RU2713881C1 - Spark protection device - Google Patents

Abstract

FIELD: electrical equipment.

SUBSTANCE: invention relates to electrical equipment, and can be used in oil and gas, ore and flour industries, and is intended for use in explosion-proof electrical equipment, having independent power sources in form of internal voltage sources and used for operation in explosive environments. Spark protection device has a field MIS transistor connected in inverse manner: source of MIS-transistor is connected to positive terminal of device, and drain to power supply circuit of device electronics, between source and gate is connected output of optoelectronic driver, polarity of which, when the optoelectronic driver is turned on, coincides with polarity of MIS-transistor gate opening, and input of optoelectronic driver is connected through limiting resistor between positive and negative terminals of device. Spark protection device allows cascade connection to increase the number of spark protection diodes to two or three in compliance with the required level of explosion safety. MIS-transistor channels are connected in series in the supply circuit, and the input circuits of the optoelectronic drivers are connected in series and connected through a common limiting resistor.

EFFECT: reduction of voltage drop in spark-proof circuit of explosion-proof device with internal source of voltage for reduction of heat losses and increase of accuracy of control of accumulator batteries charging from external charging device.

1 cl, 2 dwg

Description

Technical field

The invention relates to the oil and gas industry, and is intended for use in explosion-proof electrical equipment, which includes autonomous energy sources and is used for work in explosive atmospheres.

State of the art

Explosion safety standards (GOST R IEC 60079-11; GOST 51330-10) for an explosion-proof device (hereinafter referred to as the device), which includes autonomous energy sources, such as galvanic and storage batteries, establishes the requirement to provide protection against the possible occurrence of voltage from internal sources energy on the external circuits of the device in the event of any emergency in its electronics.

In the external power circuits of the device used to power its electronics during technological maintenance and / or charging the batteries, in accordance with the recommendations of explosion safety standards, in particular GOST 51330-10, one to three diodes (depending on the required level of explosion safety) are installed, included in series between the input connector and the power circuit of the electronics of the device. The diodes forming the electrical protection device ensure the flow of current from an external voltage source to the device electronics and guarantee the absence of voltage of internal autonomous energy sources at the terminals of the input connector of the device after disconnecting the external voltage source. Such a device has a significant drawback. When the device is powered and the batteries are charged from an external voltage source, the diode voltage drops to several volts, which leads to strong heating of the diodes when high currents flow and the need to cool them with radiators or a fan. In addition, the diodes have a non-linear current-voltage characteristic, which significantly worsens the control of the charging voltage of the batteries when charging from an external charger, carried out through the spark protection circuit.

The patent for invention RU 2479905 is also known from the prior art (Patentee: LLC Research Design Automation Laboratory) (RU), published: 04/20/2013, IPC: Н02Н 9/00, E21F 9/00).

In an intrinsically safe power source, a block consisting of a semiconductor switch is used as an intrinsic safety barrier, which disconnects the output of the power source from the load in the event of a stabilizer malfunction. Voltage limitation is performed using a stabilizer, and intrinsic safety is ensured by duplication or tripling of semiconductor elements.

By the totality of common features (a semiconductor switch, a semiconductor diode in the form of a pn junction “base - emitter”), this device is taken as a prototype of the claimed invention. In the prototype, which is an optocoupler key with a Darlington output, the reverse voltage is limited by the breakdown voltage of the transistor pn junction, of the order of 5-8 V (physical limitation). Moreover, in the forward direction, the voltage drop of the Darlington circuit is 0.5-1.5 V. This leads to heat loss during the flow of large charging currents and makes it difficult to control the charging voltage of the internal voltage sources of the device when charging from an external charger.

Disclosure of the invention

The objective of the invention is to develop a spark protection device of an explosion-proof device with improved characteristics.

The technical result of the invention is to reduce the voltage drop in the spark protection circuit of an explosion-proof device with an internal voltage source to reduce heat loss, and to improve the accuracy of monitoring the charging of batteries from an external charger.

The set of essential features sufficient to achieve the specified technical result and defining the scope of legal protection of the invention includes at least one cascade of protection, consisting of an optoelectronic driver and an MIS transistor, while

the positive terminal, the negative terminal and the cathode of the optoelectronic driver are connected respectively to the source, the gate of the MOS transistor and the negative terminal of the device;

the anode of the optoelectronic driver and the source of the MOS transistor are connected to the positive terminal of the device, and the connection of the anode of the optoelectronic driver to the positive terminal of the device is made through a limiting resistor.

In addition, this technical result is achieved in the particular case of the invention due to the fact that the spark protection device of the explosion-proof device contains at least two or more identical series-connected protection stages with a common limiting resistor installed in the anode circuit of the optoelectronic driver of the first protection stage, and the input all three optoelectronic driver circuits are connected in series.

The spark protection device of an explosion-proof device with an internal voltage source is shown in FIG. 12.

In FIG. 1 shows an spark protection device with one cascade of protection, and FIG. 2 - spark protection device with three stages of protection.

In FIG. 1, 2 positions marked:

1 - positive terminal of the device;

2 - negative terminal of the device;

3 - explosion-proof device;

4 - limiting resistor;

5 - optoelectronic driver;

6 - MOS transistor;

7 - electronics block explosion-proof device;

8 - anode of the optoelectronic driver;

9 - cathode of the optoelectronic driver;

10 - positive output of the optoelectronic driver;

11 - negative output of the optoelectronic driver;

12 - the source of the MOS transistor;

13 - drain MOS transistor;

14 - gate MOS transistor;

15- first cascade of protection;

16- second cascade of protection;

17- third cascade of protection.

