an electrically controlled switch 20, wherein the electrically controlled switch 20 is an adverb 16 from the network 10 when open. And the load (16) to the network (10) when the switch (20) is closed. 11. The leakage current according to claim 10, wherein during the dangerous state, the electrically controlled switch 20 is forcibly opened until the switch 20 is disconnected from the network 10. How to protect against The method according to any one of claims 1 to 11, Detecting current in one or more leads connected to the load 16, and Disconnecting the load 16 whenever the current is greater than a predetermined threshold Method for protecting against leakage current, characterized in that it further comprises. The method of claim 12 wherein the step of detecting current in one or more leads connected to the load 16 is performed before or after connecting the load 16 to the network 10. Method for protection against current. 14. Protection against leakage current according to any one of claims 12 to 13, characterized in that the step of detecting current in at least one conductor connected to the load (16) is carried out using a current transformer. How to. 15. The method according to any one of claims 12 to 14, wherein disconnecting the load (16) is performed using the electrically controlled switch (20). Way. A device (1) for carrying out the method according to claims 1 to 15, wherein the device is An electrically controlled switch 20 set between the network 10 and the load 16, which disconnects the load 16 from the network 10 when it is open and connects it when it is closed; 20, Detection means 30 for leakage current, said detection means 30 generating a signal proportional to said leakage current,  In order to obtain the proportional signal, the switch is connected to the detection means 30 for the leakage current, or whenever the dangerous condition is met, to drive the opening of the switch using the control signal 38, the switch Refinement Unit (50) Connected To Including, where A generator circuit (40) for generating a test leakage current, thereby verifying the efficiency and calibration of the detection means (30) and the switch (20). 17. The apparatus of claim 16, wherein the generator circuit (40) is controlled via a control signal (36) by a refinement unit (50). 18. The switch (20) according to any one of claims 16 to 17, wherein the switch (20) is a relay having an activation coil (21) controlled by a control signal (38) generated in the refinement unit (50). A device for protection against leakage currents. 19. A device according to any one of claims 16 to 18, wherein said refinement unit (50) is a micro-controller. 20. The apparatus of any one of claims 16 to 19, further comprising circuitry for generating a stable power supply for the refinement unit (50), wherein the circuit is powered from the electrical network (10). Device for protection against leakage current. 21. A device according to any one of claims 16 to 20, wherein power is supplied by a single phase AC voltage. 22. The method according to any one of claims 16 to 21, wherein the means for detecting leakage current 30 comprises a differential transformer 30 having a core, wherein conductors 12, 14 on the core. A primary winding for supplying power to the load 16, and a secondary winding 32 for generating a signal proportional to the current flowing into the primary winding. Device for 23. The generator circuit according to any one of claims 16 to 22, wherein the generator circuit 40 is connected in series to a triac 88 having conductors controlled by a signal 36 generated by the refinement unit 50. A resistor 86, the series connection of which leads to the shunt of the conductors 12, 14 for supplying power to the load 16 using the downstream and upstream terminals of the detection means 30; A device for protection against leakage currents, characterized in that it is formed. 24. Leakage current according to any one of claims 16 to 23, characterized in that an amplifier 90 for a signal proportional to the current is provided downstream of the detection means 30 for the leakage current. Device for protection against 25. The system of claim 24, further comprising circuitry for generating a stable power supply (91, 92) for the amplifier (90), said circuit being powered from the fraudulent electrical network (10). Device for protection against 26. A device according to any one of claims 16 to 25, wherein the refinement unit (50) drives a visual alert (112, 114) or an acoustic alert. 27. The timing means according to any one of claims 16 to 26, wherein the refinement unit (50) is used to scan periodic control regarding the magnitude of the leakage current before or after the switch (20) is formed. (28, 29), characterized in that the device for protection against leakage current. 28. The method according to any one of claims 16 to 27, wherein the refinement unit (50) is obtained by the detection means (30) for leakage current at a value obtained at a predetermined current value, or at a real time value. Apparatus for protection against leakage current, characterized by being provided with an arithmetic module which is used to compare the values to be made 29. An apparatus as claimed in claim 28, wherein said predetermined value is stored in a ROM inside said refinement unit (50). 30. The apparatus of any one of claims 16 to 29, further comprising means (300, 3001) for detecting a current in the leads connected to the load (16), wherein the detecting means (300, 3001) Generating a signal proportional to and connected to the refinement unit (50), whereby a shutoff of the switch (20) can be controlled if a hazardous condition is met. 31. Apparatus according to claim 30, characterized in that the means (300, 3001) for detecting a current in the lead connected to the load (16) comprises a current transformer. 32. The control signal according to claim 30 or 31, wherein the refinement unit 50 is connected to the means 300, 3001 for detecting the current in the lead connected to the load 16, or if a dangerous condition is met, 38. A device for protection against leakage current, characterized in that it is connected to the switch to control the switching off of the switch (20) by means of 38). In the electrical appliance provided with a plug 55 for connecting the electrical appliance to the electrical network 10, the electronic appliance comprises a protective device 1 according to claim 16. An electronic product, characterized in that. 34. The electronic product of claim 33, which is a hair dryer, or other consumer electronics device. A socket for powering an electronic product, the socket comprising a protective device according to any one of claims 16 to 32.

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