KR101212184B1 - Surge Protect Device having Selective Switching Function Based Surge Suppression Device - Google Patents

Abstract

The present invention provides a surge protection device based on a surge suppression device having a selective interruption function having a selective interruption function such as blocking and restoring the surge suppression device for protection and interruption for replacing the surge suppression device. Is referred to.
The present invention senses that excessive voltage is applied to the MOV of the SPD for more than a set time, and protects the MOV of the SPD by 'off' the series connected contact to separate the SPD's MOV from the power supply, and then applied to both ends of the MOV. When the voltage level is lower than the set value, the contact is turned on so that it can be reused to protect the MOV, thereby significantly reducing maintenance and repair costs, and to consider the leakage current due to characteristic degradation in the MOV of the SPD. If the abnormal current flows longer than the set time, it is considered that the MOV of the SPD has reached the end of its life and is separated from the power supply to prevent explosion, fire or power line accidents caused by leakage current.

Description

Surge Protect Device having Selective Switching Function Based Surge Suppression Device}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surge protection device based on a surge suppression device having a selective interruption function. More particularly, the present invention relates to surge suppression devices and surge suppression devices such as metal oxide varistors (MOVs). The present invention relates to a surge protection device based on a surge suppression device having a selective interruption function such as a disconnection and recovery for a surge suppression device and a replacement for a surge suppression device.

As is well known, the SPD must effectively suppress various abnormal voltages invading the power line and signal line to supply stable power and signals to the load. Therefore, impulsiveness with large and steep waveform characteristics such as switching surge and brain surge The load circuit can be protected against abnormal voltage and the surge protector itself must be designed to have sufficient dielectric strength and energy content.

To this end, it is common to design and manufacture the maximum continuous operating voltage (mcov) higher than the rated voltage in the design of the surge protector. In many cases, an overvoltage greater than the rated voltage applied to the temporary overvoltage caused by ground fault or open / close of the line is often generated. As such, the transient overvoltage lasting several hundreds to several seconds has a relatively large energy compared to the surge having a duration of several tens to hundreds of ㎲, and when the voltage is greater than the maximum continuous use voltage of the surge protector, Burnout is caused.

The surge protection device burned out by this process has a low resistance value of several ohms or less, which short-circuits the protector circuit. If such a short-circuit current flows, a fire may occur due to overheating.

Therefore, SPD should be designed to have energy content that can withstand the transient overvoltage occurring in case of system accident, and quickly disconnect in case of overheating to prevent secondary damage such as fire in case of short circuit due to damage of protection element. In order to prevent this, the overcurrent blocking measures using fuses were configured in parallel.

A representative example thereof may be found in Korean Patent 0992426 (Invention name: explosion-proof surge protection device having a thermal runaway prevention element; referred to as 'quotation invention 1'), which is shown in FIG.

As can be seen from this, the MOV must be electrically cut off as the low temperature molten metal is separated from the contacts by the heat of the MOV, which is installed integrally in the enclosure. In reality, the melting temperature is different depending on the content of the components constituting the temperature fuse, so even when the MOV is overheated, it may not be blocked at the set temperature. That is, the MOV of the same type as the citation invention is assembled by connecting the varistor in series with the temperature fuse, and this citation invention continues to overcurrent the MOV even if an excessively high voltage is applied for a time exceeding the time to destroy the MOV. Since the MOV is damaged due to the flow, there is a problem that frequently occurs inevitable replacement of the MOV.

Republic of Korea Patent 0992426 (Invention name: explosion-proof surge protection device equipped with thermal runaway protection element)

The first object of the present invention is to monitor the voltage and current applied to the SPD to solve this problem, but to protect the MOV by separating the MOV from the circuit in the situation before the destruction of the MOV over a set time range and then If the voltage applied to the MOV is below the set range, reconnect the MOV to the circuit to restore it normally.If the leakage current flows longer than the set time due to the deterioration of the MOV, disconnect the MOV from the power circuit and disconnect the MOV from the power circuit. The present invention provides a surge protection device having an overheat protection function based on a surge suppression device to prevent a fire occurrence due to an accident or an explosion of a MOV.

The present invention has a voltage sensing resistor connected in parallel to the MOV and the power supply constituting the SPD, and a relay contact and a CT connected in series to the power supply together with the MOV, to achieve the above object, the voltage sensing resistor and CT The output of is applied to each A / D converter to obtain the corresponding digital data value and decoded by the microprocessor to determine whether the overvoltage is applied beyond the set time which causes the MOV to break down and the current flowing to the MOV. It has a overheat protection function based on a surge suppression element that determines whether the value is within a range that can be regarded as deterioration above the set value, and drives the relay for operating the relay contact according to the result value. Surge protection device is proposed.

