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For split core current transformers installed in outdoor overhead lines or cable trenches, the cut surface of the transformer is exposed to the air and will be exposed to rain or soaked in water in the cable trench, which will cause rust and affect product performance. Water accumulation in the secondary terminal will also cause short circuit, so measures need to be taken to prevent rain or water accumulation. There are currently two solutions that can be used, which are briefly introduced as follows:   The first solution is to bury the secondary wire directly into the resin casting body (the wire uses a three-proof silicone wire) to prevent short circuits in the secondary terminal, and add a waterproof silicone ring to the cut surface for sealing and waterproofing. This solution has good protection for the secondary end and the cut surface, and can be widely used in all rain and water immersion occasions. In addition, because the base cannot be fixed in the cable trench, the base installation method is not used. The inner hole with a rubber plug is fixed on the cable. This installation method is used.   The second solution is the "open current transformer + silicone rubber sleeve" solution, which is also used by customers for installation on low-voltage outdoor lines. However, this method can only prevent light rain and cannot prevent immersion in water, so it cannot be used for installation in places where water may accumulate, such as cable trenches. This solution is limited by the specifications of the silicone rubber sleeve, and the inner diameter of the transformer can only be 50mm.   1. Principle of zero-sequence current transformer   In a three-phase four-wire system, the vector sum of the three-phase current is equal to zero, that is, Ia+Ib+Ic=0. If a current transformer is connected to the three-phase four-wire, the induced current is zero. When an electric shock or leakage fault occurs, there is leakage current flowing through the circuit. At this time, the vector sum of the three-phase current passing through the current transformer is not equal to zero, and its vector sum is: Ia+Ib+Ic=I (leakage current). In this way, there is an induced voltage in the secondary coil of the transformer, and this voltage is applied to the electronic amplifier circuit of the detection part. The transformer connected to the protection is called a zero-sequence current transformer. The vector sum of the three-phase current is not equal to zero, and the current generated is the zero-sequence current.   2. Application of zero-sequence current transformer   The zero-sequence current transformer is a single-turn through-type current transformer, but its primary winding is the three-phase conductor of the protected system (the three-phase conductor passes through the transformer ring core together), and the secondary winding reflects the zero-sequence current of the primary system. Zero-sequence current transformers are generally used in conjunction with small current grounding line selection devices, microcomputer detuning devices, etc. When zero-sequence grounding current is generated in the power system, it is used in conjunction with relay protection devices or signals to activate the device components to achieve protection or monitoring.   In the 10kV power supply and distribution system, zero-sequence current transformers are generally divided into high-voltage zero-sequence and low-voltage zero-sequence:   1. High-voltage zero-sequence   When a ground fault occurs on the lower side of the 10kV circuit breaker, the zero-sequence CT can detect the grounding current and trip the circuit breaker. However, when the circuit breaker is equipped with comprehensive protection (the internal software has the function of calculating zero-sequence current), the zero-sequence current can be calculated from the current of the three-phase current transformer, causing the circuit breaker to trip.   2. Transformer low-voltage zero sequence   Install at a position where all N-line currents at the neutral point of the transformer can be detected. If the three-phase load of the three-phase transformer is balanced, the total current passing through the neutral point should be 0. When an asymmetric load occurs during operation, current will pass through the neutral point, which generally does not cause damage to the equipment, but in extreme cases or when the deviation is large, voltage drift will occur, that is, the voltage is unstable and even burns out the electrical equipment or the transformer itself. Therefore, the equipment can be effectively protected by monitoring the neutral point current.   3. Selection of zero-sequence current transformer   1. Installation method   From the aspects of maintenance and installation, try to use an open-and-close zero-sequence current transformer.   2. Product structure   Select according to the actual use. Generally, most of them use cable type, and busbar type is used in very few occasions, such as zero-sequence protection of generator outlet.   3. Selection of zero-sequence current transformer ratio   For 10kV system, high-voltage zero-sequence can be selected according to the calculated protection setting. For example, when the protection setting is 80A, the protection action can be selected as 100/1 or 100/5.   Generally, transformers with a capacity of more than 500kVA are equipped with transformer low-voltage zero-sequence. The calculated current is obtained according to the installed capacity of a single transformer/0.4/1.732.   4. Selection of the inner diameter of the zero-sequence current transformer   When selecting the inner diameter of the zero-sequence current transformer, the inner diameter of the transformer is required to be 20-30mm larger than the outer diameter of the cable to facilitate installation and maintenance.

