48 results about "Capacitor voltage transformer" patented technology

A method, apparatus and system for state evaluation of metrological characteristics of a capacitor voltage transformer, relating to the technical field of voltage measurement. The method comprises the following steps: acquiring operation data of a capacitor voltage transformer, establishing a metrological performance evaluation model, and obtaining a statistical control threshold (S1); collecting in real time the operation data of the capacitor voltage transformer, and calculating a statistic of the operation data by means of the metrological performance evaluation model (S2); comparing the statistic of the operation data with the statistical control threshold to determine whether a fault occurs in the capacitor voltage transformer (S3); and detecting a change trend of a primary signal and a secondary signal of the tested capacitor voltage transformer to determine whether metrological characteristics are abnormal (S4). In the method, the concept of time is introduced, by providing a timestamp, the influence of newly obtained data on the metrological performance evaluation model is greater, and by means of real-time update, the metrological performance evaluation model can be updated, so that when in a stable state, the detection time is reduced, and the model calculation is reduced.

The invention discloses a capacitor voltage transformer harmonic error prediction method based on NRBO-BP, and belongs to the technical field of modeling prediction. The method comprises the steps of analyzing harmonic transmission characteristics, adjusting stray capacitance numerical values to simulate different operating environments, performing simulation to obtain harmonic error data, optimizing initial weight and bias of a BP neural network by using an NRBO algorithm, constructing a harmonic error prediction model, and finally predicting 2-60 times of harmonic errors by taking typical harmonic errors as characteristic parameters. The performance of the model is evaluated by adopting a mean absolute error, a root-mean-square error and a decision coefficient, wherein the NRBO algorithm comprises the steps of population initialization, Newton-Raphson search and TAO trap avoidance; the method solves the problems of low model precision and susceptibility to environmental interference in the existing CVT harmonic error prediction, effectively improves the measurement precision of the CVT in the harmonic frequency band, and provides reliable technical support for harmonic analysis of a power system.

The invention discloses a capacitor voltage transformer transient voltage measurement method, device and equipment and a medium, and relates to the technical field of power grid transient voltage measurement, and the method comprises the steps: carrying out the piecewise linear fitting of a flux linkage-current curve of a CVT intermediate transformer, and obtaining a relation function of the piecewise current and the flux linkage; constructing a voltage numerical equation from the secondary side to the primary side of the CVT, wherein the voltage numerical equation considers ground distributed capacitance parameters of the CVT; and substituting the secondary side voltage value of the CVT collected in real time into the voltage numerical equation, and calculating the primary side voltage of the CVT in combination with the relation function of the segmented current and the flux linkage. According to the method, the primary side voltage of the CVT can be obtained according to the actually measured voltage value of the secondary side by constructing the voltage numerical value relation from the secondary side to the primary side of the CVT and combining the flux linkage-current relation curve, the transient response performance of the CVT is improved, and a technical basis is provided for power grid transient voltage measurement and related research.

The present invention belongs to the technical field of online monitoring of electric power metering and discloses a method and device for predicting capacitor voltage transformer errors. The method comprises: inputting capacitor voltage transformer error data before the current moment and capacitor voltage transformer environmental parameter data at the current moment into a pre-trained prediction model to obtain the capacitor voltage transformer error at the current moment; wherein the prediction model is obtained by inputting historical capacitor voltage transformer error data and capacitor voltage transformer environmental parameter data into an RBF neural network training. Beneficial effects: The method can predict capacitor voltage transformer errors, promptly detect when the capacitor voltage transformer metering error exceeds a limit, and help maintenance personnel understand the deterioration trend of the metering error.

The invention discloses a broadband harmonic voltage measuring system and method based on an improved CVT, and the system comprises a first current sensor which is used for measuring the first current of a high-voltage capacitor of the CVT; the broadband harmonic wave acquisition device is used for sampling the first current to obtain first current sampling data; and the broadband harmonic analysis device is used for determining an amplitude frequency spectrum of the first current based on the first current sampling data and determining each frequency component of the system voltage based on the amplitude frequency spectrum of the first current. On the basis of a large number of CVTs used in a power system, the broadband harmonic voltage measurement function within the range of hundreds of kHz is achieved by improving the CVT, the original power frequency measurement function of the CVT is not changed, the operation reliability of the CVT is not reduced, and effective broadband, high-precision and low-cost harmonic voltage measurement can be achieved.

