RU170072U1 - Device for monitoring the grounding of electrical appliances - Google Patents

Abstract

The device is intended for continuous monitoring of the presence of grounding in electrical appliances of office and household appliances in a three-wire network of 220 V. The technical result consists in simplifying the device and increasing functionality. The device (Fig. 2) is part of the appliance and serves as an indicator of the presence of mains voltage. An electrical circuit is introduced into a device containing an input element (1) of three contacts for connection with phase (L), zero working (N) and zero protective (PE) wires of the network, analyzing the circuit (2) and actuator (3), ( 4), containing a series-connected limiting resistor and a diode, the first output of which is connected to the contact of the neutral working wire of the network, the second output is connected to the input of the actuating element, which is the connection point of the same outputs of two LEDs, the second output of the first LED through a sound indicator (NA1) and a resistor R4 are connected to the phase wire contact, and the analyzing circuit contains a transistor switch on the MOS transistor (5), the drain of which is connected to the second output of the second LED, the source is connected to the phase wire contact, and the gate is connected through high-resistance resistor (10) with the grounding terminal of the appliance and with the contact of the neutral protective conductor, while the value of the high-resistance resistor is chosen so that the current in the grounding circuit does not exceed the regulated current spans 0.5 mA. The device of the second embodiment has a touch-sensitive phase identifier and is used as a probe of Euro-outlets for monitoring their operability, the presence of grounding and the correct connection of the phase wire of the network. 1 s.p. f-ly, 4 ill.

Description

The proposed device relates to devices for ensuring the safe operation of office and household appliances and is intended for continuous monitoring of the presence of grounding in electrical appliances in a three-wire network of 220 V. When using electrical appliances with a metal case, grounding is necessary to ensure electrical safety of the consumer, since in case of a breakdown of the mains voltage on the case, the consumer may be energized. When using stationary computers, it is necessary to ground both the monitors themselves and the main unit, since without this the electric fields near the computers, as a rule, are 2-10 times higher than the established sanitary standards (lit. 2).

The proposed utility model relates to the field of electrical engineering and may find application in the operation of domestic and industrial electrical appliances.

A device is known for active protection against phase voltage on the device case, patent RU 2273935 C1, IPC НН Н 3/14, published October 18, 2004. The disadvantage of this device is the complexity, since there are relays, a photoconverter. The disadvantage is the lack of information about the disappearance of grounding.

A device for controlling the presence of grounding in the socket is known - patent LV 14333 V, IPC Н01Н 9/00, G01R 27/20, filed December 1, 2009. The disadvantage of this device is the impossibility of continuous monitoring of the grounding of electrical appliances, if it were used in their composition, since monitoring occurs at the moment of pressing a push-button switch that is connected directly to the ground circuit.

A device for continuous monitoring of the availability and quality of grounding of electrical equipment. Patent RU 151432 U1, IPC Н02Н 3/14, Н02Н 3/10. Published 04/10/2015. The device has a complex electrical circuit, as it includes a node for disconnecting the device from the network in the absence of grounding. The device has a measuring unit on a microprocessor to control the current in the ground circuit

The closest analogue (prototype) is the "Device for monitoring the grounding of electrical appliances" Patent RU 20413 U1, IPC Н02Н 3/10, Н02Н 3/14. Published on April 17th. 2001. The device is a power cord for office and household appliances with a built-in electronic circuit that allows sound signals to notify the worker of the disappearance of the grounding of the equipment that is connected via this power cord to the network (Ref. 2). Functional diagram is shown in the drawing (Fig. 1). The device contains an input element (1) of three contacts, including two power contacts (11) for connection with phase and neutral wires and a contact for connection with the body of the appliance (12), analyzing the electrical circuit (2) and the actuator (3). The analyzing circuit includes a voltage balancing element (4), current relay (7) and resistance (10). The current relay is made on an operational amplifier. The actuating element (3) includes a repeater on the operational amplifier and a sound emitter. The power contacts are connected to the inputs of the balancing element, the output of which is connected to the first control contact (8) of the current relay (7), the executive contacts of which are connected to the actuating element, and the contact for connecting to the grounding element of the electric device (12) is connected via resistance (10) to second control contact (8) of the current relay. The resistance value of the resistor (10) is set so that the electrical safety requirements for safety current are met. (0.5 mA). When the ground disappears, a voltage appears on the actuator, which turns on the sound indicator of the actuator. A periodic beep sounds. The disadvantage of this device is the relative complexity of the electrical circuit. Therefore, it cannot simultaneously function as an indicator of the presence of mains voltage. The device does not control to which pin of the outlet the phase wire of the network is connected.