In many applications controlled by single-chip microcomputers, split core current transformers are used to convert signals that cannot be directly measured by single-chip microcomputers into electrical analog signals that can be processed by single-chip microcomputers, such as AC transmitters, pressure transmitters, and temperature transmitters. Transmitters, fluid quality transmitters, etc. Most early transmitters are voltage output types, which convert the measurement signal into a 0-5V voltage output. This is the direct output of the operational amplifier. The signal power is <0.05W. The digital signal is converted by the analog/digital conversion circuit for the single-chip microcomputer to read and control.   The split current transformer sends the lower water and upper steam condensate in the liquid level sensor to both sides of the transmitter bellows through the meter tube. The pressure difference on both sides of the bellows drives the mechanical amplification and installation. The pointer indicates the water level. Of course, there is also a transmitter that can convert electrical analog quality into digital quantity. The above is just a conceptual clarification of the difference between sensors and transmitters. Two-wire current output AC transmitters are widely used because of their extremely high anti-interference ability.   Precautions for using split-type current transformers:   1. Pay attention to the auxiliary power supply information on the product label. The auxiliary power supply level and polarity of the transmitter cannot be connected incorrectly, otherwise the transmitter will be damaged;   2. The transmitter is an integrated structure and cannot be disassembled. It should be prevented from collision and falling;   3. When the transmitter is used in a strong magnetic interference environment, please pay attention to the shielding of the input line and the output signal should be as short as possible. When the equipment is concentrated, the equipment distance should not be less than 10mm;   4. There is no lightning protection circuit inside this series of transmitters. When the input and output feeders of the transmitter are exposed to harsh outdoor environments, lightning protection measures should be taken;   5. This product is packaged in a flame-retardant ABS plastic shell. The temperature resistance of the shell is +85℃, and it will deform when baked at high temperature, affecting the product performance. Do not use or store the product near a heat source, and do not bake the product in a high-temperature box;   6. Do not damage or modify the product label or logo, and do not disassemble or modify the transmitter, otherwise the company will no longer provide the "three guarantees" (replacement, return, repair) service of the product.   Hemei Electronics has been developing in the power industry for more than ten years, focusing on the research of electromagnetic materials, electromagnetic equipment, electromagnetic shielding and other projects, producing silicon steel, Permalloy materials, magnetic cores, current transformers, power harvesting current transformers, magnetic shielding shells, common mode inductors, coupling transformers and other electromagnetic products, which are deeply trusted and supported by domestic and foreign customers. If you have any needs in this regard, please feel free to contact us, we will customize products that satisfy you.

The detachable low-voltage current transformer is also called the split core current transformer. It is mainly used in the transformation projects of the power distribution system of 0.66kV and below. It is easy to install, without removing the primary busbar, and can be operated with power on, which does not affect the normal power consumption of customers. It saves manpower, material resources, and financial resources for the transformation projects of users and improves efficiency. This series of current transformers can be used in conjunction with relay protection, measurement, and metering installation.   In the actual application process, there are always customers asking why the split-type current transformer makes noise during operation?   1. When the split-type current transformer is in operation, if the secondary output lines S1 and S2 are not connected reliably (that is, the secondary circuit is open), a noise will be generated. If it is operated for a long time, a large open-circuit voltage will be generated due to the saturation of the magnetic core, causing the iron core to heat up until the transformer burns out. For this reason, when the split-type current transformer makes noise during operation, first check whether the secondary output lines S1 and S2 of the transformer are connected firmly and reliably.   2. When installing the split-type current transformer, it is necessary to ensure that P1 of the upper shell corresponds to P1 of the lower shell on the same side, and P2 corresponds to P2 on the same side. The core of the split-type current transformer must be used in pairs. After the unpaired core is installed, there will be a gap on the contact surface, and the transformer will make a sound when it is used; therefore, when the split-type current transformer makes a sound during operation, check whether P1 and P2 on the same side of the upper and lower shells correspond.   3. When there are foreign objects on the upper and lower contact surfaces of the split-type current transformer core, a sound will be generated. Therefore, when installing, pay attention to the contact surface of the core to ensure that it is clean and free of foreign objects.   Hemei Electronics is located in Hefei, Anhui Province, China. Our products cover more than 30 provinces, cities and districts in China and are exported to more than 20 countries. The company mainly produces magnetic materials/current sensors/current transformers/transformer cores/magnetic shielding shells/common mode inductors/coupling coils and other products, which are mainly used in power, communications, environmental protection, water affairs, automobiles, high-speed rail, military industry, new energy, rail transit, smart cities, smart fire protection, intelligent low-voltage test units, industrial Internet of Things, industrial control automation, power station area transformation and other industries. Our quality is obvious to all and is deeply trusted by consumers. If you have any needs in this regard, please feel free to contact us.

