WO2007064062A1

WO2007064062A1 - Apparatus for protecting surge and over voltage

Info

Publication number: WO2007064062A1
Application number: PCT/KR2006/001423
Authority: WO
Inventors: Hyung Jai Hwang; Kyung Ho Lee
Original assignee: Dastek Co., Ltd.
Priority date: 2005-11-29
Filing date: 2006-04-18
Publication date: 2007-06-07
Also published as: KR100575440B1

Abstract

An apparatus is provided for protecting electronic equipment against surges and overvoltages, comprising: a surge removal unit; a voltage change unit; a zero voltage detection unit; a processor unit; a power supply unit; a switching unit; and a surge counter unit.

Description

APPARATUS FOR PROTECTING SURGE AND OVER

VOLTAGE

Disclosure of Invention Technical Problem

[1] The present invention relates to an apparatus for protecting electronic equipment from surges and overvoltages, and more particularly to an apparatus for protecting electronic equipment against surges and overvoltages included or inputted into an electric power source (hereinafter referred to an electric power) for driving the electronic equipment.

[2] A surge is a sudden or intermittent rush or a burst of a current or a voltage which exceeds a normal current or voltage in an electric circuit or an electric system. The surge presents adverse impacts such as insulation breakage, malfunction, degradation and the like, on information equipment using semiconductors or integrated circuits.

[3] The surge is introduced in the form of induction, emission, or conduction into an electric wire to inflict a critical impact on the electronic equipment. The surge can be largely categorized into two types, that is, one that occurs due to a lightning strike, another type that occurs when an electric power system or a regulating voltage load is opened or closed, or that is cause by a ground fault or a short-circuit of power distribution lines.

[4] A short and sudden change in current and voltage occurs during a surge. A time duration and a rising time of the surge vary depending on causes of the surge, ranging from several nano seconds to several milli seconds. A rising speed of the surge is in the range of several micro seconds, and its energy is in the range of tens to hundreds of Joules.

[5] An overvoltage, like the surge, has a critical impact on the electronic equipment.

The overvoltage has the same phase as that of a rated voltage but has a voltage of higher level than that of the rated voltage. The overvoltage, if inputted into electronic equipment, may exceed a maximum allowable voltage causing serious damage to the electronic equipment.

[6]

Technical Solution

[7] Therefore, an object of the present invention is to provide an apparatus for protecting electronic equipment against surges and overvoltages by preventing input of the surge and the overvoltage into the electronic equipment.

[8] Another object of the present invention is to provide an apparatus for protecting electronic equipment against surges and overvoltages, capable of automatically counting the number of surges included in electric power.

[9] According to a general aspect of the present invention, an apparatus for preventing the surges and the overvoltages includes a surge removal unit, a voltage change unit, a zero voltage detection unit, a processor unit, a power supply unit, a switching unit, and a surge counter unit.

[10] The surge removal unit, if a first electric power including a surge is inputted through an input terminal, outputs the first electric power from which the surge is removed. The voltage change unit, after the surge-removed first electric power outputted from the surge removal unit is inputted to the voltage change unit, changes a voltage of the surge-removed electric power to a specific voltage value which is proportional to a voltage of the inputted first electric power and outputs the specific voltage value.

[11] The zero voltage detection unit, after receiving second electric power, detects a time when a voltage of the second electric power is "0" and outputs a detection signal. The processor unit, after receiving the detection signal outputted from the zero voltage detection unit and the specific voltage value outputted from the voltage change unit, determines if the voltage of the first electric power is an overvoltage and outputs a low signal or a high signal depending on the result of the determination.

[12] The power supply unit, after receiving the second electric power, outputs a constant electric power to operate the processor unit. The switch unit performs switching operations depending on a high or low signal outputted from the processor unit. The surge counter unit counts the number of surges included in the first electric power inputted through the electric power input terminal. The first and second electric powers may have an identical phase.

[13] The surge removal unit may include a first hold unit which holds the voltage of the first electric power to a first value and outputs an electric power from which a voltage above the first value is removed, a phase reversing unit which reverses the phase of the electric power outputted from the first hold unit, a second hold unit which holds to a second value a voltage of the electric power whose phase is reversed in the phase reversing unit and outputs the electric power from which a voltage above the second value is removed, and a third hold unit which holds a voltage of the electric power outputted from the second hold unit to a third value and outputs an electric power from which a voltage above the third value is removed.

