RU2246159C1 - Automatic reclosing device - Google Patents

Abstract

FIELD: automation of power systems; short-circuit protection of power supply equipment.

SUBSTANCE: proposed device has first, second, and third leads, circuit breaker, first electromagnetic relay, and normally closed contacts of first electromagnetic relay; newly introduced in device are voltage sensor connected on one end to second lead through normally open contacts of first electromagnetic relay and on other end, to third lead; current sensor connected in parallel with circuit breaker; OR circuit whose first and second inputs are connected to outputs of voltage and current sensors, respectively; series-connected pulse shaper, integrating circuit, switching stage, and second electromagnetic relay whose normally closed contacts are series-connected to first electromagnetic relay, and pulse shaper input is connected to output of OR circuit.

EFFECT: reduced mass and size of device.

1 cl, 1 dwg

Description

The invention relates to automation of power systems and can be used to protect power supply devices from short circuit currents (short circuit).

A device is known that contains in series the first terminal, the circuit breaker and the second terminal for connecting to the power source and to the load power circuit on the one hand and the third common terminal for connecting to the power source and to the load power circuit on the other side (see Technical Instructions maintenance and repair of power supply devices for signaling and signaling / Ministry of Railways. Main Directorate of Electrification and Energy Management. M: Transport, 1988, p.12, fig. 7 on p.15).

A disadvantage of the known device is that in the presence of a stable short circuit in the load, a circuit breaker made in the form of normally closed bimetallic contacts periodically connects a power source (for example, a transformer) to a short-circuited circuit, which causes its overheating and, under certain conditions, a catastrophic failure.

The closest device of the same purpose to the claimed invention in terms of features is a device for automatic re-inclusion, containing serially connected first output, circuit breaker, normally closed contacts of the first electromagnetic relay and second output, the first electromagnetic relay connected to the first and second output, and third general conclusion (see patent No. 2183894. “Automatic re-inclusion device”, authors Monolakov V.A., Yudin V.V. et al. Published on June 20, 2002 Bull. No. 17), taken as a prototype.

A disadvantage of the known device is that for releasing the contacts of the electromagnetic relay after self-cleaning, it is necessary to include an additional resistance parallel to the coil of the electromagnetic relay, the value of which is approximately equal to the value of the load resistance, and the power dissipated by the additional resistance is comparable with the power of the load loss, which leads to to increase the overall dimensions of the device, to the need to provide cooling of additional resistance.

The invention consists in the following. Protection against short-circuit currents by an ABM type circuit breaker (see, for example, Soroko V.I., Rosenberg E.N. Railway automation equipment. Handbook in 2 books, Book 2. - 3rd ed. - M: NPF Planeta ”. 2000, p.705, 706) is able to withstand short-term overloads that may occur, for example, when charging batteries with maintenance-free chargers. Short-circuit currents can destroy the resulting conductive bridges between the battery plates. Usually, a few seconds of exposure to short-circuit currents is enough to destroy random connections, which provides the AVM, which after a few seconds opens the power circuit after a short circuit occurs. Further action on the circuit with short-circuit currents becomes less effective (see, for example, Beneshevich II, Ovlasyuk V.Ya. et al. Automation and telemechanization of power supply devices for electric railways. - M.: Transport, 1968, p.295 ) The automatic re-inclusion device is located in a cable box with insulation from external atmospheric influences. The internal volume of the cable box is insufficient to accommodate additional resistance and the design of the box does not provide for its effective cooling. Therefore, to accommodate the additional resistance heat-generating (at the time of short circuit) additional housing is required with the same climatic conditions, which significantly increases the overall dimensions of the device.

The technical result that can be obtained by carrying out the invention is achieved by the fact that in a known device comprising a first output in series, a circuit breaker, normally closed contacts of a first electromagnetic relay and a second output, a first electromagnetic relay connected to the first and second output, and also the third common terminal, according to the invention, a voltage sensor is additionally introduced, connected on one side to the second terminal through normally open contacts of the first electric a magnetic relay and, on the other hand, with a third output, a current sensor connected in parallel with the circuit breaker, an OR circuit, the first and second inputs of which are connected respectively to the outputs of the voltage sensor and current sensor, serially connected pulse shaper, an integrating circuit, a key stage and a second electromagnetic relay , normally closed contacts of which are connected in series with the first electromagnetic relay, and the input of the pulse shaper is connected to the output of the OR circuit.

