KR960002325B1 - Digital type over-current/under-current relay method of the switch-board in electronic type - Google Patents

Digital type over-current/under-current relay method of the switch-board in electronic type Download PDF

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KR960002325B1
KR960002325B1 KR1019920015680A KR920015680A KR960002325B1 KR 960002325 B1 KR960002325 B1 KR 960002325B1 KR 1019920015680 A KR1019920015680 A KR 1019920015680A KR 920015680 A KR920015680 A KR 920015680A KR 960002325 B1 KR960002325 B1 KR 960002325B1
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current
overcurrent
low current
load
level
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KR1019920015680A
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KR940004922A (en
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허노재
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현대중전기주식회사
유재환
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The over and low current level and the delay time of an electronic distributor is set according to the rating of a load and the power is relayed according to the set level and the delay time. The method comprises the steps of: (A) sampling load current to set maximum load current and minimum load current; (B) comparing the sampled values to reference values to discriminate over or low current status; (C) reading the preset break delay time and checking that the over or low current status exceed the delay time; and (D) breaking a power supplied to a load when the over or low current status exceed the delay time.

Description

전자식 배전반의 디지탈식 과전류/저전류 계전방법Digital overcurrent / low current relay method of electronic switchgear

제1도는 본 발명의 과전류/저전류 계전방법이 적용되는 전자식 배전반의 구성을 보인 회로도.1 is a circuit diagram showing the configuration of an electronic switchgear to which the overcurrent / low current relaying method of the present invention is applied.

제2도는 본 발명의 과전류/저전류 계전방법을 보인 신호흐름도.2 is a signal flow diagram showing the over-current / low current relay method of the present invention.

본 발명은 전동기, 변압기 및 피더(FEEDER)등의 각종 부하에 전원을 공급하는 전자식 배전반에 있어서, 부하로 과전류 및 저전류가 공급되는지를 검출하고, 과전류 및 저전류가 공급될 경우에 그 과전류 및 저전류의 정도에 따라 설정된 시간후에 전원을 차단하여 부하가 손상되지 않도록 하는 전자식 배전반의 디지탈식 과전류/저전류 계전방법에 관한 것이다.The present invention is to detect whether an overcurrent and a low current is supplied to a load in an electronic switchgear that supplies power to various loads such as an electric motor, a transformer and a feeder, and when the overcurrent and a low current are supplied, the overcurrent and The present invention relates to a digital overcurrent / low current relay method of an electronic switchgear which cuts off a power supply after a predetermined time according to a low current so as not to damage a load.

일반적으로 부하에 전원을 공급하여 동작시킬 경우에 부하의 과부하, 과열, 지락사고 및 이상결선이나 전원의 불평등으로 인하여 과전류 및 저전류가 공급되면 부하가 손상되므로 부하로 공급되는 전류레벨을 검출하고, 검출한 전류레벨이 미리설정한 레벨이상의 과전류이거나 또는 미리 설정한 레벨이하의 저전류일 경우에 전원을 차단하여 부하가 손상되지 않도록 하고 있다.In general, in case of supplying power to the load, if the over current and low current are supplied due to overload, overheat, ground fault and abnormal wiring or inequality of the power, the load is damaged and thus the current level supplied to the load is detected. When the detected current level is an overcurrent above a preset level or a low current below a preset level, the power is cut off so that the load is not damaged.

과전류 및 저전류로부터 부하가 손상되지 않도록 보호하기 위하여 종래에는 가동철심형 계전기, 유동형 계전기 및 정지형 계전기등의 아날로그식 보호 계전기를 사용하여하였다.In order to protect the load from damage from overcurrent and low current, conventionally, an analog protective relay such as a moving iron core relay, a floating relay, and a stationary relay is used.

