RU183388U1 - HIGH VOLTAGE AND CURRENT PROTECTION SYSTEM PERFORMED BY THE SOLID-SWITCH OF THE SWITCHING DEVICE - Google Patents

Abstract

The utility model relates to the field of electrical engineering, namely, to elements of devices for protection against accidents, in particular to protective switches with re-closure and opening, and can be used to protect switching equipment, in particular solid-state relays, which serve to turn on and off high-power circuits using low voltages applied to the control terminals.

The objective is to increase the reliability and ease of operation of the protection of the switching device.

The inventive functional diagram (Fig. 1) consists of a DC power source 1, a load resistor 2, a capacitive filter 3 of electrostatic interference 3, an electronic fuse 4, a current limiter (suppressor) 5, a switching device 6, a state monitoring element 7, elements 8 and 9 galvanic isolation.

The electrical circuit diagram of the proposed system (Fig. 2) consists of a direct current source 1, a load resistor 2, a capacitive filter 3 of electrostatic interference, a diode 11 (limits the current flowing through the optocoupler), a resistor 12, optocoupler 8 (performs the function of decoupling the power and control parts), limiter 5 (limits the current through the solid-state relay 6 to the moment of operation of the electronic fuse 4), the keys of the solid-state relay 6 on two field-effect transistors, the power isolation element 9 and controlling second portions of the capacitive filter 18, the control FET 17, resistors 15 and 16, a NAND gate 14, "I", the microcontroller 13 and the electronic fuse 4 TBU.

The implementation of the control element of the state of the switching element on the microcontroller, which is simultaneously part of the solid-state relay reset circuit, made by two-part, one part of which is connected in front of the switching device in parallel with the electronic fuse in front of the current limiter and consists of a current limiter connected in series with a Zener diode, a resistor and optocouplers for decoupling of the power and control parts, in conjunction with the inclusion of the second part of the reset circuit after switching about the device and its connection through the second galvanic isolation element when it is executed in the form of a chain of parallel-connected filter capacitor and control field-effect transistor connected through a resistor to the control input of the microcontroller, the second input of which is connected through the logic element “I” to the optocoupler of the first part of the reset circuit , which together ensure the achievement of a given result, creating feedback on the event of the electronic fuse and excluding the “freezing” of the key in the state Protecting all over the device. 2 ill.

Description

The utility model relates to the field of electrical engineering, namely, to elements of devices for protection against accidents, in particular to protective switches with re-closing and opening, and can be used to protect switching equipment, in particular, solid-state relays, which serve to turn on and off high-power circuits with using low voltages applied to the control terminals.

A device for protecting against high voltages and currents of a switching element made on a solid-state relay, presented in the Appendix and selected as a prototype.

The known protection system of a switching device made on a solid-state relay contains a direct current source connected through a load resistor and a capacitive filter with an electronic fuse (TBU ™), the output of which is connected to a current limiter and to a switching device, the output of which is connected to the control element through a galvanic isolation element its state, made in the form of a switched source of constant voltage.

The drawing in the Appendix shows the well-known solid-state relay with active protection electronic fuse (TBU ™) and galvanic isolation of the power and control parts (T1).

A significant drawback of this circuit implementation is the lack of a reset circuit for the active protection of the electronic fuse (TBU ™) - when the protection is activated, the electronic fuse (TBU ™) will remain in the protective state even if the disturbing source disappears until the voltage of the power source VI drops below 12 V.

More specifically, the following can be noted. If the input current rises sharply or the voltage threshold is exceeded, the electronic fuse (TBU ™) enters a high impedance state and protects the device circuitry from possible damage (current limit at 1 μA).

However, if the TBU ™ limit is exceeded (exceeding the permissible current or voltage), if the key is in the ON state (the relay is closed) with the device supply voltage higher than the electronic fuse reset voltage (12 V), the TBU ™ will remain in a high impedance state even in the absence of input (interference).

Significant disadvantages of the current circuit implementation are also:

- lack of feedback on the TBU ™ event;

- “freezing” of the key in a state of protection throughout the operation of the device.

In the case of an external controller, the system must be manually reset. Thus, the known device is unreliable and inconvenient in operation.

The objective is to increase the reliability and usability of the protection of the switching device.

The problem is solved in that in the protection system against high voltages and currents made on a solid-state relay switching device containing a DC source connected through a load resistor and capacitive filter with an electronic fuse, the output of which is connected to a current limiter and to a switching device, the output of which through the galvanic isolation element is connected to the element for monitoring its state, ACCORDING TO THE USEFUL MODEL, the element for monitoring the state of the switching element is made and the microcontroller serves to control it, being at the same time a part of the solid-state relay reset circuit made by a two-part one of which is connected in front of the switching device in parallel with the electronic fuse in front of the current limiter and consists of a second current limiter on the Zener diode, a resistor and optocouple connected in series for decoupling the power and control parts, and the second part of the reset circuit is switched on after the switching device, connected to it through the second galvanic element isolation and contains a chain of parallel-connected filtering capacitor and control field-effect transistor connected through a resistor to the control input of the microcontroller, the second input of which is connected through the logic element “I” to the optocoupler of the first part of the reset circuit.