The split core current transformer is suitable for indoor equipment with a rated voltage of 10kV and below. It is used for circuit control, maintenance and other functions. There are many names for split current transformers, such as card current transformer, combined transformer, split transformer, split power transformer, etc. There are so many names, which fully illustrates the versatility of the instrument, and this versatility shows its applicability.   The split current transformer is suitable for AC power systems below 10KV, 35KV power supply equipment, and microcomputer maintenance and current measurement. If you want to fully evaluate the characteristics of split current transformers, it can be said that split current transformers have the characteristics of light weight, small size, openable, and easy installation.   There are multiple series of split current transformers, such as ZK series, LMWK series and other outdoor series, AKH-0.66-K series, etc., which are mainly used in distribution system transformation projects. Of course, there are also national standard models for indoor open transformers, such as LMZK. There are still some open transformers on the market, such as LDZK, LZK, etc. Users may have a headache when seeing so many series, but in fact, there is no difference between these series. In fact, we can all regard them as the same product.   How to install the split current transformer product? Open the transformer installation screws and nuts, remove the lower body of the transformer, install the upper body of the transformer into the primary busbar of the power distribution system, close the lower body of the transformer, pass the installation screws of the transformer through the transformer, screw on the nuts on the upper and lower body fixing holes of the transformer, fix the upper and lower bodies of the transformer together, and then fix the transformer on the busbar through the installation fixing holes on both sides of the transformer to complete the installation of the transformer. Then connect the secondary side of the transformer to the measuring device.   Hemei Electronics is an innovative and developing enterprise. The company has excellent equipment, advanced technology and a complete quality assurance system. It is also one of China's self-operated import and export enterprises.     The company has strong technical force, exquisite production technology, advanced inspection equipment and excellent equipment, including fully automatic transformer inspection bench, intelligent transformer calibrator, interference discrimination partial discharge tester, three-frequency generator, high current withstand voltage tester, balance characteristic tester, and high current load tester, which provide reliable guarantee for the quality of transformer production and win the praise of users. The products are sold well in various places and exported to more than 20 regions including Europe, America, Africa, the Middle East and Southeast Asia.

The split core current transformer is mainly used for electrical measurement and electrical maintenance. It has the characteristics of high flexibility, good linearity, reliable operation, and convenient installation, especially its open-close structure can be completed without tools. Without changing the cable, the device can be used more and more widely. We can choose the corresponding split core current transformer ratio according to the operation requirements of the system.   Split core current transformer   1. Select the corresponding specification product according to the parameters such as primary current and busbar section. A wire passes through the window of the transformer.   2. When the instrument position of this device is far away from the current transformer or the loop load is large, the specification of 1A secondary current should be given priority;   3. Pay attention to the number and specifications of the busbar, and then we can determine to choose an split core current transformer that matches the window size.   4. We can choose the ratio of the rated current ratio according to the size of the measured current. We should choose a rated current that is two-thirds larger than the measured current;   But there are things that need to be paid attention to, for example, when we open the flap, stop the secondary wiring through the crimping piece, and reset the flap after the secondary wiring is led out. Electric energy metering can be directly applied to the small hole of the flip cover to increase the seal and prevent electricity theft.   The working current of the split current transformer does not exceed 1.1 times the rated value for a long time, but it can be used for a short time at 1.2 times the rated value, but pay attention to the time, the time cannot be too long, and the time cannot exceed 1 hour;   Split current transformers are suitable for general measurement and maintenance of highly maneuverable, limited space or non-continuous power systems.   Hemei Electronics, with products covering more than 30 provinces, cities and districts in China and exported to more than 20 regions, mainly produces magnetic materials/current transformers/power supply CT/transformer cores/electromagnetic shielding shells/high-frequency current transformers and other business segments. The products are mainly used in power, communications, environmental protection, water affairs, automobiles, high-speed rail, military industry, new energy, rail transit, smart cities, smart fire protection, intelligent low-voltage test units, industrial Internet of Things, industrial control automation, power station area transformation and other industries.   Hemei Electronics is an innovative development-oriented enterprise with excellent equipment, advanced technology and a complete quality assurance system. It is also one of China's self-operated import and export enterprises.