그러나 이들 아날로그식 보호 계전기는 자력선을 발생시키는 고정철심과, 이 고정철심의 자력선에 의해 구동되면서 접점을 개폐시키는 가동철편간의 간격등을 조절하여 과전류 및 저전류에 따른 동작레벨을 설정하는 것으로서 동작레벨을 정확히 설정하기가 매우 어렵고, 숙련도를 요구할 뿐만 아니라 많은 시간이 소요되었으며, 부하를 전력량이 다른 부하로 교체시킬 경우에는 동작레벨을 다시 설정해야 되었으며, 또한 과전류 및 저전류의 정도에 따라 부하로 공급되는 전원의 차단 지연시간을 정확히 설정하지 못함은 물론 응답속도가 느려 부하를 보호하는데 한계가 있었다. 그러므로 본 발명의 목적은 부하의 전력량에 따라 간단히 과전류 및 저전류 레벨을 설정하여 검출할 수 있도록 하는 과전류/저전류 계전방법을 제공하는데 있다.However, these analog protective relays set the operation level according to the overcurrent and low current by adjusting the interval between the fixed iron core that generates the magnetic lines and the movable iron pieces that open and close the contacts while being driven by the magnetic lines of the fixed iron core. It is very difficult to accurately set the current, it requires a lot of skill, it takes a lot of time, and when the load is replaced with a different load, the operation level has to be reset, and it is supplied to the load according to the degree of overcurrent and low current. There was a limit to protect the load because the response time was not set correctly as well as the delay time of the power supply. Therefore, it is an object of the present invention to provide an overcurrent / low current relaying method that can be set and detected by simply setting the overcurrent and low current levels according to the amount of power of a load.

본 발명의 다른 목적은 과전류 및 저전류 상태의 레벨정도의 따른 전원의 지연시간을 정확히 설정하여 부하가 손상되지 않도록 함은 물론 순간적인 전류의 변동으로 인한 과전류 및 저전류가 공급될 경우에 전원이 차단됨이 없이 부하를 계속 구동시킬수 있도록 하는 과전류/저전류 계전방법을 제공하는데 있다.Another object of the present invention is to accurately set the delay time of the power supply according to the level of the overcurrent and low current state so as not to damage the load, as well as the power supply when the overcurrent and low current are supplied due to the instantaneous current change. It is to provide an overcurrent / low current relay method that can continue to drive the load without being interrupted.

이러한 목적을 가지는 본 발명의 과전류/저전류 계전방법은 과전류 및 저전류시 부하에 손상을 주지 않는 범위내에서 실험을 통하여 과전류 및 저전류의 정도에 따른 전원의 차단 지연시간을 미리 설정하여 룩업 테이블에 저장하여 둔다.The overcurrent / low current relay method of the present invention having such a purpose sets up a look-up table by setting the power-off delay time according to the degree of overcurrent and low current in advance through experiments within a range that does not damage the load during overcurrent and low current. Save it to.

그리고 부하로 공급되는 전류레벨을 일정주기로 샘플링하고, 샘플링한 데이타를 계산하여 각 상간의 전류레벨을 검출한후 최대전류 및 최소전류를 판단한다.The current level supplied to the load is sampled at regular intervals, and the sampled data is calculated to detect the current level between each phase, and then the maximum current and the minimum current are determined.

판단한 최대전류 및 최소전류은 정격 기준전류와 비교하여 과전류비 및 저전류비를 계산하고, 그 계산한 과전류비 및 저전류비에 따른 차단 지연시간을 룩업 테이블에서 리드한후 리드한 차단 지연시간동안 과전류 및 저전류 상태가 지속될 경우에 전원을 차단하여 부하로 공급되지 않도록 한다.The determined maximum current and minimum current are calculated by comparing the overcurrent ratio and the low current ratio with the rated reference current, and the overcurrent during the cutoff delay time read after reading the cutoff delay time according to the calculated overcurrent ratio and the low current ratio from the lookup table. And when the low current condition persists, cuts off the power so as not to be supplied to the load.

그러므로 본 발명의 과전류/저전류 계전방법에 의하면, 부하의 전력량에 따라 간단히 정격기준전류 레벨만을 조절하여 과전류 및 저전류 상태를 판별할수 있고, 순간적인 전원변동으로 인하여 부하에 과전류 및 저전류가 공급되어도 부하에 손상을 주지 않는 범위내에서 계속 전원을 공급하여 부하가 정지됨이 없이 계속 구동되도록 할 수 있다.Therefore, according to the overcurrent / low current relaying method of the present invention, the overcurrent and low current states can be discriminated by simply adjusting the rated reference current level according to the power amount of the load, and the overcurrent and low current are supplied to the load due to the instantaneous power supply fluctuation. In this case, the power can be continuously supplied within the range that does not damage the load so that the load can be continued without stopping.