The purpose of the proposed utility model is to simplify the device and increase functionality. This goal is achieved in that in a device containing an input element of three contacts, including two power contacts for connecting to the phase and neutral wires of the network and a contact for connecting to the grounding element of the appliance, analyzing the electrical circuit and the actuating element, an electrical circuit containing connected by a limiting resistor and a diode, the first output of which is connected to the contact of the neutral working wire of the network, the second output is connected to the input of the actuator, i a connecting point of the same terminals of two LEDs, the second terminal of the first LED through a series-connected resistor and a sound indicator is connected to the phase wire contact, and the analyzing circuit contains a transistor switch on the MOS transistor, the drain of which is connected to the second terminal of the second LED, the source is connected to the contact phase wire, the shutter is connected through a high-resistance resistor to the grounding terminal of the electrical appliance and to the contact of the neutral protective conductor of the network, while rotivleniya high-resistance resistor is selected based on the ratio:

Uin / 0.5I without <R <(Uin.R * / 2Ucab) - R *,

Where

R is the resistance value, Ohm,

Uin - voltage between the power contacts of the input element, V,

Without - safety current, A (0.5 mA),

Ucrab - voltage operation of the transistor switch, V,

R * is the resistance value of the resistor connected in parallel with the drain and source of the transistor, Ohm.

An additional goal of the utility model is the ability to control the operability of 220 V Euro sockets. This goal is achieved by introducing a touch phase identifier with its electrical connections into the device of the second embodiment (Fig. 3) according to claim 2 of the formula.

This utility model is illustrated by the drawing in FIG. 2. For use in electrical appliances, the device (Fig. 2) is implemented as a separate printed circuit board, which is located near the front panel of the device, while the light indicator of the device is also an indicator of the presence of mains voltage. The device (Fig. 2) contains an input element (1), an analyzing circuit (2), an actuating element (3), an electric circuit (4). The analyzing circuit (2) contains a transistor switch on an MOS transistor (5) with a high input resistance in the gate circuit. The actuator contains a two-color LED HL1, an audio indicator HA1 and a resistor R4, connected in series with the red light LED.

The device works as follows: when the appliance is connected to the network, the green LED “220 V network” lights up on the front panel, since grounding is present and the phase wire in the socket is turned on correctly, to the right pin of the socket. The transistor switch (5) is in the closed state, and current flows through the green LED of the indicator light. The first red light-emitting diode does not light up, since the current circuit through it and through the sound indicator is shunted by the drain-source circuit of the transistor and the second green-light LED. If the ground circuit is broken (broken), then instead of the green light, the red light of the indicator will turn on and a periodic sound signal will sound. If the phase wire is switched on incorrectly, on the left contact of the socket (when they are horizontal), the red LED is on and a periodic tone sounds, since the source of the transistor (5) is connected to the neutral wire contact and therefore there is no voltage at the key input. The user will know that the phase wire in the outlet is not turned on as recommended. If in both positions of the plug of the device’s cord, a red light is on in the socket, it means that the appliance is not earthed. The resistance of the resistor (10) is selected so that the current flowing through it in the ground circuit is less than the safety current regulated by regulatory documents (0.5 mA). The resistance value of the resistor (10) is selected in accordance with the above ratios and is at least 1 mOhm. Electrical appliances must be connected to the network through sockets tested and accepted for use.