According to the installation location, the split current transformer can be divided into indoor and outdoor. The indoor type is less than 20kV; the outdoor type is greater than 35kV and above.   According to the installation method, it can be divided into wall type, support type and load type. The wall-mounted type is installed in the hole of the wall or metal structure to save the wall bushing; the support type is installed on the plane or column; the load type is 35kV and above transformer bushing or multi-oil circuit breaker oil tank. It is called sleeve type.   Split current transformers can be divided into dry type, casting type, oil-immersed type, etc. according to insulation performance. Dry impregnated insulation glue is suitable for the opening and closing of low-voltage household current transformers; the casting type uses epoxy resin as the insulating material, which is mainly used for current transformers of 35kV and below; the oil-immersed type is mostly outdoor.   According to the coupling mode of high and low voltage components, the new split current transformer can be divided into electromagnetic wave coupling, capacitive coupling and photoelectric coupling. Among them, the optical current transformer has better performance. The new type of open-close current transformer is characterized by no direct electromagnetic connection between high and low voltage, which greatly simplifies the insulation structure; no need to consume a lot of energy during the measurement process; no saturation, wide measurement range, fast transient response, high accuracy; light weight and low cost.   In the same circuit, a large number of open-close current transformers are usually required. High-voltage current transformers are usually composed of multiple independent magnetic cores and secondary windings, without magnetic connection, and the primary winding is shared, forming multiple secondary windings with the same current ratio and current mutual inductance. Equipment For open-close current transformers of 110kV and above, the primary winding is usually divided into several groups, and the series and parallel connections of the windings are changed by switching to obtain a mutual inductance ratio of 2:3.

The split core current transformer is a commonly used current transformer in the equipment. They have good sensing effect and can improve the efficiency of the equipment. It has a good effect in controlling current and completing the conversion of upper and lower voltages. How can we restore it to make it work smoothly and avoid vibration? You can try the following steps:   1. Fix with positioning screws: The positioning screws are locked 90° between the two positioning screws. In the traditional fixing method, the front end of the screw contacts the shaft, which may damage the shaft or make it difficult to remove.   2. Fix with clamping screws: Use the tightening force of the hexagon socket bolt to narrow the gap and clamp the shaft of the split and closing current transformer. This method is convenient for installation and removal without damaging the shaft.   3. Keyway fixing: Suitable for large torque transmission. In order to avoid axial sliding, the fixing screw and the clamping screw are usually separated from each other.   4. D hole fixing: If the motor shaft is D-type, if it cannot be fixed, the fixing screw hole split current transformer can be processed into the D hole size corresponding to the motor shaft and fixed with a fixing screw without worrying about slipping.   5. Fixing of shrink sleeve: Tighten the four positioning screws on the end face to compress the sleeve, which is suitable for the connection and fixation of some high-torque stepper motors and servo motors.   The split type current transformer can switch between high and low voltages sensitively, allowing the device to switch back and forth at different voltages. The normal operation of the maintenance equipment is mainly restored through these methods.