이하 첨부된 도면을 참조하여 본 발명의 과전류/저전류 계전방법을 상세히 설명한다.Hereinafter, the overcurrent / low current relay method of the present invention will be described in detail with reference to the accompanying drawings.

제1도는 본 발명의 과전류/저전류 계전방법이 적용되는 전자식 배전반의 구성을 보인 회로도로서 이에 도시된 바와 같이, 전자식 배전반의 전체동작을 제어하는 중앙처리장치(1)와, 부하로 R 상, S상 및 T상의 전원을 공급하는 차단계전기(CB)와, 부하로 공급되는 R상, S상 및 T상의 전류를 전류를 검출하는 전류트랜스(CT1-CT3)와, 상기 전류트랜스(CT1-CT33)의 검출전류를 출력하는 센서신호 출력부(2)와, 상기 센서신호 출력부(2)의 출력신호중에서 하나의 신호를 선택 출력하는 멀티플렉서(3)와, 상기 멀티플렉서(3)의 출력신호를 디지탈 신호로 변환하여 상기 중앙처리장치(1)로 입력시키는 아날로그/디지탈 변환부(4)와, 상기 중앙처리장치(1)에 동작명령을 하는 키보드부(5)와, 상기 중앙처리장치(5)의 제어에 따라 동작상태 및 이상상태를 표시하는 표시부(6)와, 상기 중앙처리장치(5)의 동작프로그램과 과전류 및 저전류비의 정도에 대한 지연시간등을 저장 출력하는 롬(7)과, 부하의 제어에 필요한 데이타를 저장 및 출력하는 램(8)과, 상기 중앙처리장치(1)의 제어에 따라 상기 차단계전기(CB)를 제어하여 부하의 전원공급을 차단시키는 부하구동부(9)로 구성하였다.1 is a circuit diagram showing the configuration of an electronic switchgear to which the overcurrent / low current relaying method of the present invention is applied. As shown therein, a central processing unit 1 for controlling the overall operation of the electronic switchgear, R phase, Second-phase electric power (CB) for supplying power to the S-phase and T-phase, current transformer (CT1-CT3) for detecting currents of the R-phase, S-phase, and T-phase currents supplied to the load, and the current transformer (CT1-CT33). A sensor signal output unit 2 for outputting a detection current of the signal, a multiplexer 3 for selectively outputting one signal from the output signal of the sensor signal output unit 2, and an output signal of the multiplexer 3 An analog / digital converter 4 for converting a digital signal into the central processing unit 1, a keyboard unit 5 for operating commands to the central processing unit 1, and the central processing unit 5 A display unit 6 for displaying an operation state and an abnormal state under the control of; A ROM 7 for storing and outputting an operation program of the central processing unit 5 and a delay time for the degree of overcurrent and low current ratio, a RAM 8 for storing and outputting data necessary for controlling the load, In accordance with the control of the central processing unit (1) it was configured as a load driver 9 for controlling the next-stage electric (CB) to cut off the power supply of the load.

이와같이 구성된 전자식 배전반에 적용되는 본 발명의 과전류/저전류 계전방법은 제2a도에 도시된 바와 같이 차단계전기(CB)를 통해 부하로 공급되는 R상, S상 및 상의 전류를 일정주기로 샘플링 예를 들면, 1.38msec의 주기로 샘플링한 데이타를 저장한다.The overcurrent / low current relaying method of the present invention applied to the electronic switchboard configured as described above is an example of sampling the currents of the R phase, S phase, and phase supplied to the load through the next-stage electricity CB at regular intervals, as shown in FIG. 2A. For example, data sampled at a period of 1.38 msec is stored.

