(3) Overvoltage protector
1. Quadrupole combined overvoltage protector 1. Product Description: Quadrupole combined overvoltage protector is a new type of overvoltage protector developed for the weak phase-to-phase overvoltage protection level of traditional overvoltage protectors. The product adopts four-star structure, which can provide overvoltage protection to ground and interphase at the same time. In particular, it plays a very good role in protecting the interception overvoltage and reignition overvoltage caused by vacuum circuit breaker opening. It is mainly used to protect transformers, switches, buses, motors and other electrical equipment, and can play a good role in protecting atmospheric overvoltage and operating overvoltage. 2. Normal service conditions (1) are suitable for indoor and outdoor use; (2) Ambient temperature: not lower than -40℃ and not higher than+40℃; (3) The altitude does not exceed 3,000 meters; (4) Power grid frequency: 58 ~ 62hz (60hz system) and 48 ~ 52hz (50hz system); (5) The power frequency voltage applied between the terminals of the overvoltage protector for a long time shall not exceed the continuous working voltage of the overvoltage protector; (6) areas with earthquake intensity of 7 degrees and below; (7) The maximum wind speed shall not exceed 35m/s ... 3. Model description: JY-SGB-□ /□-class (A, B, C) Field Recorder of Jiyi Technology (F) Over-voltage (Z, D, R) in the field of four-pole combination use (C, W) Whether there is a gap between the rated voltages of protectors (3, 6)
(4) Grounding resistance of transformer neutral point
☆ This product is used in 6 ~ 35kV AC power grid, and the neutral point of power grid can be grounded by ungrounded, arc suppression coil grounding, large resistance grounding, medium resistance grounding and small resistance grounding. In the cable power supply system, the grounding capacitor current is large. When the current is greater than the specified value, arc grounding overvoltage may occur. The purpose of adopting resistive grounding mode is to inject resistive current into the fault point, make the grounding fault current resistive-capacitive, reduce the phase difference angle with the voltage, reduce the reignition rate of the fault point current after zero-crossing arc extinguishing, and limit the overvoltage to 2.6 times of the phase voltage. At the same time, the sensitivity of relay protection action in tripping is improved. So as to effectively protect the normal operation of the system. Transformer neutral grounding resistance is suitable for medium and small resistance grounding mode. It is installed on the neutral point of transformers or generators in 6~35kV alternating current networks, such as auxiliary power system of power plants, power supply system of substations and distribution system of industrial and mining enterprises, so as to realize the grounding operation of these networks through neutral point resistance. ☆ Product features ◆ Manufactured according to standards to meet system requirements. Transformer neutral grounding resistance is designed and manufactured in strict accordance with DL/T 780-2001(NEQ ANSI/IEEE 32-1990), which meets the system requirements. ◆ Nickel-chromium alloy resistance material is adopted, and the resistance material of transformer neutral grounding resistance with high temperature resistance is nickel-chromium alloy. The melting temperature of Ni-Cr alloy is 65,438+0,500℃, and the working temperature can reach above 65,438+0,000℃. Therefore, this resistor is resistant to high temperature, especially suitable for systems with large grounding capacitance current. ◆ High resistivity, low temperature coefficient and stable resistance. Compared with other stainless steel materials, Ni-Cr alloy material has high resistivity, up to1.08 μ ω om, low temperature coefficient and stable resistance, which is beneficial to ensure the sensitivity of relay protection. The mechanical strength of Ni-Cr alloy material with high tensile strength and toughness is basically unchanged at high temperature, and it still maintains good toughness under the condition of rapid temperature change, and it is not easy to break, so it is suitable for the working condition of instantaneous large current impact at neutral point. ◆ Modular unit, flexible and convenient to use. When designing the grounding resistance of transformer neutral point, the use situation should be fully considered. The resistance unit is modular and can be combined in series and parallel at will to meet the needs of different currents, voltages and resistance values. Meanwhile, the resistor can be used in parallel with a resistor or a reactor. Generally, the initial power grid construction scale is relatively small, so the resistance of neutral point resistance is relatively large and the grounding current is relatively small. However, with the gradual expansion of the system, it is required that the grounding resistance be reduced and the grounding current be increased. At this time, as long as a suitable resistor is connected in parallel with the original resistor, the capacity expansion and capacity expansion can be conveniently realized. Reactors can also be connected in parallel to form an impedance grounding mode. ◆ Heat dissipation structure design ensures the safe operation of the equipment. The heat capacity of metal resistance is small, and the temperature rises when working. Therefore, when designing, the need of heat dissipation was fully considered. The cabinet structure has a cooling airflow channel, which has good heat dissipation effect and ensures the rapid cooling of resistance elements and the safe operation of resistance under various working conditions. ◆ The monitoring function is complete, providing analog output for microcomputer protection. The neutral grounding resistor of transformer is equipped with current transformer and action counter, which can monitor the unbalanced current of neutral point under normal circumstances, and the action counter can effectively record the times when the resistor is connected to the power grid (that is, the times of single-phase grounding). And can provide analog output to the protection and monitoring system according to the requirements of relay protection. ◆ It can be used with grounding transformer. When the transformer windings are connected in a triangle, and it is necessary to install a Z-winding grounding transformer separately, the neutral grounding resistance of the transformer can be used together with the grounding transformer. ◆ It can be used in different working environments. Transformer neutral grounding resistance shell can be sprayed with stainless steel or cold-rolled steel plate according to user's requirements to meet the needs of different indoor and outdoor environments. Moreover, the nickel-chromium alloy material has strong oxidation resistance: it can still maintain good oxidation resistance at high temperature and can be applied to a wide range of working environments. ◆ Various incoming modes The incoming modes of neutral grounding resistance of JY-JZB transformer can be different according to the needs of users, such as up and down, so as to facilitate on-site installation. In addition, disconnectors can be installed according to users' needs, which is convenient for maintenance.