[14] The surge count unit may include an electric power input display unit which displays, if the first electric power is inputted, a filter unit which filters out the surge from the first electric power when the surge is included in the first electric power, a rectification unit which performs a full- wave rectification of the surge filtered out by the filter unit, a signal change unit which changes a time duration of the surge when the time duration of the full- wave rectified surge by the rectification unit is below a reference time, a voltage drop unit which drops a voltage of the surge whose time duration is changed by the signal change unit, a pulse generation unit which generates a pulse having a duty cycle while the voltage of the surge, dropped by the voltage drop unit, holds, a current supply unit which supplies to the pulse generation unit a current above a reference current to operate the pulse generator unit, and a counter unit which counts the number of pulses generated by the pulse generation unit. The filter unit may include a variable device whose impedance converges to "0" when the electric power without the surge is inputted to the variable device. [15]

Advantageous Effects

[16] The present invention provides an advantage of preventing surges and overvoltages from being inputted to electronic equipment, thus protecting the electronic equipment against damage. Furthermore, the present invention provides another advantage of automatically determining and analyzing the number of the surges included in the electric power.

[17]

Brief Description of the Drawings

[18] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

[19] In the drawings :

[20] FIG. 1 is a circuit diagram illustrating a surge removal unit in an apparatus for protecting electronic equipment against surges and overvoltages according to an exem plary embodiment of the present invention;

[21] FIG. 2 is a circuit diagram illustrating a protection unit in the apparatus for protecting electronic equipment against surges and overvoltages according to the exemplary embodiment of the present invention; and

[22] FIG. 3 is a circuit diagram illustrating a surge counter unit in an apparatus for protecting electronic equipment from a surge and an overvoltage according to the exemplary embodiment of the present invention. Mode for the Invention

[23] Reference will now be made in detail to an embodiment of the present invention, examples of which are illustrated in the accompanying drawings.

[24] FIG. 1 is a circuit diagram illustrating a surge removal unit in an apparatus for protecting electronic equipment against surges and overvoltages according to an exemplary embodiment of the present invention. Referring to FIG. 1, a surge removal unit includes a first hold unit 100, a phase reversing unit 110, a second hold unit 120, and a third hold unit 130.

[25] The first hold unit 100 holds a voltage of surge-included first electric power inputted through an electric power input terminal to a first value and outputs the electric power from which a voltage above the first value is removed. The first hold unit 100 includes a plurality of arresters Al, A2, and A3. The first arrester Al is connected to the first electric power input terminal CON 1 and a ground terminal, the second arrester A 2 is connected to the second electric power input terminal CON 2 and the ground terminal, and the third arrester A 3 is connected to the fist electric power input terminal CON 1 and the second electric power input terminal CON 2. Each arrester operates when a threshold voltage is applied thereto. The arrester does not allow a leakage current to flow therein and has a surge-resistant characteristic. Thus, the arrester is widely used in holding the surge-included electric power to a specific value.

[26] Each of the arresters Al, A2, and A3, for example, includes a gas tube arrester.

Both ends of the arrester allow the current to flow and the voltages of both ends of the arrester are held to the first value, if a voltage above the first value is applied to both ends of the arrester. That is, the voltage above the first value is removed if the voltages of both ends of the arrester are held to the first value. The first value is related to an arrester capacity.

[27] The arresters Al and A2, each being connected to the ground terminal, enable a surge voltage to be limited to the first value, even if the surge is inputted through the ground. Each of the arresters Al, A2, and A3 has the same capacity, thus allowing the first hold unit 100 to stably operate. Another arrester A4 may be connected in parallel to prepare against a possible unstable operation resulted from demage to the arresters.

[28] The phase reversing unit 110 serves to reverse a phase of the electric power outputted from the first hold unit 100. The phase reversing unit 110 reverses the phase of the electric power outputted from the first hold unit 100, for example, by way of a ring-shaped coil.

[29] The second hold unit 120 holds to a second value the voltage of the electric power whose phase has been reversed by the phase reversing unit 110 and outputs the electric power from which a voltage above the second value is removed. The second hold unit 120 includes a plurality of varistors Vl, V2, and V3. The first varistor Vl is connected to one end of the phase reversing unit 100 and a ground terminal, the second varistor V2 is connected to the other end of the phase reversing unit 100 and a ground terminal, and the third varistor V3 is connected to said one end of the phase reversing unit 100 and said other end of the phase reversing unit 100. The varistor generally defines a resistor device having a non-linear current/ voltage characteristic. The varistor maintains a high impedance upto a preset breakdown voltage in a normal state, but the impedance of the varistor rapidly decreases when the voltage above the breakdown voltage is inputted. That is, a varistor allows a current to flow and voltages of both ends of the varistor are held to a second value if the voltage above the second value is applied to the both ends of the varistor. The voltage above the second value is removed if the voltages of the both ends of the a varistor are held to the second value. The second value is related to a varistor capacity. Connection of the varistors Vl and V2 to a ground terminal enables a surge voltage to be held to the second value, even if the surge is inputted through the ground. Each of the arresters Vl, V2, and V3 has the same capacity, thus stabilizing the operation of the second hold unit 120. A varistor V4 may be connected in parallel to prepare against a possible malfunction caused by damage to the varistors.

