Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

The world's first transformer was developed in 1876. It featured a very simple design and used air as its insulation medium. In 1885, engineers in Hungary successfully built the first modern transformer with a closed magnetic circuit and air insulation, marking the beginning of rapid development and widespread application of transformers. Since then, the transformer industry has continuously advanced toward higher voltages and greater capacities.In 1912, the oil-immersed transformer was invented

Currently, traditional-type breathers are widely used in transformers. The moisture-absorbing capability of silica gel is still judged by operation and maintenance personnel through visual observation of the color change of silica gel beads. Subjective judgment by personnel plays a decisive role. Although it has been clearly stipulated that silica gel in transformer breathers should be replaced when more than two-thirds of it changes color, there is still no accurate quantitative method to deter

1. Overview Ultra-high-voltage (UHV) transformers are core equipment in modern power systems. Understanding their voltage ratings, complex structure, precision manufacturing processes, and critical production techniques reveals why they represent the pinnacle of a nation’s power equipment manufacturing capability. Voltage Level DefinitionThe term "ultra-high-voltage transformer" typically refers to transformers used in AC transmission lines rated at 1,000 kV or higher, or DC transmission lines r

When a transformer is operating under no-load conditions, it often produces louder noise than under full load. The primary reason is that, with no load on the secondary winding, the primary voltage tends to be slightly higher than nominal. For example, while the rated voltage is typically 10 kV, the actual no-load voltage may reach around 10.5 kV.This elevated voltage increases the magnetic flux density (B) in the core. According to the formula:B = 45 × Et / S(where Et is the designed volts-per-

When installing an arc suppression coil, it is important to identify the conditions under which the coil should be taken out of service. The arc suppression coil should be disconnected under the following circumstances: When a transformer is being de-energized, the neutral-point disconnector must be opened first before performing any switching operations on the transformer. The energizing sequence is the reverse: the neutral-point disconnector should be closed only after the transformer is energ

Failures in power transformers are commonly caused by severe overload operation, short circuits due to winding insulation degradation, aging of transformer oil, excessive contact resistance at connections or tap changers, failure of high- or low-voltage fuses to operate during external short circuits, core damage, internal arcing in oil, and lightning strikes.Since transformers are filled with insulating oil, fires can have severe consequences—ranging from oil spraying and ignition to, in extrem

Transformer Longitudinal Differential Protection: Common Issues and SolutionsTransformer longitudinal differential protection is the most complex among all component differential protections. Misoperations occasionally occur during operation. According to 1997 statistics from the North China Power Grid for transformers rated 220 kV and above, there were 18 incorrect operations in total, of which 5 were due to longitudinal differential protection—accounting for approximately one-third. Causes of

Measure DC resistance: Use a bridge to measure the DC resistance of each high- and low-voltage winding. Check whether the resistance values among phases are balanced and consistent with the manufacturer’s original data. If phase resistance cannot be measured directly, line resistance may be measured instead. The DC resistance values can indicate whether the windings are intact, whether there are short circuits or open circuits, and whether the contact resistance of the tap changer is normal. If

The tap changer operating handle shall be equipped with a protective cover. The flange at the handle shall be well sealed with no oil leakage. Locking screws shall securely fasten both the handle and the drive mechanism, and the handle rotation shall be smooth without binding. The position indicator on the handle shall be clear, accurate, and consistent with the tap voltage regulation range of the winding. Limit stops shall be provided at both extreme positions. The insulating cylinder of the t

Overhaul Items for Transformer Conservator:1. Ordinary-Type Conservator Remove the end covers on both sides of the conservator, clean rust and oil deposits from inner and outer surfaces, then apply insulating varnish to the inner wall and paint to the outer wall; Clean components such as the dirt collector, oil level gauge, and oil plug; Check that the connecting pipe between the explosion-proof device and the conservator is unobstructed; Replace all sealing gaskets to ensure good sealing with n