KR20140080566A - Remote detection and cut-off system for current leakage type of sensor network - Google Patents

Abstract

Disclosed is a sensor network type remote electric leakage detecting and breaking system. The present invention implements a resistance leakage current detection algorithm and develops an over-voltage and over-current composite measurement module. The system integrates and designs a communications module to build a remote monitoring and controlling system. According to the present invention, the system can generalize products associated with resistive leakage current techniques which have been applied to only in several expensive measuring instruments.

Description

[0001] The present invention relates to a sensor network type remote leakage detection and blocking system,

The present invention relates to a sensor network type remote leakage detection and shutdown system, and more particularly, to a system for detecting a short circuit by a plurality of leakage detectors constituting a sensor network, .

Every year, 8,000 electric fires and 700 electric shocks occur (52 deaths in 2008). Particularly, in the case of electric fire, the proportion of fire caused by overcurrent is very high.

year
system
Short (Short)
overload
Leakage
Poor connection
2002
9,513
75%
12%
6%
2%
2003
8,985
70%
12%
7%
3%
2004
8,863
67%
11%
5%
5%
2005
8,554
64%
13%
6%
6%
2006
8,059
64%
13%
5%
6%

In the case of electric shocks, among the 1,448 deaths from work-related accidents in 2009, the death rate from electric shock is 11.6%, which is 4 to 22 times higher than other causes of death such as falling, tearing, In addition, the electric shock accident death rate in Korea is 5.67 per 1 million workers, 4 ~ 21 times higher than the US / UK / Japan. According to the 2003-2007 statistics of the National Emergency Management Agency (NEMA), an average of 166 casualties occurred during the summer rainy season (June to July) due to an electric shock, accounting for 24% of the total average of 688 people. Therefore, it is necessary to develop and distribute a safety circuit breaker with high safety to prevent electric shock (electric shock, fire).

Leakage current is the current that flows out due to the damage of the distribution / electrical equipment, and the leakage current of resistive type among the two components of the leakage current (resistive leakage current, capacitive leakage current) is the cause of the electric accident. However, since the conventional earth leakage breaker operates by the combined leakage current, there is a high possibility of malfunction due to harmless capacitive leakage current.

The leakage current criterion of the existing earth leakage breaker is set high so that the dangerous leakage current is not blocked. In Korea, the leakage current limit is specified as 30mA. In case of the existing leakage circuit breaker, the circuit breaker can be operated by the capacitive leakage current because it operates by the combined leakage current, and the leakage current which is the cause of the electric accident can not be blocked Lt; / RTI > Therefore, it is necessary to develop a blocking technique based on a resistive leakage current to secure the safety by reinforcing the leakage current standard.

Although the safety current standards of electric / electronic devices are different from each other, existing electric leakage circuit breakers apply the same standard to cut off current. The air conditioner has a safety current of 15A, but the electric mat is 1.5A. If the same safety current standard is cut off, a fatal electric current may flow in a certain device. Therefore, it is necessary to develop a product that can prevent over current by various standards.

In order to stabilize the power system, the current limiter simply cuts off the current above the reference current. Without analysis of the blocking position and blocking cause, continuous operation of the circuit breaker may occur and stable power can not be used. Therefore, it is necessary to establish a monitoring / control system that can secure safety and expand user convenience by monitoring and analyzing the abnormality of power location and monitoring history. It should also be easy to install in existing power systems using wireless communications.

Since the remote monitoring / control system of a small-sized development product is constructed in a limited space, signal interference between the measurement module and the communication module may occur. Signal interference between modules can reduce the reliability of breaker malfunctions and blocking causes analysis. In order to ensure the reliability of the remote monitoring / control system, it is necessary to design the optimal grounding structure and shielding structure that minimize EMI / EMC analysis and signal interference between modules.

Currently, existing leakage circuit breakers measure composite leakage currents, which include capacitive leakage currents that do not cause fire / electric shock, and are measured to be larger than resistive leakage currents that cause actual accidents. Therefore, if the blocking criterion is set to a low value, a malfunction may be caused in which the power is cut off even if there is no danger. As a result, the leakage current criterion is set high, causing serious safety problems.

IEL Semiconductor Co., Ltd., which has a number of patents related to resistive leakage current measurement using integral method, is leading the resistive earth leakage circuit breaker in Korea. IK Semicon Co., Sensing IC. Jinheung Electric Co., Ltd. and Winners Co., Ltd. have developed resistive earth leakage breaker and leakage detection socket using IK Semicon products. We have developed a number of resistive leakage current measuring instruments using Japanese patented technology.

Overseas power semiconductor companies mainly concentrate on the development of PMICs with high voltage devices, and the development of leakage current related ICs is insignificant. The ADI (ADE7753) and Cirrus Logic (CS5461A) sell RMS power measurement ICs, but no resistive leakage current measurement products.

The present invention is directed to a sensor network type that has developed and integrated a resistive leakage current detection technology, an overcurrent measurement technology, and a Zigbee type wireless remote monitoring / control system technology, Remote leakage detection and shutdown system.

According to an aspect of the present invention, there is provided a sensor network type remote leakage detection and shut-off system, including a portion for generating various signals from a power supply voltage, a portion for performing integration for calculating a resistive leakage current from each signal, And a part for sampling the integration result to output the final resistive leakage current.

According to the sensor network type remote leakage detection and shutdown system, resistive leakage current technology which has been applied only to some expensive measuring instruments and related products can be generalized. In addition, by accurately measuring the resistive leakage current, the leakage current is sensed in real time, and as soon as it enters the abnormal phase, measures are taken to prevent a short circuit accident in advance. The detection method of the overcurrent can be grasped quickly by the separate MCU module, and the electric accident can be prevented quickly. A remote sensing system is available to easily identify power anomalies. In addition, it can monitor the overcurrent and electric leakage of electric / electronic devices in real time and automatically cut off the power at the time of danger, so it can be expected to make an excellent contribution to prevention of electric safety accidents. In addition, when the electric cutoff devices are applied to industrial equipment such as factories by lowering the electric cutoff devices by the minimum devices, it does not affect the operation of many normal devices due to leakage or overcurrent, . Further, the sensor network type remote leakage detection and shutdown system according to the present invention can integrate the MCU module and the communication module in the existing earth leakage breaker to enable rapid shutdown of the overcurrent as well as the resistive leakage current. In addition, remote monitoring and control is possible, so user convenience and safety will be increased, and it is expected that prevention of personal injury and economic loss will be possible due to prevention of electric disaster.

1 to 92 are views for explaining a sensor network type remote leakage detection and shutdown system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a sensor network type remote leakage detection and shutdown system according to the present invention will be described in detail with reference to the accompanying drawings.

)와 용량성 누설전류(Capacitive Leakage Current,

)로 구성된다. 저항성 누설전류는 전원전압과 동상인 성분으로 전선로 또는 전선로에 연결된 부하의 대지 절연저항의 열화가 주된 요인이다. 저항성 누설전류가 흐르면 발열량(

)에 의하여 주변온도가 높아지고, 선로 주변에 발화점이 낮고 폭발의 위험성이 있는 분진, 가스(Gas) 등의 인화성물질이 존재 하는 경우에는 화재 등 전기재해를 일으키게 되며, 특히 저항성 누설전류가 인체를 통하여 흐르는 경우에는 인명사고를 유발하게 된다. 한편 용량성 누설전류는 전원전압보다 위상이 90빠른 성분으로 전선로 또는 전선로에 연결된 부하와 대지간의 정전용량으로 인하여 흐르게 된다. 특히 접지된 금속관 내부에 전선로가 설치되는 경우와 같이 전선로의 대지 정전용량이 큰 경우에는 비교적 많은 양의 용량성 누설전류가 흐르게 된다. 그러나 용량성 누설전류는 저항성 누설전류와는 달리 변위전류(Displacement current)의 형태로 흐르고, 따라서 전기화재와 같은 재해를 유발하지 않는 성분이라 할 수 있다.The leakage circuit breaker is a device that cuts off the circuit when a leakage current above the reference value flows in order to prevent an electric fire or a human body electric shock due to a leakage current. The leakage current flowing through the electric line is generally referred to as resistive leakage current,

) And capacitive leakage current (Capacitive Leakage Current,

). The resistive leakage current is a component that is in phase with the supply voltage and is mainly caused by deterioration of the ground insulation resistance of the load connected to the electric wire or the electric wire. When a resistive leakage current flows, the calorific value (

), When the surrounding temperature is high and the ignition point is low around the line and there is a flammable substance such as dust or gas which is a danger of explosion, it causes an electric disaster such as a fire. Especially, If it flows, it will cause human accidents. On the other hand, the capacitive leakage current flows due to the capacitance between the ground and the load connected to the electric wire or the electric wire by the component whose phase is 90 times faster than the power supply voltage. Particularly, when the earth capacitance of the electric wire is large, as in the case where the electric wire is installed in the grounded metal pipe, a relatively large amount of capacitive leakage current flows. However, the capacitive leakage current flows in the form of displacement current unlike the resistive leakage current, so it can be said that it does not cause disaster such as electric fire.