[30] The third hold unit 130 holds the voltage of the electric power outputted from the second hold unit 120 to a third value and outputs the electric power from which a voltage above the third value is removed. The third hold unit 130 includes a first pair of ZDl and V5, a second pair of ZD2 and V7, and a third pair of ZD3 and V6. The first pair of ZDl and V5 and the third pair of ZD3 and V6 (two pairs being connected in series) are connected in parallel to the second hold unit 120. The second pair of ZD2 and V7 is connected between the ground and a node connecting the first pair of ZDl and V5 to the third pair of ZD3 and V6. The zener diodes ZDl, ZD2, and ZD3 are connected with each cathode of the zener diodes facing the node connecting the first pair and the second pair. The voltage of the electric power outputted from the second hold unit 120 is set to a specific value by voltages of the zener diodes ZDl, ZD2, and ZD3. The voltage set to the specific value is held to the third value by the varistor. That is, the third hold unit 130 removes a voltage above the third value from the electric power outputted from the second hold unit 120.

[31] The surge voltage may be held to the third value by connecting at least one pair of zener diodes and varistors among the plurality of pairs to the ground terminal, if the surge is inputted through the ground terminal. The varistors of each pair have the same capacity and the zener diodes of each pair have the same zener voltage, thus stabilizing operation of the third hold unit 130.

[32] As described above, the second value is smaller than the first value, but larger than the third value. This makes it possible to gradually hold a high voltage surge to the third value. That is, if the surge-included electric power is inputted, the first hold unit 100 reduces the voltage level of the surge-included electric power to the first value, the second hold unit 120 again reduces the voltage level of the surge-included electric power to the second value which is smaller than the first value, and the third hold unit 130 in turn reduces the voltage level of the surge-included electric power to the third value which is smaller than the second value. Thus, the voltage of the electric power which the surge removal unit outputs becomes the third value.

[33] The surge removal unit constructed of a single hold unit cannot remove a surge if the surge having a voltage below a specific value is inputted to the surge removal unit. Therefore, the surge removal unit, as in the embodiment of the present invention, has to include a plurality of the hold units in order to hold the surges at different levels of voltages to their respective specific values.

[34] A spark prevention circuit (Cl and Rl) prevents electric sparks from arising from the first electric power in which the voltage is held to the third value by the surge removal unit, and the first electric power is inputted to input terminals (CON 6 and CON 7) of the electronic equipment. However, the first electric power, if it is an overvoltage, is not permitted to be inputted to the input terminals (CON 6 and CON 7) of the electronic equipment. This will be described later.

[35] Now, referring to FIG. 2, an overvoltage protection unit includes a voltage change unit 200, a power supply unit 210, a zero voltage detection unit 220 and a processor unit 230.

[36] The voltage change unit 200 receives the surge-removed electric power outputted from the surge removal unit and changes a voltage of the received electric power to a specific voltage value which is proportional to the voltage of the first electric power. The voltage change unit 200 composed of diodes Dl to D4 includes a bridge rectifier circuit.

[37] The bridge rectifier circuit is inputted with the electric power through an input thereof. The bridge rectifier circuit is connected in series at an output terminal thereof with a plurality of resistors (R2 and R3). One of the resistors R3 is connected in parallel with a condenser C2, a diode D5 and a light emitting part of a photocoupler UI. The voltage of the electric power outputted by the surge removal unit is divided by the resistors (R2 and R3) after flowing through the diodes of the bridge rectifier circuit. The electric power whose voltage has been divided by the resistors (R2 and R3) is smoothened and inputted to the light emitting part of the photocoupler Ul to generate light.

[38] A light receiving part of the photocoupler Ul and the resistor R4 are connected in series between the ground and a constant electric power Vcc outputted from the power supply unit 210. The condenser C3 is connected in series to the resistor R4. The voltage applied to both ends of the light receiving part of the photocoupler Ul increases in proportion to an amount of light that the light emitting part of the photocoupler Ul emits. The photocoupler includes a light emitting part which receives a specific signal and emits light and a light receiving part which processes the specific signal based on the received light. The photocoupler is widely used for signal transfer because of many advantages such as noise-resistance and no occurrence of backflow phenomenon of a light receiving signal generated from a light receiving part flowing backward to a light emitting part. The photocoupler is noise-resistant because light is used in transferring a signal. Therefore, the voltage applied to both ends of the resistor R4 also increases in proportion to the amount of light emitted by the light emitting part of the photocoupler Ul. That is, according as the voltage value inputted to the voltage change unit 200 increases, the voltage value applied to both ends of the resistor increases. This makes it possible to increase a specific voltage value outputted from the voltage change unit 200. The voltage change unit 200 is not limited to the above mentioned configuration, but includes any configuration in which the voltage change unit 200 can change the input voltage to a specific value.

[39] The power supply unit 210 outputs a constant electric power for operating the processor unit 230. The power supply unit 210 includes a bridge rectifier circuit operated by the second electric power. A regulator and a plurality of condensers C4 and C5 are provided at a load terminal of the bridge rectifier circuit. A first condenser C4 is connected between a first end of the regulator and the ground, a second condenser C5 is connected between a second end of the regulator and the ground, and the third end is connected to the ground. A potential difference between the ends of the second condenser C5 is outputted to the processor unit 230. The voltage is stabilized by a condenser Cl and outputted to the processor unit 230.

