KR20140062625A - Reliability estimation apparatus and method of surge protective device for power and signal - Google Patents
Reliability estimation apparatus and method of surge protective device for power and signal Download PDFInfo
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- KR20140062625A KR20140062625A KR1020120128640A KR20120128640A KR20140062625A KR 20140062625 A KR20140062625 A KR 20140062625A KR 1020120128640 A KR1020120128640 A KR 1020120128640A KR 20120128640 A KR20120128640 A KR 20120128640A KR 20140062625 A KR20140062625 A KR 20140062625A
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- surge protector
- voltage
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- circuit
- microprocessor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
- G01R31/2827—Testing of electronic protection circuits
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Electric Properties And Detecting Electric Faults (AREA)
Abstract
Description
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a surge protector (SPD) reliability evaluation apparatus and method, and more particularly, to a surge protector (SPD) And more particularly, to a device and method for evaluating reliability of a surge protector.
Recently Surge Protective Device (SPD) has been widely applied to protect equipment from overvoltage and surge caused by lightning. Currently, most surge protectors for power supply use MOV (Metal Oxide Varistor) as a protection element. These MOV devices are mainly connected to the line-to-ground and remain in a very high impedance state in the steady state, and they are instantaneously deformed into a short-circuited low-impedance circuit upon surge penetration to discharge the surge current and suppress the limiting voltage across the protection device Thereby protecting the equipment.
However, such MOV devices are degraded and burned out when exposed to temporary overvoltages caused by repetitive intrusion of excessive surges or power system failures. When the MOV is burned down, the impedance is kept low. Therefore, if the rated voltage is maintained in this state, there is a possibility that it may develop into a short-circuit accident or a fire.
Therefore, in order to prevent such accidents, it is necessary to be able to diagnose and analyze the current state of the surge protector installed in the field. Most of the products that are currently applied to the market include the state of the fuse connected to the MOV by the LEDs, etc., in order to diagnose the deterioration state of the surge protector, such as the failure indication method, the surge counting method, the temperature measurement method, The fault indication method indicated by the lamp is applied. The fault indication method is a structure in which a fuse is inserted in series with MOV, which is a surge protection element between LG (power supply - ground), and LED is installed at both ends of the fuse. In normal condition, LED does not turn on because there is no voltage across the fuse. do. However, when the MOV is burned due to temporary overvoltage, the fuse is melted and the LED is turned on. This method has a very simple circuit configuration and can easily detect the failure state of the surge protector but can not judge the progress of deterioration until the fuse is blown. Therefore, there is a disadvantage in that it is difficult to prevent this beforehand since it must be recognized by the administrator after the occurrence of the protector burnout and replaced after the protection.
The surge count method detects the surge intrusion and records the number of intrusions. It consists of a current sensor that detects the surge current, a rectifier, a capacitor, and a counter circuit. When the surge current flows through the current sensor, the voltage induced across the sensor coil is proportional to the time variation of the magnetic flux passing through the end face of the coil. Therefore, an output voltage is generated in proportion to the magnitude of the surge current, Thereby driving the circuit. As the counter circuit, an analog device such as an op-amp (OP-amp) or a microprocessor may be used, and a magnetic counter or the like may be used. However, this method simply means that the surge has been activated by the intrusion of the surge, but we can not get detailed information about the current state of the protector. The correlation between the number of surge protectors and the lifetime of the surge protector varies depending on the size of the surge and the characteristics of the protection device used in the protector.
The temperature measurement method is to detect the temperature rise by MOV, which is a surge protection device, due to the overcurrent in case of abnormality, by using IC sensor for thermistor or temperature detection and to determine the deterioration. Each sensor used should be installed for each varistor used for accurate measurement There is a disadvantage to the sensor output, and an AD converter (analog to digital converter) or microprocessor has to be added to display the sensor output, and the reaction speed to detect the temperature is rather slow.
Therefore, a method of measuring leakage current of MOV is used for accurate deterioration diagnosis. As the measurement method, there are a method of measuring in a state in which a protector is operated largely, and a method of measuring by separating a protector from a system. The method of measurement when the power is applied to the site and the SPD is in use is to measure the leakage current only by measuring the leakage current on the ground side without separating the surge protector. It is more accurate to measure after separation because it can cause error.