,

)에 의한 자장이 서로 상쇄되어 영상변류기 2차측의 출력은 영이 된다. 그러나 전선로에 누설전류가 흐르면 전류의 균형이 붕괴되어, 영상변류기 2차측에는 두 전류의 차이에 비례하는 신호가 출력되고, 일정 이상의 누설전류가 흐르면 차단기가 동작하여 선로를 개방시킨다. 즉, 도 1의 현재 이용 중인 누전차단기는 저항성 누설전류는 물론 용량성 누설전류에 의해서도 동작하여 회로를 차단하게 됨을 알 수 있다. 따라서 용량성 누설전류가 아주 작은 경우에는 그 동작에 별 문제가 없지만, 전선로가 금속성 보호관 내에 설치되는 경우와 같이 용량성 누설전류가 많이 흐르는 경우에는 저항성 누설전류가 아주 작은 경우에도 회로를 차단하게 된다. 이는 엄밀한 의미에서는 누전차단기의 오동작에 의하여 회로가 차단됨을 의미하여, 이로 인하여 많은 문제들이 야기되고 있다. 특히 누설전류로 인한 전기재해를 방지하기 위하여 누설 감도전류를 현행 30mA에서 15mA 등으로 낮추는 경우에는 더욱 심각해진다. 이러한 점들을 고려할 때 누설전류에 의한 전기재해를 방지한다는 관점에서 보면 누전차단기는 마땅히 저항성 누설전류에 의하여 동작하여야 한다.FIG. 1 shows a household single-phase circuit breaker which is widely used today, and is largely composed of a leakage current detector, a control circuit, and a switch. If leakage current does not flow, two currents (

,

) Are canceled each other and the output of the secondary side of the video transformer becomes zero. However, when the leakage current flows through the electric line, the current balance is collapsed, a signal proportional to the difference between the two currents is output to the secondary side of the image transformer, and when the leakage current exceeds a certain value, the circuit breaker operates to open the line. That is, it can be seen that the current leakage circuit breaker currently in use in FIG. 1 operates also by the resistive leakage current as well as the capacitive leakage current, thereby blocking the circuit. Therefore, when the capacitive leakage current is very small, there is no problem in its operation. However, when a large amount of capacitive leakage current flows, such as when the power line is installed in the metallic protection tube, the circuit is shut off even if the resistive leakage current is very small . This means that the circuit is cut off due to a malfunction of the earth leakage breaker in a strict sense, which causes a lot of problems. Especially, when the leakage sensitivity current is reduced from the current 30 mA to 15 mA in order to prevent an electric disaster caused by the leakage current, it becomes more serious. Considering these points, the earth leakage circuit breaker should operate by resistive leakage current in view of preventing electric disaster caused by leakage current.

This need has led to the development of several methods to detect and isolate the resistive leakage current from the composite leakage current. We have already compared and analyzed the advantages and disadvantages of these methods. In order for the resistive leakage current detection method to be applied to the ground fault circuit breaker with the operation time specification value of 30 ms, the detection time of the resistive leakage current should be approximately 24 ms or less in consideration of the operation time (approximately 6 ms) of the opening / closing mechanism currently used. However, the proposed and developed methods are inadequate for application to the earth leakage circuit breaker due to excessive resistance leakage current detection time.

The leakage circuit breaker according to the present invention operates with a new resistive leakage current which can be maintained in price competitiveness in the future because the leakage current detection time of the leakage current is theoretically maximum 16.67ms or less.

는 수학식 1과 같이 표현된다.The instantaneous value of the composite leakage current flowing in the line

Is expressed by Equation (1).

는 합성 누설전류의 실효치로서 저항성 누설전류 실효치(

)와 용량성 누설전류 실효치(

)와는 수학식 2와 같은 관계를 가진다.here,

Is the effective value of the composite leakage current and the effective value of resistive leakage current (

) And capacitive leakage current effective value (

) Have the relationship as shown in Equation (2).

)와의 위상차이다. 이로부터 저항성 누설전류(

)를 구하기 위하여,

를 전원전압의 한주기에 대하여 적분만 한 것을

, 그리고 이의 평균치를

라고 하면 이들은 각각 수학식 3과 수학식 4로 표현된다.θ is the supply voltage and the composite leakage current (

). From this, resistive leakage current (

),

Is integrated only for one period of the power supply voltage

, And the average value of

They are expressed by Equations (3) and (4), respectively.

Equation (4) means that the DC component (average value) can be directly detected using a low-pass filter without separately performing the integral operation and the averaging operation. However, this method has a disadvantage in that detection time is long as described above. Therefore, in order to shorten the detection time, the detection theory proposed by the present invention is represented by the following equation (5).

This means that it is possible to detect the resistive leakage current by integrating only the half period. In general, this process can be easily implemented using an operational amplifier (OP-AMP) and a capacitor. When the integration operation for the first half period is completed in this calculation process, the integrator must be initialized before the next half- do. This is because if the initialization process is not performed, the result of integration is accumulated and saturated with the saturation voltage of the operational amplifier. Thus, an initialization signal is needed to initialize the integrator, which can be obtained from the supply voltage signal.

)에 해당하는 부분은 적분연산이 종료되는 시점에서 적분기가 초기화되는 순간까지만 출력되기 때문에, 이 시간동안에 신호를 취득하기 위해서는 별도의 샘플링 회로를 이용해야 한다. 본 발명에서는 전원전압 신호로부터 샘플링 신호를 구하였다.In addition, the resistive leakage current

) Is output only until the instant at which the integrator is initialized at the end of the integral operation. Therefore, in order to acquire the signal during this time, a separate sampling circuit must be used. In the present invention, a sampling signal is obtained from a power supply voltage signal.

FIG. 2 illustrates a resistive leakage current calculation algorithm according to an embodiment of the present invention. The resistive leakage current calculation algorithm includes a part generating various signals from a power supply voltage, a part performing integration for calculating a resistive leakage current from each signal, And outputs a resistive leakage current.

를 반파적분기로 보내어 동기신호에 따라 전원의 반파 기간씩 적분하면, 전원의 반파 마다 저항성 누설전류가 얻어진다. 이 때, 전류센서를 이용하여 사용 전류를 측정할 수 있다. 도 3에는 이상을 구현한 누전차단기의 블록 다이어그램이 도시되어 있다.Detects a power supply voltage, and generates a synchronization signal every half cycle of the power supply. Then, the detected ZCT (Zero Current Transformer)

To the half-wave integrator and integrates the half-wave period of the power source according to the synchronizing signal, a resistive leakage current is obtained for each half-wave of the power source. At this time, the current used can be measured using the current sensor. Fig. 3 shows a block diagram of a circuit breaker implementing the above.

Design the communication module to control the resistive earth leakage breaker through the international standard 2.4GHz wireless communication (IEEE 802.15.4) module. At this time, the communication module design low power driving circuit within 0.3W. Measure the overcurrent, leakage current, and power consumption through the measurement circuit of the existing earth leakage breaker, and transmit the measurement data to the server while performing bidirectional wireless communication with the server through the communication module. In addition, if a current exceeding the leakage current cutoff criterion flows, the communication circuit module that can be applied to the circuit breaker is developed so that the earth leakage breaker can be operated by automatically receiving the cutoff signal from the server while operating the earth leakage breaker. Fig. 4 is a configuration diagram of a resistive earth leakage breaker capable of remote control to be designed.

A remote monitoring / control server system is developed as shown in Fig. 5, which can control the remote resistive earth leakage breaker. IEEE 802.15.4 is applied to the inter-module communication technology for remote monitoring / control. IEEE 802.15.4 is a standard for short-range wireless networks, featuring low power and a transmission rate of 20K to 250Kbps. Design small communication module using built-in antenna. The server system plans to increase user convenience by displaying information such as electricity usage, electricity rate and short circuit. In addition, it is possible to monitor in real time whether or not the resistive leakage current and the normal operation of the earth leakage breaker. Also, the history of overcurrent and resistive leakage current can be managed and analyzed, and if necessary, the earth leakage breaker can be operated by sending a control signal from the server system.

Develop applications that can be remotely monitored and controlled. The application program consists of remote leakage detection and control S / W and DB linked program for leakage current / overcurrent history management. Finally, the remote leakage monitoring / control module is implemented by integrating the IEEE 802.15.4 communication module in the earth leakage breaker. Then build a central server, provide application programs, and develop to a demonstrable level.

Accurate signal transmission between the resistive leakage current and overcurrent composite measurement circuit module and the remote monitoring / control modules must be performed to reduce the malfunction of the circuit breaker through the remote control. Therefore, it is necessary to find the part where the signal transmission is not smooth by analyzing the electromagnetic field distribution of each existing module. The PCB substrate designed for this purpose is modeled by an EM simulation tool as shown in FIG.

By analyzing the electromagnetic field distribution of the system module, we plan to optimize the PCB and ground structure in order to reduce unnecessary waves. Here, the optimal design is to use an evolutionary strategy algorithm. The evolutionary strategy algorithm is one of the probabilistic optimization methods, and the predetermined set of design variables becomes the first parent generation. Generate random variables within a certain range from this parent generation to generate the next generation. Generated households are separated from the parent households and are called child households. The parent households constitute the next parent household by choosing the most suitable set of variables for the desired objective function values through the parent households and the whole child households. In this way, the optimal design parameters that best match the objective function are obtained while controlling the variation of the variation. Therefore, an optimal sensor network type remote leakage detection and shutdown system circuit module and a shielding structure are designed by implementing an evolutionary strategy technique as shown in FIG.

In addition to earth leakage protection systems, complex lines must be designed on multilayer boards to integrate sensor network modules. At this time, signal transmission may not be smooth due to interference between lines. In the present invention, as shown in FIG. 8, the optimization technique is applied to minimize the influence of the lines, thereby minimizing the electrical noise.

In order to design the optimal grounding and shielding structure of the remote earth leakage protection / control system, design variables are set as follows: the position of the sub-ground ground point, the length and width of the upper substrate (Lpp, Wpp) 2 position (Xp1, Yp2, Zp2), and the objective function is determined by a scalar function that minimizes the impedance profile of Z21. In this way, optimal design of the optimal grounding structure of system PCB board is performed to minimize the malfunction rate of the system module.