[40] The second electric power has the same phase as that of the first electric power, but has the voltage value lower than that of the first electric power. The second electric power is generated by inputting the electric power having the same phase as that the first electric power to a transformer. The second electric power inputted to the power supply unit 21 undergoes a full- wave rectification at the bridge rectifier circuit and is converted to a constant voltage by the regulator provided at the load terminal of the bridge rectifier circuit. The capacitors (C4 and C5) connected to the regulator serve to improve a characteristic of the constant voltage and prevent an oscillation. The constant voltage outputted from the regulator charges the second capacitor C5, and the voltage stored in the second capacitor C5 is inputted to the processor unit 230. It should be noted that the power supply unit 210 is not limited to the above mentioned configuration, but includes any configuration in which the power supply unit 210 can supply a constant voltage to the processor unit 230.

[41] The zero voltage detection unit 220 receives the second electric power, detects a time when the voltage of the second electric power is "0" and outputs a detection signal. The time when the second electric power is "0" and the time when the first electric power is "0" are the same because the phase of the second electric power and that of the first electric power are the same. The second electric power and the light receiving part and the resistor R5 of the photocoupler U2 are connected in series in the zero voltage detection unit 220. The light receiving part and the resistor R6 are connected in series between the constant electric power and the ground. The light receiving part of the photocoupler U2 is connected in parallel to the condenser C6. A potential difference between the ends of the condenser C6 is outputted to the processor unit 230.

[42] The second electric power whose phase is the same as that of the first electric power is inputted to the zero voltage detection unit 220 through the electric power input terminal. The voltage of the input second electric power drops at the resistor R5. The second electric power whose voltage is dropped by the resistor R5 enables the light emitting part to emit light. The light emitting part of the photocoupler U2 emits light when an absolute value of the voltage of the second electric power is "0" or over, even though the second electric power is in the form of alternating current. That is, the light emitting part of the photocoupler U2 does emit light only when the second electric power has the voltage value of "0".

[43] The light receiving part of the photocoupler U2 is turned on when the light emitting part of the photocoupler U2 emits light, and the current, which is produced by the constant voltage connected in series to the light receiving part of the photocoupler U2, flows to the ground. As a result, no voltage is charged in the condenser C6 to make the voltage inputted to the processor 230 "0". However, when the light emitting part of the photocoupler U2 does not emit light, the light receiving part of the photocoupler U2 is turned off, and the constant voltage Vcc connected to the light receiving part of the photocoupler U2 in series is inputted to the condenser C6. The voltage charged to the condenser C6 is inputted to the processor unit 230. As noted above, when the second electric power having the same phase as that of the first electric power has a zero voltage value, the voltage is charged to the condenser, and the voltage charged at the condenser is inputted to the processor unit 230, such that the zero voltage detection unit 220 can discriminate a time when the first electric power is zero. A detection signal having a specific voltage is outputted to the processor unit 230, when the voltage of the first electric power is "0". The zero voltage detection unit 220 is not limited to the above mentioned configuration, but includes any configuration in which the time when the voltage of the second electric power is can be detected.

[44] The processor unit 230 determines if the first electric power includes the overvoltage based on the detection signal outputted from the zero voltage detection unit 220 and the specific voltage value outputted from the voltage change unit 200, and selectively outputs a high signal or a low signal. A value list of set-up values cor- responding to specific voltage values inputted from the voltage change unit 200 is stored in the processor unit 230. For example, the voltage of the first electric power is changed to a specific value of " IV." if the voltage of the first electric power is "500V." and the processor unit 230 sets up the IV inputted from the electric power to 100 according to the value list.

[45] The set-up value list is proportional to the voltage value outputted from the voltage change unit 200 and the value outputted from the voltage change unit 200 is proportional to the voltage value of the first electric power Therefore, the set-up value on the value list in the processor unit 230 is proportional to the voltage value of the first electric power. For example, the corresponding set-up value on the value list is "140", if the voltage value of the first electric power is "600V". The corresponding set-up value on the value list would be "200", if the voltage value of the first electric power is "800 V". The processor unit 230 determines that the first electric value is an over- voltage if the set-up value is above a reference value. The processor unit 230 outputs a high signal if it is determined that the first electric power is not an over- voltage.

[46] Alternatively, the processor unit 230 outputs a low signal if the first electric power is determined to be of an overvoltage. The processor unit 230 outputs the low signal at the time when a detection signal is inputted from the zero voltage detection unit 220. That is, the time when the detection signal is inputted from the zero voltage detection unit 220 corresponds to the time when the voltage value of the first electric power is "0". Accordingly, the processor unit 230 outputs a low signal at the time of receiving the detection signal from the zero voltage detection unit 220, in order to prevent the overvoltage-included electric power from being inputted to the electronic equipment.