In this way, the present invention senses that overvoltage is applied to the SPD's MOV for more than a set time, and protects the MOV of the SPD by 'off' the series connected contact to separate the SPD's MOV from the power supply, and then the both ends of the MOV. When the voltage level is below the set value, the contact is 'on' so that it can be reused, thereby protecting the MOV and significantly reducing maintenance and repair costs.

If an abnormal level current, which is considered leakage current due to characteristic deterioration, flows over the set time in the SPD's MOV, the MOV is deemed to have ended and the MOV It is possible to prevent the occurrence of explosion, fire or power line accidents that may occur due to overheating due to leakage current, and it is useful to reduce safety and maintenance costs due to accidents.

1 is a circuit diagram of a surge protection device equipped with a conventional MOV.
Figure 2 is an exploded perspective view illustrating a state of assembling a surge protection device based on the surge suppression element having a selective interruption function according to the present invention.
Figure 3 is a circuit diagram showing an electrical configuration of applying a surge protection device based on a surge suppression element having a selective interruption function according to the present invention to a single-phase power line.
4 is a circuit diagram showing an example in which a surge protection device based on a surge suppression element having a selective interruption function according to the present invention is applied to a three-phase power line.
5 is an operation explanatory diagram of a surge protection device based on a surge suppression element having a selective interruption function according to the present invention;
Fig. 6 is a waveform diagram illustrating a connection function for disconnection and normal recovery of a MOV corresponding to a transient overvoltage according to the present invention.
Fig. 7 is a waveform diagram illustrating the MOV separation operation according to the MOV leakage current amount according to the present invention.
Figure 8 is a circuit diagram showing an embodiment using a shunt resistor as another embodiment for measuring the leakage current amount of the MOV in the present invention.
9 is a flowchart showing the operation of the embodiment using the shunt resistor as another embodiment for measuring the amount of leakage current of the MOV in the present invention.

With reference to the accompanying drawings, the present invention will be described in detail with reference to the embodiments of the present invention to be easily carried out by those skilled in the art.

First, FIG. 2 shows the overall appearance of a surge protection device based on a surge suppression element having a selective interruption function according to the present invention.

As can be seen from the present invention can be manufactured integrally with the MOV, it can also be produced separately from the MOV.

First, according to the embodiment of Figure 2 produced in one piece the present invention is a PCB 200 and relay contacts 301 and CT 302, relay 300 for implementing the function according to the MOV 100 and the present invention It is separated into partition walls 400 for insulation and insulation, and has a structure that can prevent malfunction or failure due to heat of the MOV 100, and puts a casing 500 on them to prevent foreign substances such as dust from penetrating. prevent.

3 shows an example in which the electrical configuration of the surge protection device having the overheat protection function based on the surge suppression element according to the present invention is applied in the case of a single phase.

As can be seen from the above, the present invention provides a voltage sensing resistor 303 connected in parallel with the MOV 100 constituting the SPD 600 and a power supply, and a relay connected in series with the MOV 100 with the power supply. A contact 301 and a CT 302 are provided, and the outputs of the voltage sensing resistor 303 and the CT 302 are applied to the respective A / D converters 304 to obtain corresponding digital data values, which are then microprocessors. It is composed of a driving circuit 306 for passing a current to the relay coil 305 for reading by (700) to drive the relay contact 301.

In the present invention as described above, the microprocessor 700 is connected to the MOV 100 when the power supply voltage is overvoltage or higher than the set voltage causing the breakdown of the MOV 100 and the holding time is longer than the set time and the input voltage is normal. If the flowing current value is greater than or equal to the set current value larger than the normal leakage current value, the relay 300 is driven to 'turn off' the relay contact 301. Furthermore, the power supply voltage causes the MOV 100 to be destroyed. The relay contact 301 when the power supply voltage is less than the set voltage to monitor the power supply voltage after the relay contact 301 is 'off' because the holding time is greater than or equal to the set time. On 'so that the normal recovery operation of the MOV 100 is performed.

4 shows an example of the electrical configuration applied to the RST three-phase power line applied to implement the functions of the present invention.

As can be seen from this, in the present invention, three MOVs 100 are connected between RST three phases and N to which a power supply and a load are connected, and a GDT is connected between N and G and MOVs may be connected.

Also, each MOV 100, relay contact 301, and CT 302 are connected in series between each RST and N, and the output terminal of the CT 302 is connected to the input of the A / D converter 304. Connected, and its output is coupled to a microprocessor 700 via a multiplexer. In addition, a plurality of voltage sensing resistors 303 are connected in series with the MOV 100, and an input of the A / D converter 304 is connected to a connection point of these resistors. In addition, the output of the A / D converter 304 is connected to the microprocessor 700 through the first multiplexer 307, the control output terminal of the microprocessor 700, the second multiplexer 308 and the relay of each phase The driving circuit 306 for driving the coil 305 and the relay coil 305 for driving the relay contact 301 of each phase connected thereto are connected.