즉, 부하로 공급되는 R상, S상 및 T상의 전류가 전류트랜스(CT1-CT3)에서 검출된후 센서신호 출력부(2)로 입력되어 센서신호 출력부(2)는 R상, S상 및 T상의 전류를 출력하고, 출력한 전류는 멀티플렉서(3)에서 선택되고, 아날로그/디지탈 변환부(4)에서 디지탈로 변환되어 중앙처리장치(1)로 입력되며, 중앙처리장치(1)는 아날로그/디지탈 변화부(4)로부터 입력되는 R상, T상 및 T상의 전류데이타를 샘플링하여 저장한다.That is, the current of the R phase, S phase, and T phase supplied to the load is detected by the current transformers CT1-CT3, and then input to the sensor signal output unit 2, so that the sensor signal output unit 2 is R phase, S phase. And outputs a current of the T phase, and the output current is selected by the multiplexer 3, converted into digital by the analog / digital converter 4, and input to the central processing unit 1, and the central processing unit 1 is The R, T, and T phase current data input from the analog / digital change unit 4 is sampled and stored.

이와같이 1주기의 전압데이타들이 저장되면 중앙처리장치(1)는 저장된 데이타를 계산하여 R-S상, S상 및 T상의 전류를 검출하고, 검출한 전류는 최고전류(Imax) 및 최저전류(Imin)을 결정한다.When voltage data of one cycle is stored in this manner, the central processing unit 1 calculates the stored data and detects the currents of the RS, S, and T phases, and the detected currents represent the highest current (Imax) and the lowest current (Imin). Decide

여기서 각 상의 전류는 실수부 전류와 허수부 전류로 분리하여 계산하는 것으로 실수부의 전류는 다음의 식과 같이 계산한다.Here, the current of each phase is calculated by dividing the real part current and the imaginary part current, and the real part current is calculated as follows.

여기서, IR, Is및 It는 R 상, S상 및 T상의 실수부 전류이고, RN, SN및 TN(여기서, N은 0-11의 자연수임)는 N번째 샘플링한 R상, S상 및 T상의 전류이며, C1-C3는 상수이다.Where I R , I s and I t are the real part currents of R phase, S phase and T phase, and R N , S N and T N (where N is a natural number of 0-11) are the Nth sampled R Phase, S, and T phases are currents, and C 1 -C 3 are constant.

그리고 허수부의 전류는 다음의 식과 같이 계산한다.The current in the imaginary part is calculated as follows.

여기서, jIR, jIS및 jIT는 R상, S상 및 T상의 허수부 전류이다. 이와같이 하여 각 상간의 실수부 전류 및 허수부 전류가 계산되며, 그 실수부 및 허수부의 합성전류를 구하여 가장 높은레벨의 합성전류를 최고전류(Imax)로 설정하고, 가장 낮은레벨의 합성전류를 최소전류(Imin)로 설정한다.Here, jI R , jI S and jI T are imaginary part currents of R phase, S phase and T phase. In this way, the real part current and the imaginary part current between each phase are calculated, the synthesized current of the real part and the imaginary part is obtained, and the highest level synthesized current is set to the highest current (Imax), and the lowest level synthesized current is minimized. Set to current (Imin).

이와같이 최고전류(Imax) 및 최소전류(Imin)가 설정되면, 제2도의 (b)에 도시된 바와 같이 일정주기의 인터럽트 즉, 예를 들면 50msec주기의 인터럽트시마다 최고전류(Imax) 및 최소전류(Imin)를 미리설정된 정격 기준전류(IR)과 비교한다.When the maximum current Imax and the minimum current Imin are set in this way, as shown in (b) of FIG. 2, the maximum current Imax and the minimum current (At each interrupt of a certain period, for example, 50 msec periods) Imin) is compared with a predetermined rated reference current I R.

이때 Imax＞IR이면 Imax/IR을 계산하여 과전류비를 구하여, 과전류비가 미리설정된 일정드레시홀드 레벨이상인지를 판별하여 드레시홀드 레벨이상일 경우에는 과전류로 판단하고, 과전류비에 해당하는 차단 지연시간을 룩업 테이블에서 리드하며, 저전류 누적시간(Tmin)은 리세트시키며, 과전류 누적시간(Tmax)에 인터럽트의 주기시간을 증가시킨후 리드한 차단지연시간과 과전류 누적시간(Tmax)를 비교하여 차단지연시간이 경과되는지를 판단하며, 차단지연시간이 경과될 경우에는 부하구동부(9)가 전원차단기(CB)를 제어하여 R상, S상 및 T상의 전원이 부하에 공급되지 않도록 한다.In this case, if Imax> I R, the Imax / I R is calculated to determine the overcurrent ratio, and if the overcurrent ratio is above the predetermined constant threshold level, if it is above the threshold level, the overcurrent is determined, and the cutoff delay time corresponding to the overcurrent ratio Reads from the lookup table, resets the low current accumulated time (Tmin), increases the interrupt cycle time to the overcurrent accumulated time (Tmax), and then compares the blocked delay time and the overcurrent accumulated time (Tmax). It is determined whether the delay time has elapsed, and when the blocking delay time has elapsed, the load driver 9 controls the power circuit breaker CB so that the power of the R phase, the S phase, and the T phase is not supplied to the load.