The invention provides a hooking system for a capacitor voltage transformer test. The hooking system comprises a base, a lifting device, a first rotary telescopic device, a first hook, a first patch cord and a control module, the lifting device is used for driving the first rotary telescopic device to ascend and descend in the vertical direction. The first rotary telescopic device is used for driving the first hook to rotate in the vertical direction and driving the first hook to stretch out and draw back in the horizontal direction. The first end of the first patch cord is arranged on the base, and the second end of the first patch cord is connected with the first hook; and the control module is used for controlling the lifting device and the first rotary telescopic device, so that the first hook is hooked at a target position of the capacitor voltage transformer. According to the hooking system for the capacitor voltage transformer test, mechanical adjustment of the spatial position of the first hook is realized, so that the first hook is efficiently and safely hooked at the target position of the capacitor voltage transformer.

The invention discloses a capacitor voltage transformer state monitoring method and device, equipment, a storage medium and a product, and relates to the technical field of fault diagnosis, and the method comprises the steps: collecting the operation state data, including a plurality of sub-operation state data, of each capacitor voltage transformer in real time; comparing the sub-operation state data with the corresponding sub-reference state data to obtain a first comparison result, and if the value of the sub-operation state data is greater than a corresponding threshold value, determining that a fault risk exists; otherwise, determining a fault characteristic value through the multiple sub-operation state data, and judging whether the fault characteristic value is greater than a fault threshold value or not to determine whether a fault risk exists or not. The fault feature value is determined by firstly determining each sub-feature value and then integrating the sub-feature values. After a fault risk exists, a priority value to be detected is obtained, a surface image of the largest value is shot, an abnormal part is analyzed and determined, and analysis comprises the steps of image segmentation, part image and reference image comparison and the like. The method can accurately diagnose faults and position abnormal parts.

The utility model belongs to the technical field of voltage transformers, and particularly relates to a capacitive voltage transformer, which comprises an oil tank and a transformer main body arranged on the upper surface of the oil tank, and is characterized in that the top of the oil tank and the top end of the transformer main body are fixedly sleeved with connecting discs through bolts; the two connecting plates are symmetrically arranged up and down, the connecting plates are installed on the two sides of the two connecting plates, the connecting plates are each provided with three sets of buffering and reinforcing devices from top to bottom, and the buffering and reinforcing devices are used for buffering and reinforcing the surface of the transformer body, so that the wind resistance is high, and the situation that the transformer body is damaged when encountering strong wind weather is avoided. And the capacitor voltage transformer is easy to break.

The invention provides a capacitor voltage transformer excitation characteristic test method based on model predictive control, which optimizes a voltage scanning strategy by constructing a model predictive optimization controller and adopting a model predictive control technology, can reduce the number and time of point-by-point scanning on the premise of ensuring the test precision, and improves the test efficiency. And the test efficiency is improved. By calculating the optimal control strategy in real time, the excessive voltage applied to the equipment in the test process is reduced, so that the overheat risk of the capacitor voltage transformer is reduced, the equipment is prevented from being damaged, and the long-term healthy operation of the equipment is ensured. The position of the inflection point is judged through the distortion coefficient, the demarcation point of the nonlinear area and the linear area of the capacitor voltage transformer can be accurately determined, an accurate excitation characteristic curve can be drawn through the least data points, and a large amount of time and resources in a traditional detection method are saved. The method is suitable for detection and health assessment of the capacitor voltage transformer.

The invention relates to the technical field of online monitoring of capacitor voltage transformers, in particular to a calibrator and method for an online monitoring device of a capacitor voltage transformer, the calibrator comprises a difference adding module, an algorithm module and a judgment module, the difference adding module generates a plurality of groups of differential voltage signals, inputs the differential voltage signals into the online monitoring device and forms parameter vectors to be estimated; the algorithm module obtains a related voltage amplitude calculation theoretical ratio error, and constructs a hybrid optimization algorithm in combination with a Markov chain Monte Carlo method and a simulated annealing algorithm to calculate a posterior probability density so as to obtain the uncertainty of an error measurement result; and the judgment module combines the historical average uncertainty, the real-time temperature and the use year of the online monitoring device to calculate a verification parameter, compares the verification parameter with a preset threshold value and outputs an abnormal judgment result. According to the invention, non-power-cut verification can be realized, the verification efficiency and accuracy are improved, and the reliability of power supply of a power grid is guaranteed.