The remote earth leakage protection / control system and the power line are connected to each other. Particularly, the power line enters through an opening for input / output connection of a remote earth leakage blocking / control system enclosure, and this opening serves to combine the electromagnetic fields inside and outside. Therefore, the remote ground fault interception / control system enclosure should be able to block internal and external electromagnetic fields to prevent malfunction of the internal module due to the electromagnetic field of external electric power.

In the present invention, as shown in FIG. 10, an optimal structure of the enclosure is designed through electromagnetic wave shielding analysis of the enclosure. We plan to conduct a study on the opening surface for the connection of the remote earth leakage prevention / control system and the power line. The shielding performance according to the position and size of the opening surface will be analyzed. We design an optimal remote leakage monitoring / control system enclosure shielding structure using the evolution strategy algorithm for the design parameters of the enclosure opening surface.

The leakage current and the overcurrent are detected by using the existing earth leakage breaker as shown in FIG. 11, and the measurement information is provided to the communication module so that the remote server can control the breaker.

As shown in FIG. 5, the circuit breaker and the communication module exchange sensor signals and control signals through the connector, which is a very easy to install in existing facilities. In the measuring circuit of the earth leakage breaker, the communication module is designed to transmit the leakage current and the overcurrent measurement information as well as the synchronization signal, and the transmission line between the circuit breaker and the communication module is designed so that the breaker can operate by receiving the remote control signal from the communication module . Here, the selection of a connector having reliability and functionality is directly related to the overall performance, and thus, much research and verification is required.

The remote circuit breaker is an important device directly connected with electrical safety and requires safety and continuous reliability. Therefore, before the commercialization of the earth leakage breaker with communication module integrated, the performance of the prototype should be tested through an independent testing laboratory through self-testing. In order to test the circuit breaker according to the present invention, the circuit breaker specifications (K60898-1, K60947-1, -2) and the earth leakage circuit breaker specifications (K61008, K61009, K60947-2 The test will be carried out on a circuit breaker incorporating a communication module through a testing institute such as the Korea Electrotechnology Research Institute. In the process of consultation with test institutes and test items and methods, tests on remote control circuit breakers are to be carried out by adding test items to communication module as well as general breaker specification items. In addition, the remote control earth leakage circuit breaker shall be inspected by the test institute and shall be supplemented and modified so as to satisfy the breaker specification as necessary.

Earth Leakage Breaker (ELB-Earth Leakage Breaker) is installed to prevent electric shock, fire and damage of machine and equipment in low voltage line of AC 600V or less. Main purpose of use is electric shock protection, leakage fire protection, Protection of the environment, and prevention of the spread of accidents to other systems.

The basic ratings for determining the leakage protection function of the earth leakage breaker are sensitivity current and operating time. The rated sensitivity current should be 30mA or less for protection against lethal hit by direct live contact to the human body, or 200mA, 500mA, 1000mA for preventing leakage fire. Table 2 shows the classification according to the type of sensitivity of the earth leakage breaker.

Sensitivity current purpose of use High sensitive type
(5, 6, 10, 15, - When the risk of electric shock is high, such as in a wet place
- protection against human body accidental contact with live wire
- If there is a risk of disconnection of grounding wire such as mobile type or portable type
- When grounding is difficult Medium sensitivity type
(100, 200, 500, 1000 mA) - When the equipment is grounded and the electric shock is protected by a short circuit
- For the purpose of protection against short-circuiting fire
- In case of unnecessary operation in high sensitivity type

There are two kinds of voltage-operated type and current-operated type as shown in Fig 2.1 depending on the leakage detection principle of the earth leakage breaker.

The voltage-operated type shown in Fig. 13 (a) operates by detecting a ground fault current having a dedicated ground line and returning to the ground line via a ground when a ground fault occurs. The current-operated type uses a ZCT (Zero Current Transformer) that directly detects a ground fault current, and most of them are currently adopting this method.

There are two types of current-operated leakage circuit breakers: pure electronic and electronic. The net electronic system directs the output of the ZCT directly to the magnetic circuit using a permanent magnet and operates by reducing the attracting force of the magnet. This method does not require a control power source, so there is an advantage that leakage current can be protected even if the power source side of the earth leakage breaker is in a phase-lag state. On the other hand, it is difficult to miniaturize and various kinds of sensitivity currents are difficult to make.

The electronic circuit determines the output of the ZCT as an electronic circuit and operates it. The electronic circuit of the earth leakage breaker can be miniaturized and multi-functionalized by the miniaturization of the semiconductor device and the development of the technology.

The operation principle of the earth leakage breaker using ZCT is that the current flowing through the ZCT and the current flowing through the ZCT are the same in the absence of leakage current and the magnetic fluxes generated in the ZCT cancel each other according to the flowing current, , A current difference flowing through the ZCT is generated, and a magnetic flux is generated in the ZCT due to the difference in current, and a voltage is induced in the secondary side of the ZCT. The induced voltage is detected by the detection unit including the amplification unit, and the circuit is shut off by the trip unit.

The detection section including the amplification section of a general earth leakage breaker is configured as shown in Fig. 15 by using an IC for the earth leakage breaker.

The dedicated IC for amplifying the voltage induced in the ZCT generally uses the GL7101. The inside of the GL 7101 is composed of an input section, a timing circuit, and an output section as shown in FIG.

The input part of the dedicated IC of the earth leakage breaker is a circuit that receives the input signal of ZCT, compares it with the reference voltage, charges the capacitor, and obtains the delay time. Consists of.

17 is a circuit of an input section of a dedicated IC. The input unit compares the input voltage with the reference voltage and drives the Q1.

The voltage at which the comparator (Comp1A) operates is set to a trip voltage, typically 13.5 mV. Therefore, when the Vin voltage is higher than the Vref voltage by more than 13.5 mV, the output of the comparator becomes high and Q1 turns on. On the other hand, if the difference between the Vin voltage and the Vref voltage is less than 13.5 mV, the output of the comparator becomes low and Q1 turns off. When the voltage induced in ZCT is detected and exceeds the rated sensitivity current through the comparator, the timing circuit and the output section are driven.

The timing circuit that receives the output signal of the input unit adjusts the trip time according to the capacity of the delay capacitor. 18 is a configuration diagram of a timing circuit and an output section.

In FIG. 19, the trip delay time is determined by the charging time according to the capacity of the capacitor CDLY. The trip delay time can be obtained by the equation (6).

는 커패시터 용량이며

와

는 각각 Latch Threshold 전압과 Charaging 전류이다. here,

Is the capacitance of the capacitor

Wow

Are the Latch Threshold voltage and Charging current, respectively.

The positive feedback structure keeps the SW open / closed continuously, and the output of Cmp2 maintains high when the latch operation is maintained for more than 4ms.

The trip operation timing for the dedicated IC of the earth leakage breaker is shown in Fig.

As can be seen from FIG. 20, when the voltage Vin of the input unit is 13.5 mV or less than the voltage Vref, the output of the comparator Cmp1 of the input unit remains high while delaying the trip time while charging the delay capacitor of the timing circuit. After the capacitor is charged, the output of the comparator (Cmp2) of the timing circuit becomes high, so that the circuit breaker is driven to operate the circuit breaker.

It is necessary to change the circuit of a conventional earth leakage breaker as shown in Fig. 21 in order to design a remote earth leakage breaker that can be remotely sensed and controlled by applying a communication module to a conventional earth leakage breaker.

The conventional earth leakage breaker uses a dedicated IC to connect a trip switch operated by a trip coil to a power line between the distribution board and the load in series as shown in Fig. 21, and a rectifier circuit for rectifying the current to be supplied to each component of the leakage circuit breaker Respectively.

In the existing circuit breaker, the current induced by the ZCT on the secondary side is converted to a voltage by the resistor and amplified by the dedicated IC. At this time, the amplified voltage is compared with the reference voltage according to the blocking current, and the switching transistor of the control circuit is turned on / off in the dedicated IC so that the trip coil operates the trip switch. The current induced in ZCT contains capacitive leakage current and can not detect only resistive leakage current which causes disasters such as direct human accidents and fire. Therefore, in order to detect the resistive leakage current in the present invention, the voltage output from the ZCT must be transmitted to a separate detection circuit. In order to calculate the resistive leakage current, the power supply circuit is implemented to supply power to the multipoint control unit (MCU) module while synchronizing with the AC power supply. In order to detect the overcurrent and overvoltage in the MCU module, an overcurrent and overvoltage detection circuit is additionally designed in the existing circuit of the earth leakage breaker.

However, the MCU and communication module including resistive leakage current, overcurrent, and overvoltage detection function are basically driven at 5V, so the conventional power supply circuit can not be used. Therefore, a power supply circuit is implemented to supply power to the dedicated IC and the MCU module.

22 is an ideal circuit for applying a bridge circuit of an earth leakage breaker in using a communication module and a ground portion commonly using a DC-DC converter. However, when the maximum output current is 20mA and the maximum current is used, heat is generated in the resistor (# 1) and the transistor (# 2) and the maximum current is insufficient for the communication module to operate.

As shown in FIG. 23, the circuit is implemented by using a separate power bridge for the power supply of the IC for the earth leakage breaker and the power supply of the communication module. However, since the potentials of the MCU module and the earth leakage breaker are different, there is a disadvantage that the grounding can not be commonly used. Therefore, there is a problem that the result of synchronization with the AC power source for calculating the resistive leakage current of the MCU module is different from that of the leakage circuit breaker power source, so that leakage current detection error may occur.