Conventionally, as a method of diagnosing the deterioration of a surge protector, there is a method of analyzing a resistive leakage current by measuring a leakage current flowing through a MOV, and a surge protector incorporating such a function is disclosed in Korean Patent Laid- 0003804). However, such a high-function surge protector is generally expensive, and there are absolutely many products that have only MOV and simple display function as above. In addition, the MOV installation location and quantity are installed under various conditions in each manufacturer, so that the measurement accuracy is lowered in order to determine the degree of deterioration by measuring only the leakage current of the ground wire in the use environment where the surge protector is connected to the power source.
SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a surveillance system capable of diagnosing the current state of a surge protector and further improving the reliability of an operating system. A surge protector including a DC power supply, a voltage / current measuring device and an embedded system for analysis, and a surge protector for a signal, which is configured to measure the deterioration state of the surge protector, And a reliability evaluation apparatus and method.
In order to accomplish the above object, according to one aspect of the present invention, there is provided a surge protector reliability evaluation apparatus for detecting a deterioration state of a surge protector, comprising: A voltage divider circuit consisting of connected series resistors; A shunt resistor whose one end is connected to a second terminal of the DC power supply; And a second terminal of the DC power supply and a second terminal of the shunt in accordance with the LN (power line-neutral line), LG (power line-ground wire) A relay module in which the other terminal of the resistor is connected to the two terminals of the surge protector; And controlling the mode through the ON / OFF control of the plurality of switches, and controlling a power supply voltage of the DC power supply to measure a current flowing in the shunt resistor for measuring a current flowing in the surge protector , Estimating a leakage current flowing from the current measured at the first voltage of the DC power supply to the auxiliary circuit connected to the surge protector and subtracting the leakage current flowing in the auxiliary circuit from the current measured at the second voltage, And a microprocessor for detecting a deterioration state of the surge protector by determining whether the calculated value exceeds a reference value after calculating only the leakage current flowing through the MOV.
The first voltage may be 20 to 30V, and the second voltage may be 10 times or more the first voltage.
According to another aspect of the present invention, a surge protector reliability evaluation apparatus for detecting a deterioration state of a surge protector includes: a microprocessor; A surge generator for generating a high voltage pulse boosted from an AC input under the control of the microprocessor and applying the high voltage pulse to the surge protector; And a meter for converting a limit voltage appearing at an output terminal of the surge protector into a digital signal when an output pulse of the surge generator is applied to an input terminal of the surge protector under the control of the microprocessor, Controls the magnitude of the pulse and controls the pulse to be sequentially applied from the surge generator according to each mode installed in a power line, a neutral line, or a ground line of the surge protector. If the limit voltage exceeds the reference value And detecting a deterioration state of the surge protector.
The surge protector reliability evaluating apparatus is characterized by detecting a deterioration state of the surge protector for power supply or signal.
The surge protector reliability evaluation apparatus can not detect the deterioration state of the surge protector even when the additional circuit in the surge protector is connected without separating the metal oxide varistor (MOV) device installed in the surge protector (SPD) from the surge protector circuit Thereby diagnosing the disease.
The microprocessor may display the deterioration state on the display device and generate an alarm sound when the deterioration state is detected.
The surge protector reliability evaluation device can be manufactured as a portable type.
The surge generator includes: a boosting circuit for boosting the AC input; A charging circuit and a capacitor for charging the charge according to the output of the step-up circuit under the control of the microprocessor; A discharge switch that is turned on under the control of the microprocessor; An R / L circuit for generating a predetermined pulse voltage / current waveform according to a voltage of the capacitor transferred through the discharge switch; And a relay module that operates the switch according to the mode under the control of the microprocessor to sequentially apply an output pulse to each input terminal of the surge protector.
The measuring device includes: an impulse voltage dividing circuit for dividing a pulse-like limited voltage; A signal adjusting circuit for removing noise from the output of the impulse voltage dividing circuit; And an AD converter for converting an output of the signal adjustment circuit into a digital signal.