The utility model discloses an MCU control module suitable for a capacitor voltage transformer, and the MCU control module comprises a host MCU and a slave MCU, and the host MCU and the slave MCU support wireless or wired communication. A host MCU chip (STM32L431RCT6) and a host clock circuit are arranged in the host MCU, and the slave MCU is provided with a slave MCU chip (also STM32L431RCT6) and a slave clock circuit. According to the design, accurate control and monitoring of the capacitor voltage transformer are achieved through efficient MCU cooperative work, and the operation efficiency and safety of a power system are improved.

The application discloses a kind of 110kV capacitor voltage transformer does not remove lead test method, comprising, by through-type current transformer, the test current flowing through primary lead is converted into secondary current;Utilize negative feedback amplification circuit to amplify the secondary current of the through-type current transformer, and the through-type current transformer is shielded and protected by full metal shield cover;The amplified through-type current transformer is connected into Xilin bridge, and the main capacitance, the voltage dividing capacitance, the main capacitor dielectric loss factor and the voltage dividing capacitor dielectric loss factor of the through-type current transformer are calculated.The application does not need to remove and restore high voltage lead, does not need high place operation, work intensity is greatly reduced, eliminates the risk of falling in high place operation;At the same time, accurate measurement of capacitance and dielectric loss can be realized.

The invention relates to a capacitive voltage transformer for a converter station of an extra-high voltage direct current transmission project, which is characterized in that a secondary coil A, a secondary coil B and a secondary coil C in a secondary winding of an intermediate transformer have the same wire diameter, and when the secondary winding is wound, a secondary residual coil is wound on an insulating paper tube; the da end of the secondary residual coil is led out from the head end of the insulating paper tube, the dn end of the secondary residual coil is led out from the tail end of the insulating paper tube, then a secondary coil D is wound on the secondary residual coil, the 4a and 4n ends of the secondary coil D are led out from the tail end of the insulating paper tube, and then a secondary coil A, a secondary coil B and a secondary coil C are simultaneously wound on the secondary coil D in parallel, and 1a and 1n ends of the secondary coil A, 2a and 2n ends of the secondary coil B and 3a and 3n ends of the secondary coil C are led out from the head end of the insulating paper tube. The method has better accuracy performance and higher overvoltage bearing capacity, and can meet the use requirements of the converter station of the extra-high voltage direct current transmission project.

The utility model discloses a wired synchronization module suitable for a capacitor voltage transformer. The wired synchronization module comprises a synchronous current detection circuit and a sequential circuit. The synchronous current detection circuit utilizes a current detection chip U1, receives 3.3 V working voltage synchronous signals through a signal input pin VI of the current detection chip U1, and outputs current detection signals to a VREF end through a signal output pin VO. The capacitor C1 and the capacitor C2 are respectively connected in series between the grounding pin GND and the signal input pin VI and between the grounding pin GND and the signal output pin VO to play a filtering role. The sequential circuit comprises a connector J1, an array resistor, a reverse protection diode D1 and two operational amplifier comparators U2 and U3. The operational amplifier comparator U2 and the operational amplifier comparator U3 further process the current detection signal and finally output a synchronizing signal through a 220SYNC line. According to the design, the precision of clock synchronization is improved, the anti-interference capability of the module is enhanced, and the stability and the reliability of a capacitor voltage transformer system are ensured.

The application relates to a capacitor voltage transformer for an extra-high voltage direct current transmission engineering converter station, wherein the wire diameters of a secondary coil A, a secondary coil B and a secondary coil C in a secondary winding of an intermediate transformer are the same, the secondary winding is wound on an insulating paper cylinder, a secondary residual coil is first wound on the insulating paper cylinder, a da end of the secondary residual coil is led out from a head end of the insulating paper cylinder, a dn end of the secondary residual coil is led out from a tail end of the insulating paper cylinder, a secondary coil D is then wound on the secondary residual coil, 4a and 4n ends of the secondary coil D are led out from the tail end of the insulating paper cylinder, the secondary coil A, the secondary coil B and the secondary coil C are simultaneously and parallelly wound on the secondary coil D, 1a and 1n ends of the secondary coil A, 2a and 2n ends of the secondary coil B and 3a and 3n ends of the secondary coil C are led out from the head end of the insulating paper cylinder. The application has better accuracy level performance and higher overvoltage bearing capacity, and can meet the use requirements of the extra-high voltage direct current transmission engineering converter station.

