交流发电机输出脉动电压分析

交流发电机输出的直流电动势会有较大的脉动电压。市场上与汽车、拖拉机、农业机械、工程机械等配套的发电机,在一定转速下脉动电压也是一项主要性能参数。简单介绍过大的脉动电压造成的影响,分析脉动电压的形成,重点论述设计和制造中如何控制脉动电压,以满足市场生产高性能发动机的技术要求。     

电析土壤微粒悬浮液的维恩(Wien)效应及其影响因子

The electrical conductivity of suspensions and their supernatants from the electrodialyzed clay fractions of latosol, yellow-brown soil and black soil equilibrated with nitrate solutions were determined at different field strengths using a short high-voltage pulse apparatus to demonstrate the Wien effect in soil suspensions and to investigate factors affecting it. It was found that Wien effect was much stronger in suspensions with a clay content of 30 g kg-1 from the soils equilibrated with a 1 × 10-4 KNO3 solution than in their supernatants.The threshold field strength (TFS), at which the relative conductivity is equal to 1.05, i.e., the Wien effect begins to be obvious, of the yellow-brown soil suspensions (clay content of 30 g kg-1) equilibrated with different nitrate solutions of a concentration of 1 × 10-4/z mol L-1 , where z is the valence, varied with the type of nitrates, being lowest for NaNO3 (47 kV cm-1) and highest for Ca(NO3)2 (98 kV cm-1). At high field strengths (larger than 130 kV cm-1), the relative conductivities of yellow-brown soil suspensions containing different nitrates diminished in the order: NaNO3 ＞ KNO3 ＞ Mg(NO3)2 ＞ Zn(NO3)2 ＞ Ca(NO3)2. The rates and intensities of the Wien effect in the suspensions of the three soils equilibrated with 5 × 10-5 molL-1 Ca(NO3)2 solution were in the order of the yellow-brown soil ＞ the latosol ＞ the black soil. The results for the yellow-brown soil suspensions (clay concentration of 30 g kg-1) equilibrated with KNO3 solutions of various concentrations clearly demonstrated that the more dilute the solution, the lower the TFS, and the larger the relative conductivity of the suspensions at high field strengths. The results for yellow-brown soil suspensions with different clay concentrations indicated that as the clay concentration increased, the low field electrical conductivity, EC0, also increased, but the TFS decreased, and the Wien effect increased.     

变电站计量电压失电告警装置的研制

变电站电能表电压回路失压是高压电能计量装置的主要故障之一,是造成丢失电量、须要追补电量的主要原因,尤其是电能表电压回路全失压,后果更为严重,并且由此造成的电量追补缺乏足够依据,随意性较大,丢失电量和追补电量对结算的公正性也有影响。     

电栅拦鱼设备

电除用作捕鱼以外,还可用于拦鱼,以防止鱼类进入水电站的涡轮机和水泵中。     

拖拉机电器系统故障排除

1.电系总开关导电不良的处理方法 拖拉机和农用运输车,电路总开关经长期使用后,总开关中与钥匙接触的触点臂,由于自然磨损间隙变大,在行车中插入钥匙接通电路后,往往出现时通时断,接触不良或有断路的故障现象。     

纳米技术在油墨中的应用

一、油墨的细度和纯度油墨的细度和纯度对印刷品质量有很大影响。要印刷出高质量的产品,必须要有细度、纯度高的油墨作保证。油墨的细度是指油墨中的颜料(包括填充料)颗粒的大小与颜料、填充料分布于连结料中的均匀度。它既反映到印品的质量,同时又影响到印版的耐印率。工艺实践情况表明,彩印产品用     

串级调速系统在水厂的应用

作者依据实例,提出了在水厂水泵控制程序中采用异步电动机串级调速技术,并对控制方式、措施、设备选择进行了阐述。     

清扫二次线的注意事项

目前我国居民用电常用的配电方式有TN—S系统、TN—C—S系统和TN—C系统3种类型。其中,TN—C系统是配电变压器低压侧中性点直接接地,系     

电力变压器纵差保护TA二次回路实用接线

电力变压器纵差保护是 6 30 0 k VA及以上主变内部故障时的主保护 ,主要用来反映各种短路故障 ,动作于瞬时断开变压器各侧断路器。在变压器两侧各装设用于纵差保护的 TA,TA二次侧按循环电流法接线。纵差保护中差动线圈“T”接在纵差 TA二次回路的循环回路间 ,流过变压器两侧 TA二次电流之差。变压器正常带负荷运行时 ,由于两侧 TA流进差动线圈中的电流大小相等 ,方向相反 ,总电流极小 (仅为不平衡电流 ) ,差动继电器不动作。当变压器内部故障时 ,变压器两侧 TA二次电流一侧突然增大 ,另一侧为零 ,差动线圈中的电流突然增大为故障电流 …