When the split core current transformer is operating normally, everyone should stop the device according to the technical requirements such as the specification book. To be more clear, let's take a look at this.   1. The split-type current transformer is constructed according to the drawings, the wiring is correct, the wire number labels at both ends are clear, and the label range meets the requirements.   2. The current and voltage circuits should be grounded at the secondary side outlet of the transformer. The voltage circuit should be maintained with a fuse.   3. The secondary circuit of the panel cabinet should not have a connector, and there should be no connector in the middle of the control cable or line. If there is a connector, it should be connected through its long junction box.   4. The secondary circuit of the split-type current transformer should be well insulated from the ground, and the voltage circuit and the current circuit should not be mixed.   5. The wiring of the secondary circuit should be arranged evenly and beautifully, and the connecting screws of the wiring and electrical components and junction boxes should not be loose. The spacing between the wiring binding points should meet the requirements.   6. The cycle cannot be reversed, and the phase sequence and phase difference should meet the design and specification requirements. For the transformer wiring with differential maintenance, it is necessary to measure the phasor diagram of the two arms before putting it into operation to check the correctness of the wiring.   7. Copper wire should be used for the secondary circuit conductor or cable. The cross section of the voltage transformer loop shall not be less than 1.5mm. Special current terminals should be selected for the socket junction box. The unused secondary winding of the transformer should be short-circuited and grounded on the terminal board.   The above are the requirements that should be followed when installing the split-type current transformer. In order to ensure normal operation and prevent future problems, everyone needs to follow the correct installation steps when installing. While meeting their technical requirements, we hope to deepen everyone's understanding of the product.

At present, many automation equipment requires some induction equipment, such as split core current transformers. As long as the split current transformer is used, the induction work can be completed and the automation of the equipment can be completed. You can also change the voltage. So, what kind of equipment do we need to test the transformer?   1. Current booster: used in conjunction with the voltage regulator, it can generate various experimental currents required. Its capacity and cost increase with the increase of current.   2. Standard current transformer: used as a standard instrument for verifying transformers. Its accuracy is usually more than two levels higher than the accuracy of the device under test.   3. Transformer calibrator: can measure the error between the standard current transformer and the experimental switch current transformer, and display the working current.   4. Load box: can simulate the actual working state of the switch current transformer under experimental conditions.   5. Voltage regulator: used to adjust and test current, usually on the same control platform as the maintenance switch device, divided into coarse adjustment and fine adjustment voltage regulators to meet the needs of fine adjustment.   6. High current connection cable: used to connect hundreds or thousands of amperes of current.   The open-close current transformer has a strong inductive ability and can be used flexibly to switch between high and low voltages. During operation, it can prevent abnormal operation of the equipment due to excessively high or low voltage.   Hemei Electronics attaches great importance to technological innovation and product development, and has obtained a number of intellectual property rights. The company has strong technical strength, exquisite production technology, advanced inspection equipment and excellent equipment, including fully automatic transformer inspection bench, intelligent transformer calibrator, interference discrimination partial discharge tester, three-frequency generator, high current withstand voltage tester, balance characteristic tester, and high current load tester, which provide reliable guarantees for the quality of transformer production and are well received by users. The products are sold well in various places and exported to more than 20 regions including Europe, America, Africa, the Middle East and Southeast Asia.   On the way of exploration and discovery, leading the industry with innovation and setting a benchmark with quality has always been the purpose of Hemei's development. We are anxious about what customers are anxious about, think about what customers think about, and always put the interests of customers in mind. From understanding customer needs, to designing and producing products, to delivering products to customers in a timely manner, and to providing follow-up services, Hemei people always have only one thought in mind: service and customer satisfaction. Seeking truth and innovation is the unremitting pursuit of Hemei people.

The opening and closing of the split current transformer often encounters various problems in practical applications. The following summarizes several common faults and treatment methods in transformer applications:   1. Insulation caused by thermal breakdown.   Jewelry can accept high-voltage split current transformers with better stability, but in individual cases, when the current is large, but due to the high voltage, a higher insulation medium temperature will be generated. Once the acceptable temperature is exceeded, they can raise high-temperature insulation materials. Failure, resulting in split current transformer failure.   2. Problems caused by partial discharge.   The main capacitor of the 220kV normally open jewelry split current transformer is evenly distributed, but if the process does not meet the specifications, due to the stability of the process, the capacitor plate will not meet the requirements, which will cause the surrounding insulation to loosen. If it is not grasped well, it will cause uneven capacitor screen dislocation, U-shaped clips, because the credit card is too tight, the insulation will be deformed, the integrated bubbles and it is easy to change the voltage distribution, which will make the field strength of the other capacitor screen higher than the other, resulting in partial discharge, if not tested and handled in time, capacitor core rod failure will occur.   3. Humid environment.   Due to its poor quality, the gem of the internal open-close current transformer can produce intense discharge. The liquid produced in a humid environment will accumulate at the bottom of the capacitor core rod, so the curved part of the capacitor core rod becomes a heat-insulating material. The effect is very poor. Because they are in working condition for a long time, it is easy to form a capacitor core rod synthesis, which makes it produce power problems.   4. Reasons for insufficient drying and degassing.   CT needs to stop the vacuum oil filling project, otherwise the gas cannot be discharged and the vacuum state cannot be formed. In addition, the short degassing time leads to unclean degassing. Under the dual action of voltage and temperature, the current sensing device will heat up from time to time, causing mobile phone aging and failure, causing problems.   5. Personnel use errors.   The open-close current transformer is a relatively common fault, which is more likely to be caused by personnel, mainly due to personnel use errors, which together lead to loosening due to poor quality, secondary winding open circuit and other reasons during the vacuum oil stop process. , These uses will only cause partial overheating or discharge of the local power system. The emergence of these conditions will cause abnormal results of oil-soluble gas chromatography analysis.

