Surge, also known as surge, as the name suggests, is an instantaneous overvoltage that exceeds the normal operating voltage. Essentially, a surge is a strong pulse that occurs only in a few millionths of a second. Possible reasons for surge generation include bulky equipment, short circuits, power switching, or large engines. Products with surge blocking devices can effectively absorb sudden and huge energy, protecting connected equipment from damage. Surge protector, also known as lightning arrester, is an electronic device that provides safety protection for various electronic equipment, instruments and communication lines. When a sudden peak current or voltage occurs in the circuit or communication line due to external interference, the Surge protector can shunt in a very short time, so as to avoid the damage of surge to other DC Surge protector devices in the circuit. The graded protection of Surge protector (also called surge arrester) needs to release the lightning energy to the ground gradually through graded discharge because of the huge lightning energy. The first level lightning arrester can release direct lightning current or the enormous energy transmitted by transmission lines when subjected to direct lightning strikes. For places that may be directly struck by lightning, primary lightning protection must be implemented. The second lightning arrester is a protective device for the residual voltage of the previous lightning arrester and induced lightning strikes in the area. After the energy of the previous lightning stroke is absorbed, there is still a large part of energy for the device or the third arrester. The DC Surge protector needs to be further absorbed by the second arrester. At the same time, the transmission line through a lightning protection device will also induce lightning Electromagnetic pulse radiation LEMP. When the line is long enough, the induced lightning energy will become large enough, so the second lightning protection device needs to further release the lightning energy. The third lightning protection device protects LEMP and the remaining lightning energy passing through the second lightning protection device. The length of the connection should be as short as possible. One of the essence of device protection is to ensure that the high voltage of the circuit is less than the high withstand voltage of the device. The protection level of surge protectors needs to be selected according to the specific protected equipment. One rule to observe is that the wiring length from the grounding terminal of the surge protector to its protective circuit breaker (fuse) shall not exceed 50 cm, and the feeder of the DC Surge protector standby equipment to be protected must be correctly connected with the surge protector terminal and the protective circuit breaker terminal. The phase line, zero line and ground wire must be closely connected to reduce the surface area of the circuit. The wiring of the incoming and outgoing lines of the Surge protector must be independent of each other to reduce the interference to the protected line. The cables must be laid flat on the metal frame of the distribution cabinet to reduce the circulation of the frame and enhance the effectiveness of shielding interference. If the protected load is particularly sensitive to overvoltage, but the distribution box is made of plastic, the plastic distribution box must be replaced with a metal distribution box. In any case, it is necessary to check whether the metal frame of the distribution cabinet is grounded through a short circuit. Finally, if shielded cables are used, invalid additional cable lengths must be removed, otherwise the shielding effect will be reduced.

When the single-phase line is under voltage, the line will be cut off and the single-phase line voltage will return to normal. After a delay, the line will automatically reset and connect without the need for manual operation. 2. When transient or transient overvoltage occurs on the line, the protector will not cause misoperation. 3. When the voltage of the circuit is unstable due to faults such as accidental contact, or when there is a sudden power outage or incoming call, the protector will not connect the circuit. When the circuit fault voltage is high, the protector itself will not be damaged. 5. The protector is characterized by inverse time action, with an action time of ≤ 1s. 6. Voltage protection range: 0~450V below 40A, 0~600V for 50/60A. 7. Impulse withstand voltage: 4kV (in accordance with Class III electrical safety standards). 8. The protector has a dual color LED indicating the working status, green indicating normal voltage, and red indicating undervoltage or delay. 9. Modular design of appearance and installation of guide rails. 10. Wiring capacity: Insulated wires of 25mm2 and below.

Soft starter and frequency converter are two widely used devices in the field of industrial control. The following will explain the differences between soft starter and frequency converter: 1. The control principles of soft starter and frequency converter are different. Soft starter is actually an excessive control device, which is an industrial control product between the star triangle starting device and frequency converter. Its functions are more than the star triangle starting device, but less than the frequency converter. From the perspective of the main circuit of the soft starter, it is a three-phase anti parallel thyristor connected in series between the power supply and the controlled motor. Then, the internal digital circuit controls the moment when the thyristor conducts within a complete sine waveform of AC power. If the thyristor is allowed to conduct at the beginning of an AC cycle, the output voltage of the soft starter is high. If the thyristor is allowed to conduct at a certain position in an AC cycle, So the voltage output by the soft starter is low. We use this method to gradually increase the voltage at the motor end during the starting process, thereby controlling the starting current and torque of the motor to achieve a smooth start. It can be seen that the soft starter can only change the voltage of the power supply, not the frequency of the power supply. The principle of the frequency converter is relatively complicated. Its function is to change the power supply with voltage of 380V/220V and frequency of 50HZ into an AC power conversion device with adjustable voltage and frequency. The torque and speed of the AC motor can be adjusted by adjusting the frequency and voltage of the power supply. We can see from the main circuit that its main circuit is composed of another six Field-effect transistor, Under the precise control of the control circuit, six field-effect transistors are turned on in turn. The more times the tubes are turned on per unit time, the higher the output voltage and frequency. Therefore, this main circuit is controlled by a digital control circuit to achieve frequency regulation and voltage regulation of the output power supply. 2. The purpose of soft starters and frequency converters is different. The main problem that soft starters solve is to reduce the starting current of large loads and reduce the impact on the power grid. The startup of large equipment will generate a very large starting current, which will cause a significant voltage drop. If traditional step-down methods such as star delta are used, it will not only cause a significant current impact on the power grid, but also cause a significant mechanical impact on the load. In this case, a soft starter is often used for startup to achieve a smooth start of the motor and reduce the power supply capacity. The frequency converter is mainly used in places with speed regulation. It can control the speed of three-phase motors. For example, the frequency converter can be used in the speed regulation of spindle motors of CNC machine tools, the transmission control of mechanical conveyor belts, large fans, and applications of heavy machinery. In general, its function and practicability are far greater than those of soft starters The control function of the frequency converter of the soft starter is different. The main function of the soft starter is to adjust the starting voltage of the motor, achieve smooth starting of the motor, and reduce the impact of the motor on the machinery and power grid. However, because it controls the voltage by controlling the conduction angle for chopping, and the output is an incomplete sine wave, this leads to low starting torque, high noise, and high harmonics, which can pollute the power grid. Although the soft starter also has various functions such as limited current function setting and startup time setting