The application relates to an equal-potential core clamping plate for installing a capacitive voltage transformer, which belongs to the technical field of capacitors and comprises a clamping plate body, a binding belt groove, a binding belt, a brass insert, a fastening screw, a conductor ring, a connecting screw, a recessed groove and a buffer ring. The brass insert is integrally cast in the clamping plate body, effectively improving the fixing stability of the brass insert to the binding belt. The fastening operation of the clamping plate body and the binding belt is simple, effectively improving the bundling efficiency of the capacitive core stacking module. The multiple brass inserts are connected in series through the conductor ring, so that they are at the same potential, thereby reducing the potential difference between different insert tubes and reducing the discharge risk, and further effectively improving the electrical performance of the stacked capacitive core module. The brass insert is integrally connected in series with the conductor ring, effectively improving the integrally cast manufacturing of the brass insert and the clamping plate body, and facilitating the mass production and processing of the clamping plate body.

The present application relates to a kind of wind farm transmission line three-phase adaptive reclosing method and system based on frequency difference, belong to the field of power system relay protection.The method first in the maximum sliding time window, using capacitor voltage transformer (CVT) acquisition line M end voltage wave data and pre-processing;Using Fourier transform (FFT) to voltage signal is spectrum analyzed, obtain the amplitude-frequency curve with frequency as abscissa and amplitude as ordinate;Calibrate amplitude-frequency curve local peak, calculate the difference between the frequency corresponding to each peak;Adjacent sliding time window is judged whether the difference of frequency is equal, if equal, fault still exists, not reclosing circuit breaker, if the difference of frequency is not equal, then judge fault disappears, calculate the moment of fault disappearance, combined with the ionization after fault disappearance and determine reclosing time, output closing signal.The present application has lower sampling rate requirement, smaller error, easy to realize.

The present invention discloses a method for testing the ratio error of a capacitive voltage transformer using an equivalent method, belonging to the field of transformer measurement technology. Based on the Thevenin law, the CVT electromagnetic circuit is equivalent to a pure circuit, and the CVT ratio K is obtained to be equal to the product of the capacitive voltage divider CVD ratio K1 and the equivalent intermediate voltage transformer IVT ratio K2. The ratio error r% is approximately equal to the sum of r1% and r2%, simplifying the testing process. High-precision standard equipment and the differential measurement method are used to improve test accuracy. This method is applicable to CVTs with voltage levels of 110kV and above and is not restricted by environmental, spatial, and other factors.

The utility model discloses a clock chip module suitable for a capacitor voltage transformer, and the clock chip module comprises a clock chip U14, and is connected with a host MCU or a slave MCU through a serial clock pin SCL and a serial data pin SDA. The clock chip U14 is further provided with a clock signal output pin FOUT, a voltage input pin VDD, a grounding pin GND, an enabling pin FOE and an interruption pin INT. Wherein the SCL pin and the SDA pin are respectively connected with a 3.3 V MCU working voltage line through a resistor R79 and a resistor R80 so as to ensure that signals are stable; a VDD pin is connected with a 3.3 V working voltage line through a capacitor C71 to realize power supply filtering; and the FOE pin and the INT pin are respectively connected with the 3.3 V MCU working voltage line through a resistor R81 and a resistor R82 so as to enhance circuit protection. The module aims at providing high-precision and stable clock signals for the capacitor voltage transformer and ensuring reliable operation of a power system.

The utility model discloses a capacitor voltage transformer dielectric loss on-line monitoring device, which comprises a first electrode, a second electrode, a capacitor voltage transformer, a cross-core current transformer, a filter, an amplifier, a current detection unit and a signal processing unit, the first electrode and the second electrode are both sleeved on a supporting column of the capacitive voltage transformer, the cross-core current transformer is arranged on a low-voltage side of the capacitive voltage transformer, the filter is connected with the first electrode and the second electrode, and the amplifier is connected with the filter and the signal processing unit. The current detection unit is respectively connected with the straight-through current transformer and the signal processing unit; the capacitive voltage transformer dielectric loss on-line monitoring device provided by the utility model realizes accurate on-line monitoring of the dielectric loss of the capacitive voltage transformer, and improves the sensitivity and reliability of system fault detection.