The invention is based on the structural features of field effect transistors with an MIS structure (metal - dielectric - semiconductor). In the manufacturing process of the MOS transistor 6 between its drain 13 and source 12, an additional semiconductor diode is automatically formed, turned on in the opposite direction.

The spark protection device (Fig. 1) has a MOSFET transistor 6 connected inversely: the source 12 of the MOSFET transistor 6 is connected to the positive terminal of the device 1, and drain 13 to the power supply circuit of the electronics unit 7, between the source 12 and the gate 14 the optoelectronic output is connected driver 5, the polarity of which, when the optoelectronic driver 5 is turned on, coincides with the polarity of the opening of the gate 14 of the MOS transistor 6, and the input of the optoelectronic driver 5 is connected through the limiting resistor 4 between the positive 1 and negative 2 terminals of the device. With this inclusion, the diode of the MOS transistor 6 replaces the diode used in the prototype.

Positive 1 and negative 2 terminals of the device are used to connect an external charger (not shown in the drawings) during periodic charging of rechargeable batteries (not shown in the drawings) of the electronics unit 7.

Thus, the positive terminal 10, the negative terminal 11 and the cathode 9 of the optoelectronic driver 5 are connected respectively to the source 12, the gate 14 of the MOS transistor 6 and the negative terminal of the device 2.

The anode 8 of the optoelectronic driver 5 and the source of the MOS transistor 6 are connected to the positive terminal of the device 2, and the anode 8 of the optoelectronic driver 5 is connected to the positive terminal of the device 1 through the limiting resistor 4. Alternatively, the intrinsically safe circuit of the explosion-proof device can be implemented with the optoelectronic driver implemented based on the PVI1050 chip.

The idea of the invention is to create an “ideal diode”, that is, a circuit with an almost zero voltage drop when a large current flows in the forward direction and locks in the opposite direction. In this case, switching should occur automatically when the polarity of the voltage on the key changes. According to the authors, the essence of the claimed spark protection scheme does not follow explicitly from the prior art for a specialist and determines the inventive step of a technical solution.

The spark protection device allows a cascade connection to increase the number of spark protection diodes to at least two or more in accordance with the required level of explosion protection. In this case, the channels of the MOS transistors 6 are connected in series in the power supply circuit, and the input circuits of the optoelectronic drivers 5 are connected in series and connected via a common limiting resistor 4. The two-stage spark protection circuit provides a higher level of protection compared to a single-stage circuit. The three-stage spark protection circuit provides the highest level of protection - “especially explosion-proof ia” according to GOST R IEC 60079-11.

This variant of the spark protection device of an explosion-proof device with an internal voltage source contains (Fig. 2) serially connected the first cascade of protection 15, the second cascade of protection 16 and the third cascade of protection 17 with a common limiting resistor 4 installed in the anode circuit of the optoelectronic driver 5 of the first cascade of protection 15. All protection stages 15,16,17 have the same structure and consist of an optoelectronic driver 5 and an MOS transistor 6.

The claimed device operates as follows.

Explosion protection device is used in explosion-proof device 3 and is used to power the device electronics module 7 from an external battery charger. If there is no voltage at the positive 1 and negative 2 terminals of the device, the input circuit of the optoelectronic driver 5 is de-energized, there is no voltage at the output of the optoelectronic driver 5, MIS transistor 6 is locked and spark protection is provided by its diode. After connecting an external charger to the terminals 1.2 of the device, a current will flow through the input resistor 4 in the input circuit of the optoelectronic driver 5, causing a voltage at its output due to the photoelectric effect, which will open the channel of the MOS transistor 6.

At the same time, its diode will be shunted by the low resistance of the open channel, and the voltage drop in the spark protection circuit will be negligible, which ensures a reduction in heat loss. The low resistance of the open channel of the MOS transistor, which amounts to hundredths of an ohm, makes it possible to increase the accuracy of monitoring the charging of batteries from an external charger, since the accuracy depends on the value of the resistance of the charging circuit. In addition, the use of an optoelectronic driver with a photoelectric output provides reliable galvanic isolation between the driver input circuit and the power circuits of the spark protection device at a level of at least 500 V.

The operation of two and three-stage spark protection devices is completely analogous to the operation of a single spark protection device.

The invention has been successfully tested and implemented by the Center for Technical Diagnostics (Transneft Diascan, JSC) in the construction of an in-line inspection device, the electronics of which uses internal rechargeable batteries for power supply, which are periodically recharged during maintenance from an external charger.

Claims (2)

1. The spark protection device of an explosion-proof device with an internal voltage source containing at least one cascade of protection, consisting of an optoelectronic driver and an MOS transistor, while the positive terminal, negative terminal and the cathode of the optoelectronic driver are connected respectively to the source, gate of the MIS transistor and negative the terminal of the device, the anode of the optoelectronic driver and the source of the MOS transistor are connected to the positive terminal of the device, and the connection of the anode of the optoelectronic driver to positive The lemma of the device is made through a limiting resistor. 2. The spark protection device according to claim 1, characterized in that the device contains at least two identical series-connected protection stages with a common limiting resistor installed in the anode circuit of the optoelectronic driver of the first protection stage, and the input circuits of all three optoelectronic drivers are connected in series.

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