PT resonance occurs in the neutral point ungrounded system of electric distribution network frequently . The root cause of PT resonance is the nonlinear characteristics of the electromagnetic voltage transformer .
PT谐振大多数发生在中性点 不 直接 接 地的配电网中，由电磁式电压互感器 饱和引起，电磁式电压互感器的非线性特性是铁磁谐振产生的根源。
Protection for single phase to earth fault line selection for Ungrounded Power System by injecting signal
用注入法实现 小 电流 接 地 系统单相接地选线保护
For an ungrounded neutral low voltage power system in mine its insulance ( r ) capacitance ( C ) and leakage resistance ( R ) to the ground are three important parameters in determining the zero sequence voltage .
对于中性 点 不 接 地的矿井低压 电网，其对地绝缘电阻r，电容C和漏电电阻R，是决定零序电压的3个重要参数。
It is difficult fo select wire when there be single phase grounded fault in neutral point ungrounded system .
中性点 不 接 地 系统发生单相接地故障时， 信号 微弱，不易选线，对于谐振 接 地 系统选线更加困难。
This paper infers the probability distribution function of the overvoltage in transmission lines in ungrounded system when the single phase is grounded at the first arcing over .
本文推出 中性 点 不 接 地 系统在单相着 雷接 地第一次发弧时，健全相的过电压概率分布密度函数。
Voltage swells usually have durations of several seconds or less but can last several hours in an ungrounded system .
电压升高通常持续数秒或略少些，但也可在 中性 点 不 接 地 系统中持续数小时。
Then the characteristics during single phase ground fault in neutral-point ungrounded system and neutral-point earthed via petersen coil system are respectively analyzed and capacitor injection method is put forward .
分析了中性点 不 接 地和中性点经消弧线圈接 地系统单相接地的故障特征，深入分析了电容器助增选线方法。
Fault Analysis and Its Precautionary Measures for Electromagnetic Voltage Transformer in Ungrounded System
电磁式电压互感器在 不 接 地 系统中的故障简析及防止措施
With normal balanced operation the neutrals of an ungrounded or isolated system are held at ground potential because of the presence of the system capacitance to earth .
正常对称运行时， 中性 点 不 接 地或绝缘 系统的中性点由于系统对地电容的存在而保持地电位。
By MATLAB the transient process of TV in ungrounded power system is simulated both in normal service or in some kinds of grounding fault conditions . This paper discusses the magnetizing inrush current flowing through TV and the abnormal overvoltage of opened delta-winding .
用MATLAB软件仿真研究了 中性 点 不 接 地 系统中电磁式电压互感器在 系统正常和接地故障运行的全过程，分析了TV励磁涌流造成熔丝熔断的规律性及开口三角绕组电压异常的原因。
Analysis and Suppression Study of Ferromagnetic Resonance in Neutral Ungrounded System
中性 点 不 接 地 电网中铁磁谐振的分析与抑制研究
In order to watch three phase-to-ground voltages inductive Potential Transformers ( PTs ) are connected to the bus of power substation or generator in ungrounded power distribution system .
在 中性 点 不接地的配电 网中，为了监视三相对地电压，变电站和发电机的母线上通常都接有电磁式电压互感器。
In the neutral ungrounded power system ferroresonance over-voltage due to electromagnetic transformer takes place frequently .
在中性 点 不 接 地 电网中，频繁发生由电磁式电压互感器引起的铁磁谐振现象。
For a mining ungrounded neutral power system in a coal mine its insulance and capacitance to the ground are two important parameters in determining the safety conditions of the electrical power supply .
对于煤矿井下 中性 点 不 接 地的供电 系统，其对地绝缘电阻和电容是决定供电安全条件的两个重要参数。
The active filter acts as an infinite impedance to the external for the fundamental frequency and as a low resistor for harmonic frequencies . The Study of Single-phase-to-earth Fault Line Selection Device Based on Shortly Turning on and off Low Resistor Method Without Impulsion in Ungrounded Neutral System
对外 电路而言，在基波频率下有源滤波器被控制为无限大阻抗，在谐波频率下被控制为小电阻。 中性点无冲击短时投切低阻的中压 电网单相接地故障选线装置的研究
Compared with neutral ungrounded power system ferroresonance overvoltage occurred in neutral grounded power system has more new features and the research about it is much less .
相对于中性 点 非 直接 接 地 系统而言，发生在中性点 直接接 地系统中的铁磁谐振过电压有着许多新的特点，而且对它的研究相对较少。
Based on distributed parameter circuit theory the algorithm of fault diagnosis-multifrequency excited method to locate single-line-to-ground fault on the ungrounded 3-phase system is proposed in accordance with the characteristic of the system .
基于分布参数电路理论，针对 中性 点 不 接 地三相 系统特点，提出了树型配电线路单相 接 地的多频法故障诊断。
The Study of Single-phase-to-earth Fault Line Selection Device Based on Shortly Turning on and off Low Resistor Method Without Impulsion in Ungrounded Neutral System
中性点无冲击短时投切低阻的中压 电网单相接地故障选线装置的研究
Bases on multi conductor transmission line theory and symmetrical component theory a new algorithm of single line to ground double line to ground and triple line to ground fault location for the ungrounded 3 phase system is proposed .
基于多导体传输线理论和对称分量法理论，提出了 不 接 地三相 系统单相接地、两相接地和三相接地故障测距的新算法。
In the field experiment of artificially triggering lightning conducted near Nanchang Jiangxi in the summer of 1996 3 lightning flashes were successfully triggered by use of newly-developed technique with ungrounded rocket-wire system in negative ambient electric field of thunderclouds .
1996年夏季在江西南昌附近进行的人工触发闪电野外实验中，用新开发的 不 接 地的火箭－导线技术成功 地在雷暴云 下的负环境电场中触发了云对地闪电。
In ungrounded distribution system the single-phase-grounding and the ferro-resonance caused by the PT ( Potential Transformer ) are of the frequent accidents .
在 中性 点 非 直接接地 电网中，单相接地及由电压互感器（PT）引起的谐振过电压均是多发性的事故。
As the iron core of inductive Potential Transformer ( PT ) has a nonlinear magnetizing characteristic if the inductance of it matches the line-to-ground capacitance under transient impact ferroresonance may be caused in ungrounded distribution system .
由于电磁式电压互感器的 铁心具有非线性励磁特性，在暂态冲击下，如果其电感与线路对地电容满足参数匹配，将可能导致 系统发生铁磁谐振。
Take the electricity leaks protection which in the middle point ungrounded electric power system as researched object . explains the concept and the important meaning of alternative electricity leakage protection ;
以中性 点 不 接 地供电 系统漏电保护作为研究对象，阐述了选择性漏电保护的概念及其重要意义；
不接地制