In order to accurately calculate the resistive leakage current, an earth leakage breaker circuit is implemented as shown in FIG. 24 using one power bridge so that the power of the earth leakage breaker and the power of the MCU module can be synchronized.

As shown in FIG. 23, one power supply bridge circuit is designed to supply the dedicated IC power of the conventional circuit breaker, and the power of the MCU and the communication module. Since the instantaneous maximum current consumption of the MCU and the communication module is 80mA, it is designed to supply 100mA of DC 5V from the bridge circuit using the AC-DC converter to supply power to the MCU module.

In order to detect the resistance leakage current, overcurrent and overvoltage through the MCU module, the existing circuit breaker circuit and the interface circuit between the MCU module and the circuit breaker circuit can be transferred to the MCU module so that the existing earth leakage breaker can transmit the 220V power status information to the MCU module. Respectively.

In order to detect the resistive leakage current, the current induced in the additional ZCT is converted to a voltage using the resistor R12 in FIG. 25, and the voltage information according to the magnitude of the leakage current is transmitted to the MCU module.

Conventional circuit breakers use bimetal to cut off the overcurrent. However, the bimetal for blocking the overcurrent is basically composed of a combination of a metal which is not swollen and a metal which is swollen by utilizing the bending property according to temperature. The temperature of the bimetal is increased by the overcurrent, and the current is forcibly blocked while bending the metal. However, the current interruption due to the bimetal temperature rise due to the overcurrent takes a long time to operate. In addition, when the overcurrent is generated and the distance from the earth leakage breaker is long, the heat conduction through the wire must be made to the bimetal, so that fire and electric shock accidents occur at the point of occurrence of the overcurrent before the earth leakage breaker operates. In this task, an overcurrent detection circuit is additionally designed in the existing circuit breaker circuit as shown in Fig. 26 to detect the overcurrent by using CT (Current Transformer) in the MCU and to operate the circuit breaker before an accident occurs.

The current induced in the CT is converted into a voltage by the resistor R14 in Fig. 26, and an interface is constructed so that the MCU module can calculate the overcurrent.

The circuit for overvoltage detection is designed as shown in FIG. Since the overvoltage detected at this time basically forms a voltage of 220V, the voltage drop is performed using a resistor to calculate the overvoltage in the MCU module using the low voltage.

The trip coil, which is a breaking device of the existing earth leakage breaker, is used to forcibly operate the earth leakage breaker when the leakage current, over current and over voltage are detected and the MCU module exceeds the reference value. In this case, the cut-off circuit is designed as shown in FIG. 28 so that the trip coil can be driven by transmitting the cut-off signal from the MCU module to the trip coil drive circuit connected to the dedicated IC of the existing earth leakage breaker.

The basic circuit of the earth leakage breaker is designed as shown in Fig. 29 so that the user can drive the breaker function of the earth leakage breaker through the communication module as well as drive the rapid trip coil according to the leakage current, overcurrent and overvoltage information detected by the MCU module .

In order to integrate the existing earth leakage breaker and MCU module, the interface is designed to transmit the power supply circuit of maximum 100mA and 5V, leakage current, overcurrent, and overvoltage detection information to the MCU module and receive the cutoff control signal of the MCU module. The circuit breaker was manufactured.

Table 3 shows the measured results for MCU module power supply, leakage current, and leakage cut-off time.

sample
Item #One #2 DC power supply DC-Out AC220V standard
DC 5V Less than 100mA 5.04V 5.01V Short circuit
electric current Sensitivity current (mA) 15 ~ 30mA 23.6 mA 24.0mA Operating time (mS) Within 30mS 15mS 14mS

It was confirmed that DC voltage for power supply of MCU module was 5V AC220V. It was confirmed that the leakage circuit breaker operates within 15ms at about 15mA to 15mA of leakage current test standard.

When the rated current was 30 A, 10 to 60 A was applied to the overcurrent, and the induced current in the CT was converted by the resistor R14 of FIG. 26 and the output voltage was measured. The output voltages are shown in Fig. 31 and Table 4.

Overcurrent (A) AC-Vpp RMS (AC-V) 10A (33%) 1.0 V 282 mV 20A (66%) 2.0 V 553mA 30A (100%) 2.88 V 828mA 37.5A (125%) 3.68 V 1033mA 60A (200%) 5.92 V 1650mA

As shown in Table 4 and Fig. 31, when the current of 10 ~ 60A is applied to the earth leakage breaker, it is confirmed that the converted voltage is proportional to the applied current. Using the conversion voltage, the MCU module can determine the overcurrent and calculate the consumption current.

The output voltage was measured by using the resistance of the overcurrent detection circuit of FIG. 27 to decrease the voltage and is shown in Table 5.

Overvoltage (V) Output voltage (V) 220 1.16 240 1.24 260 1.32 275 1.40

The half-wave output voltage according to the overvoltage was measured with an oscilloscope and is shown in FIG. FIG. 29 is a graph showing the half-wave output voltage according to the applied voltage.

Table 6 shows the measurement results of the basic test items of the earth leakage breaker by fabricating an earth leakage breaker capable of combining the MCU module and the communication module.

Item Measurement result Remarks DC-Out AC220V standard
DC 5.0V-max 100mA 5.04 Good Sensitivity current (mA) 15 ~ 30mA 23.6 Good Operating time (mS) Within 30mS 15 Good For synchronous signal
AC voltage (V) 176V (80%) 6.37 Rms measurement 220V (100%) 8.00 242V (110%) 8.81 264V (120%) 9.51 275V (125%) 9.94 Overcurrent
Output voltage (mV) 10A (33%) 282 Rms measurement 20A (66%) 553 30A (100%) 828 37.5A (125%) 1033 60A (200%) 1650 Overvoltage
Output voltage (V) 220V 1.16 Half-wave measurement 240V 1.24 260V 1.32 275V 1.40 Short circuit test button Good RF-control input signal Good Good Burst-noise-test No-trip Good RF emission radio noise test (80MHz ~ 2GHz) No-trip Good

In order to calculate the resistive leakage current, the AC voltage for the synchronizing signal is synchronized with the AC 220V power supply, so that the MCU can detect the resistive component and transmit the voltage of 220V to the MCU module with a voltage drop of 8V as shown in FIG. Respectively. As a result, it is judged that it is possible to send and receive the detection information and the control signal with the MCU module as a result of the measurement on the earth leakage breaker. Fig. 31 is a layout of a circuit board of the earth leakage breaker circuit.

A circuit diagram implementing the resistive leakage current calculation algorithm of FIG. 2 is shown in FIG.

)은 도 33(a)와 같이 수학식 7로 표현된다.A voltage of 10 V obtained by using a voltage divider circuit composed of a resistor from a 220 V power supply (

Is expressed by Equation (7) as shown in Fig. 33 (a).

은 전압(

)의 실효치다.here,

The voltage (

).

는도 37(b)와 같이 전원 전압(

)의 부호를 나타내는 신호로 연산증폭기(OP1)를 이용하여 얻어지고, 그 크기는 연산증폭기(OP1)의 포화전압

에 해당한다. 동기신호

는 수학식 8로 표현된다.Synchronous signal

As shown in FIG. 37 (b)

) Is obtained by using an operational amplifier OP1 as a signal indicating the sign of the saturation voltage of the operational amplifier OP1,

. Synchronous signal

Is expressed by Equation (8).

인 구간에서만 입력된 신호가 통과하도록 하므로, 초기화 가능 적분기(1)과 초기화 가능 적분기(2)는 각각

인 구간에서 수학식 5의

과

를 계산하여 각각 저항성 누설 전류를 산출하게 된다. A resettable integrator is introduced to detect a resistive leakage current by an integration operation with respect to a half period of the power supply voltage. The resettable integrator is implemented using an operational amplifier and a transistor, such as OP10 and OP11 in FIG. In order to calculate the resistive leakage current, i.e., to perform the integration of Equation (5), the analog switch AS1 and the analog switch AS2 are

So that the initializable integrator 1 and the initializable integrator 2 can be set to

In Equation 5,

and

Respectively, to calculate resistive leakage currents.

)는 전원 전압(

)신호의 위상을 90 지연시킨 후 연산증폭기(OP3)를 이용하여 출력된 구형파 신호에서 동기신호

를 감산하여 얻을 수 있는데, 본 발명에서는 연산증폭기(OP5)로 구현된 감산기를 이용하였다. 초기화 신호(

)는 도 33(c)에 나타낸 바와 같이 다음 식으로 표현된다.Integrator initialization signal (

) Is the power supply voltage (

) Signal is delayed by 90 and the square wave signal outputted by the operational amplifier OP3 is used as a synchronization signal

. In the present invention, a subtracter implemented by an operational amplifier OP5 is used. Initialization signal (

) Is expressed by the following equation as shown in Fig. 33 (c).

와

는 서로 180위상차를 가지며,

와

는 각각 초기화 가능 적분기(OP10)와 초기화 가능 적분기(OP11)의 트랜지스터에 입력된다.here,

Wow

Are 180 degrees out of phase with each other,

Wow

Respectively, are input to the transistors of the initializable integrator OP10 and the initializable integrator OP11.

가 흐를 때, ZCT의 출력전압은 통상의 경우 수 mV 수준이고, 이를 연산증폭기(OP8)로 증폭하여 얻어지는 출력신호(

)는 도 33(d)와 같이 다음 식으로 표현된다.Composite leakage current in line

The output voltage of the ZCT is usually several mV, and the output signal obtained by amplifying this by the operational amplifier OP8

Is expressed by the following equation as shown in Fig. 33 (d).