[47] The set-up value list is changeable from equipment to equipment depending on the definition of an overvoltage. The change of the set-up value list is possible by inputting a specific program. Reference numeral 240 is employed for input of the specific program.

[48] A switching unit 250 performs switching operations depending on the signal (high or low) outputted from the processor unit 230. The constant electric power Vcc of the power supply unit 210, a resistor RlO, a light emitting part of a photo Triac coupler U4, and a signal output terminal are connected in series in the switching unit 250. The light emitting part of the photo Triac coupler U4 constituting the switching unit 250 emits light when the processor unit 230 outputs a low signal. That is, the light emitting part of the photo Triac coupler U4 emits light when the low signal is inputted to a cathode of the light emitting part of the photo Triac coupler. It is because an anode of the light emitting part of the photo Triac coupler is connected to the resistor RlO and the constant electric power Vcc.

[49] One end of the light receiving part of the photo Triac coupler U4 is connected to a gate terminal of a Triac Ql and a resistor Rl 1. The resistor Rl 1 is connected to a Tl terminal of the Triac Ql. The other end of the light receiving part of the photo Triac coupler U4 is connected to a resistor Q 12. The resistor Q 12 is connected to a T2 terminal of the Triac Ql. The Tl and T2 terminals of the Triac Ql are connected to a surge-removed first electronic power which is outputted from the surge removal unit. The light receiving part of the photo Triac coupler U4 is turned on if the light emitting part of the photo Triac coupler U4 emits light. The Tl and T2 terminals of the Triac Ql are connected to an electronic power from which surge is removed. The electronic power is inputted to the gate terminal of the Triac Ql if the light receiving part of the photo Triac coupler U4 is turned on. Then, the Triac Ql is turned on and is short- circuited. However, the Triac Ql is turned on, only if the voltage of the electronic power inputted to the gate terminal is above a threshold voltage. That is, if the Triac Ql is turned on, impedance of the Triac Ql becomes nearer to "0" and the electronic power applied to both ends of the Triac Ql causes the current to flow through the Triac Ql. So, the current inputted to the power input terminals (CON 6 and CON 7) of the electronic equipment becomes "0". If the overvoltage is applied, the Triac Ql is turned on to allow the current to flow. Thus, the current inputted to the power input terminals (CON 6 and CON 7) of the electronic equipment becomes "0". This protects the electronic equipment against the overvoltage.

[50] The light receiving part of the photo Triac coupler U4 is not turned on, if the light emitting part of the photo Triac couple U4 does not emit light. So, the Triac Ql is turned off and the electronic power applied to both ends of the Triac Ql does not cause the current to flow through the Triac Ql. Thus, the first electric power from which the surge is removed is outputted to the electronic equipment.

[51] FIG. 3 is a circuit diagram illustrating the surge counter unit in the apparatus for protecting electronic equipment against surges and overvoltages according to the embodiment of the present invention. Referring to FIG. 3, the surge counter unit includes a power input display unit 300, a filter unit 310, a current rectification unit 330, a signal change unit 340, a voltage drop unit 350, a pulse generation unit 360, and a counter unit 370.

[52] The power input display unit 300 displays presence or absence of the electric power. The power input display unit 300 includes a Light Emitting Device (LED 1) which emits light when the electric power is inputted. There exists a likelihood that the voltage of the electric power, which is inputted for the LED 1 to emit light, is great enough to cause damage to the LED 1. Therefore, a plurality of voltage drop elements such as resistors R13 and R14 are used to distribute the input voltage and the distributed voltage is inputted to the LED 1.

[53] The filter unit 310 serves to filter out surges from the first electric power when the surges are included in the first electric power. A resistor Rl 5 and a coil (an inductor) L2 are connected in series to a load terminal of the filter unit 310. The filter unit 310 includes a bridge rectifier circuit consisting of diodes (DlO, Dl 1, D12, and D13), and a plurality of diodes (D14 and D15) connected in parallel to a load terminal of the bridge rectifier circuit. The plurality of diodes (D 14 and D 15) are connected in series to each other in a forward direction. A ground terminal is connected to a connection node between the plurality of diodes (D14 and D15).

[54] The load terminal according to the present invention includes the resistor Rl 5 and the coil L2 which are connected in series to each other. The coil L2 is configured in such a way that the impedance converges to "0", when a surge-included signal is applied to the coil L2. The impedance cannot physically become "0" if a signal free of a surge is applied to the coil L2. However, the impedance is assumed to be "0", because the impedance of the coil is negligible even if the surge-included signal is applied to the coil.

[55] The impedance of the coil L2 converges to"0", if no surge is included in the first electric power inputted to the bridge rectifier circuit. Thus, the potential difference between both ends of the coil L2 converges to "0". However, the impedance comes to be a specific value when the surge-included first electric power is applied to the bridge rectifier circuit. Thus, the potential difference between both ends of the coil L2 comes to be a specific value. If there exists a load connected in parallel to the coil, a specific electric power is applied to the load.