The electrical circuit of the second embodiment of the device is shown in FIG. 3. In this case, the device can be implemented as part of an electrical appliance, or in a separate housing. The appearance of the prototype device (FIG. 3) is shown in the photo of FIG. 4. The device is used as a probe for a quick check of the operability of the 220V Euro sockets by builders, plumbers, and office workers. The probe has a touch phase identifier implemented on an MOS transistor (6) having a large input gate resistance. The outlet is working if, when you touch the outside of the probe body with your hand in the place where the touch contact E is located on the inside of the housing wall, the probe indicator green light is green. The probe detects a dangerous double fault when the left contact and the ground contact in the outlet are under the potential of the phase conductor of the network and a neutral working or zero protective conductor of the network is connected to the right contact. In this case, the transistor switch (5) is closed (Fig. 3), and the transistor switch (6) is open, since there is no current in the sensor contact circuit when a hand is touched. In this case, the green light of the probe indicator does not light. Well-known testers MS6860D (http://www.testers.ru/catalog/index.php) and EL-Eurotester (info@new-line.nl) do not detect this malfunction of outlets, as they do not have a touch phase identifier. When there is no grounding, an audible signal sounds in both positions of the probe in the outlet and the red indicator light is on, as the transistor (5) is open due to the lack of current in the gate circuit. When the transistor (5) is closed, the sound indicator does not work, as it is shunted by the circuit: the source-drain of the transistor (5), diode VD2. Touch contact Ε is made in the form of a metal plate 20 × 20 mm fixed on the inner wall of the probe body. The resistance value of the resistor R5 is 5-20 mOhm. The pilot operation of the device confirms the possibility of monitoring the operability of 220 V Euro sockets. The devices (Fig. 2) and (Fig. 3) are used in the operation of electrical appliances that are included in a three-wire 220 V network using a connecting plug with an earthing pin of a European (German) standard. In this case, the phase wire of the appliance is connected to the right terminal of the plug.

Literature

1 Certificate for utility model 20413 U1 RU, IPC Н02Н 3/10, Н02Н 3/14 "Device for monitoring the presence of grounding of electrical appliances." Stated April 17, 2001. Application 2001109917/20.

2. Afanasyev A.I. Electromagnetic background of industrial frequency 50 Hz "Safety and labor protection" 2006 Nr3.

3. Patent LV 14333 V, IPC Н01Н 9/00, G01R 27/20 "Device for monitoring the presence of grounding in the socket." Declared December 1, 2009. Application R-09-212

4. "Device for continuous monitoring of the availability and quality of grounding of electrical equipment" Patent 151432 Ul RU, IPC Н02Н 3/14, Н02Н 3/10. Announced September 15, 2014.

Claims (9)

1. A device for continuous monitoring of the grounding of electrical appliances, containing an input element of three contacts, including two power contacts for connecting to the phase and zero working wires of the network and a contact for connecting to the grounding element of the electrical device, analyzing the electrical circuit and actuator, characterized in that an electric circuit containing a series-connected limiting resistor and a diode, the first output of which is connected to the contact of the neutral working wire of the network, the second water is connected to the input of the actuating element, which is the connection point of the same terminals of two LEDs, the second output of the first LED through a series-connected resistor and a sound indicator is connected to the contact of the phase wire, and the analyzing electrical circuit contains a transistor switch on the MOS transistor, the drain of which is connected to the second output of the second LED, the source is connected to the contact of the phase wire, and the gate is connected through a high-resistance resistor to the contact of the neutral protective wire of the network and to the contact ohm grounding the appliance, the high-resistance value of the resistor is selected based on the ratio: Uin / 0.5I without <R <(Uin R * / 2Usrab) -R *, Where R is the resistance value of the high-resistance resistor, Ohm; Uin - voltage between the power contact of the input element, V; Ibez - safety current, A; Usrab - transistor switch tripping voltage, V; R * is the resistance value of the resistor connected in parallel with the drain and source of the transistor, Ohm. 2. The device according to claim 1, characterized in that a second transistor switch on the MOS transistor is inserted into the analyzing circuit, the source of which is connected to the drain of the first transistor switch, the drain is connected to the second output of the second LED, and the gate is connected through the resistor to the device’s touch contact , and a diode is introduced into the actuator, the first output of which is consistently connected by the connection point of the resistor and the first output of the sound indicator, the second output of which is connected to the contact of the phase wire, and the second output is ode is connected to the drain of the first transistor switch.

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