Discussion on generator short-circuit protection of high-voltage current-limiting fuse combination protection device Guo Sijun Hefei Kaili Electronics Co., Ltd., Hefei, Anhui Province, and protection device, and discusses its principle. Structure and characteristics, expounding its scope of application and its development in the future. Overview With the continuous increase of electricity consumption, the installed capacity of power stations is continuously increasing, which has higher requirements on the reliability and economical efficiency of power station operation. The short-circuit protection of the power system of the power plant puts forward higher requirements that not only can the circuit breaker cut off the normal load, but also can reliably eliminate the short-circuit fault in the event of a short-circuit fault. At the same time, it can also assume the dual tasks of control and protection. China's small and medium-sized generators directly use 3,10,200-type low-oil circuit breakers, which have the disadvantages of long closing time, unsuitable for frequent operation, large volume and large maintenance volume. Therefore, many manufacturers nowadays use vacuum circuit breakers. However, No matter whether it is a low-oil switch or a vacuum circuit breaker, there are many problems in the short-circuit current. The non-periodic component is very large. When the generator port fails, the short-circuit current at this time is provided by the generator due to the generator 1 and 1 is the synchronous reactance of the generator, and the total resistance of the generator stator circuit is large, so the short-circuit current decay time constant when the fault occurs is large, causing the current in several weeks but zero, that is, the so-called zero-crossing due to the alternating current The disconnection is based on the fact that the input fracture energy is zero when the current zero crosses and the arcing time is as short as possible. The zero-loss phenomenon seriously deteriorates the working condition of the circuit breaker, resulting in difficulty in opening and closing the arc, even if the circuit breaker can open and close the short-circuit current. The protection provided has a definite lag with respect to the time of occurrence of the fault, especially for many types of AC circuit breakers, which can only quench the arc when the current passes through zero. The time difference between the final purpose screen for reaching the breaking fault and the relay protection is too long. Usually it takes several cycles. This long time does not provide proper protection for certain electrical equipment. The peak value of the bean current has been several times inrushing the generator circuit breakers and transformers, and the generators and circuit breakers have a lot of electric power and thermal effects. Therefore, the circuit breaker protection method is not very effective at the time of receiving the publication date of 199930. Several major accidents may have damaged the generators that cost millions of dollars in Taiwan's production costs, and cows may have a coal-fired circuit breaker. The short circuit of the core occurs at the input end of the transformer. The mountain circuit breaker cannot quickly cut off the short circuit current. The arc energy generated by the long-term short-circuit current will make the rated current of the transformer blow-out breaker during normal operation very small, and when a short circuit fault occurs. Short circuit current is very large, there is a contradiction between the rated current and the short-circuit current is too large, especially the continuous increase in the capacity of modern power systems, the short-circuit current value is also rising, a strong short-circuit current generated by the electrodynamic destructive will be greater, open circuit The device is selected according to the short-circuit and open circuit, and the equipment circuit and the circuit breaker itself must be designed with sufficient thermal stability. Therefore, the investment in the equipment plus the artificial price is too high. The electric appliance is set up so that a short circuit can be found short-circuited instantaneously, and the short-circuit current is not yet present. Cut the cap! When the value is high, the current of the plate making circuit will be prevented from being subjected to extreme thermal shock and electric force. Here, we recommend a new type of circuit protection equipment, that is, high-voltage current-limiting fuse combination protection device is abbreviated as 2 basic structure and operation principle. Foolish is mainly composed of the following three parts: 1. Current-limiting fuses; high-energy zinc oxide resistors; An organic combination of load switch users replaces the circuit breaker, and the circuit breaker fast fuse of the set control and protection body is opened, and the general overload current and the rated current are broken by the load switch, and the limit of the high energy zinc oxide resistance is utilized. Pressure and energy transfer enable rapid arc extinguishing to limit overvoltage 1 Current limiting fuses Current limiting fuses have two significant advantages over circuit breakers, namely current limiting and rapidity. A large half-wave short-circuit current also has to rise in the future to limit and forcibly cut off the short-circuit current 02, so that the current reaches the desired short-circuit current peak. 1. When the short-circuit current rises, the fuse blows and shuts off. The cutoff current is only about 1 of the expected current peak. However, the arc voltage will be generated when the fuse is blown, and it may reach several tens or even hundreds of atmospheric pressures. In order to solve the problem of the overvoltage of the fuse, the nonlinearity of the zinc oxide resistance is used to realize the voltage limiting energy dissipation and the arc voltage generated by the fuse. The current is submerged in and the zinc resistance rapidly decays. Each phase fuse is loaded with a single striker. As long as there is a phase fuse action, the striker strikes the load switch and trips. The auxiliary auxiliary switch sends a signal to the control room and displays the action signal on the screen. . The load switch action is no electricity breaking, which prolongs the inspection period and service life, and at the same