[56] The filter unit 310 includes a plurality of bridge rectifier circuits because a plurality of diodes (D14 and D15) are connected in series to a load terminal of the bridge rectifier circuit. The plurality of diodes are connected in parallel to the load terminal and in series to each other in a forward direction. In the plurality of diodes connected in series to each other, an anode of the diode D 14 is connected to anodes of the diodes (DlO and D 12) and a cathode of the diode D 15 is connected to cathodes of the diodes (Dl 1 and D 13). A ground terminal is connected to a connection node between the cathode of the diode D 14 and the anode of the diode D 15. The plurality of diodes (D 14 and D 15) enable the electric power to be inputted to the filter unit 310 through the first and second connectors (CONl and CON2). In this way, a first bridge rectifier circuit including the diodes (DlO, Dl 1, D12, and D13), a second bride rectifier circuit including the diodes (DlO, Dl 1, D14, and D15), and a third bridge rectifier circuit including (D12, D13, D14, and D15) are configured.

[57] As described above, only the surge is outputted if the filter unit 310 outputs a signal applied to both ends of the coil L2. It is because the impedance of the coil L2 converges to "0", if a surge-free electric power is inputted.

[58] The rectification unit 330 performs a full wave rectification of the surge filtered out by the filter unit 310. The surge outputted from the both ends of the coil L in the filter unit 310 is inputted to the rectification unit 330, comprising the bridge rectifier circuit. The surge may be included if the input electric power is in the form of positive potential, as well as negative potential, in a case where the input electric power is in the form of alternating current. The rectification unit 330 performs a full wave rectification of the surge outputted from the filter unit 310 so that the rectification unit 330 can count the surge included when the input electric power is in the form of negative potential. The bridge rectifier circuit includes a plurality of diodes (D16, D17, D 18, and D 19). A load terminal thereof includes the signal change unit 340, a voltage drop unit 350, a pulse generation unit 360, and a counter unit 370.

[59] The signal change unit 340 includes a condenser or a capacitor C8. The signal change unit 340 changes a surge time duration so that the pulse generation unit 360 can generate a pulse when the surge time duration is below a reference time. The surge tim e duration defines a time for which the surge lasts. There occur cases when the pulse generation unit 360 may not work when the surge time duration is below the reference time. The pulse generation unit 360 to which the surge is inputted may not work depending on the surge because of various reasons including clocks. A condenser can be charged and discharged but the condenser is not discharged before being completely charged. So, the surge time duration can be increased by charging and discharging the capacitor C included in the signal change unit 340. This enables the pulse generation unit 360 to process the surge, when the surge is inputted to the pulse generation unit 360.

[60] The voltage drop unit 350 drops an absolute value of the voltage of the surge filtered out by the filter unit 310. The voltage drop unit 350 includes a variable resistor R 19 and a zener diode ZD4 each being connected in series. The surge filtered out by the filter unit 310 is a signal having a high voltage value. So, when the surge is applied to the pulse generation unit 360 as it is, the device constituting the pulse generation unit 360 may be damaged because the rectification unit 360 and the signal change 340 have a critical impact on voltage drop of the surge. Accordingly, the voltage drop unit 350 drops the voltage of the surge to a voltage level which is slightly above or slightly below the voltage of the electric power necessary for operating the pulse generation unit 360. In other words, the voltage drop unit 350 drops the voltage of the surge to a predetermined level of voltage using the variable resistor R19. The zener diode ZD4 enables the surge of the voltage to drop to the predetermined level by way of the variable resistor R19 and to have the voltage value within a breakdown voltage range. The voltage drop unit 350 may include devices which can provide a stable voltage to the pulse generation unit 360, not limited to the above mentioned configuration in which the variable resistor R19 and the zener diode ZD4 are connected in series to each other. The pulse generation unit 360 generates a pulse having a duty cycle as long as the surge whose voltage was dropped by the voltage drop unit 350 holds. The pulse generation unit 360 includes a photocoupler U5. A light emitting part of the pho- tocoupler U5 constituting the pulse generation unit 360 emits light as long as the surge whose voltage was dropped by the voltage drop unit 350 holds. A transistor of the light receiving part is turned on and the pulse having the duty cycle is generated when the light emitted from the light emitting part is inputted. At this point, a specific electric power is connected in series to the light receiving part to generate the pulse. As a result, the pulse generation unit 360 generates the pulse having the duty cycle only while the surge holds. However, when the surge is not included, i.e., when a signal has a very small voltage value, the photocoupler does not work and thereby the pulse having the duty cycle is not generated. The pulse generation unit 360 may include devices which can generate the pulse having the duty cycle while the surge holds, but not limited to the above mentioned configuration in which the pulse generation unit 360 consists of the photocoupler Ul.

