RU174735U1 - OVERHEATING CONTACT CONTACTS FOR PLUGGING CONTACTS - Google Patents

Abstract

The device for protecting the contacts of the plug connection from overheating belongs to the fire-fighting electrical equipment and solves the technical problem of overheating of the contacts due to various reasons. The technical problem is solved by the device for protecting the contacts of the plug connection from overheating in the mains protected by an RCD, including a phase conductor, a neutral conductor connected to the contacts of the plug connection protective conductor, in which near the contacts of the plug connection connected to the phase and zero To the conductors, there is a normally open thermocouple connected between the phase and protective conductors. As a thermocouple, you can use a thermistor, or a thermal relay connected to the protective conductor through a current-limiting resistor. The device can be mounted in the socket of a household outlet, or placed near the contacts in any other way, just and inexpensive to manufacture, prevents overheating of contacts and subsequent ignition of the plug connection.

Description

The utility model relates to fire-fighting electrical equipment, namely, to devices for protecting contacts of plug connections from overheating and subsequent fire.

The prior art design of receptacles aimed, including to increase fire safety. For example, in the design of the plug connection there is a current sensor with a device for opening the retainer of the safety spring, which contributes to the mechanical ejection of the block of contact pins when exceeding the permissible current (RF patent No. 2266593 for the invention "Plug connection", IPC H01R 13/62, H01R 13/187, publ. 20.12.2005, bull. No. 35). The device uses the principle of a thermal release operating on an overload current. However, with an increased load on the plug connection, a gradual or rapid heating of its contacts occurs regardless of the magnitude of the current passing through the sensor and may lead to fire. In addition, the contacts and details of the proposed plug connection, which is heated due to overloads, can be deformed, which will lead to "sticking" of the contacts, the fusion of non-metallic components and unreliable operation if immediate disconnection is necessary.

Existing modern requirements for the installation of industrial electrical networks and electric networks of the housing stock include mandatory electrical safety measures, in particular, the installation of residual current circuit breakers designed primarily to protect people from electric shock (see, for example, GOST R 50807-95 "Protective devices controlled by differential (residual) current ", entered into force 01.01.1996, p. 2).

Residual current circuit breakers (RCDs) controlled by differential (residual) current are widely known in the art and are switching devices that respond to the difference in currents in the phase and neutral conductors in a three-wire network and in phase and zero conductors in a five-wire network, which when exceeded differential current set value lead to the disconnection of the electrical circuit. UZO industry produces both in the form of independent devices and as an addition to the circuit breaker. The RCD immediately disconnects the network when a leakage current occurs.

A known socket network protected by a residual current device consisting of contacts of a socket connected to a phase conductor (L), a neutral conductor (N), a protective conductor (PE) via the TN-CS system (see, for example, G.N. Opoleva "Schemes and substations of power supply. Reference" M. Publishing House "Forum" - INTRA-M, 2009, p. 69, Fig. 2.5.4). The network is protected against overloads by the residual current circuit breaker and circuit breakers, however, in the frequent cases of connecting several consumers to the contacts of one socket, a poor contact of the plug connection and, for other reasons, overheating of the plug contacts and even subsequent fire occurs. By the combination of essential features and purpose, this scheme is taken as a prototype.

The technical problem to which the claimed device is directed is overheating, for various reasons, of the contacts of the plug connection in the circuit protected by the residual current device.

The technical problem is solved by the device for protecting the contacts of the plug connection from overheating in the power supply network protected by the RCD, including the phase conductor, the neutral conductor and the protective conductor connected to the contacts of the plug connection, in which a normally open thermocouple is located near the plug contacts connected to the phase and zero conductors, connected between phase and protective conductors.

As a thermocouple, a thermal relay with a series-connected current-limiting resistance, a thermistor, or other devices that close the circuit at a given temperature can be used.

The technical result obtained in this case is to increase the degree of fire protection of the plug connection by preventing overheating of the contacts by forcing the creation of a leakage current (to ground) with an additional thermocouple. When a leakage current occurs, the consumer disconnects from the circuit using an RCD.

The essence of the utility model in a single-phase network protected by an RCD is illustrated by the circuit diagram of the device (Fig. 1), an embodiment of the device in a three-phase network protected by an RCD is shown in FIG. 2. An embodiment of placing the device inside a household outlet is shown in FIG. 3.

The device consists of a normally open thermocouple 1, located near the contacts 2 of the plug connected to the phase conductor (L) 3, the neutral conductor (N) 4, and the protective conductor (PE) 5. The distance from the thermocouple 1 to contacts 2 should be minimal thermocouple response to an increase in contact temperature. A normally open thermocouple 1 is connected to a phase conductor 3 and to a protective conductor 5. In the case when a thermal relay is used as part of the thermocouple 1, it is connected to the protective conductor 5 through a current-limiting resistance (resistor) 6. The plug connection is located in the network protected by RCD 7 .

Microthermological elements are manufactured by industry and are widely used in various electrical appliances.

A thermocouple can, for example, have a resistance of R≥0.5 MΩ at temperatures from -25 ° C to 45 ° C, and in the temperature range from 45 ° C to 70 ° C, it is necessary to reduce its resistance to 2-1.5 kΩ.

The device can be placed in the body of the shoe 8 of a household outlet, without requiring additional manufacturing of body parts.

The operation of the device is as follows.

The thermocouple 1 with the specified temperature parameters is mounted near the contacts 2 connected to the phase conductor 3 and the neutral conductor 4 of the plug connection at a minimum distance from them, to ensure a clear response to temperature changes. Installation can be carried out in block 8 of a household outlet, or otherwise. Then the thermocouple 1 leads connected to the phase conductor 3 and the protective conductor 5. If the thermocouple 1 uses a thermal relay, then the current-limiting resistance 6 is connected in series.

In normal network operation, thermocouple 1 is in the open state. In the case of an increase due to various reasons, the temperature of contacts 2 is higher than that set by the parameters of thermocouple 1, its contacts are closed and forced leakage current is generated. The RCD 7 of the network immediately responds to the leakage current artificially created in the circuit and opens the network until it can melt or ignite non-metallic components of the plug connection.

For example, in an alternating current network with voltage U = 380/220 V, the rating of the current-limiting resistance is 6, R = 1.5 ÷ 2 kOhm, the leakage current ΔI = 110 ÷ 147 mA will flow, which will be sufficient for the instantaneous operation of the RCD 7 with the setting value ( 10, 30 or 100 mA) and at the same time prevent the passage of short circuit current.

A simple and inexpensive device installed in plug-in connections will prevent contact heating and protect sockets, electrical appliances and rooms from fire.

Claims (3)

1. A device for protecting the contacts of the plug connection from overheating in the power network protected by the residual current device, including a phase conductor, a neutral conductor and a protective conductor connected to the contacts of the plug, characterized in that it is normally located near the plug contacts connected to the phase and zero conductors open thermocouple connected between phase and protective conductors. 2. The device according to p. 1, characterized in that a normally open thermal relay with a series-connected current-limiting resistance is installed as a thermocouple. 3. The device according to claim 1, characterized in that a thermistor is used as a thermocouple.

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