The endurance function of the insulation field is widely concerned in the power system. According to the equality between the two dimensional Weibull distribution and the Law of electrical aging, after the method for estimation of the voltage endurance coefficient is presented by the maximum likelihood estimation and the minimum square estimation of the two dimensional Weibull distribution par...

In the substation of Mianyang, a majority of 35kV lines power the military plants for scientific research or manufacture. For the line corridor was a mountainous area with complex landform and high soil resistivity, the line lightning protection measure was weak. And for history reasons some 35kV lines were not all spanned with lightning conductor. The operation data in recent years reveals th...

In power system, neutral low current grounded system\\\’ s line-selection protection devices are deficient in the speed of response and the accuracy of selection. A high-speed thirty-two channels data acquisition and processing system is made of TI\\\’ s DSP TMS320F206 and two piece of MAXIM\\\’ s 2×4-channel simultaneous sampling 14-bit DAS MAX125. In addition, a Philip\\\&...

Low sensitivity and low reliability in the relays of single-phase-to-earth fault line selection\\\’s device are always the problems in ungrounded neutral system. Through reviewing of the existing theories on fault line selection systematically, this paper points out the defects and drawbacks of those. It points out the single-phase-to-earth fault line selection project that turning on an...

With the development of power network interconnection, the scale of power system is extending, the scale of the Non-Effectively Grounded Power Systems is increasing. Because the voltage class of the Non-Effectively Grounded Power Systems is lower, single phase grounding fault is easily occurred. If single phase grounding fault is occurred, fault current is very small, so it can continue to run...

Operation experiences indicate that over voltage for ferroresonance may occur in multi-voltage grade network. Excessive accidents brought by ferroresonance, especially in the power network below 35 kV , have been a concerned problem. In non-grounding system ferroresonance caused by voltage transformer saturation and single-phase grounding fault are easily confused, so it is difficult to resol...

Domestic and international the electric power net circulate data express, the breakdown of the power transmission line in the electric power net have greatly part, and the breakdown caused by thunder have the specific weight compare of the power transmission line. Particularly the power transmission lines in the South China, the lines breakdown is basically caused by thunder. Therefore lookin...

This thesis is founded on the investigation of the ion migration of 500kV DC ceramic support insulators for the production of the 500kV DC ceramic support insulators.In the test system, we added the grounding switch for each circuit and the mutual switch, prescribed the four status of the current measuring program, making the measurement system more stabile.on the base of the IEC standard of D...

With the rapid development of the national economy, the demand for electricity is growing, the range of electric network is expanding, the transient process of the electromagnetic power is more complicated, and the electromagnetic decay is more slowly. In order to ensure the security and stability for the electricity lines, higher remand is necessary for the relay protection, but the traditio...

Small current earth at neutral point is popular in power distribution networks. This kind of earth is advantageous to reliability of power supply, but presents a objectionable problem that when single-phase grounding fault occurs, it is difficult to implement fault circuit selection and protection. The raison is that single-phase grounding fault does not form a ...