그리고 상기에서 계산한 과전류비가 드레시홀드 레벨이하일 경우에는 정상 전류상태인 것으로 판단하고, 과전류 누적시간(Tmax)에서 인터럽트의 주기시간을 감산하면서 계속 부하로 공급되는 전류레벨을 체크한다.When the overcurrent ratio calculated above is less than the threshold level, it is determined to be in a normal current state, and the current level supplied to the load is checked while subtracting the interrupt cycle time from the overcurrent accumulation time Tmax.

또한 상기에서 Imin＜R이면 Imin/IR을 계산하여 저전류비를 구하고, 저전류비가 미리 설정된 일정드레시홀드 레벨이상인지를 판별하여 드레시홀드 레벨이상일 경우에는 저전류로 판단하고, 저전류비에 해당하는 차단 지연시간을 룩업 테이블에서 리드하며, 과전류 누적시간(Tmax)은 리세트시키며, 저전류 누적시간(Tmin)에 인터럽트의 주기시간을 증가시킨후 리드한 차단지연시간과 저전류 누적시간(Tmin)을 비교하여 차단 지연시간이 경과되는지를 판단하며, 차단 지연시간이 경과될 경우에는 부하구동부(9)가 전원차단기(CB)를 제어하여 R상, S상 및 T상의 전원이 부하에 공급되지 않도록 한다.In addition, if Imin < R, Imin / I R is calculated to obtain a low current ratio, and it is determined whether the low current ratio is above a predetermined constant threshold level, and when it is above the threshold level, it is determined as a low current. The corresponding cutoff delay time is read from the lookup table, the overcurrent accumulating time (Tmax) is reset, and the cutoff delay time and low current accumulating time (Read) are increased after increasing the interrupt cycle time to the low current accumulating time (Tmin). Tmin) is compared to determine whether the cutoff delay time has elapsed, and if the cutoff delay time has elapsed, the load driver 9 controls the power breaker CB to supply the R phase, S phase and T phase power to the load. Do not

그리고 상기에서 계산한 저전류비가 드레시홀드 레벨이하일 경우에는 정상 전류상태인 것으로 판단하고, 저전류 누적시간(Tmin)에서 인터럽트의 주기시간을 감산하면서 계속 부하로 공급되는 전류레벨을 체크한다.When the low current ratio calculated above is less than the threshold level, it is determined to be in a normal current state, and the current level supplied to the load is continuously checked while subtracting the interrupt cycle time from the low current accumulation time Tmin.

이상에서 상세히 설명한 바와 같이 본 발명은 부하로 과전류 및 저전류가 공급될 경우에 과전류비 및 저전류비에 따른 차단 지연시간후에 정확히 전원을 차단하여 부하가 손상되지 않고 부하의 설치 및 교체시 과전류 및 저전류의 레벨을 설정할 경우에는 간단히 정격 기준전류만을 가변시킴면 되어 그 작업이 매우 간편함은 물론 작업소요시간이 단축되며, 부하에 손상을 주지 않는 범위내에서의 순간적인 전류변동이 있는 경우에는 부하로 계속 전원을 공급하여 동작시킬 수 있는 등의 효과가 있다.As described in detail above, in the present invention, when overcurrent and low current are supplied to the load, the power is correctly cut off after the shutdown delay time according to the overcurrent ratio and the low current ratio, so that the load is not damaged and the overcurrent and When setting the low current level, simply change the rated reference current, which makes the work very simple and shortens the work time, and in case of instantaneous current fluctuation within the range that does not damage the load This can be operated by continuously supplying power.