Here, K is a constant including a gain ratio of the operational amplifier OP8 and a switching ratio of the video current transformer.

가 양(+)인 구간에서의 적분연산은 다음과 같이 수행된다.Synchronous signal

The integration operation is performed as follows.

가 양(+)인 구간에 신호

를 통과되도록 하면, 아날로그 스위치(AS1)의 출력

는 도 33(e)와 같이 다음 식으로 표현된다.By using the analog switch AS1,

(+) ≪ / RTI >

The output of the analog switch AS1

Is expressed by the following equation as shown in Fig. 33 (e).

를 연산증폭기(OP10)를 이용하여 적분 연산된 출력

는 도 37(f)와 같이 다음 식으로 표현된다.Output of analog switch (AS1)

To the integrated output (OP10) using the operational amplifier OP10

Is expressed by the following equation as shown in Fig. 37 (f).

)는

구간에서는 그 크기가 영이 된다. 따라서 연산증폭기(OP10)는

에 입력되는 신호에 대해서만 적분연산을 수행하고 나머지 구간(

)동안에는 그 입력이 영이므로, 결국 저항성 누설 전류에 해당하는 부분은 적분연산이 종료되는 시점(

)부터 다음 적분을 수행하기 위하여 적분기가 초기화되는 순간(

)까지 출력됨을 알 수 있다. 또한 통상 연산증폭기로 구현되는 적분기는 그 출력이 반전된 신호 이므로, 이득이 -1인 연산증폭기(OP12)를 이용하여

를 반전시켜 양(+)의 부호를 갖는 신호를 얻게 된다. 한편, 동기신호

가 음(-)인 구간에서의 적분연산은 도 32에서와 같이 아날로그 스위치(-)와 초기화 가능 적분기(2)를 이용하여 동일한 방법으로 수행된다.Here, as can be seen from Fig. 33 (f), the output signal of the analog switch AS1

)

In the interval, the size becomes zero. Therefore, the operational amplifier OP10

And performs the integral operation only on the signal input to the remaining section (

), The input corresponding to the resistive leakage current is zero at the time when the integral operation ends (

) From the moment the integrator is initialized to perform the next integral (

). Also, since the integrator implemented by a normal operational amplifier is a signal whose output is inverted, the operational amplifier OP12 having a gain of -1

So that a signal having a positive sign is obtained. Meanwhile,

The integration operation in the interval of negative (-) is performed in the same manner using the analog switch (-) and the initializable integrator (2) as shown in FIG.

)동안에 DC전압형태로 출력되며, 이는 저항성 누설 전류의 실효치에 비례하는 신호이다. 따라서 그 신호만을 획득할 필요가 있으며 이를 위해 본 논문에서는 샘플링 회로를 이용하였고, 트랜지스터를 이용하여 구현하였다. 따라서 샘플링 회로를 활성화시키기 위한 샘플링 신호가 필요하며, 이는 전원전압 신호를 이용하여 만들어 진다.The signal corresponding to the resistive leakage current among the output signals of the initializable integrator is a signal from the moment when the half-period integration operation is completed to the moment when the initialization signal is input,

), Which is a signal proportional to the rms value of the resistive leakage current. Therefore, it is necessary to acquire only the signal. In this paper, we have implemented a sampling circuit and a transistor. Therefore, a sampling signal is needed to activate the sampling circuit, which is made using the supply voltage signal.

)는 전원 전압(

)신호의 위상을 90지연시킨 후 연산증폭기(OP3)를 이용하여 출력된 구형파 신호와 동기신호

를 가산 연산하여 얻을 수 있다. 본 발명에서는 연산증폭기(OP4)로 구현된 가산기를 이용하였다. 샘플링 신호(

)는 도 33(g)에 나타낸 바와 같이 다음 식으로 표현된다.The sampling signal of the sampling circuit (

) Is the power supply voltage (

) Signal is delayed by 90 and then the square wave signal outputted by using the operational amplifier OP3 and the synchronizing signal

Can be obtained. In the present invention, an adder implemented by an operational amplifier OP4 is used. Sampling signal (

) Is expressed by the following equation as shown in Fig. 33 (g).

와

는 서로 180위상차를 가지며,

는 샘플링회로(TR1)에 입력되고,

는 샘플링회로(TR2)에 입력된다.here,

Wow

Are 180 degrees out of phase with each other,

Is input to the sampling circuit TR1,

Is input to the sampling circuit TR2.

,

에 의해 활성화되는 시간동안에 해당하는 신호만을 출력하며, 이 신호가 저항성 누설 전류에 해당하는 신호이다. 두 샘플링회로의 출력

,

은 모두 저항성 누설 전류의 실효치(

)에 비례하며, 최종적으로 저항성 누설 전류는 도 33(h)와 같이 다음과 같은 식으로 표현된다.Signals output from the operational amplifiers OP12 and OP13 are input to the sampling circuits TR1 and TR2, respectively. The sampling circuit outputs a sampling signal

,

The signal corresponding to the resistive leakage current is outputted. Output of two sampling circuits

,

The rms value of the resistive leakage current

). Finally, the resistive leakage current is expressed by the following equation as shown in FIG. 33 (h).

와

,

와

,

와

,

와

,

와

,

와

,

와

는 각각 서로 180의 위상차를 가진다. As can be seen from FIG. 32, the operational amplifiers OP2, OP6, OP7, and OP9 are circuits for inverting the input signal by 180 degrees,

Wow

,

Wow

,

Wow

,

Wow

,

Wow

,

Wow

,

Wow

Have a phase difference of 180 from each other.

)의 실효치에 비례하는 신호(

)와 신호(

)는 서로 180의 위상차를 두고 노드 (

)에 교대로 출력되며 이 신호는 연산증폭기(OP14)로 구현된 비교기로 입력된다.Resistive Leakage Current (

) ≪ / RTI >

) And signal (

) Have a phase difference of 180 from each other and a node

And this signal is input to a comparator implemented by an operational amplifier OP14.

Microcontroller, which is the control chip of MCU module, uses ATmega16A. As shown in FIG. 34, ATmega16A has 8 channels and 32 I / O ports with a 10-bit ADC, so it is possible to provide sufficient support for resistive leakage current, overcurrent / overvoltage, control port, and data transmission / reception port between communication modules. The 10-bit ADC has eight channels for easy detection of resistive leakage current and overcurrent / overvoltage.

ATmega16A is a chip that runs basically at 2.7 ~ 5.5V. In order to drive the MCU module and the communication module, power must be supplied from the earth leakage breaker. Therefore, as shown in FIG. 35, DC 12V of maximum 100mA is supplied from the earth leakage breaker and 5V is outputted to use 5V op amp with 5V zener diode. Since the MCU uses 3.3V, 3.3V regulator is used to generate 3.3V.

A circuit capable of detecting a resistive leakage current is implemented as the block diagram of FIG. In this case, voltage detector and combined leakage current detector are implemented in the circuit of the developed earth leakage breaker, and a synchronous signal generator and half - wave integrator are implemented in MCU module.

To calculate the resistive leakage current, the integrator must be synchronized with the AC power. As shown in FIG. 37, the AC input voltage is converted to a 3.3V level by using a photocoupler. The output signal of the photocoupler is changed to trigger signal using 74LVC14 and used as sampling strobe.

Since the voltage converted through ZCT has a fine value, the amplifier circuit is designed as shown in FIG. 38 to amplify the voltage. The resistive leakage current was calculated from the amplified leakage current using the synchronous signal and the integrator in the MCU module.

The detection characteristics of the resistive leakage current in the MCU module are determined as shown in Table 7. Fig. 39 shows the waveforms of the synchronous signal and the leakage current by implementing the resistive leakage current detection circuit.

Performance Specifications unit Min Typ. Max Remarks Leakage Current Measurement Range mA 5 30 Measured leakage current
Maximum content of the capacity component % 10 30 Measured current contrast
Non-resistive current ratio

The synchronous signal is a square wave (yellow) and the composite leakage current is a sinusoidal wave (blue). The waveform of the leakage current is sampled on the basis of the synchronous signal to calculate a value.

In order to verify the resistive leakage current detection algorithm, the leakage current testing apparatus shown in FIG. 40, which can control the resistive component and the capacitive component, respectively, was implemented and the experiment was performed.

AC 220V, and 60Hz lines were measured. The resistive leakage current was controlled by using 50 variable resistors. The capacitive leakage current was controlled by a combination of capacitors connected in parallel. The ammeter was installed separately to measure the combined leakage current, resistive leakage current and capacitive leakage current. In order to detect the resistive leakage current through the resistive leakage current detection algorithm as shown in FIG. 41, integration for one period was performed using the composite leakage current and the synchronous signal measured by the oscilloscope as shown in FIG.

The resistive leakage current detects the composite leakage current from ZCT. Select the appropriate level resistor across the leakage current input to adjust the magnitude of the voltage converted by the resistor. The converted small voltage is amplified to an appropriate voltage that can be recognized by the ADC using the OP amp. And converts it into a digital signal in real time using an ADC having 10-bit resolution. Finally, the ADC value is sampled in the MCU and the resistive leakage current detection algorithm is applied so that only the resistive leakage current can be detected in the combined leakage current.

Figs. 43 to 45 show resistive leakage current measurement results.

