Detailed explanation of series reactor selection difficult problem

Series reactor (hereinafter referred to as series resistance) is a parallel capacitor device (hereinafter referred to as the capacitor device or capacitor group) is one of the main components, which plays a limit capacitor bank (back to back) closing surge in power harmonic suppression, to prevent the capacitor Damage, and to avoid the capacitive device access to the harmonic harmonic over-amplification and resonance and so on an important role.However, string resistance and capacitor can not be arbitrarily combined, if not consider the capacitance device access to the actual situation of the grid, the "one size fits all" (Such as capacitors are equipped with a reactance of 5% to 6% of the string resistance), often counterproductive, leading to a serious amplification of harmonics and even resonance, endanger the safety of devices and systems.Because of the presence of oil immersed distribution transformer harmonics The complexity and randomness of the capacitive devices, and the difference of the structure and characteristics of the electric network in which the capacitive devices are located make the choice of the harmonic response and the series reactance rate of the capacitor devices a difficult problem and a research topic. However, with the deepening of the research work and the accumulation of practical experience, many consensus opinions or effective measures have been put forward, or some suggestions have been made for the design of string reactors in the design of capacitor installations. Lessons Learned. The string resistance has both the advantages of suppressing inrush current and harmonics, but also has its additional power loss and construction investment and operating costs of the shortcomings.Therefore, the new expansion of the capacitor device, Or has been put into operation of the capacitor device in the series of anti-selection program, the technical and economic comparison is necessary.This paper focuses on the part of the capacitor device engineering design followed the choice of 6% string anti-problem analysis, with a view to device construction and Operation has some benefits.

Transient Effect of Magnetic Saturation on Transformer

Magnetic saturation transient effect of the transformer Note that magnetic flux should be checked for saturation near minimum input voltage and maximum pulse width. As the input voltage is high, the pulse width will be narrowed, so the core is far from saturated. In a transient load, when the input voltage is high and the load current is small, if the load current suddenly increases, the control circuit immediately increases the pulse width to provide the supplemental power. In this way, the input voltage and pulse width are simultaneously maximized, even if for a short period of time, the single phase step down transformer will appear saturated, and cause out of control and failure. Here are some measures to avoid runaway. (1) transformer in accordance with high input, voltage, wide pulse design, the core work in low flux density and winding more primary winding. The disadvantage of this method is to reduce the efficiency of the transformer, increasing the size of the Amorphous Core Transformers weight. (2) the control circuit should be in the high sensitivity to determine the state of work, when the high input voltage appears to be able to quickly limit the pulse width, it is still safe value. (3) in the control circuit to improve performance, so that the switch in the current work cycle to quickly respond to control. UC1846 / UC1847 current mode control chip, can automatically achieve this limit action.

Power transformer type and characteristics

Power transformer type and characteristics of commonly used power transformer classification can be summarized as follows: (1) by the number of phases: (1) single-phase power transformer: for single-phase load and three-phase power transformer group. (2) three-phase power transformer: three-phase system for the rise and fall voltage. (2) by cooling: (1) dry power transformer: rely on air convection cooling, generally used for local lighting, electronic circuits and other small-capacity power transformers. (2) oil-immersed power transformers: rely on oil for cooling medium, such as oil from the cold, oil-immersed air-cooled, oil-immersed water, forced oil circulation. (3) by the use of points: (1) Power Transformer: transmission and distribution system for the rise and fall voltage. (2) Instrument 10kva single phase transformer: such as voltage transformers, current transformers, for measuring instruments and relay protection devices. (3) test transformer: can produce high voltage, high voltage test of electrical equipment. (4) special transformers: such as electric furnace transformers, rectifier transformers, transformers and so on. (4) according to the form of winding: (1) dual-winding transformer: used to connect the two power system voltage level. (2) three-winding transformer: generally used for power system regional substation, connecting three voltage levels. (3) auto-transformer: used to connect different voltage power system. Can also be used as an ordinary step-up or down after the transformer. (5) according to the core form: (1) core prefabricated compact transformer: for high voltage power transformer. (2) amorphous alloy transformer: Amorphous alloy core transformer is a new magnetic materials, no-load current decreased by about 80%, is the ideal energy-saving effect of distribution transformers, especially for rural power grids and developing areas Load rate is low. (3) shell-type transformers: for high-current special transformers, such as electric furnace transformers, welding transformers; or for electronic equipment and television, radio and other power transformers.

