高压谐振变压器的研究

论述了谐振变压器的原理,设计方法及研制中应注意的几个问题,并通过计算值与实测值对比的方法证明了中计算公式的精确性和实用性。     

高频功率脉冲变压器的设计

设计了超声波发生器全桥逆变电路中的高频变压器，并用高频脉冲变压器原边串联电容的方法来抑制铁心磁偏，试验证明了其必要性和有效性。     

单相四柱变压器铁心主磁通分布特性研究

建立了基于型号DSP-223000/500变压器1∶10铁心模型的变压器主磁通试验平台,开展仿真计算和试验研究,分析了铁心磁密工作点对单相四柱式铁心主磁通分布特性的影响.     

新型铁心柱绑扎结构在浇注型干式变压器中的应用

介绍了浇注干式变压器选用的一种新型铁心柱绑扎材料及耐热性能,对不同绑扎材料成本进行了对比.     

适用于零序电压补偿的立式变压器电磁特性研究

三相立式铁心相较于三相芯式变压器具有磁路对称,空载损耗小等优点。现有立式卷铁心不包含零序通路,零序阻抗大。本文作者提出了一种改进立式铁心结构,并对该结构在原边电压不对称运行状况下进行磁路分析,最后在Comsol中进行电磁仿真,验证了该结构的可行性。     

自动化立体仓库在变压器铁心生产中的应用

介绍了自动化立体仓库在变压器铁心生产中的应用,对立体仓库在铁心生产中的整体布局、使用效果进行了论述.     

微波炉用漏磁变压器稳压性能的研究

漏磁变压器,是指通过漏磁支路对主磁通的分流作用,而实现稳压功能的一种特种变压器.文中针对一种微波炉用漏磁变压器,详细地阐述了其利用主磁路的饱和效应及漏磁支路的非饱和特性,实现稳压的工作原理与工作条件,并在此基础上,给出了漏磁变压器的设计原则.基于电磁关系的分析,文中建立了漏磁变压器的等效电路与仿真模型.最后,通过实验验证了等效电路与仿真模型的准确性,对漏磁变压器的设计提供了有效的指导.     

微波炉的变频技术

我公司生产的变频微波炉采用了变频技术,其关键技术是变频器与变频磁控管的匹配,通过理论与实验相结合得出有关匹配的调节规律,调节变频器输入脉冲信号的占空比,根据实际需要达到连续调节微波炉输出功率的目的。同时在正常运行时不断监控变频器工作状况,一旦发生异常,立刻采取保护措施。(1)原理 变频器的输入是工频电源(220V/50Hz),通过整流桥进行整流,获得约300V的直流电压。在控制信号PWM的控制下,通过高频变压器升压,获得约2000V的交流高压,再倍压整流,就获得提供给磁控管约4000V的直流高压。其功能块图如附图所示。(2)系统电路结…     

Minimizing Radiation Leakage from Microwave Ovens

In this article, an effective solution to minimize radiation leakage from microwave ovens, a microwave "choke" is discussed. This greatly simplified choke design was recommended to the manufacturer, was built, and was tested for functionality. It exhibited the very low leakage sought to meet health and safety considerations. This choke design was found to be economical to manufacture, very reliable, and very tolerant of the spacing between door and oven chamber. The choke was adopted for oven manufacture since it addressed feasibility, safety issues, and economy. In current microwave ovens, the choke is hidden from view by an opaque plastic strip near the oven cavity periphery. The strip can be easily cleaned to remove food spillage that would inhibit choke effectiveness.     