A causal relationship between the totality of the essential features listed above from the claims and the above technical result is as follows.

In the device adopted for the prototype, disconnecting the load circuit from the power source and automatically re-enabling the load after the self-elimination of the short circuit carries out the first electromagnetic relay, in parallel with the coil of which resistance is connected. Resistance is necessary in order to ensure reliable shutdown of the electromagnetic relay at the moment of short circuit disappearance, as it is necessary to reduce the current in the relay coil circuit to a value less than the release current of the coil. By selecting the resistance value, it is not difficult to achieve such a regime. However, a decrease in the resistance value leads to an increase in power dissipation. In the limit, in order to ensure stable relay tripping, it is necessary to reduce the release current to zero. To do this, in the claimed invention, the relay power circuit is interrupted at the moment of short circuit disappearance. The current is interrupted by normally closed contacts of the second electromagnetic relay, the command to turn on which comes from the voltage sensor. Thus, the release of the first electromagnetic relay after the disappearance of the short-circuit occurs not due to the flow of the release current through the coil shunted by the resistance, but due to the interruption of the power supply circuit of the coil. The current sensor interrupts the power supply circuit of the coil of the first electromagnetic relay in case self-elimination of the short circuit occurs earlier than the time the circuit breaker returns to its initial (closed) state.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information, and the identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find an analogue characterized by features identical to all the essential features of the claimed invention. The definition from the list of identified analogues of the prototype, as the closest in the set of essential features of the analogue, allowed to identify the set of essential distinguishing features in relation to the applicant's technical result in the claimed device set forth in the claims.

Therefore, the claimed invention meets the condition of "novelty."

To verify the compliance of the claimed invention with the condition “inventive step”, the applicant conducted an additional search for known solutions in order to identify signs that match the distinctive features of the claimed device from the prototype. The search results showed that the claimed invention does not follow explicitly from the prior art for a specialist, since the influence of the transformations provided for by the essential features of the claimed invention on the achievement of a technical result is not revealed from the prior art as defined by the applicant, in particular, the following transformations are not provided for by the claimed invention:

- addition of a known product by any known part (s) attached to it according to known rules to achieve a technical result, in relation to which the effect of such additions is established;

- replacement of any part (s) of a known product with another known part to achieve a technical result, in respect of which the influence of such a replacement is established;

- the exclusion of any part (element) of the product with the simultaneous exclusion of its function and the achievement of the usual result for such exclusion (simplification, reduction of weight, dimensions, material consumption, increased reliability, etc.);

- an increase in the number of elements of the same type to enhance the technical result due to the presence in the tool of just such elements;

- the implementation of a known tool or part (s) of a known material to achieve a technical result due to the known properties of this material;

- the creation of a tool consisting of known parts, the choice of which and the relationship between them are based on known rules, recommendations, and the technical result achieved in this case is due only to the known properties of the parts of this tool and the relationships between them.

The described invention is not based on a change in a quantitative characteristic (s), the presentation of such signs in relationship or a change in its form. This refers to the case when the fact of the influence of each of these characteristics on the technical result is known, and new values of these signs or their relationship could be obtained on the basis of known dependencies and patterns.

Therefore, the claimed invention meets the condition of "inventive step".

The drawing shows a diagram of the device. The device contains an automatic circuit breaker AB, a voltage sensor 1, a current sensor 2, an OR 3 circuit, a pulse shaper 4, an integrating circuit 5, a key stage 6, terminals “1” - “3”, the first electromagnetic relay K1 with normally closed contacts K1.1 and normally open contacts K1.2, the second electromagnetic relay K2 with normally closed contacts K2.1, the load supply circuit from terminals “2” and “3” and the load resistance R _H.

The operation of the device is as follows. In the absence of a short circuit in the load power circuit, the load current from the power source flows sequentially through terminal “I”, the automatic circuit breaker AB (made in the form of normally closed contacts, which, when heated by the passing electric current through them, are disconnected and return to a normally closed state after cooling) , normally closed contacts K1.1 of the first electromagnetic relay K1, terminal “2”, load supply circuit, load resistance R _H , terminal “3”, power source. The direction of the current is chosen arbitrarily and corresponds to the instantaneous value of the alternating current. If there is a short circuit in the load power circuit, the AB circuit breaker disconnects the power circuit after a while. The coil of the first electromagnetic relay K1 is under the potential of the power source, the response current of the relay K1 flows from terminal “1” through the normally closed contacts K2.1 of relay K2, the relay coil K1, the short-circuited load supply circuit, terminal “3” of the device. At the same time, the current sensor 2 detects the presence of an abrupt increase in voltage, which is supplied to the second input of the OR circuit 3, then to the pulse shaper 4 connected in series, the integrating circuit 5, the key stage 6, and the second electromagnetic relay K2.