46 and 47 show the results of experiments in which a trip signal is generated when the earth leakage cutoff reference value is set to 15 mA. In FIG. 46, it can be confirmed that a leakage signal is not generated in the MCU module when a resistive leakage current of 14.7 mA is applied. 47 shows that a trip signal is generated. At this time, the resistive leakage current is 15.8mA, which is higher than the tripping reference of 15mA. The time division of the oscillation signal is 10ms and the output waveform interval is within 20ms. Therefore, the shutdown operation time is within 100ms.

In this way, it is designed to output the trip signal within 20ms and transmit it to the circuit breaker by measuring only the resistive leakage current except the capacitive in the combined leakage current. Tables 8 to 10 show the measurement result (unit: mA) according to the change of the resistive leakage current in the composite leakage current. It is shown in Tables 8 to 10 that a resistive leakage current can be detected from 1 mA to 30 mA in the composite leakage current.

Meter Measures Meter Measures Igr Ig Igc Igr Ig Igr Ig Igc Igr Ig One One 0 One 2 16 16 0 16 17 One 12 12 One 12 16 20 12 16 21 One 25 25 One 25 16 31 25 16 33 One 51 50 2 51 16 55 50 16 56 One 68 67 2 68 16 73 67 16 72 2 2 0 2 3 17 17 0 17 18 2 13 12 2 13 17 21 12 17 22 2 26 25 2 26 17 32 25 17 33 2 51 50 3 51 17 55 50 17 56 2 68 67 3 68 17 73 67 17 72 3 3 0 3 4 18 18 0 18 19 3 13 12 3 13 18 22 12 18 23 3 27 25 3 27 18 32 25 18 34 3 51 50 3 51 18 56 50 18 56 3 69 67 4 68 18 74 67 18 73 4 4 0 4 5 19 19 0 19 20 4 13 12 4 14 19 23 12 19 24 4 27 25 4 27 19 33 25 19 34 4 51 50 4 51 19 56 50 19 57 4 69 67 4 68 19 74 67 19 73 5 5 0 5 6 20 20 0 20 21 5 13 12 5 14 20 24 12 20 25 5 27 25 5 28 20 34 25 20 35 5 51 50 5 51 20 56 50 20 58 5 69 67 5 68 20 74 67 20 74

Meter Measures Meter Measures Igr Ig Igc Igr Ig Igr Ig Igc Igr Ig 6 6 0 6 7 21 21 0 21 22 6 14 12 6 15 21 24 12 21 26 6 27 25 6 28 21 34 25 21 36 6 52 50 6 51 21 57 50 21 58 6 69 67 6 68 21 74 67 21 74 7 7 0 7 8 22 22 0 22 23 7 14 12 7 15 22 25 12 22 27 7 28 25 7 28 22 35 25 22 36 7 52 50 7 51 22 57 50 22 59 7 70 67 7 68 22 75 67 22 75 8 8 0 8 9 23 23 0 23 24 8 15 12 8 16 23 26 12 23 28 8 28 25 8 29 23 36 25 23 37 8 52 50 8 52 23 58 50 23 59 8 70 67 8 69 23 75 67 23 75 9 9 0 9 10 24 25 0 24 26 9 15 12 9 16 24 27 12 24 29 9 29 25 9 29 24 37 25 24 38 9 53 50 9 52 24 58 50 24 60 9 70 67 9 69 24 76 67 24 76 10 10 0 10 11 25 25 0 25 26 10 16 12 10 17 25 28 12 25 30 10 29 25 10 30 25 37 25 25 38 10 53 50 10 53 25 58 50 25 60 10 71 67 10 69 25 76 67 25 77

Meter Measures Meter Measures Igr Ig Igc Igr Ig Igr Ig Igc Igr Ig 11 11 0 11 12 26 27 0 26 28 11 16 12 11 17 26 30 12 26 31 11 29 25 11 30 26 38 25 26 39 11 53 50 11 53 26 59 50 26 61 11 71 67 11 70 26 77 67 26 77 12 12 0 12 13 27 28 0 27 30 12 17 12 12 18 27 31 12 27 32 12 30 25 12 31 27 39 25 27 40 12 54 50 12 54 27 59 50 27 61 12 71 67 12 70 27 77 67 27 77 13 13 0 13 14 28 28 0 28 30 13 18 12 13 19 28 31 12 28 33 13 30 25 13 31 28 39 25 28 41 13 54 50 13 54 28 60 50 28 61 13 72 67 13 71 28 77 67 28 78 14 14 0 14 15 29 30 0 29 31 14 19 12 14 20 29 32 12 29 34 14 30 25 14 32 29 40 25 29 41 14 54 50 14 55 29 60 50 29 62 14 72 67 14 71 29 78 67 29 79 15 15 0 15 16 30 31 0 30 32 15 19 12 15 20 30 33 12 30 34 15 31 25 15 32 30 41 25 30 42 15 55 50 15 55 30 61 50 30 62 15 72 67 15 71 30 78 67 30 79

The overcurrent detection circuit for the operation of the circuit breaker is implemented as shown in the block diagram of FIG. 48 by comparing the current value detected from the CT with the overcurrent cutoff reference of the circuit breaker, and the detection circuit is designed as shown in FIG.

Overcurrent detection detects the current by CT and converts appropriate level resistance to voltage across current input. The converted voltage is half-wave rectified using a diode and converted to a real-time digital signal using an ADC with 10-bit resolution. The ADC value is sampled in the MCU and the overcurrent detection circuit is designed to detect the overcurrent according to the overcurrent detection algorithm as shown in FIG.

The current detected from the CT is converted into voltage in the earth leakage breaker circuit and input to the A / D converter of the MCU module, and the current value is digitized and compared with the overcurrent cutoff reference. At this time, the overcurrent detection circuit specifications were determined as shown in Table 11.

Performance Specifications unit Min Typ. Max Remarks Current measurement range A - 10 60 Variable by product

The overcurrent is detected and the trip signal is designed to be transmitted from the MCU module after a certain period of time required by the test standard. Table 12 shows the measurement results for the overcurrent. It is confirmed that the maximum error of the input current and the measured current value is about 2A, and that the error is 1A when the current is less than 50A. By using the overcurrent detection circuit, it is possible to prevent the overcurrent accident quickly by detecting the result within about 4% of the overcurrent.

Meter Measures Meter Measures 11 11 36 37 12 12 37 38 13 13 38 39 14 14 39 40 15 15 40 41 16 16 41 42 17 17 42 43 18 18 43 44 19 19 44 45 20 20 45 46 21 21 46 47 22 22 47 48 23 24 48 49 24 25 49 50 25 26 50 51 26 27 51 52 27 28 52 54 28 29 53 55 29 30 54 56 30 31 55 57 31 32 56 58 32 33 57 59 33 34 58 60 34 35 59 61 35 36 60 62

The overvoltage detection circuit implemented in order to operate the circuit breaker by comparing the voltage across the power line with the overvoltage cutoff reference of the circuit breaker is shown in the block diagram of FIG. 52 is an overvoltage detection circuit diagram.

The overvoltage detects the voltage directly across the AC 220V power line. It is designed to detect the voltage by connecting a voltage divider resistor across the voltage input. In this case, the capacitors are connected in parallel to eliminate the noise of the power source so that more accurate voltage can be detected. The ADC value is sampled in the MCU and the overvoltage can be detected by the overvoltage detection algorithm as shown in FIG.

It is designed to detect the voltage on the power line of the earth leakage breaker and sample it for one cycle in the MCU module, and compare it with the reference voltage and generate the trip signal by digital data in A / D converter. As shown in Table 13, the overvoltage detection specification is designed to be up to 280V.

Performance Specifications unit Min Typ. Max Remarks Voltage measurement range V - 220 280 Variable by product

The overvoltage is detected and the trip signal is designed to be transmitted from the MCU module after a certain time required by the test standard. Table 14 shows the measurement results for overvoltage.

The maximum error between the input voltage and the measured voltage was 3V, which confirmed the detection error within about 1%. It was confirmed that the reliability of the overvoltage measurement of 220 V to 280 V was high.

Meter Measures Meter Measures 221 221 251 253 222 222 252 254 223 223 253 255 224 224 254 256 225 225 255 257 226 226 256 258 227 227 257 259 228 229 258 260 229 230 259 261 230 231 260 262 231 232 261 263 232 233 262 264 233 234 263 265 234 235 264 266 235 236 265 267 236 237 266 268 237 238 267 269 238 239 268 270 239 240 269 272 240 241 270 273 241 242 271 274 242 243 272 275 243 244 273 276 244 245 274 277 245 246 275 278 246 248 276 279 247 249 277 280 248 250 278 281 249 251 279 282 250 252 280 283

54 is a layout of a PCB substrate on which an MCU module is designed.

Figure 55 is a tentative work of an MCU module to control a remote sense / control earth leakage breaker.

Probabilistic optimization techniques include Genetic Algorithm, Simulated Annealing, and Evolution Strategy. The genetic algorithm simulates adaptive evolution of living organisms by adapting to changes in environment. Simulated annealing is a method that demonstrates the process by which the metal becomes the most stable energy state through the annealing process during the metal smelting process. The evolution algorithm is a synthesis of genetic algorithm and simulated annealing.

The first is the reproduction process in which the life forms reproduce the next generation within a certain genetic constraint. The second is a process in which mutations are caused by other external factors. Third, there are two processes of reproduction and mutation which are repeated and adapt to the changed environment.

The evolution algorithm is a method of repeatedly performing the procedure shown in Equations (15) and (56) to find a value converging on an objective function.

The evolution strategy technique generates a child generation in the parent generation as shown in Equation (16) in Step 3 of the evolution algorithm according to Equation (15).

은 표준편차가 1이고 평균이 0인 임의의 수이다.here,

Is an arbitrary number with a standard deviation of one and an average of zero.

