RU2133540C1 - Protection device for radio electron unit - Google Patents

Abstract

FIELD: radio electronics. SUBSTANCE: proposed device is designed for protection of radio electron units against short-time overvoltages in alternating current power supply network. It has two voltage limiters 5, 6 connected in series and in opposition one to another and linked between conductors feeding supply voltage to radio electron unit. Specific feature of device is that first resistor 10 and first light guide 8 are connected in series and form first network, second resistor 11 and light guide 9 form second network. Both networks are connected in series and linked to conductors feeding supply voltage to radio electron unit. First and second light guides are connected in opposition. Points of connection of networks and voltage limiters are connected via third light guide 12. During positive half-period of network voltage limiter 5 conducts current, limiter 6 is shut, light guide 12 glows but light guide 9 will not glow though current of inverse polarity limited by high-resistance resistor 11 will flow through it as through diode. In case of short-time pulse of overvoltage light guide 12 alone will glow. If damage threshold of voltage limiter 5 or 6 is achieved either light guide 8 or light guide 9 will glow. If both light guide 8 and 9 glow and light guide 12 does not glow it shows that both voltage limiters 5 and 6 have failed. Invention makes it possible to provide for indication of failure of overvoltage limiters 5, 6 which enhances operational reliability of radio electron unit. Device also indicates presence of absence of network voltage. EFFECT: enhanced operational reliability of radio electron unit. 1 dwg

Description

 The present invention relates to electrical engineering, and in particular to devices for protecting electronic devices connected to an alternating current network.

 It is known that in an alternating current network with a voltage of 220 (127) volts high-frequency overvoltages up to 500 V and more occur, short-term pulses with an amplitude of more than 1 kV are possible. These surges, passing through a power source, can damage semiconductor devices and microcircuits or cause malfunctions in electronic devices.

 To prevent overvoltage, special circuits are used with gas arresters, varistors, zener diodes. But all these devices have a large interelectrode capacitance, limiting their use at high frequencies (V. A. Kolosov. Power supply of stationary radio-electronic equipment. M: Radio and communication, 1992, p. 111).

 Therefore, to protect electronic devices from high-frequency overvoltages in the power supply network, voltage limiters (restrictive diodes), which have high-frequency properties, are used.Voltage limiters break through if a voltage is applied to them that exceeds the value of their breakdown voltage. A device for protecting electronic devices from overvoltages in the power supply using voltage limiters (prototype) is described, for example, in the Handbook "Electronic Devices for Protecting REA from Electrical Overloads" (authors V.P. Cherepanov, A.K. Khrulev and I.P. Bludov, Moscow: Radio and Communications, 1994, p. 42, Fig. 10.6).

 The device for protecting a radio electronic device from short-term overvoltages in an alternating current network contains two voltage limiters connected in series and opposite each other and connected between conductors, through which a supply voltage is supplied to the device. When an overvoltage appears in the network, one of the voltage limiters is in a conductive state, and the other breaks briefly, while the overvoltage pulse is limited and does not lead to interference or malfunctions in the electronic device. Two voltage limiters connected in series and opposite to each other can be made in the form of a single device - a symmetrical voltage limiter, while the connection point of the limiters is additionally displayed.

 However, if one of the voltage limiters fails (an open in it, for example, during a short circuit due to a high current), the power supply of the device will not be disturbed, but the device will be deprived of surge protection. A malfunction in the protection device is thus not detected immediately and therefore not eliminated. This reduces the reliability of electronic equipment.

 The proposed invention solves the technical problem of increasing the reliability of electronic equipment. In addition, more favorable operating conditions for electronic equipment are provided by reducing interference.

 The essence of the claimed invention lies in the fact that the protection device of the electronic device contains two voltage limiters connected in series and counter to each other and connected between the conductors through which the supply voltage to the electronic device is supplied (further distinguishing features follow). The device also contains the first, second and third LEDs and the first and second resistors, the first resistor and the first LED are connected in series and form the first LED circuit, the second resistor and the second LED are connected in series and form the second LED chain. Moreover, both LED circuits are connected in series and connected to conductors, through which voltage is supplied to the electronic device. The LED chains are interconnected so that the first and second LEDs are turned on one against the other, and the connection point of the LED chains is connected to the connection point of the voltage limiters through the third LED. The polarity of the terminals of the first and second LEDs connected through the third LED to the connection point of the voltage limiters is similar to the polarities of the interconnected terminals of the voltage limiters, and the polarity of the output of the third LED connected to the first and second LEDs is similar to the polarities of the interconnected terminals of the first and second LEDs.

 The proposed device to protect the electronic device from short-term overvoltage in the AC power network is illustrated in the drawing.

The list of symbols on the drawing:
1 - AC power network;
2 - electronic device;
3 - the upper (in the figure) conductor through which the supply voltage is supplied;
4 - lower (in the figure) conductor through which the supply voltage is supplied;
5 - the first voltage limiter;
6 - second voltage limiter;
7 - connection point of voltage limiters;
8 - the first LED;
9 - second LED;
10 - the first resistor;
11 - second resistor;
12 - the third LED;
13 - the connection point of the LED chains.

 The drawing shows a device for protecting the electronic device 2 from short-term overvoltage in the AC power supply network 1. The AC supply voltage from the network is supplied through conductors 3 and 4. Voltage limiters 5 and 6 are connected in series and counter to each other and at point 7 they are connected. They are connected between conductors 3 and 4, through which the supply voltage to the electronic device 2.