The invention provides a capacitor breakdown fault diagnosis method for a capacitor voltage transformer, a simulink model is established by analyzing the structure of the CVT and the characteristics represented by capacitor breakdown fault types of different degrees, voltage signals under different capacitor breakdown degrees are simulated and output based on CVT data collected by a real power grid power station, and the fault diagnosis method for the capacitor breakdown fault of the capacitor voltage transformer is established. A voltage amplitude time sequence obtained by simulation is taken as an object, data of different time points at a fixed-size sliding window segmentation position is used, features extracted by a Minirocket algorithm are combined with step features, then the combined features are fused with a gradient boosting tree classifier, a time sequence with a fault point is classified and identified, and then a time interval of fault occurrence is determined. According to the method, shutdown detection is not needed, abnormal data can be clearly and quickly identified, and the depth of fault diagnosis types is improved while quick fault diagnosis of the capacitor voltage transformer is realized.

The present application relates to the technical field of high-voltage measuring device of electric multiple unit power system, and particularly relates to a capacitive voltage transformer for electric multiple unit. The voltage transformer is formed into an integrated full-enclosed main insulator by epoxy resin vacuum casting, and the primary high-voltage terminal is a stepped round table type standard C head structure. The inside is composed of a high-voltage capacitor and a low-voltage capacitor to form a capacitive divider, cooperate with a reactor to realize impedance compensation, cooperate with a damper to suppress resonance and overvoltage, and set a protection gap to realize overvoltage protection, and all wiring terminals are arranged in a sealed secondary wiring table. The present application has the advantages of capacitive voltage division and electromagnetic measurement, has the characteristics of small size, flexible installation, anti-resonance, anti-interference, high precision, strong protection, maintenance-free, etc., can adapt to the compact space and harsh operating environment of electric multiple unit, and is suitable for high-voltage measurement and relay protection system of electric multiple unit.

The present invention provides a method for measuring the voltage-dividing capacitance of a capacitor voltage transformer based on short-circuit frequency scanning, which belongs to the field of electrical insulation detection of power equipment. The method comprises: performing a first short-circuit impedance test on the capacitor voltage transformer, measuring the frequency-variable short-circuit impedance including the second capacitor, and obtaining a first frequency-variable short-circuit impedance; performing a second short-circuit impedance test, measuring the frequency-variable short-circuit impedance including the first capacitor and the second capacitor, and obtaining a second frequency-variable short-circuit impedance; drawing a frequency-variable short-circuit impedance curve based on the first frequency-variable short-circuit impedance and the second frequency-variable short-circuit impedance, and calculating a first capacitance reference value and a second capacitance reference value; using the first capacitance reference value and the second capacitance reference value, combined with the ratio of the intermediate voltage transformer, calculating the measured value of the voltage-dividing capacitance, and completing the voltage-dividing capacitance measurement of the capacitor voltage transformer. The present invention solves the problems of existing capacitance value measurement methods, such as complex wiring and a large influence of the wiring method on the accuracy.

The invention discloses a method and a device for preventive testing of a capacitor voltage transformer, and relates to the technical field of preventive testing of voltage transformers, and the method comprises the following steps: training an upper section error prediction model, a middle section error prediction model and a lower section error prediction model; reading an upper-section error prediction model, a middle-section error prediction model and a lower-section error prediction model corresponding to the model, and respectively obtaining an upper-section test dielectric loss value, a middle-section test dielectric loss value and a lower-section test dielectric loss value of the voltage transformer to be tested by using a test method without dismantling the high-voltage lead; on the basis of the lower section error characteristics, the lower section test dielectric loss value and the lower section error prediction model, lower section correction dielectric loss is obtained, and comprehensive dielectric loss is calculated; when a non-high-precision dielectric loss instrument is used for preventive testing, the measurement effect of a high-precision dielectric loss instrument can be achieved, and the purchase cost of the dielectric loss instrument is reduced.

The invention discloses a method, a system, a medium and a device for monitoring the abnormal voltage change of a capacitor voltage transformer (CVT), and relates to the technical field of electric power measurement monitoring, and the method comprises the steps: collecting the data of the CVT during normal operation, and constructing a reference time point variance data set; monitoring operation data of the current CVT, and constructing a monitoring time point variance data set; and comparing the reference time point variance data set with the monitoring time point variance data set to judge whether abnormal movement exists, and determining an abnormal phase according to the voltage fluctuation deviation. According to the method, the mathematical model is established for the collected CVT secondary voltage history and operation data, the operation data are compared and monitored, and the operation state of the metering device within a period of time is dynamically analyzed, so that the secondary voltage transaction can be found in time, the operation and maintenance personnel are assisted to detect the operation and maintenance on site in time, and the abnormality study and judgment capability and the working efficiency of the CVT device are improved.