We repeat the adaptation process as shown in Equation 17 so that the objective function converges while repeating the mutation and the reproduction process.

Where s is the number of objective function convergence and n is the number of design variables.

The algorithm of the evolutionary strategy technique is shown in Table 15 in five steps.

Step 1: Initialization

Step 2: Fitness Evaluation

Step 3: Mutation

Step 4: Selection

Step 5: Change Step length

The process of repeating steps 3 to 5 until the objective function converges is shown in FIG. 57 in the flowchart of the evolutionary strategy.

Evolutionary programming techniques are similar to evolutionary strategies, but differ in how children are created and selected in the process of steps 3 ~ 5. The variation process of evolutionary programming is shown in equation (18).

,

으로

은 모든 부모개체군의 변이 과정에 적용되며

은 개별 개체의 변이에 적용된다. 진화프로그래밍에서의 선택은 부모개체군과 자식개체군과의 목적함수 비교에서 가장 목적함수의 수렴도 높은 개체를 자식세대 개체로 정하며 목적함수 수렴도가 좋은 개체군을 부모세대로 설정하여 변이 과정을 거치면서 자식세대 개체군을 생성한다. 이와 같은 과정을 반복 수행하여 목적함수에 수렴하는 설계 변수를 찾아 간다. 진화 프로그래밍 알고리즘은 다음의 표 16과 같다.here,

,

to

Is applied to the mutation process of all parental populations

Is applied to the mutation of individual individuals. The selection in evolutionary programming is based on the comparison of the objective function between the parent population and the child population. The population with the highest convergence of the objective function is defined as the child generation entity. The population with good convergence of the objective function is set as the parent generation, Generate a population of generations. This process is repeated to find design variables that converge to the objective function. Evolutionary programming algorithms are shown in Table 16 below.

Step 1: Initialization

Step 2: Fitness Evaluation

Step 3: Mutation

Step 4: Tournament

Step 5: Selection The most "w": Selected to be the parents of the next generation

Figure 58 shows a flowchart of evolutionary programming.

In order to apply the evolution algorithm in designing the circuit breaker circuit board, it is necessary to implement an interfaced interface environment between the electromagnetic analysis program and the optimization program. We implemented an automation program of optimal design using Excel program by using script command of electromagnetic field analysis program HFSS and CST. The basic structure of the program implemented in Fig. 59 is shown.

60 is an optimal design automation program implemented to verify the API implemented by the evolution strategy technique and the HFSS.

61 is implemented in order to confirm the process of converging to the objective function and to determine the optimum design variable value by repeating it according to the flowchart of the optimum design automation program as shown in FIG.

Prior to the optimal design of the three-dimensional PCB structure, an optimal design was performed for a simplified two-dimensional PCB and ground structure as shown in FIG. Here, the position (X2, Y2, Z2) of the hole defining the port 2 to which the signal connected to the ground plane is transmitted and the height of the substrate are set as design variables. In this case, the characteristic impedance Z21 between the ports 1 and 2 must be minimized in order for signals generated at port 1 to be transmitted to the port 2 through the sub-ground plane with high signal integrity. Therefore, we set the impedance profile Z21 as the objective function and optimized the design to minimize it.

The optimal design values of Y2 and H were obtained by defining the objective function of the optimum design as shown in Equation (19).

The positions (X1, Y1, Z1) defining the port 1 of the design variables and the positions (X2, Y2, Z2) of the holes defining the port 2 are 0 mm, 20 mm, ) Were set as initial design values.

FIG. 63 shows the convergence degree of the objective function according to the result of the optimum design.

Table 17 and Figure 64 show the comparison between the initial results and the optimal design results.

Y ₂ (mm) H (mm) Initial design value 40 5 Optimum design value 36.26 8.66

In Table 17, it can be seen that the impedance becomes lower as the value of H is larger and the value of Y2 is smaller.

Modeling was performed using an electromagnetic wave analysis tool as shown in FIG. 65 for analyzing electromagnetic waves induced on a PCB substrate by external electromagnetic waves to the substrate of the MCU module.

In order to analyze the electromagnetic wave conducted on the PCB conductive surface of FIG. 52, an electromagnetic wave of 10 V / m was applied in a direction of the MCU module 1 m away from the electromagnetic wave source as shown in FIG.

Table 18 and FIG. 67 show the current density (unit: mA / m) induced on the conductor surface of the PCB substrate according to the frequency by the external electromagnetic wave.

GHz Line GND top bottom top bottom 0.1 0.0109 0.0078 0.0530 0.0663 0.2 0.0141 0.0071 0.0740 0.0623 0.3 0.0237 0.0147 0.1084 0.1252 0.4 0.0157 0.0109 0.0901 0.1066 0.5 0.0215 0.0102 0.1322 0.0806 0.6 0.0323 0.0266 0.2047 0.1793 0.7 0.0405 0.0376 0.2111 0.2478 0.8 0.2276 0.1269 0.8570 0.8155 0.9 0.0297 0.0221 0.1513 0.1431 One 0.0416 0.0368 0.2142 0.2299

It can be seen that the current density is most induced in the PCB substrate at 0.8 GHz. FIG. 68 shows the current density induced at 0.8 GHz.

In order to combine the earth leakage breaker and the MCU module, the MCU module was made of polycarbonate (PC) to make the remote earth leakage circuit breaker. As shown in FIG. 69, the electromagnetic wave analysis was performed on the substrate of the MCU module together with the enclosure having the material of PC.

Table 19 and Fig. 70 show the current density (unit: mA / m) induced on the conductor surface of the PCB substrate according to the frequency caused by the external electromagnetic wave when the PC having the dielectric constant 3.0 has the MCU module enclosure. And FIG. 71 shows the current density (PC material enclosure) induced on the PCB substrate at 0.8 GHz.

GHz Line GND top bottom top bottom 0.1 0.0422 0.0253 0.0580 0.0704 0.2 0.0227 0.0123 0.0738 0.0617 0.3 0.0249 0.0153 0.1086 0.1254 0.4 0.0205 0.0132 0.0976 0.1091 0.5 0.0252 0.0125 0.1483 0.0865 0.6 0.0289 0.0224 0.1786 0.1595 0.7 0.0487 0.0598 0.2758 0.2857 0.8 0.1656 0.0930 0.6430 0.6345 0.9 0.0333 0.0250 0.1685 0.1630 One 0.0817 0.1274 0.3674 0.3602

PC enclosures manufactured for prototype manufacture can not be tested for enclosure such as heat resistance test in breaker specification. Therefore, it is necessary to study the injection molding material and the injection material applied to the breaker for the commercialization.

In general, nylon-66 (PA66) and phenol resin (PF) are used as enclosure materials that meet breaker test standards. Electromagnetic study on PA66 and PF was carried out.

The dielectric constant and dielectric loss of PA66 are 3.3 and 0.02, respectively. Figure 72 and Table 20 show the current density (unit: mA / m) induced on the PCB conductor surface by frequency for electromagnetic waves, reflecting the material properties of the enclosure using electromagnetic field analysis tools.

GHz Line GND top bottom top bottom 0.1 0.0389 0.0189 0.0577 0.0719 0.2 0.0229 0.0113 0.0881 0.0704 0.3 0.0257 0.0152 0.1089 0.1252 0.4 0.0205 0.0123 0.0948 0.1093 0.5 0.0247 0.0116 0.1447 0.0862 0.6 0.0364 0.0298 0.2411 0.2041 0.7 0.0447 0.0452 0.2444 0.2834 0.8 0.3146 0.1818 1.1587 1.1832 0.9 0.0366 0.0301 0.1816 0.1726 One 0.0450 0.0476 0.2343 0.2396

At 0.8 GHz, it was confirmed that the electric current was induced by the electromagnetic wave on the PCB substrate. Figure 73 shows the current induced at the substrate conductor surface at 0.8 GHz. 73, it can be confirmed that a large current is induced in the vicinity of the MCU chip and the line near the connector when the PA66-made enclosure is used.

On the other hand, when the PF having a dielectric constant of 4.5 and a dielectric loss of 0.015 is used, the induced current is concentrated at 0.8 GHz, as shown in Table 21 and FIG. 74, but is smaller than that of PA66. And FIG. 75 shows the current density (PC material enclosure) induced on the PCB substrate at 0.8 GHz.

GHz Line GND top bottom top bottom 0.1 0.0345 0.0205 0.0564 0.0692 0.2 0.0184 0.0097 0.0729 0.0609 0.3 0.0251 0.0154 0.1087 0.1255 0.4 0.0203 0.0130 0.0988 0.1106 0.5 0.0253 0.0127 0.1514 0.0882 0.6 0.0326 0.0262 0.2130 0.1835 0.7 0.0494 0.0605 0.2788 0.2916 0.8 0.1727 0.0979 0.6697 0.6676 0.9 0.0359 0.0285 0.1809 0.1768 One 0.0748 0.1131 0.3353 0.3348

If the MCU module enclosure is manufactured using the PC material and PA66 and PF materials, it is impossible to completely block the external electromagnetic wave because all three are plastic series. However, when PF material was used, it was confirmed that the current density induced on the PCB substrate was lower than that of PA66. Therefore, in order to commercialize remote monitoring / control circuit breaker, we plan to minimize the influence of external electromagnetic wave by using phenol resin as an enclosure of MCU module.

Each signal (resistive leakage current, overcurrent, overvoltage) sensed by RF communication is transmitted to AP and it is designed to be able to real time monitoring through GUI. 76 is a simplified block diagram of a remote monitoring system. The communication format between the MCU module and the AP is as shown in FIG.