[61] The current supply unit 320 supplies current above the reference current to the pulse generation unit 360 to operate the pulse generation unit 360. The current supply unit 320 is configured in such a manner that a resistor Rl 6 is connected between an output terminal of the filter unit 310 and the first connector CONl, a resistor R17 is connected between the output terminal of the filter unit 310 and the second connector CON2, and a resistor Rl 8 is connected between the output terminal of the filter unit 310 and a ground terminal. One end of the coil L2 constituting the filter unit 310 is connected to a connection node between the plurality of resistors (R16 and R17) or (R16 and R18). The current supply unit 320 stays inoperative if no sufficient current is supplied. So, the current supply unit 320 to which the electric power is inputted should supply the sufficient current to the pulse generation unit 360.

[62] The counter unit 370 counts the number of pulses generated by the pulse generation unit 360. There is a correlation between the number of pulses generated by the pulse generation unit 360 and the number of surges included in the electric power. Because the counter unit 370 counts the number of pulses generated by the pulse generation unit 360, the number of the surges included in the electric power can be counted.

[63] The present invention can be embodied in a method, a device, and a system. When the present invention is embodied in computer software, elements of the present invention may be replaced by code segments necessary for operation of the present operation. Programs or code segments may be stored in microprocessor-processible media and transmitted in the form of computer-readable data through transmission media or wireless telecommunication networks.

[64] The microprocessor-processible media includes media whose data can be stored in and transmitted through an electric circuit, a semiconductor memory device, a Read- Only Memory (ROM), a flash memory, an Electricly Erasable Programmable Read- OnIy Memory (EEPROM), a floppy disk, an optical disk, a hard disk, an optical fiber, and a wireless network. The computer-readable data includes data which can be transmitted via a network channel, an optical fiber, an electromagnetic field and a wireless network.

[65]

Industrial Applicability

[66] As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.

[67]

[68]

[69]

Claims

[1] An apparatus for protecting electronic equipment from surges and overvoltages, comprising: a surge removal unit outputting a first electric power from which the surge is removed when the first electric power including the surge is inputted through an electric power input terminal; a voltage change unit receiving the surge-removed electric power outputted from the surge removal unit, changing a voltage of the surge-removed electric power to a specific voltage value which is proportional to a voltage of the input first electric power, and outputting the specific voltage value; a zero voltage detection unit receiving a second electric power, detecting a time when a voltage of the second electric power is "0", and outputting a detection signal; a processor unit receiving the detection signal outputted from the zero voltage detection unit and the specific voltage value outputted from the voltage change unit, determining if the voltage of the first electric power is an overvoltage, and outputting a high or low signal; a power supply unit receiving the electric power and outputting a constant electric power to operate the processor unit; and a switching unit performing a switching operation depending on the high or low signal, wherein a phase of the first electric power is identical to that of the second electric power.

[2] The apparatus according to claim 1, further comprising a surge counter unit counting the number of surges included in the first electric power inputted through the electric power input terminal.

[3] The apparatus according to claim 2, wherein the surge removal unit comprises: a first hold unit holding the voltage of the first electric power at a first value and outputting the electric power from which a voltage above the first value is removed; a phase reversing unit reversing a phase of the electric power outputted from the first hold unit; a second hold unit holding to a second value the voltage of the electric power whose phase is reversed by the phase reversing unit and outputting the electric power from which a voltage above the second value is removed; and a third hold unit holding the voltage of the electric power outputted from the second hold unit to a third value and outputting the electric power from which a voltage above the third value is removed.

[4] The apparatus according to claim 3, wherein the second value is smaller than the first value but larger than the third value.

[5] The apparatus according to claim 3, wherein the first hold unit comprises a plurality of arresters, with a first arrester being connected between a first electric power input terminal and a ground terminal, a second arrester being connected between a second electric power input terminal and the ground terminal, and a third arrester being connected between the first electric power input terminal and the second electric power input terminal.

[6] The apparatus according to claim 3, wherein the second hold unit comprises a plurality of varistors, with a first varistor being connected between one end of the phase reversing unit and a ground terminal, a second varistor being connected between the other end of the phase reversing unit and the ground terminal, and a third varistor being connected between the one end of the phase reversing unit and the other end of the phase reversing unit.

[7] The apparatus according to claim 3, wherein the third hold unit comprises three pairs in which one zener diode and one varistor are connected in series to each other, with the first and third pair connected in series to each other being connected in parallel to the second hold unit, the second pair being connected to a connection node between the first pair and the third pair, and a cathode of the zener diode in each pair being connected toward a connection node between the first pair and the second pair.

[8] The apparatus according to claim 5, wherein each of the arresters has the same capacity.

[9] The apparatus according to claim 6, wherein each of the varistors has the same capacity.

[10] The apparatus according to claim 7, wherein each varistor comprising each pair has the same capacity and each zener diode has the same breakdown voltage.