The integrating circuit 5 delays the operation of relay K2 with respect to the operation of relay K1. Otherwise, if the response time of relay K2 is less than the response time of relay K1, then relay K1 after the occurrence of short-circuit currents will not be able to operate due to an interruption in the passage of the operating current through the contacts K2.1.

Relay K1 contacts K1.1 repeatedly opens the power supply circuit of the short-circuited load R _H and contacts K1.2 connects the voltage sensor to terminals “2” and “3”. The voltage in this case will be almost zero. After a certain cooling time of the contacts of the AB circuit breaker, they will close again, however, the position of the contacts in the device will not change. In this mode, the device can be arbitrarily long until the causes of the short circuit are eliminated. After the disappearance of the short circuit on the load resistance R _H there will be a voltage due to the flow of current through the relay coil K1 and the load resistance R _n . The voltage that appears through the OR 3 circuit is converted by the pulse shaper 4 into the control signal of the relay K2, which, having passed the integrating circuit 5 and the key stage 6 for current amplification, is fed to the coil of the relay K2. Relay K2 contacts K2.1 opens the power circuit of relay K1, and the device automatically re-turns on the power to the load in normal operation.

In the case when the short circuit disappeared before the AB contacts closed after cooling, the voltage sensor 2 detects the presence of voltage at the load R _n , which generates a signal to turn on relay K2 through the already known circuit. K2.1 contacts open the K1 power circuit, which prepares the load power circuit with K1.1 contacts and disconnects the voltage sensor with K1.2 contacts. In this case, since the AB contacts remain open, the current sensor 2 generates a signal to turn on the relay K2 via a known circuit, since current flows through the current sensor through the circuit terminal “1”, current sensor 2, normally closed contacts K1.1, terminal “2 ”, Load supply circuit, load resistance R _H and beyond.

The current sensor 2 generates single-half pulses, which, having passed the OR 3 circuit, are formed into a pulse sequence by the shaper 4. Despite the different voltage levels from the outputs of both sensors, from the output of the pulse shaper 4 we will have a constant pulse duration. The integrating circuit 5, in addition to the turn-on delay, converts the pulse sequence to a constant voltage level, sufficient to open the key stage 6 and activate the relay K2. The relay K2 contacts K2.1 opens the power circuit of the relay K1 until the contacts of the circuit breaker AB after the cooling. After the AB contacts are closed, the load power circuit is completely restored and relay K2 is turned off, since the current sensor 2 is shunted by the closed AB contacts.

Thus, the above information indicates the following conditions are met when using the claimed device:

- the tool embodying the claimed device in its implementation is intended for use in industry, namely, to intensify the drying of small easily deformable products and bulk materials;

- for the claimed device in the form described in the independent clause of the claims, the possibility of its implementation using the means and methods described in the application or known prior to the priority date is confirmed;

- a tool embodying the claimed invention in its implementation, is able to ensure the achievement of the perceived by the applicant technical result.

Therefore, the claimed invention meets the condition of “industrial applicability”.

Claims (1)

A device for automatically reconnecting, comprising in series connected a first terminal, a circuit breaker, normally closed contacts of the first electromagnetic relay and a second terminal, a first electromagnetic relay connected to the first and second terminal, and a third common terminal, characterized in that a sensor is additionally introduced therein voltage connected on the one hand to the second terminal through the normally open contacts of the first electromagnetic relay and on the other hand with the third terminal, a current sensor, parallel to the circuit breaker, an OR circuit, the first and second inputs of which are connected respectively to the outputs of the voltage sensor and current sensor, a pulse shaper connected in series, an integrating circuit, a key stage and a second electromagnetic relay, the normally closed contacts of which are connected in series with the first electromagnetic relay, and the input of the pulse shaper is connected to the output of the OR circuit.