The present invention wirelessly communicates using 2.4 GHz, which is the most general frequency band internationally. For wireless communication, the development of effective communication protocols is essential. In particular, the data area is designed to maintain the minimum required data length, and an ACK is added to ensure communication stability. The following describes the communication protocol between ELB (Earth leakage breaker), AP (access point), AP and UI (User Interface).

78, the communication protocol from the ELB to the AP is shown. And Fig. 79 shows the details of each item. The data structure shown in FIGS. 79 and 79 realizes functions such as leakage current, real-time power, standby power, and automatic shutdown.

The data structure responding to the ELB in the AP has the structure shown in FIG. 80 because there is no sensor data. 81 shows a description of the Control Flag.

First, the communication protocol from the UI to the AP is shown in FIG. The data protocol must also be defined for communication between the UI and the AP. Here, the ID of the AP and the number of EBLs communicated in the AP are recorded. In FIG. 83, a detailed description of the AP ID is shown, and the AP ID is designed to support up to 50 APs at the same time.

84 and 85, communication protocols from the AP to the UI are shown. The data provided by the AP to the UI includes a lot of sensor values of the ELB, so a lot of data must be sent, and the data length for the communication becomes long. 86 shows a detailed description of each item.

Zigbee is an international industry standardization technology for low power consumption, low cost, many sensor nodes, interconnected sensor and control measurement wireless networks, and Zigbee communication is used for communication between MCU module and AP. Table 22 and Table 23 show the configuration and function of the Zigbee specification and architecture.

Item Contents frequency 2.4GHz ISM band Transmission speed 250 kbps Network capacity Up to 65,536 nodes Topology Star, Mesh, Cluster Tree Configuring device Coordinator, Router, End Device

Floor name Abbreviation main function Application layer APL The user's communication application Application Support
APS Establishing a logical communication path between applications
Exchange data between applications
Confirm message receipt and request retransmission between applications Network layer NWK Network Management, Routing Management
Sending messages within a network Media access layer MAC Sending messages within one hop
Request acknowledgment and retransmission in one hop Physical layer PHY Frequency, channel, modulation scheme, frame structure used in communication

The physical layer of the hardware is a protocol relating to a physical medium required for wireless communication, and is composed of frequency, channel, modulation scheme, basic communication frame, and the like. The MAC layer specifies that the message is delivered correctly within the range (1 hop) where radio waves are directly reached. Error detection, error correction, retransmission request, and ACK response in the case of normal reception when a communication error occurs due to an interference radio wave or the like. In the network layer that defines the message transmission method in the network under the network management and routing management, the network layer functions to mutually trust the network nodes through network activation, network participation, and network address allocation. In the case of a wireless network in which radio waves are not directly received, a route is selected so that messages can be transmitted through the relay function of the intermediate node.

A communication path between nodes in the network layer is established, but it is possible for a plurality of applications to coexist in one node, so that a logical communication path between applications such as a TCP port is required. One of the main functions of the application support layer is to support endpoints as such logical subchannels. Also, the information that can be transmitted at the network layer is only a binary data payload of a certain length or less. Since there are many applications of the user, the required data formats are also different. It is the role of this layer to transform the transmission data from the application into the required format in the network layer to build the frame or to convert the payload data from the network layer into a message that the application can understand. The acknowledgment and transmission request of the established communication frame is also a function of this layer. However, Zigbee Specification 1.0 does not yet support fragmentation (automatic fragmentation and transmission of messages with large data sizes).

The Zigbee specification provides an application framework for building applications easily. As a special application, ZigBee device object (ZDO) which manages Zigbee network is required to be implemented.

The communication modulation scheme of the remote monitoring / control system is composed of a modulation circuit as shown in FIG. 87 as modulation of QPSK (Quadrature Phase Shift Keying).

Modulation of QPSK is performed by modulating a signal as shown in FIG. 88 by the following method.

(1) Convert the bit stream of the base band to be transmitted by dividing the bit stream by 4 bits into symbols. For example, a bit stream such as 1010 is converted to a symbol 5. In IEEE802.15.4, since it is determined to be transmitted in order from the least significant bit (LSB: Least Significant Bit), the order of the bit stream is not 0101 but 1010 in reverse.

(2) Converts the obtained symbol into a chip string (32 chips) of the corresponding PN code and performs spread spectrum. The PN code chip sequence of the symbol 5 becomes 00110101001000101110110110011100.

(3) The converted PN code chip sequence is divided into an odd-numbered chip and an even-numbered chip, which are used as an I-phase PSK signal and a Q-phase PSK signal, respectively. For example, the I-phase PSK signal and the Q-phase PSK signal of the PN code of 5 become 0100010111101010 and 0111000010110110, respectively.

(4) D / A conversion is performed on the I-phase PSK signal and the Q-phase PSK signal, respectively, and converted into an analog signal. The circuit from here is an analog circuit. The waveform of the I-phase and Q-phase pulse of the symbol 5 becomes a half-sine wave.

(5) By multiplying the obtained two analog signals by the orthogonal reflection wave obtained by passing the carrier wave and the carrier wave respectively, orthogonal components of the in-phase component of the modulated wave can be obtained.

⑥ By adding in-phase component and quadrature component of modulated wave to generate modulated high frequency and amplifying signal with power amplifier, it becomes possible to send out from antenna.

A demodulation circuit for extracting information from a modulated signal from a transmitter is configured as shown in FIG.

The method of demodulating the modulated signal is as follows.

(1) phase detection is performed after separating the modulated high-frequency received from the antenna into an in-phase component and a quadrature component according to an orthogonal carrier wave obtained by a / 4 delay circuit, respectively.

(2) A / D conversion is performed on the analog signal of the in-phase component and the quadrature component, respectively, and converted into a digital signal to form a chip string of I-phase and Q-phase. The circuit from here is a digital circuit. For example, when symbol 5 is correctly received, the I and Q phase chip strings are 0100010111101010 and 0111000010110110.

(3) The I and Q phase chips are synthesized as odd-numbered chips and even-numbered chips, respectively. In the case of all the examples, chip heat such as 00110101001000101110110110011100 becomes possible.

(4) Calculate the correlation between the synthesized chip sequence and the 16 types of PN code sequences used as symbols, and select the symbol corresponding to the PN code sequence with the highest correlation. In the case of all examples, symbol 5 is obtained.

(5) Converts the obtained symbol into 4-bit data. In case of symbol 5, 1010 baseband signal with LSB as the head is sent to upper layer and processed as payload.

The topologies that connect to network elements such as links and nodes include star topology, tree topology, and mesh topology.

The structure of the star topology is simple in that it is controlled by a coordinator in the connection mode as shown in FIG. The terminal node does not need to operate normally, and it can sleep without power while it does not communicate. Therefore, the terminal node can be configured as a low cost RFD, and since it is only one hop communication, it is possible to control the maximum delay time of data transmission within a certain range. Since it is a single communication router, unnecessary messages rarely occur, and it is a disadvantage from the viewpoint of reliability but has an advantage in terms of effective use of communication bandwidth.

The tree topology is structured as shown in FIG. 91, and the parent node always grasps the state of its own node, and the coordinator is an easy structure to grasp the connection state of the entire network. The balance of the network configuration can be controlled by the coordinator and the communication distance exceeds the limit of one hop, and multi-hop communication is possible. In addition, since the communication path is established, no extra message is generated and the maximum delay time of message transmission can be predicted. However, when a communication failure occurs due to interference propagation or the like, there is a problem that a message can not be reached because the communication path is fixed to a single one. There is also the possibility that the message transmission may not be the optimal route. Since information is concentrated on the vertices, the closer to the coordinator, the more communication traffic is required, the balance of network resource utilization is not good, and since the parent node is always operating, the message transmission function to the child node is required. There is a problem that it is difficult to mount.

In order to solve the problem of the tree topology, a remote monitoring / control system is constructed by the mesh topology connection method as shown in FIG. The characteristics of the mesh topology are as follows.

① Multi-hop communication is possible beyond the limit of 1 hop communication distance.

(2) Reliability of communication can be improved by providing redundancy of communication route. If a communication failure occurs due to interference propagation, etc., the message can be reached by diverting to a separate communication path.

③ Since the message relay function is required, it is required to always operate, so it is very difficult to implement the sleep function for no power.

(4) In the case of multi-hop communication, the delay time required for data transmission is hardly controlled.

⑤ There is a difference depending on the stack of the network layer, but it takes a processing time of several tens of milliseconds or more for one relay. This is because it relays frames that have been rewritten in the routing process, such as the computation of communication path costs as well as the transmission of frames.

(6) Since the management information is distributed to each node, it is difficult to grasp all information of the network configuration.

(7) Since a routing table or the like is implemented, resources such as a larger memory are required.

From the viewpoint of effective use of the communication band, it is a disadvantage to transmit multiple paths of the same message. The number of extra messages generated by the routing algorithm of the mesh network is also different. The number of extra messages has a trade-off relationship between reliability and built-in performance.

The present invention can also be embodied as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission via the Internet) . The computer-readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation in the embodiment in which said invention is directed. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

Claims (1)

A synchronization signal generator for detecting a power supply voltage and generating a synchronization signal every half cycle of the power supply;
A leakage current calculation unit for integrating the effective value of the combined leakage current flowing in the line connected to the power source in a half cycle unit of the power source according to the synchronization signal to calculate a resistive leakage current; And
And an earth leakage blocking unit for comparing the calculated resistive leakage current with a preset reference value to determine whether the power source is shut off.

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