The implementation of the control element of the state of the switching element on the microcontroller, which is simultaneously part of the solid-state relay reset circuit, made by two-part, one part of which is connected in front of the switching device in parallel with the electronic fuse in front of the current limiter and consists of a current limiter connected in series with a Zener diode, a resistor and optocouplers decoupling of the power and control parts, in conjunction with the inclusion of the second part of the reset circuit after switching about the device and its connection through the second galvanic isolation element when it is executed in the form of a chain of parallel-connected filter capacitor and control field-effect transistor connected through a resistor to the control input of the microcontroller, the second input of which is connected through the logic element “I” to the optocoupler of the first part of the reset circuit , ensuring in aggregate the achievement of a given result, creating feedback on the event of the operation of the electronic fuse and eliminating the “freezing” of the key in the state Protecting all over the device.

EFFECT: reliable operation of a reset circuit when a protection is triggered, ensuring reliable operation of a protection device of a switching device.

The utility model has a novelty in comparison with the prototype, differing from it in such essential features as the implementation of the control element of the state of the switching element on the microcontroller and its use to control it, as part of a solid-state relay reset circuit, performing a two-part reset circuit, one of which is connected in front of the switching device parallel to the electronic fuse in front of the current limiter when performing it from a second current limiter connected in series with each other Nerov diode, resistor and optocoupler for decoupling the power and control parts, switching on the second part of the reset circuit after the switching device, its connection with it through the second galvanic isolation element when performing the reset circuit in the form of a chain of parallel connected filter capacitor and control field-effect transistor, communication through a resistor with a control input of the microcontroller, the connection of the second input of the microcontroller through the logic element "I" with an optocoupler of the first part of the reset circuit, which together provide ti achieve the desired result.

The utility model can be used in electrical engineering to protect switching equipment made on solid-state relays to turn high-power circuits on and off using low voltages and therefore meets the criterion of "industrial applicability".

The utility model is illustrated by drawings, which are presented on:

- FIG. 1 is a functional diagram of a protection system;

- FIG. 2 is a circuit diagram of a protection system.

The inventive protection system against high voltages and currents made on a solid-state relay switching device (Fig. 1) contains a power source 1 connected through a load resistor 2 and a capacitive filter 3 with an electronic fuse 4. The output of the electronic fuse 4 is connected to a current limiter 5 and with on a solid-state relay with a switching device 6, the state control element 7 of which is isolated through the elements 8 and 9 of galvanic isolation from the power part of the system. In this case, the state monitoring element 7 of the solid state relay of the switching device 6 is made on the microcontroller, which is part of the reset circuit of the solid state relay 6. The reset circuit 10 (Fig. 2) is made of two-part, one part of which is connected in parallel with the electronic fuse 4 in front of the current limiter 5. This part of the reset circuit 10 includes a current limiter 11 on the Zener diode, a resistor 12, and an optocouple 8 for decoupling the power and control parts in series. The second part of the reset circuit 10 includes a microcontroller 13 connected through an AND gate 14, resistors 15 and 16, a control field effect transistor 17, a capacitive filter 18, and a galvanic isolation element 9 with a switching device 6.

In normal operation of the device, the current from the DC power supply 1 flows through the series-connected load resistor 2, electronic fuse 4 and solid-state relay 6.

Capacitive filter 3 is a standard element of most protective circuits, which require protection of the electronics from electrostatic discharge.

The main role in protecting solid-state relays 6, or any other switching equipment, is played by electronic fuse 4, made on a TBU ™ chip from Bourns.

TBU ™ Electronic Fuse 4 is a type of active protection from Bourns. During normal operation of the circuit, the TBU ™ monitors the amount of current flowing through the protected line. If the current exceeds a predetermined level, the TBU ™ disconnects the line, protecting it from high voltages and currents.

Using the electronic fuse on the TBU ™ provides high-speed protection (TBU ™ response time is only 1 μs) from many different influences, such as:

- electrostatic discharge;

- nanosecond impulse noise;

- microsecond impulse noise according to the line-rack circuit;

- microsecond impulse noise according to the line-line scheme;

- short circuit;

- low load resistance;

- DC overvoltage;

- protection of the circuit from AC 220 V;

- overheating of the device during overvoltage / exceeding the maximum permissible current.

If the input current rises sharply or the voltage threshold is exceeded, the TBU ™ 4 electronic fuse enters a high impedance state and thereby protects the device circuitry from possible damage (current limit at 1 μA).

The transition time of the electronic fuse 4 in the protection state is about 1 μs. To protect the solid-state relay 6, or any other switching device, during the operation of the electronic fuse 4, a current limiter 5 is used, which is very fast (the response time is up to 1 picosecond), thereby protecting the solid-state relay from overvoltage during the period of operation of the electronic fuse four.