The invention provides a method and device for detecting the health state of a capacitor voltage transformer, and the method comprises the steps: collecting the secondary voltage data of a to-be-detected capacitor voltage transformer; the collected secondary voltage data is compared with a preset voltage abnormity judgment threshold value, and when the capacitor voltage transformer is in an operation state and the duration time when the voltage is not in a normal range reaches a preset time threshold value, an abnormity alarm is given; wherein the voltage abnormity judgment threshold value is determined according to the voltage grade and type of the capacitor voltage transformer and the corresponding reference voltage. By monitoring the change of the secondary voltage of the capacitor voltage transformer, the defects of the capacitor voltage transformer are found in time, and the safety and reliability of a power system are improved.

The application discloses a kind of for ceramic capacitor electric, thermal and force synergistic optimization method and system, belong to high-voltage electrical insulation and ceramic capacitor design technical field.The method of the present application comprises: obtaining the calculation result of multi-physical field coupling model, based on the calculation result, multiple sensitive regions are identified, and the correlation between structure design variables and multiple sensitive regions is established;Determine the optimization target and / or constraint condition of the ceramic capacitor to be designed, and establish the evaluation function based on the optimization target and / or constraint condition;Based on the evaluation function and the correlation, iterative calculation is performed on the structure design variables to obtain the optimal structure parameters of the ceramic capacitor to be designed, and the optimal structure parameters are used as the optimization scheme, and the structure parameters of the ceramic capacitor to be designed are optimized based on the optimization scheme.The present application can be widely used in the design of capacitor voltage transformer, capacitor voltage dividing device, voltage equalizing capacitor and other high-voltage ceramic capacitor devices.

The present invention belongs to the technical field of mutual inductor measurement error identification, and discloses a CVT error online monitoring method and system based on the maximum approximate coefficient growth rate. The method of the present invention comprises: measuring the three-phase voltage data of the secondary side of the capacitor voltage transformer CVT, classifying the three-phase voltage data according to preset requirements, and obtaining training data; calculating the maximum approximate coefficient growth rate MACGR of the training data based on the wavelet analysis method; using the phase with the highest MACGR mean as the error exceeding limit check phase; calculating the error exceeding limit of the error exceeding limit check phase based on the kernel density algorithm; fitting the functional relationship between the error exceeding limit and MACGR to obtain a fitting result; evaluating the fitting result with a preset evaluation index, and monitoring the CVT error online through the evaluation result. The present invention can smoothly collect the CVT secondary side voltage and can identify the error exceeding limit of the CVT.

A method for measuring a dissipation factor of a voltage divider of a capacitor voltage transformer (CVT). The CVT includes a capacitor voltage divider (CVD), an intermediate voltage transformer (IVT), and a compensating reactor (CR). The CR is connected between the CVD and the IVT. The method includes measuring a grounded specimen test (GST) mode current that passes through a first capacitor of the CVD by coupling the current sensor in series with the first capacitor, measuring an ungrounded specimen test (UST) mode current that passes through a second capacitor of the CVD by coupling the current sensor in series with the second capacitor, and obtaining a dissipation factor of the CVD based on the GST mode current and the UST mode current.

The utility model relates to the technical field of transformer detection, and discloses an integrated mutual inductor detector which comprises a box body, one surface of the box body is used as a panel, and the panel is provided with a display screen, a CT line bank, a PT line bank, a power switch button and a selection switch button set. An electromagnetic voltage transformer detection board, a capacitor voltage transformer detection board and a current transformer detection board are installed in the box body. Data acquisition ports of the electromagnetic voltage transformer detection board, the capacitor voltage transformer detection board and the current transformer detection board are respectively connected with a CT connector bar or a PT connector bar through contacts of corresponding relays, and power supply ports are respectively connected with power supply wiring holes used for accessing a power supply through the contacts of the corresponding relays and a power supply switch. And the signal input and output ports are respectively connected with the display screen through contacts of the corresponding relays. According to the utility model, the detection convenience is improved.