[11] The apparatus according to claim 1, wherein the power supply unit comprises a bridge rectifier circuit operated by the second electric power, with a regulator and a plurality of condensers being connected to a load terminal of the bridge rectifier circuit, the first condenser being connected between a first end of the regulator and a ground terminal, the second condenser being connected between a second end of regulator and the ground terminal, a third end of the regulator being connected to the ground terminal, and a potential difference between ends of the second condenser being outputted to the processor unit.

[12] The apparatus according to claim 1, wherein the voltage change unit comprises a bridge rectifier circuit, with a plurality of resistors being connected in series at a load terminal to the bridge rectifier circuit, a condenser, a diode, and a light emitting part of a photocoupler being connected in parallel to one of the plurality of resistors, a light receiving part of the photocoupler and a resistor being connected in series between the constant electric power outputted from the power supply unit and the ground terminal, the resistor being connected in parallel to the condenser, and a potential difference between both ends of the capacitor being inputted to the processor unit.

[13] The apparatus according to claim 1, wherein the zero voltage detection unit is configured in such a manner that the second electric power of the power supply unit, and a light emitting part of the photocoupler and a resistor of a resistor are connected in series to each other, a light receiving part of the photocoupler and a resistor are connected in series between the constant electric power outputted from the power supply unit and the ground terminal, the light receiving part of the photocoupler is connected in parallel to a condenser, and a potential difference between both ends of the condenser is inputted to the processor unit.

[14] The apparatus according to claim 1, wherein the processor unit outputs a high signal if the voltage of the first electric power is not an overvoltage.

[15] The apparatus according to claim 1, wherein the processor unit outputs a low signal if the voltage of the first electric power is an overvoltage and a detection signal is inputted from the zero voltage detection unit.

[16] The apparatus according to claim 1, wherein the processor unit determines if the voltage of the first electric power is an overvoltage, based on a set-up value corresponding to a specific voltage value outputted from the voltage change unit.

[17] The apparatus according to claim 1, wherein the switch unit is configured in such a manner that the constant electric power outputted from the power supply unit, a resistor, a light emitting part of the a photo Triac coupler are connected in series to a signal output terminal of the processor unit, one end of a light receiving part of the photo Triac coupler is connected to a gate terminal of a Triac and a first resistor, the first resistor is connected to a Tl terminal of the Triac, the other end of the light receiving part of the photo Triac coupler is connected to a second resistor, the second resistor is connected to a T2 terminal of the Triac, and the Tl and T2 terminals are connected to the surge-removed electric power outputted from the surge removal unit.

[18] The apparatus according to claim 1, wherein the surge counter unit comprises: an electric power display unit displaying presence or absence of input of the first electric power; a filter unit filtering out a surge from the first electric power if the surge is included in the first electric power; a rectification unit performing a full- wave rectification of the surge filtered out by the filter unit; a signal change unit changing a surge time duration if the time duration of the surge full- wave rectified by the rectification unit is below a reference time; a voltage drop unit dropping a voltage of the surge whose time duration is changed by the signal change unit; a pulse generation unit generating a pulse having a duty cycle as long as the voltage of the surge, dropped by the voltage drop unit, holds; a current supply unit supplying to the pulse generation unit a current above a reference current in which the pulse generator unit can operate; and a counter unit counting a number of the pulses generated by the pulse generation unit, wherein the filter unit comprises a variable device whose impedance converges to "0" if the electric power free from the surge is inputted to the variable device.

[19] The apparatus according to claim 18, wherein the electric power display unit co mprises a light emitting device emitting light by way of the first electric power.

[20] The apparatus according to claim 18, wherein the filter unit comprises a bridge rectifier circuit, with a resistor and the variable device being connected in series to a load terminal thereof.

[21] The apparatus according to claim 18, wherein the filter unit comprises: a bridge rectifier circuit having a resistor and the variable device connected to a load terminal thereof; and a plurality of diodes being connected in parallel to the load terminal of the bridge rectifier circuit, wherein the plurality of diodes are connected in series to each other in a forward direction and a ground terminal is connected to a connection node between the plurality of diodes.

[22] The apparatus according to claim 18, wherein the rectification comprising a bridge rectifier unit is connected in series to a variable device provided in the filter unit, with the voltage change unit, the signal change unit, the pulse generation unit, and the count unit being connected in parallel to a ground terminal of the bridge rectifier unit.

[23] The apparatus according to claim 18, wherein the signal change unit comprises a condenser, with the condenser being connected in parallel to the voltage drop unit.

[24] The apparatus according to claim 18, wherein the voltage drop unit comprises a variable resistor and a zener diode which are connected in series to each other, with the zener diode being connected in parallel to the pulse generation unit.

[25] The apparatus according to claim 18, wherein the pulse generation unit comprises a photocoupler.

[26] The apparatus according to claim 18, wherein the current supply unit comprises a plurality resistors and the variable device is connected to a connection nod of the plurality of resistors.

[27] The apparatus according to any one of claims 18, 20, 21, 22, or 26, wherein the variable device is an inductor