When described in detail with reference to the flow chart shown in Figure 5 the operation of the present invention as follows. In the present invention, when the power is turned on and the normal power is applied, the impedance of the MOV 100 is very high and the leakage current is only a few ㎂ so that the state is actually blocked. Therefore, there is almost no output value by the CT 302, and the voltage values of the normal power supply are detected by the plurality of voltage sensing resistors 303, which are applied to the A / D converter 304. Therefore, the digital data value corresponding to the normal voltage value is output from the A / D converter 304, which is input to the microprocessor 700 to not apply the driving output to the driving circuit 306 to the coil of the relay 300. Since no current flows, the contact 301 of the relay 300 is maintained in an 'on' state.

In this process, the microprocessor 700 that monitors the voltage induced by the voltage sensing resistor 303, if the input power supply voltage exceeds the normal range, is the transient voltage exceeding the normal range maintained for more than a predetermined time? If the transient voltage is maintained for a predetermined time or more, the relay 300 is immediately driven to cause the contact 301 to be 'off', thereby disconnecting the MOV 100 from the circuit. A step of determining whether or not the voltage has been maintained for a set time or more is performed.

In this process, in the present invention, when the transient voltage applied to the MOV 100 is maintained for a predetermined time or more, a large current flows in the MOV 100 due to a sudden decrease in impedance due to nonlinear characteristics. In this case, the MOV 100 is disconnected from the circuit since the damage is inevitable. After that, when the power supply voltage is detected by the voltage sensing resistor 303, the transient voltage is restored to a state in which the transient voltage is not maintained for a set time or more. The MOV 100 is connected to the circuit. For this purpose, the output for driving the relay 300 is stopped so that the relay contact 301 is 'on'. In addition, the present invention, if the leakage current flowing in the MOV (100) for a long time in a state in which the power supply voltage of the normal range is maintained more than several ㎂ for a long time the life of the MOV (100) to consider the deteriorated state In this case, the MOV 100 is disconnected from the circuit.

To this end, the present invention is determined to be the normal range in the step of determining whether the input voltage is in the normal range, and in the step of determining the case where the leakage current is more than the set value, the maximum leakage current value that can be seen as the set value If the value exceeds the normal leakage maximum current value that is greater than or equal to the value, and the three conditions that are maintained for the set time or more are satisfied in the step of determining whether such a state is maintained for more than the set time, the function is restored due to deterioration of the MOV 100. Since it is impossible to replace the microprocessor 700, the microprocessor 700 drives the driving circuit 306 to immediately flow an output current to the relay coil 305 so that the relay contact 301 is 'off' so that the new MOV 100 can be turned off. The MOV 100 will be separated from the circuit until it is replaced with.

This function is performed separately for each RST phase, and for this purpose, an independent A / D converter 304 and a microprocessor 700 may be used for each phase.

However, in this case, an increase in manufacturing cost and volume is inevitable, so in order to avoid such disadvantages, the MOV 100, the relay contact 301, and the CT 302, which are inevitable to be used independently by using a multiplexer, have a plurality of voltage sensing resistors ( 303), the A / D converter 304, the driving circuit 306 and the coil of the relay 300 operated by the driving circuit 306 are installed for each phase, and sequentially controlled by one microprocessor 700 It could be.

In addition, the waveform diagram for explaining the operation of the present invention in detail illustrated in Figure 6, the various values presented here are selected for the convenience of operation description, thereby not limiting the technical features of the present invention.

In Fig. 6, overvoltage is introduced at a certain time while the normal power supply is made, and the duration thereof becomes considerably longer, so the energy (hatched portion) due to the overvoltage exceeds the internal capacity of the MOV 100, so that the MOV 100 It can be seen that the state in which damage is expected is shown in the waveform diagram.

That is, assuming that the voltage input of the MOV 100 may be destroyed when the duration of time beyond the limit is 100 mS or more, the microprocessor 700 sets the first set time to 100 mS in the above-described operation process, As soon as the overvoltage is input, the relay contact 301 connected in series with the MOV 100 of the phase line is 'off'. This state is subsequently monitored by the microprocessor 700, and in the middle and the second half of FIG. 6, since the voltage is below the limit and the duration is 100 mS or less, the relay contact 301 is 'on' again so that the MOV 100 is turned on. By allowing the operation of to resume normally, the MOV 100 is temporarily removed from the circuit in the state where the damage of the MOV 100 is expected to be implemented.