According to the apparatus and method for evaluating the reliability of a surge protector for power and signal according to the present invention, it is possible to measure only the resistive leakage current without separating in a state where it is installed in the system, regardless of the arrangement state of the MOV element and the connection state of the additional circuit, It is possible to evaluate the deterioration state of the surge protector more accurately than the leakage current measurement method in the state.
1 is a view for explaining the operation of a general MOV element (ZnO varistor).
Fig. 2 is an example of a single-phase surge protector when the protection mode is LN.
3 is a diagram for explaining a surge protector reliability evaluation apparatus (resistive leakage current detection apparatus of a surge protector) according to an embodiment of the present invention.
4 is a diagram for explaining a surge protector reliability evaluation apparatus (simple type limit voltage measurement apparatus) according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.
First, a method for analyzing deterioration due to leakage current measurement of a Surge Protective Device (SPD) based on MOV (Metal Oxide Varistor) is as follows. For example, a MOV element (ZnO varistor) constituted by a ZnO (zinc oxide) component constituting a surge protector can be equivalent to a parallel combination of a capacitor and a nonlinear resistor as shown in Fig. 1, Is directly applied to the ZnO varistor, a minute leakage current (It) always flows through the ZnO varistor. The total leakage current (It) flowing through the ZnO varistor is the sum of the resistive leakage current (Ir) and the capacitive leakage current (Ic).
The capacitive leakage current (Ic) is the leakage current due to the capacitance component due to the shape of the MOV. When the MOV is deteriorated, the capacitive current hardly changes but the resistive current (Ir) increases rapidly. If the resistive leakage current (Ir) of the MOV increases due to natural or artificial deterioration due to long-term use, the amount of heat increases and eventually the heat is destroyed, failing to fully function as a protection device and causing accidents. That is, if the performance is deteriorated due to the nonlinear resistance characteristic, the resistive leakage current (Ir) is an important factor for the diagnosis of deterioration of the MOV.
Detecting such a resistive leakage current (Ir) in a live state connected to a power line is a very useful method, but a precise non-contact current sensor is required and an error may be caused by the influence of ambient harmonic noise. In the present industrial field, there are many places where the surge protector is installed in front of the surge protector for the maintenance of the surge protector. In this case, it is easy to isolate the protector from the line by shutting off the switch. In case of no surge protector, However, in the present invention, regardless of the arrangement state of the MOV element and the connection state of the additional circuit in a state where the power is cut off to the surge protector, the MOV element can be separated A method for diagnosing a deterioration state of a surge protector without describing the deterioration state of the surge protector.
As mentioned above, MOV, which is the main protection element of surge protector, can be equivalent to resistive and capacitive components, and double resistive leakage current (Ir) is the dominant factor in deterioration. If a DC voltage is applied across the MOV to measure this, the current in the capacitive component does not flow, so the total leakage current can be regarded as a resistive leakage current. However, most surge protectors currently installed in the field are not single-use MOV devices between lines (between power lines) or line-to-grounds (between power lines and ground) . Generally, in a single-phase surge protector, the MOV element is installed between the protection mode LN (power line-neutral line), LG (power line-ground line) and NG (neutral line-ground line) In the case of a single-phase surge protector for a single phase, a separator such as a fuse for preventing short-circuiting is connected in series with the MOV, and a resistor, a diode, and an LED lamp for indicating the state of the separator An additional circuit includes a display device.
In the example of the surge protector circuit as shown in FIG. 2, when the DC voltage is applied between the LN (power supply line and neutral line) to measure the return current, the sum current of the leakage current of the MOV and the current flowing to the additional circuit appears as the measurement current . Therefore, in order to measure the accurate resistive leakage current (Ir), it is necessary to remove the current flowing to the additional circuit.