Power Supplies for Electronic High-Voltage Measuring-Current Transformers

A power supply for electronic high-voltage measuring-current transformers with extraction of energy from the measured current that flows through a high-voltage line has been considered. A magnetic core of the supply transformer from the windings of which the necessary power is extracted is mounted on the line for this purpose. When the line current changes over a wide range, the supply transformer should have a quickly saturated magnetic core. It has been shown that, to reduce the losses and decrease the loading of the elements of a power-supply circuit in a wide current range, a ballast load should be introduced in the circuit of a secondary winding. Three variants of the ballast load have been compared: resistive, capacitive, and in the form of a transistor-current limiter. The results of simulations in the VisSim software have been considered for all three variants, as well as for the case of absence of a ballast load in the power-supply circuit. The simulations were carried out for the lowest and highest measured currents, as well as for the line short-circuit mode. The results of simulations have shown the advantages of a power supply based on a saturated transformer with a transistor-current limiter. A variant of a circuit of a transistor-current limiter has been suggested.     

对微波炉电容器产品标准的几点意见

微波炉电容器国家标准GB／T18939．1—2003系等同采用IEC61270—1：1996国际标准。现提出几点意见供商榷。     

对微波炉电容器产品标准的几点意见

微波炉电容器国家标准GB/T18939.1-2003[1]系等同采用IEC61270-1:1996国际标准[2].     

基于系统等值阻抗的变压器抗短路能力核算

为评估在运的大型电力变压器抗短路能力水平,确保电网安全稳定运行,文章提出了一种基于系统等值阻抗的变压器短路电流核算方法。在对变压器高中侧的外部系统进行等值基础上,通过已知的母线短路电流和变压器参数反推系统的等值阻抗,然后根据系统阻抗和变压器参数求得各种短路情况下流过变压器的短路电流。仿真及实例验证说明了算法的准确性,应用算法可以实现对变电站各种方式下短路电流的快速批量计算。使用文章提出的方法对母线短路电流、变压器并联数量等因素对变压器短路电流的影响进行了分析,并结合制造厂提供的短路电流限值对变压器的抗短路能力进行评估,为生产管理部门的技术改造提供技术参考。     

A Comparison of Methods for Determining the Wattage Output and Energy Distribution in Microwave Ovens

Two characteristics of microwave ovens that are important to consumers as they select and use microwave ovens are the wattage output (cooking power) and the evenness of distribution of energy within the oven cavity. Several test methods have been proposed to measure each of these characteristics, but there is not agreement in the industry on realistic methods of their measurement. The purpose of this study is to evaluate a variety of methods for determining cooking power and energy distribution. Cooking power was measured using the temperature rise of water loads. The influence of initial load temperature, quantity of water, profile, and location of the load within the cavity (centrally located versus dispersed) was determined. Energy distribution was measured using nonfood loads (a three-dimensional copying paper load and various water loads), a simple food (gelatin), and a complex food (custard). Placement of the load, the profile, and the composition of the load affected the apparent energy distribution. Recommendations for standardized tests resulted from this research.     

Detection of Winding Radial Deformation in Power Transformers by Confocal Microwave Imaging

In this article, a new bi-static method for the detection and determination of magnitude and location of winding radial deformation in power transformers has been proposed. In this method, which is based on confocal microwave imaging, a ultra-wideband transceiver is utilized to emit a short pulse toward the transformer winding and determine its reflection at several points along a linear path. The measured signals are then processed to obtain a 2D image of the winding. The effectiveness of this algorithm for radial deformation is demonstrated through four different experiments. The resultant image provides satisfactory information of the magnitude and position of the radial deformation in transformer.     

Cast Coil Transformers: An Alternative to Conventional Dry Type Transformers

Now that askarel insulated transformers are no longer available because of environmental regulations, engineers are looking to new approaches in design of nonflammable transformers. Cast coil construction is one promising new design. Cast coil construction is compared with the more familiar conventional dry type construction with particular attention to 15 kV class units up to 5000 kVA in rating. Questions of reliability, energy efficiency, performance characteristics, maintenance requirements, and initial costs are explored in detail.     

配电变压器损耗电量计算方法

大多数用户的配电变压器,单台容量较小,供电企业通常采用高供低计的供电方式,即高压供电低压计量。由于用电计量装置无法记录到变压器的损耗电量,按国家规定每月要加收变压器损耗电量。