Transformer damp treatment method

10kva step up transformer damp treatment method is: the use of transformer normal operation of the no-load loss and load loss as a transformer drying treatment of heat source, the transformer insulation paper in the water gradually penetrate into the transformer oil, the use of online oil filter device to remove the transformer oil And then the transformer oil enters into the vacuum vessel through the inlet filter, and the transformer oil is ejected by using the vacuum pressure nozzle (the absolute vacuum in the vacuum vessel should be controlled at about 1 500 Pa), and the pressure nozzle is used to eject the oil film Gas and water vapor transfer to the role of the air, thus completing the degassing of insulating oil and dehydration process. The purified oil is collected at the bottom of the vessel and filtered through the filter element and re-injected into the dry electric transformer. During operation, a container and the corresponding valve should be installed in the lower part of the return oil filter to detect and discharge air bubbles to prevent gas from entering the transformer. On-line transformer body moisture treatment methods, with a short power outage, heating uniformity, not easy to cause transformer insulation damage and other characteristics, in place in full safety measures, to avoid being processed transformer gas protection malfunction.

Cause Analysis of Temperature Variation during Operation of Transformer

The main cause of the overall temperature change in the single phase step voltage regulators operation is the loss of the transformer and the influence of the ambient air temperature. Transformer losses include transformer no-load loss and load loss, the no-load loss in the transformer has been put into operation after the load loss with the transformer load with the size of the change, the greater the single pole transformer load, the more loss, the transformer The higher the temperature rise; the greater the load change, the greater the temperature change of the transformer. In addition from the national electricity load market changes throughout the year the actual situation, the more cold or hot weather, electricity load growth faster, the higher the temperature rise of the transformer; even on the same day, due to changes in day and night temperature and Load peak-valley difference of the superposition of changes, but also caused a significant change in the temperature of the transformer a major factor. As a result of these various factors, resulting in transformer temperature is changing, thus affecting the long-term safe operation of transformer and service life.

Measures of Improving Power Transformer Resistance to Short Circuit

10kva single phase transformer safety, economic, reliable operation and output, depending on their manufacturing quality and operating environment and maintenance quality. This chapter attempts to answer the transformer operation and maintenance process, the effective measures to prevent transformer sudden failure.

The power grid often as a result of lightning, relay protection malfunction or refuse to move and other short-circuit, short-circuit current strong impact may damage the 500kva power transformer, so from all aspects of efforts to improve the transformer short-circuit withstand ability. Transformer short-circuit impact accident statistics show that the cause of manufacturing accounted for about 80%, while the operation and maintenance reasons accounted for only about 10%. The relevant design and manufacturing measures are discussed in Chapter 2, and this chapter focuses on the measures to be taken in the course of operation and maintenance. Operation and maintenance process, on the one hand should minimize the short-circuit fault, thereby reducing the number of shocks suffered by the transformer; the other should be timely testing of transformer winding deformation, preventive measures.

china electrical transformer mainly by the high-frequency transformer core (core) and two or more coils, they do not change position, from one or more of the electrical circuit, through the AC power through electromagnetic induction, Into AC voltage and current. In the electronic circuit plays a boost, buck, isolation, rectification, frequency, phase, impedance matching, inverter, energy storage, filtering and so on. 2. Electronic transformer works - constitute

A simple conventional type transformer consists of a closed magnet and two windings. One of the windings is connected to the AC source and is called the primary winding Np. The other winding can be connected to the load, called the secondary winding Ns. If the primary winding is connected to the power supply of the AC voltage Ui, the transformer is in no-load and the alternating current Io is generated in the primary winding, and Io is called the no-load current.