RU2599379C2 - Device for monitoring ground circuit of information processing equipment - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention can be used in electrical engineering. Device for monitoring earthing circuit of information processing equipment includes electric branch connected between current-conducting wire of supply mains and ground and including limiting resistor (R1) and electronic circuit formed by half-wave rectifier (diode VD1, capacitor C1), loaded on resistor (R2), comparison unit (comparators D1.1, D1.2, resistors R3-R7), AND logical element (transistor VT1, diodes VD2 VD3, resistors R8, R9), sound source (active piezoelectric transducer B1).

EFFECT: technical result-increase of efficiency of monitoring safety.

1 cl, 3 dwg

Description

The invention relates to devices for ensuring the safe operation of technical means of information processing, containing network noise filters and metal housings (screens), connected to individual grounding devices, and is intended for automatic control of the integrity of the ground circuit.

A device is known - an analyzer of the installation quality of the power supply system of general-purpose electrical appliances (status indicator of power outlets ISER-01) with sound and light alarms (see Afanasyev AI Electromagnetic background of industrial frequency 50 Hz [Text] // Safety and labor protection, 2006 . - No. 3. - p. 51).

The device contains indicator plugs (A) connected in series with pin 1, a limiting resistor (R1), a trimming resistor (R2) connected to the connection point of two branches, one of which is a series circuit including a second limiting resistor (R3) and a second indicator (B), and the other branch contains a third indicator (C), also connected to two branches, one of which contains a third limiting resistor (R4) connected to ground, and the other a fourth limiting resistor (R5), but coupled with the fourth indicator (D), which in turn is connected through a branch indicator in contact with two forks.

The reasons that impede the achievement of the technical result indicated below when using a known device include the fact that the known device is used for the case of connecting equipment to sockets with grounding contacts, i.e. grounded on the common ground loop of the building (structure). Therefore, the known device is not applicable for monitoring the grounding of information processing equipment, metal cases (screens) of which (according to the requirements of information protection and (or) electromagnetic compatibility) must be grounded to an individual (separate) grounding device and do not have a direct metal connection with zero ( N or PEN) by the power supply conductor and the common ground loop (PE) (Fig. 1).

In addition, the dimensions of the known device make it difficult to install it inside the equipment.

The closest device of the same purpose to the claimed one according to the maximum number of similar features is a device for monitoring the presence of grounding in the socket (US Pat. 2341841 Russian Federation, IPC H01H 9/00, G01R 27/20. Device for monitoring the presence of grounding in the socket [Text] / Serdyuk BC, Zinkov A.S., Yanchiy A.V .; applicant and patentee of the State Educational Institution of Higher Professional Education “Omsk State Technical University.” Application. 01.03.2007; publ. 20.12.2008. Bull. No. 35). The device contains (Fig. 2) two electrical branches interconnected, and the other with the corresponding contacts of the plug. Each branch includes an indicator element connected by a limiting resistor. Indicator elements are made in the form of LEDs, turned on counter. The ground contact is derived from the midpoint of the electrical circuit connecting both branches.

The device is compact and will work when it is installed inside the equipment and connected between live conductors and the “ground” (the metal casing (screen) of the equipment having a grounding contact that connects to an individual grounding device).

However, the reasons that impede the achievement of the technical result indicated below when using the known device include the fact that when using the known device, the insulation resistance of electric circuits decreases below the values established by regulatory documents.

This is due to the fact that for the normal glow of the LEDs, the resistance of the limiting resistors included in the circuit of the known device, R1 and R2 should be

R = (U _pit. -U _pad. ) / (I 0.75),

where R is the resistance of the resistor (Ohm);

U _pit . - voltage of the power source (V);

U _pad . - direct voltage drop on the LED in volts (indicated in the specifications and is usually in the region of 2 V);

I is the direct current of the LED in amperes (indicated in the specifications and is usually either 10 or 20 milliamps);

0.75 - reliability factor for the LED.

With a supply voltage of 220 V (amplitude value of 311 V) and a maximum forward current through a 10 mA LED, the resistance of resistors R1 and R2

R = (311 V-2 V) / (10 mA 0.75) = 41.2 kΩ.

At the same time, according to the Electrical Installation Rules (Ch. 1.8 PUE) and GOST R 50571.16-99. Acceptance tests (IEC 60364-6-61-86), Table 61A, the insulation resistance of the electrical network between each current-carrying conductor and the ground must be at least 500 kOhm.

In addition, the device does not have an audible indication, which reduces the likelihood of the operator perceiving information about the violation of the ground circuit parameters.

The objective of the invention is to provide a device for monitoring the grounding circuit of technical means of information processing, devoid of the above drawbacks and which improves safety monitoring of the use of technical means of processing information containing network noise suppression filters and metal cases (screens) connected to individual grounding devices.

The specified technical result is achieved by the fact that in the known device for monitoring the presence of grounding in a socket containing an electric branch with a limiting resistor, connected between the current-carrying wire of the power supply network and the ground, instead of the LED acting as an indicator, an electronic circuit formed by a half-wave rectifier is included, the comparison node, the logical element AND, the source of sound, which is used as an active piezo emitter.

An analysis of the prior art made it possible to establish that analogues that are characterized by a combination of features identical to all the features of the claimed technical solution are absent, which indicates the compliance of the claimed device with the patentability condition of "novelty".