If the limits for electronic fuse 4 on TBU ™ are exceeded (by voltage or current), if the key is in the ON state (solid-state relay 6 is closed) when the device’s supply voltage is greater than the reset voltage (12 V for TVU ™), the electronic fuse 4 will remain in a state of high impedance even in the absence of input (interference).

To reset the TBU ™ 4 electronic fuse, a reset circuit 10 is used. In the case of the transition of the electronic fuse to the protection state, all current begins to flow through the reset circuit 10. The reset circuit 10 provides a reset of the electronic fuse 4 in the event of its operation by opening the solid-state relay 6 and, thereby, reducing the supply voltage in the system below the voltage level necessary to reset the electronic fuse. It should be noted that the reset circuit 10 has a galvanic isolation from the power part of the circuit.

After resetting the electronic fuse 4, the protection system fully restores its functionality.

More specifically, the protection system is as follows, (see Fig. 2).

The electrical circuit diagram of the proposed system (Fig. 2) consists of a direct current source 1, a load resistor 2, a capacitive filter 3 of electrostatic interference, a current limiter 11 on the diode, which limits the current flowing through the optocoupler 8, resistor 12, optocoupler 8, which performs the function isolation of the power and control parts, limiter 5, which limits the current through the solid-state relay 6 to the moment of operation of the electronic fuse 4, the keys of the solid-state relay 6 on two field-effect transistors, element 9 galv nical interchange power and control portions of the capacitive filter 18, the control FET 17, resistors 15 and 16, a NAND gate 14, "I", the microcontroller 13 and the electronic fuse 4 TBU.

The scheme works as follows.

In normal operation (no disturbance), the resistance of the electronic fuse 4 (TBU ™) is small (from 4 to 20 Ohms, depending on the selected parameters Impulse voltage rating and Trigger current, presented in the documentation for the device), the current flows through it and the keys of the solid state relay 4, made on two field-effect transistors. In the event of an input action (interference), the resistance of the electronic fuse 4 on the TBU ™ increases stepwise within 1 μs, thereby breaking the line leading to the solid-state relay 6. To protect the solid-state relay 6 during the response time of the electronic fuse 4 (the response time is about 1 μs) a limiter 5 is used, limiting the current flowing through the solid-state relay 6, or any other switching device, until the electronic fuse 4 is activated. etit that this circuit implementation does not require a powerful selection suppressor 5 - enough to withstand the operation input for 1 microsecond.

After the operation of the electronic fuse 4, the load current begins to flow through the current limiter 11 on the Zener diode and resistor 12, causing the optocoupler 8. The optocoupler 8 switches the field-effect transistor 17 to the open state, which leads to a bypass of the control action and, as a result, to closure keys of solid-state relay 6 (switching the relay to OFF, the relay is open).

When the field effect transistor 17 is opened, the microcontroller 13 registers the fact that the protection was triggered from the logic element “14” and, depending on the embedded program code, notifies the end user of the fact of the operation, or turns off the circuit “forever”, or resets the key 17 to snap off the solid-state relay 6 and resetting the supply voltage to a level below the reset voltage of the electronic fuse 4.

As a galvanic isolation 9 of the power and control parts, any of the existing isolation (transformer, optoelectronic, etc.) can be used.

After resetting the keys of the solid-state relay 6 and reducing the supply voltage on the electronic fuse 4 (TBU ™) below the level of the reset voltage, the electronic fuse 4 goes into the open state and the circuit is fully restored.

The advantages of the proposed circuit implementation are:

- return of the electronic fuse on the TBU ™ to the operational state in case of its operation;

- automated control over the state of the entire circuit;

- galvanic isolation of the power and control parts;

- ease of implementation of comprehensive protection of the device from a number of influences.

Conducted repeated experimental checks of the claimed electrical circuit confirmed its efficiency and high efficiency.

In comparison with the prototype of the claimed protection system is more reliable in operation.

Claims (1)

A protection system against high voltages and currents made on a solid-state relay switching device containing a DC source connected via a load resistor and a capacitive filter with an electronic fuse, the output of which is connected to a current limiter and a switching device, the output of which is connected through the galvanic isolation element to the element control of its state, characterized in that the control element of the state of the switching element is made on the microcontroller and serves to control to them, being part of a solid-state relay reset circuit made by a two-part circuit, one of which is connected in front of the switching device in parallel with the electronic fuse in front of the current limiter and consists of a second current limiter connected in series with a Zener diode, a resistor and an optocoupler for decoupling the power and control parts , and the second part of the reset circuit is switched on after the switching device, connected to it through the second galvanic isolation element and contains a chain of parallel but connected filter capacitor and a control FET connected through a resistor to the control input of the microcontroller, the second input of which a logic element "I" is connected with the first part optocoupler reset circuit.

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