After conducting DC resistance measurement operations on power transformers, residual magnetism will remain in their iron cores. If residual magnetism is not handled, it may have many adverse effects on the relay protection devices and primary equipment of power transformers. Excessive excitation inrush current can cause the transformer to fail…

Grounding resistance is an important parameter used to measure whether the grounding status is good. It is the resistance encountered by the current flowing from the grounding device into the ground and then passing through the ground to another grounding body or spreading to a distance. It includes the resistance…

Wire and cable play an important role in the infrastructure construction of our country. Power cables are commonly used in urban underground power grids, power station outgoing lines, internal power supply of industrial and mining enterprises, and underwater transmission lines crossing rivers and seas. They are composed of four parts:…

DC high voltage generator, also known as high voltage generator, is mainly suitable for power maintenance departments, industrial and mining, metallurgy, steel and other enterprises' power departments to conduct DC withstand voltage tests on high-voltage electrical equipment such as zinc oxide lightning arresters, power cables, transformers, generators, and high-voltage switches. The…

1. Uniformity of electric fieldThe uniformity of the electric field has a greater impact on the breakdown voltage of SF6 gas gaps than air. Under extremely non-uniform electric fields, the breakdown voltage of SF6 gap will be three times lower than that of air. As the degree of electric field…

What is winding deformation?The definition of winding deformation in the power industry standard DL/T911-2004 "Frequency Response Analysis Method for Power Transformer Winding Deformation" is: the axial or radial dimensional changes that occur in the winding of a power transformer under mechanical or electric force, usually manifested as local twisting, bulging,…

With the increase of cable lines, the morning noise of cable faults on power supply reliability is increasing day by day. Therefore, quickly and accurately detecting the location of the fault point is of great significance to ensure timely repair of the faulty cable. The detection method for cable faults…

1. The host cannot find the resonance point.Reason: The resonance point of the system is outside the output frequency range of the host; System wiring error;The system is not reliably grounded; High voltage sampling feedback signal open circuit or unreliable connection; The test sample has a malfunction.Exclusion method:① Check the…

Introduction to Variable Frequency Series Resonance: It consists of a variable frequency power supply, an isolation transformer (also known as an excitation transformer), a reactor, and a capacitive voltage divider. The capacitor and reactor of the test sample form a series resonant connection; The voltage divider is connected in parallel…

Precautions for power frequency withstand voltage test:1. Test personnel should divide responsibilities, set a safe distance at the test site, carefully inspect the grounding of the test sample and test transformer, and assign a dedicated person to monitor safety and observe the status of the test sample.2. The main parts…