In order to solve this problem, the present invention first applies a low voltage at which the MOV device does not operate. For example, MOV devices for 220V are generally used when a DC voltage of about 270V is applied to a DC voltage of 1mA. When a low voltage of about 20-30V is applied to a MOV device, Since no current flows, this can be ignored. Therefore, when a low voltage is applied to the MOV element, all the currents can be regarded as flowing only through the additional circuit in Fig. 2, and are usually 10 mA or less. If the current exceeds this value, MOV is burned down and the resistance can be regarded as a state in which the resistance is rapidly lowered. When the current flowing in the additional circuit is measured by applying a low voltage of about 20 to 30 V to the MOV element, the current of the additional circuit composed of the resistor, the diode, and the LED is linearly proportional to the applied voltage. The current can be calculated.
For example, when a current of 1 mA is measured between the LN (power supply line and neutral line) of FIG. 2 or the MOV device at 30 V, it can be determined that a current of about 10 mA flows through the additional circuit if the maximum continuous use voltage is 300V have. After estimating the current flowing to the additional circuit and measuring the total leakage current by applying the actual maximum continuous use voltage, the resistive leakage current (Ir) value is obtained by removing the current flowing through the pre- have. If the measured resistive leakage current value exceeds the reference value of the steady state, it can be judged as a deteriorated state.
FIG. 3 shows a surge protector reliability evaluation apparatus or a resistive leakage
3, the apparatus for detecting a leakage current of a surge protector according to an exemplary embodiment of the present invention includes a
3, the variable DC power supply 120 is designed to supply a DC voltage to a surge protector (SPD), which is capable of varying the voltage from a voltage of 10-20 V to a maximum continuous use voltage of various products up to a maximum of 1 kV . R1 and R2 connected in series to both ends of the variable DC power supply 120 are voltage dividing circuits for measuring the applied voltage and are connected to one terminal of the variable DC power supply 120 and the
For example, according to the control of the
On the other hand, it is possible to diagnose the deterioration state of the surge protector for power supply SPD by the method using the leakage
Most signal surge protectors (SPDs) are serially inserted in the middle of the line and are rated for performance by applying a surge voltage to the input and measuring the suppressed voltage at the output. In the case of a surge protector (SPD) for 24-48V signal lines, 1.2 ~ 50μsec of brain impulse voltage of several kV should be suppressed at 100 ~ 200V. However, the majority of protection devices currently in use in the field are being used without verification of these capabilities.
Therefore, the present invention intends to implement a simple (portable) limit voltage measuring device for use in the field. To measure the limit voltage of a signal surge protector (SPD), an impulse voltage measurement device such as a surge generator and an oscilloscope is required. These facilities are very expensive and bulky, making it difficult for managers to carry them in the field.
4 is a diagram for explaining a surge protector reliability evaluation apparatus or a simple type limit
4, an economical surge protector reliability evaluation apparatus or a simplified limited
The
The
The charging
Accordingly, when an impulse (surge voltage) of the
When the 1.2 / 50μsec standard brain impulse voltage of about several kV is applied, the limit voltage should be kept within the reference value, that is, several hundred V, and the damage of the surge protector (SPD) itself should not occur. Also, after the surge test, again check the leakage current measurement test to see if there is a short circuit fault or any abnormal symptom in the surge protector (SPD) circuit. The surge generation and measurement items are designed to be relatively low for the portability of the equipment, but can also be used for verifying the performance of the power surge protector (SPD).
While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.
The
The variable DC power supply 120,
The relay module (130)
The resistors R1, R2, R3,
The
The surge generator (220)
Meter (230)
In the
Claims (9)
A voltage dividing circuit composed of series resistors connected to both ends of the DC power supply; A shunt resistor whose one end is connected to a second terminal of the DC power supply; And a second terminal of the DC power supply and a second terminal of the shunt in accordance with the LN (power line-neutral line), LG (power line-ground wire) A relay module in which the other terminal of the resistor is connected to the two terminals of the surge protector; And
Controlling the power supply voltage of the DC power supply to measure a current flowing through the shunt resistor for measuring a current flowing in the surge protector, Estimating a leakage current flowing from the current measured at the first voltage of the DC power supply to the auxiliary circuit connected to the surge protector and subtracting the leakage current flowing from the current measured at the second voltage to the auxiliary circuit, A microprocessor for determining a deterioration state of the surge protector by determining whether the calculated value exceeds a reference value after calculating only the resistive leakage current flowing in the surge protector,
And the reliability of the surge protector.