Search results for known solutions in this and related fields of technology in order to identify features that match the distinctive features of the claimed object from the prototype showed that they do not follow explicitly from the prior art. The prior art also did not reveal the popularity of the impact provided for by the essential features of the claimed invention, the transformations to achieve the specified technical result. Therefore, the claimed invention meets the condition of patentability "inventive step".

Due to the introduction of a set of essential distinguishing features into a known object, the claimed device for monitoring the ground circuit of information processing technology allows to increase the efficiency of safety monitoring of the use of information processing equipment containing network noise suppression filters and metal cases (screens) connected to individual grounding devices.

Improving the effectiveness of security control of the use of technical means of information processing, when using the claimed device, is expressed in:

automatic (with audible alarm) monitoring of the ground circuit of information processing equipment, the screens of which are grounded to an individual grounding device;

reducing the overall dimensions of the device, ensuring its installation inside the equipment;

the exclusion of a decrease in the insulation resistance of current-carrying wires of the power supply network relative to the ground below the minimum acceptable value (0.5 MΩ) when the device is connected to test points.

The drawings show:

FIG. 1 - power supply circuit of technical means of information protection (TSOI) with an individual grounding device;

FIG. 2 is a circuit diagram of a prototype device;

FIG. 3 is a circuit diagram of the claimed device for controlling the ground circuit of information processing equipment.

The device for monitoring the ground circuit of technical information processing tools contains an electric branch, including a limiting resistor R1 and an electronic circuit formed by a half-wave rectifier (diode VD1, capacitor C1), loaded on resistor R2, a comparison unit (comparators D1.1, D1.2, resistors R3-R7), a logical element AND (transistor VT1, diodes VD2, VD3, resistors R8, R9), a sound source (active piezo emitter B1).

The device is connected between the current-carrying wire of the power supply network and the metal casing (screen) of the equipment having an earthing contact, for example, parallel to any capacitor C1 or C2 (so-called Y capacitors) of the network noise filter (see Fig. 1).

The device operates as follows.

The condition of the ground circuit is determined by the circuit of the device according to the voltage level on the capacitor C1 or C2 of the line filter of the information processing equipment. In the absence of grounding Y, the capacitors form a capacitive voltage divider. Therefore, the voltage across each capacitor is approximately 110 V (half the voltage of the power supply network). In the case of a working ground circuit, the voltage on one of the capacitors becomes equal to the voltage of the power supply, and on the other is close to zero.

Reduced, rectified and smoothed voltage from the output of the rectifier is supplied simultaneously to the direct input of the comparator D1.1 and to the inverse input of the comparator D1.2. The value of this voltage is proportional to the voltage between the current-carrying wire of the power supply network and the equipment case having an earthing contact. Exemplary voltages generated by the divider on resistors R3-R5 are applied to the second inputs of the comparators. If the voltage at the test point is 220 V (0 V), then the voltage from the rectifier output is greater (less) than both reference voltages. As a result, a low level voltage is set at the output of one of the comparators, which leads to the opening of a diode connected to this output (VD2 or VD3) and ensures the closed state of transistor VT1.

If the ground circuit is interrupted, the voltage at the test point becomes equal to half the voltage of the power supply network (110 V). In this case, the voltage output from the rectifier turns out to be less than the reference voltage supplied to the direct input of the comparator D1.1 and more than the reference voltage supplied to the inverse input of the comparator D1.2. As a result, high-level voltages are set at the outputs of both comparators, the diodes VD2 and VD3 are closed, which leads to the opening of the transistor and the start of the piezo emitter.

In the practical implementation of the device, the following should be considered. To prevent a decrease in the insulation resistance of the current-carrying wires of the power supply network relative to the ground below the permissible limit, the resistor R1 must have a resistance of at least 1 MΩ. In this case, the value of the resistor R2 is selected in such a way as to provide a sufficient difference between the voltage at the output of the rectifier and the model voltages for reliable operation of the device with voltage fluctuations in the power supply network. The capacitance of the capacitor should be sufficient to smooth out the ripples of the rectified voltage (several microfarads). To reduce the dimensions of the device, it is advisable to use comparators located in one housing of the chip. For example, a domestic chip K1464CA1 (in the usual version) or K1464CA1T (version for planar mounting). The prototyping carried out showed that when using the second option and SMD components, the dimensions of the printed circuit board of the device circuit will not exceed 20 × 30 mm. The device can be powered from the secondary power source of the information processing equipment (power supply circuit 5 ... 15 V).

Information sources

1. A.I. Afanasyev. Electromagnetic background of industrial frequency 50 Hz // Safety and labor protection. - 2006. - No. 3. - S. 51.

2. Pat. 2341841 Russian Federation, IPC H01H 9/00, G01R 27/20. Device for monitoring the presence of grounding in the socket [Text] / Serdyuk B.C., Zinkov A.S., Yanchiy A.V .; applicant and patent holder GOU VPO Omsk State Technical University. Claim 03/01/2007; publ. 12/20/2008. Bull. Number 35.

3. Rules for the installation of electrical installations. Seventh Edition. Approved by the Order of the Ministry of Energy of Russia of 08.07.2002

4. GOST R 50571.16-99 (IEC 60364-6-61-86). Electrical installations of buildings. Part 6. Tests. Chapter 61. Acceptance tests.

Claims (1)

A device for monitoring the ground circuit of technical information processing equipment, containing an electric branch connected between the current-carrying wire of the power supply network and the ground and including a limiting resistor and an electronic circuit formed by a half-wave rectifier, a comparison unit, a logical element And, a sound source, which is used active piezo emitter.

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