In addition, Fig. 7 shows a state in which the leakage current amount of the MOV 100 in the normal operating state flows and the leakage current amount reaches 300 mA due to deterioration at some point. In this case, in the present invention, since the increased leakage current flows even after the second set time of 500 mS or more, in this case, the microprocessor 700 continuously flows current to the corresponding relay coil 305 only when the power supply voltage is normal. Accordingly, the MOV 100 connected to the corresponding relay contact 301 may be separated from the circuit until a new one is replaced.

In addition, the present invention according to the embodiment as shown in FIG. 8 is connected to the MOV 100 constituting the SPD 600 and the power supply in parallel with the voltage sensing resistor 303 and the MOV 100 to the power supply. And a relay contact 301 and a shunt resistor 309 connected in series with each other. The outputs of the voltage sensing resistor 303 and the shunt resistor 309 are applied to the respective A / D converters 304 so as to provide a corresponding digital signal. A data value may be obtained and read by the microprocessor 700 to configure a driving circuit 306 for flowing a current to the relay coil 305 for driving the relay contact 301. According to this embodiment, similar to the above-described embodiment using the CT 302, the amount of current flowing through the MOV 100 and the voltage induced therein are proportional to each other. Therefore, the voltage induced therefrom is applied to the respective A / D converters 304 together with the voltage of the voltage sensing resistor 303 as in the case of the CT 302 described above to obtain a corresponding digital data value, The voltage across the shunt resistor 309 increases by more than a set value by controlling the driving circuit 306 for reading current by the processor 700 and flowing a current to the relay coil 305 for driving the relay contact 301. If the state lasts longer than the set time, the drive circuit 306 is continuously controlled until it is replaced, thereby supplying a current to the relay coil 305 to turn off the relay contact, thereby blocking the MOV 100 from the circuit. This operation is shown in FIG.

In addition, in the present invention, as described above, the CT or the shunt resistor may be used to detect the current flowing in the MOV 100, and various types of current sensing sensors such as other current sensing integrated circuits may be used.

In addition, the present invention is not limited to the above-described embodiments, and may be implemented in various forms by combining various elements known within the spirit and concept of the present invention.

100: MOV 200: PCB 300: Relay
301: relay contact 302: CT 303: sensing resistance
304: A / D converter 305: Relay coil 306: Drive circuit
307: first multiplexer 308: second multiplexer 309: shunt resistor
400: compartment wall 500: casing 600: SPD
700: microprocessor

Claims (5)

A voltage sensing resistor connected in parallel to the MOV and the power supply constituting the SPD, and a relay contact and a CT connected in series with the power supply together with the MOV. The voltage sensing resistor and the output of the CT are respectively converted into an A / D converter. It is applied to obtain a corresponding digital data value and read it by a microprocessor to control the drive circuit for flowing a current to the relay coil for driving the relay contact,
The microprocessor turns off the relay contact connected in series with the MOV at the moment when an overvoltage exceeding the threshold that causes the power voltage to break the MOV is input, and then the voltage input is below the threshold and less than a predetermined duration. A surge protection device based on a surge suppression device, characterized in that the relay contact is 'on' again to disconnect and restore the MOV from the circuit.
delete delete Three MOVs are connected between RST three-phase and N to which power and load are connected, GDT or MOV is connected between N and G, and each MOV and relay contact and CT are connected in series between each RST and N. Connected to the input of the A / D converter, the output of which is sequentially provided to the microprocessor via a first multiplexer which outputs an input selected by the microprocessor, and a plurality of voltages in parallel with the MOV. The sense resistors are connected in series, the input of the A / D converter is connected to the connection point of these resistors, and the output of the A / D converter is connected to the microprocessor through a first multiplexer which outputs the input selected by the microprocessor. And the microprocessor is configured to supply a control output signal to the three driving circuits sequentially by driving the microprocessor. It is connected to the flexure and the driving circuit, characterized in that to drive the relay coil of each phase,
The microprocessor turns off the relay contact connected in series with the MOV at the moment when an overvoltage exceeding the threshold that causes the power voltage to break the MOV is input, and then the voltage input is below the threshold and less than a predetermined duration. A surge protection device based on a surge suppression device, characterized in that the relay contact is 'on' again to disconnect and restore the MOV from the circuit.
A voltage sensing resistor connected in parallel to the MOV constituting the SPD and the power supply, and a relay contact and a shunt resistor connected in series with the MOV together with the MOV. It is applied to the / D converter to obtain a corresponding digital data value and read by the microprocessor to control the drive circuit for passing the current to the relay coil for driving the relay contact,
The microprocessor turns off the relay contact connected in series with the MOV at the moment when an overvoltage exceeding the threshold that causes the power voltage to break the MOV is input, and then the voltage input is below the threshold and less than a predetermined duration. A surge protection device based on a surge suppression device, characterized in that the relay contact is 'on' again to disconnect and restore the MOV from the circuit.

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