Claims (2)

부하의 이상 상태로 판정하기 위한 최고전류, 최저전류등의 기준 레벨과, 부하로부터 감지한 전압, 전류 등의 값을 서로 비교하여, 그 비교 결과로부터, 과전류 상태 또는 저전류 상태인 경우에는 부하의 공급되는 전원을 차단시키고 경보 등을 수행하는 전원 제어 방법에 있어서, 각 상간의 전류를 설정된 주기로 샘플링하여, 그 샘플링 데이타로 각 상간의 전류 레벨을 계산하고, 그 중에서 가장 높은 전류 레벨 및 가장 낮은 전류 레벨을 최고 전류 및 최저 전류로 설정하는 제1과정과, 상기 최고 전류 및 최저 전류를 정격 기준전류와 각각 비교하여 과전류비 및 저전류비를 구하고, 구한 과전류비 및 저전류 비가 미리 설정된 소정의 기준레벨 이상일 경우에 과전류 및 저전류 상태로 판정하는 제2과정과, 상기 제2과정에서 과전류 상태 또는 저전류 상태이 판단시에, 과전류비 또는 저전류비에 해당되는 미리 설정된 차단 지연 시간을 리드하고, 과전류 누적시간 또는 저전류 누적 시간을 증가시키면서, 차단 지역 시간이 경과되는지를 판단하는 제3과정과, 상기 제3과정에서 차단 지연시간 이상으로 과전류 또는 저전류 상태가 계속될 경우에 부하의 전원을 차단시키는 제4과정으로 제어함을 특징으로 하는 전자식 배전반의 디지탈식 과전류/저전류 계전방법.The reference levels such as the highest current and the lowest current for judging the abnormal state of the load, and the values such as the voltage and current sensed from the load are compared with each other. In a power supply control method that cuts off the power supply and performs an alarm, the current between each phase is sampled at a set period, and the current level between each phase is calculated from the sampling data, and among them, the highest current level and the lowest current. The first process of setting the level to the highest current and the lowest current, and comparing the highest current and the lowest current with the rated reference current to obtain an overcurrent ratio and a low current ratio, and the obtained overcurrent ratio and the low current ratio are predetermined criteria. A second process of determining an overcurrent and a low current state when the level is higher than the level; and an overcurrent state or a low current state in the second process. And a third step of determining whether the cutoff time is elapsed while reading the preset cutoff delay time corresponding to the overcurrent ratio or the low current ratio, and increasing the overcurrent accumulation time or the low current accumulation time. A digital over current / low current relay method of an electronic switchgear, characterized in that the control is performed in a fourth process of shutting off the power of the load if the over current or low current state continues beyond the cutoff delay time in three processes. 제1항에 있어서, 상기 제1과정에서의, 샘플링 데이타를 실수부 및 허수부 전류로 분리하여 계산하고 계산한 실수부 및 허수부 전류의 합성 전류를 각 상간의 전류레벨로 설정하는 것을 특징으로 하는 전자식 배전반의 디지탈식 과전류/저전류 계전방법.The method of claim 1, wherein the composite current of the real part and the imaginary part currents calculated and calculated by separating the sampling data into the real part and the imaginary part currents in the first step is set to a current level between each phase. Digital overcurrent / low current relay method of an electronic switchgear.
KR1019920015680A 1992-08-31 1992-08-31 Digital type over-current/under-current relay method of the switch-board in electronic type KR960002325B1 (en)

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CN107565507A (en) * 2017-10-09 2018-01-09 珠海格力电器股份有限公司 Compressor overcurrent protection device and method and electrical equipment

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KR100988763B1 (en) * 2007-12-28 2010-10-20 김현우 Dignostic method for manufacturing intelligent distrtibuting board cabinet panel and power supply
KR101256322B1 (en) * 2011-12-30 2013-04-18 엘에스산전 주식회사 Current calculating method and relay using the same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107565507A (en) * 2017-10-09 2018-01-09 珠海格力电器股份有限公司 Compressor overcurrent protection device and method and electrical equipment
CN107565507B (en) * 2017-10-09 2019-09-10 珠海格力电器股份有限公司 Compressor overcurrent protection device and method and electrical equipment

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