Wherein the first voltage is 20 to 30 V and the second voltage is at least 10 times the first voltage.
A microprocessor; A surge generator for generating a high voltage pulse boosted from an AC input under the control of the microprocessor and applying the high voltage pulse to the surge protector; And a meter for measuring a limit voltage generated at an output terminal of the surge protector under the control of the microprocessor and converting the limited voltage into a digital signal,
The microprocessor controls the magnitude of pulses applied to the surge protector and performs control so that the pulses are sequentially applied from the surge generator according to each mode installed in the power line, neutral line, or ground line of the surge protector And the deterioration state of the surge protector is detected by determining whether the limit voltage exceeds a reference value.
And the deterioration state of the surge protector for power supply or signal is detected.
Wherein the deterioration state of the surge protector is diagnosed even when the additional circuit in the surge protector is disconnected without disconnecting the MOV element from the surge protector.
Wherein the microprocessor displays the deterioration state on a display device and generates an alarm sound in a deteriorated state.
Wherein the surge protector reliability evaluation apparatus is manufactured in a portable manner.
The surge generator includes:
A boosting circuit for boosting the AC input;
A charging circuit and a capacitor for charging the charge according to the output of the step-up circuit under the control of the microprocessor;
A discharge switch that is turned on under the control of the microprocessor;
An R / L circuit for forming a predetermined pulse voltage and current according to the voltage of the capacitor transferred through the discharge switch; And
A relay module for operating the switch according to the mode under the control of the microprocessor and applying an output pulse of the R / L circuit to each input terminal of the surge protector;
Wherein the surge protector includes:
The measuring device includes:
An impulse voltage dividing circuit for dividing the limiting voltage in pulse form;
A signal adjusting circuit for removing noise from the output of the impulse voltage dividing circuit signal; And
An AD converter for converting an output of the signal adjustment circuit into a digital signal;
And the reliability of the surge protector.
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Cited By (6)
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KR101465401B1 (en) * | 2014-06-26 | 2014-12-05 | 삼현씨앤에스 주식회사 | Lifetime estimating device of surge protector and method thereof |
KR101636772B1 (en) * | 2014-12-30 | 2016-07-07 | 한국 전기안전공사 | System for evaluating the lightning protection equipment with electrical safety index and method therefor |
KR20180047057A (en) * | 2016-10-31 | 2018-05-10 | (주) 솔루윈스 | Voltage measurement Circuit with dual voltage divider circuit |
CN109406905A (en) * | 2018-12-07 | 2019-03-01 | 珠海德利和电气有限公司 | A kind of lightning current shock measuring system |
CN109799404A (en) * | 2019-01-17 | 2019-05-24 | 深圳市艾睿科电气有限公司 | The deterioration rate detection method and system of surge protective device |
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KR101655110B1 (en) * | 2015-05-07 | 2016-09-07 | 김진학 | Surge preotection apparatus having function of alarming detioration |
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KR100900734B1 (en) * | 2007-05-18 | 2009-06-05 | 한국전기연구원 | Module for detecting electrical degradation current of metal oxide varistor |
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KR101465401B1 (en) * | 2014-06-26 | 2014-12-05 | 삼현씨앤에스 주식회사 | Lifetime estimating device of surge protector and method thereof |
KR101636772B1 (en) * | 2014-12-30 | 2016-07-07 | 한국 전기안전공사 | System for evaluating the lightning protection equipment with electrical safety index and method therefor |
KR20180047057A (en) * | 2016-10-31 | 2018-05-10 | (주) 솔루윈스 | Voltage measurement Circuit with dual voltage divider circuit |
CN109406905A (en) * | 2018-12-07 | 2019-03-01 | 珠海德利和电气有限公司 | A kind of lightning current shock measuring system |
CN109406905B (en) * | 2018-12-07 | 2023-09-08 | 珠海德利和电气有限公司 | Lightning current surge test system |
CN109799404A (en) * | 2019-01-17 | 2019-05-24 | 深圳市艾睿科电气有限公司 | The deterioration rate detection method and system of surge protective device |
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