 The electronic device protection device comprises a first LED 8 and a second LED 9, a first resistor 10 and a second resistor 11. The first resistor 10 and the first LED 8 are connected in series and form the first LED circuit. The second resistor 11 and the second LED 9 are connected in series and form a second LED circuit. Both LED circuits are connected in series at point 13 and connected to conductors 3 and 4. The first and second LED circuits are connected so that the first 8 and second 9 LEDs are turned on one against the other, and the connection point 13 of the LED circuits is connected to the connection point 7 of the voltage limiters through third LED 12. The polarity of the terminals 13 of the LEDs 8 and 9 are similar to the polarities of the terminals 7 of the voltage limiters 5 and 6 connected at point 7. The polarity of the output of the third LED 12 connected to the point connect the LED strings 13, similar conclusions polarities LEDs 8 and 9 are connected to point 13 connect the LED chains.

 The operation of the proposed device is described below.

 The AC power supply voltage from the network 1 is supplied through conductors 3 and 4 to the electronic device 2. During normal operation of the AC power supply network, in the positive half-period of the mains voltage (on the upper wire 3 - plus), the upper voltage limiter 5 is connected directly to this half-period direction, conducts current, and the second of the voltage limiters 6 (lower), included counter to the upper one, is closed. The current passing through the upper voltage limiter 5 passes through the third LED 12 and the second (lower) LED circuit with the second LED 9 and the second resistor 11 (current passes through the second LED 9 despite the fact that the LED 9 is turned on in reverse polarity; this current limited by a high-resistance resistor 11 and the reverse voltage on the LED 9 is determined by the negative branch of the current-voltage characteristics of the LED). In this case, the third LED 12 will light up, and the second LED 9 will not light (the forward current of the third LED 12 is sufficient for its illumination; the reverse current of the LED 9 does not cause the LED 9 to glow). LED 8 will also not be lit, since both ends of the first LED string are at almost the same potential (voltage drops at limiter 5 and LED 12 are small).

 During a negative half-period of the mains voltage (on the upper wire 3 - minus), a second (lower) voltage limiter 6 conducts current. In this case, the current passes through the third LED 12 and the first (upper) LED circuit - the first LED 8 and the first resistor 10. The third LED 12 again emits light, the first LED 8 does not light up, the second LED 9 also lights up (the operation of the protection device is similar to that described for the positive half-cycle).

 If the overvoltage in the AC power supply exceeds the permissible reverse voltage of the voltage limiters 5 and 6, one of them, turned on in the forward direction, conducts current, and the second, turned on in the opposite direction to the first, breaks briefly and thereby limits the surge voltage in the network and protects equipment. If the power of the overvoltage pulse does not exceed the threshold destruction power of the voltage limiter, then the operation of the device then continues normally. With a short-term overvoltage pulse, which does not destroy the voltage limiters, nothing changes for the user, LEDs 8 and 9 do not light up, and LED 12 remains on.

 If the power of the overvoltage pulse exceeds the destruction threshold of the voltage limiter 5 or 6, then one of the voltage limiters fails (burns out).

 Let the voltage limiter 5 blow out. At the same time, the current does not pass through the voltage limiter 5. With a positive voltage on wire 3, the current will go through the first resistor 10, the first LED 8 (in the forward direction), the second LED 9 (in the reverse direction) and the second resistor 11. The first LED 8 starts to glow (enough current develops for this as a result of about half the mains voltage), the second LED 9 does not light (the reverse current does not cause the LED to glow), and the third LED slightly reduces the light intensity As now passes therethrough only the current from the negative half-wave of the mains voltage through a voltage limiter 6. Thus, the first illumination LED 8 indicates the failure of the first voltage limiter 5.

 Similarly, the glow of the second LED 9 indicates the failure of the second voltage limiter 6. If both LEDs 8 and 9 are lit, and the LED 12 is not lit, then both voltage limiters have failed. If none of the LEDs is lit, then there is no supply voltage on wires 3 and 4.

 If one third LED 12 is lit, then there is a supply voltage and voltage limiters are working correctly and the protection device of the electronic device is working properly.

 Such an indication of the operation of the device for protecting the electronic device from surge surges in the AC power network allows the user to be sure of the constant protection of his device and take immediate measures to replace the failed protection device.

 From the point of view of industrial feasibility of the proposed device, it can be manufactured using widely used elements. It does not require the development and production of special electro-radio elements. If necessary, the manufacture of the device lends itself to automation.

 Structurally, it is advisable to place the device in a small sealed enclosure with the subsequent filling of radio elements, moreover, the case has protruding luminous parts of the LEDs and two terminals for connecting to the network.

 Such an indication of the operation of the device for protecting the electronic device from surge surges in the AC power network allows the user to be sure of the constant protection of his device and take immediate measures to replace the failed protection device. In addition, due to the high-resistance of the first and second resistors, the protection device of the electronic device selects small currents from the power supply network, which reduces the power dissipated by the device and reduces the size of the protection device.

Claims (1)

 A device for protecting a radio electronic device, containing two voltage limiters connected in series and opposite to each other and connected between conductors that supply power to the electronic device, one of which breaks briefly during short-term overvoltage in the AC mains and thereby limits the overvoltage pulse to network and protects this electronic device, characterized in that it contains the first, second and third LEDs, the first and second res orors, the first resistor and the first LED are connected in series and form the first LED circuit, the second resistor and the second LED are connected in series and form the second LED circuit, both LED circuits are connected in series and connected to the conductors that supply voltage to the electronic device, while the LED the circuits are interconnected so that the first and second LEDs are turned on one against the other, and the connection point of the LED circuits is connected to the connection point voltage limiters through the third LED, and the polarity of the terminals of the first and second LEDs connected through the third LED to the connection point of the voltage limiters are similar to the polarities of the interconnected terminals of the voltage limiters, and the polarity of the output of the third LED connected to the first and second LEDs is similar to the polarities of the connected between the findings of the first and second LEDs.