The secondary grounding of the split current transformer refers to the grounding of the secondary S2 terminal of the current transformer or the grounding of the N terminal of the voltage transformer. The secondary and primary windings of the split current transformer only need to be grounded at a single point. Before grounding, the secondary winding has no potential contact with the earth. After grounding, the split current transformer will not form a loop with the ground, and the current will not flow to the ground during normal operation. When the insulation layer between the primary winding and the secondary winding is damaged, the primary high voltage is connected in series to the secondary circuit, and the primary high voltage is grounded at a fixed potential, so that the current flows to the ground. The secondary voltage of the split current transformer is grounded to ensure the secondary appearance and personal safety.   Note: The current transformer can only be grounded at one point. Regarding the secondary circuit of the current transformer, it is maintenance grounding. Grounding can avoid grounding current between multiple connection addresses and affect the information collected by the split current transformer.   1. What is the significance of a small stranding?   Answer: The secondary side of the current/voltage transformer is grounded at a certain point on its n line.   2. Why is the current transformer grounded only at one point?   Answer: The current at the two grounding points of the secondary circuit will be deflected. In other words, some current flows into the air through one point and then flows back through another point. Stop the current sampling of the connected maintenance/measurement/metering equipment, which may lead to incorrect maintenance use.   3. Why can the voltage transformer only be grounded at one point?   Answer: Two-point grounding will cause the neutral point potential of the secondary voltage circuit n line (ie N600) to shift. Stop the voltage sampling on all equipment, which can easily lead to incorrect maintenance use.

Transformers are an indispensable part of the power system. Its core function is to measure current or voltage and provide accurate primary current and voltage measurements for secondary maintenance and control equipment. Measurement accuracy, transient characteristics, stability and anti-interference performance are important indicators for measuring the quality of transformers. With the increase in voltage levels and the continuous increase in transmission capacity of power systems, the defects of traditional current transformers such as difficult insulation, easy saturation, poor transient performance and large size have gradually become prominent. In order to suppress the various shortcomings of traditional transformers and ensure the stable operation of the power grid, after years of technical research, flexible transformers have been successfully developed. The core equipment of this transformer adopts an all-optical structure, which can accurately transmit DC components, fundamental components and higher harmonics. One coil can measure currents of hundreds of thousands of amperes, and the instantaneous error of transient current is reduced to less than 10%, which is an effective improvement. It has high harmonic control accuracy and strong anti-electromagnetic interference ability, and is suitable for different industries such as large thermal power, nuclear power, gas, hydropower, etc. It is also suitable for rapid investigation and positioning of open cable faults in large cities. In order to limit the small space of the device, the volume and overweight of the transformer, the sensor ring is made into an optical cable by utilizing the soft and flexible characteristics of the sensor optical fiber, which can be installed on wires of all shapes. The weight of the surrounding area is reduced by more than 90%, with the advantages of sensitive equipment, cumbersome maintenance, and strong compliance. At the same time, the sensor optical fiber ring cannot cut off the original primary circuit in the station during installation, and can temporarily or permanently increase the measurement points in the system, so that the device stops running when the substation is running without causing power outages on the measured line. It is particularly suitable for substation transformation, power plants and other applications.   It is understood that the flexible transformer has been recognized by the industry as a promising new type of current transformer. After years of hard work, a complete product line of photoelectric current transformers has been formed, covering various voltage levels from 66kV to 800kV, covering column type, GIS type, bushing type, flexible type, etc., and many devices have been stably operated in smart substations.