time, it avoids that the load switch combined with the fuse, such as the missing phase operation set of the electric appliance, only needs to be able to break the rated current and the general overload current. Short-circuit current and short-circuit current withstand dynamic stability and thermal stability, there is no requirement that such a load switch body can be done much less than the oil and Khan Kuan and vacuum circuit breakers, the price is very low, a few simple structure and The high-energy zinc oxide electric muscles are connected in parallel and installed on the power supply side of the load switch. They can also be installed on the feed side of the load switch. When the fuses do not need to be frequently exchanged, the former arrangement should be adopted so that the fuses can protect the load switch itself. In the event of a short circuit accident, the latter arrangement should be used to facilitate the use of 2 high-energy zinc oxide resistors as non-linear resistors with solid-state sensitive components that have non-linear volt-ampere characteristics and suppress transient overvoltages, when the terminal voltage is lower than a certain When the threshold is reached, the current is almost zero; when the threshold is exceeded, the current will be large and sharp with the terminal voltage. Using the good nonlinearity of the zinc oxide resistor, the operating overvoltage generated when the fuse is opened can be limited to 25 times the phase voltage. At the same time, the energy of the zinc oxide resistor can be tens or even more monolithic. This ensures that there is enough capacity to absorb the magnetic field energy in the system when the corresponding cut-off current decays to zero. The pressure on the crowbar housing is relieved so that the electrical equipment is no longer subject to the impact of large currents, and at the same time, the current is quickly attenuated to zero within 0 to 2, and the energy provided by the power source is minimized. Its non-linear characteristic 2, is the direct current 1 reference voltage, the residual pressure when the current flows into the current in the zinc oxide valve slice through the zinc oxide valve slice accurately measures and selects, together, the small online connection contains the ballast to be able to realize the mishap . Can carry cargo load switch negative load switch with Shangzhong fire arc chamber device can also be used as closing and breaking no-load long-line no-load transformer and capacitor load switch function as isolating switch Complete equipment installed in the transformer, side, into On behalf of him, the principle of the installation of the power-supply equipment is that the disconnector is only a zinc oxide resistor, 15 is a load switch = 3 is the fuse of the fuse zinc oxide resistance and the load switch parameter is selected, the principle of the mouth parameter selection is that, in addition to the short circuit , Do not operate under any circumstances, limit and remove the short-circuit current as soon as possible in the short-circuit fault, 4 According to the combination curve of rectification, enthalpy, and fatigue, the rated current of the fuse is greater than the 4 of the transformer core, ie 1.47, cut off. The ampere-second characteristic curve 1 of the device should be located at about 25 of the transformer overload line 2 side, so that the transformer can be ensured, and the misalignment of the transformer can be prevented from malfunctioning. The magnetizing impulse current at the time of closing is 12 times of the full load current, and the allowable duration is 0.18. Therefore, the fuse must pass the 12 times change the full load current of the instrument and the 018 curve 4 and continuous impact 100 times without aging. Phenomenon According to the above-mentioned vertical selection, the cut-out of the factory transformer occurred at 26 o'clock; the jet was not affected by the boundary, and when 凡 = 3.8, the mixing of the jet and the environmental water was severely affected by the bottom boundary. The jet continuous jet flow is mixed with the ambient water body to a very large extent; the extremities are the same; when the initial stage of the jet is smaller than the jet duration, the pulsed jet stream has no difference with the continuous jet stream, but, when The extent to which the non-dimensional position of the front of the pulse jet has no relation to the duration of the pulse jet is independent of the degree to which the floating jet no longer has a decrease in momentum. This characteristic is the same as that of the continuous jet. The influence of the bottom boundary on the jet is mainly determined by the buoyancy acceleration of the jet outlet flow duration and the influence of the jet orifice from the bottom boundary.
This research method and preliminary results have laid the foundation for the research, development and work of river bottom jets. Yu Guoliang, 1964, Male, Changsha, Hunan Province, College of Hydroelectric Researcher, engaged in research on river sediment dynamics; Zhuang 1957, female, Chengdu, engineer at the State Key Laboratory of Speed ​​Hydraulics at the University, engaged in research on hydraulics and river dynamics; Liao Neiping 15 years, male, Yibin, engineer of Southwest Electric Power Design Institute of National Electric Power Company, engaged in thermal power plant Hydraulic engineering and other design work.
The load switch is only used for breaking the rated current and general overload current, greatly reducing the burden of the load switch, prolonging the service life and the dangerous period. The fuse of the fuse can avoid the lack of phase transport hall, and its action is linked with the standby power supply. The host computer does not shut down the high-energy zinc oxide resistors to limit the operation over-voltage and protect the equipment's insulation safety.
The device is simple in structure, small in size and low in cost. High-voltage current-limiting fuse 41. Xi'an Jiaotong University Press, 1991.2 Wang Jimei. High-voltage AC load switch Beijing Machinery Industry Press, 1997. Author brief introduction Guo Sijun 1965, male, Hefei, Anhui, deputy general manager of Hefei Kaili Electronics Co., Ltd., engineer, mainly engaged in the development of large current short circuit protection of power system
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