• Product
  • Suppliers
  • Manufacturers
  • Solutions
  • Free tools
  • Knowledges
  • Experts
  • Communities
Search


MENU

What are the fault diagnosis and handling technologies for 35kV combined transformers?

Felix Spark
Field: Failure and maintenance
China
For fault diagnosis and handling of 35kV combined transformers, the following technical means can be adopted:
Insulation Fault Diagnosis
Use equipment such as high-voltage test transformers, power frequency withstand voltage testers, and partial discharge detection systems to conduct a comprehensive assessment of the insulation performance of combined transformers. When the insulation resistance is found to be lower than 1000MΩ or the dielectric loss factor tanδ exceeds 0.5%, an application for shutdown and maintenance should be made immediately. For SF₆ equipment, the presence of gas leakage can be determined using an infrared leak detector or a pressure monitoring system.
Ferromagnetic Resonance Diagnosis
Identify the presence of resonance by analyzing changes in zero-sequence voltage (3U₀) and three-phase voltage unbalance through fault recording. When 3U₀ voltage is found to gradually increase or three-phase voltages are severely unbalanced, the possibility of ferromagnetic resonance should be considered. In addition, the risk of resonance can be assisted in judgment by monitoring changes in system parameters (such as the ratio of capacitive reactance to inductive reactance) and operation records (such as ground recovery and switching operations).
Electromagnetic Interference Diagnosis
Use electromagnetic compatibility testing equipment to evaluate the electromagnetic compatibility performance of combined transformers. Methods such as monitoring partial discharges via capacitive coupling, detecting discharge locations with ultrasonic waves, and observing abnormal temperature rises through infrared thermal imaging can identify the degree of influence of electromagnetic interference. For combined transformers in a GIS environment, it is also necessary to monitor the intrusion of high-frequency transient electromagnetic waves into low-voltage acquisition units.
Mechanical Vibration Diagnosis
Use acceleration sensors to monitor vibration waveforms and identify abnormal frequencies through spectrum analysis. By comparing with standard vibration signals, it can be judged whether there is vibration caused by partial discharge or mechanical structural looseness. In addition, infrared temperature measurement can also help detect local overheating caused by poor contact due to vibration.
Secondary Circuit Fault Diagnosis
Check the status of secondary fuses, measure the resistance of secondary circuits, and observe abnormal instrument indications. When a secondary fuse of a certain phase is found to be blown, check whether the indications of the voltmeter, power meter, etc. of that phase are reduced; if an open circuit in the secondary circuit is found, it will be accompanied by a loud "buzzing" sound and abnormal instrument indications, and power should be cut off for processing in a timely manner. In addition, partial discharge measurement can also detect discharge phenomena caused by abnormalities in the secondary circuit.
Calibration and Load-Related Fault Diagnosis
Use a three-phase calibration system to apply three-phase voltage and current simultaneously, simulate actual working conditions, and evaluate the measurement performance of the combined transformer. By comparing the error differences between the single-phase method and the three-phase method, the degree of influence of electromagnetic interference on measurement accuracy can be judged. In addition, infrared temperature measurement can also monitor abnormal temperature rises caused by overload.
SF₆ Gas Leakage Diagnosis
Use equipment such as infrared imaging leak detectors, wavelet analysis signal processing systems, and pressure monitoring devices to conduct a comprehensive assessment of the sealing performance of SF₆ equipment. Infrared imaging leak detection can visually locate leak points, while wavelet analysis can improve detection accuracy, making it suitable for monitoring micro-leaks. For SF₆ equipment with severe leaks, it should be immediately taken out of operation for maintenance.
Give a tip and encourage the author!
About experts
Felix Spark
China
Expertise area
Failure and maintenance
Professional article
101
Recommended
More
Analysis of Abnormal Causes of High-Voltage Cable Grounding Circulation and Typical Cases
I. Introduction to Cable Grounding Loop CurrentCables rated 110 kV and above use a single-core structure. The alternating magnetic field generated by the operating current induces a voltage on the metallic sheath. If the sheath forms a closed circuit through the earth, a grounding loop current will flow on the metallic sheath. Excessive grounding loop current (loop current exceeding 50 A, more than 20% of the load current, or a ratio of maximum-to-minimum phase current greater than 3) not only a
Felix Spark
09/03/2025
Repair of high-voltage cable metallic sheaths
I. Functions of Metallic Sheaths and Necessity of RepairThe metallic sheath of high-voltage cables is a metal shielding structure laid outside the insulation layer, including types such as lead sheaths, aluminum sheaths, and steel wire armor. Its core functions include mechanical protection (resisting external impact and compression), electrochemical corrosion protection (isolating moisture and soil pollutants), electromagnetic shielding (reducing electromagnetic interference to the environment)
Felix Spark
09/03/2025
Working Principle and Arc Extinction Mechanism of Magnetic Blowout Device in DC Circuit Breakers
The arc extinguishing system of a DC circuit breaker is crucial for the safe operation of equipment, as the arc generated during current interruption can damage contacts and compromise insulation.In AC systems, the current naturally passes through zero twice per cycle, and AC circuit breakers take full advantage of these zero-crossing points to extinguish the arc.However, DC systems lack natural current zero crossings, making arc extinction significantly more difficult for DC circuit breakers. T
Felix Spark
09/02/2025
Analysis of Common Operational Fault Causes in Smart Electricity Meters
With the continuous development of smart grids, smart electricity meters are being increasingly widely applied, and various types of operational faults in smart meters are frequently encountered in energy measurement work. This paper analyzes the causes of smart meter failures and proposes corresponding solutions, using several actual operational fault cases as examples.1. Black ScreenA black screen refers to a powered meter with no display, which is the most commonly occurring fault in field-op
Felix Spark
09/01/2025
About experts
Felix Spark
China
Expertise area
Failure and maintenance
Professional article
101
Source professional electrical partners, experts, and explore smart grid & energy solutions.
Seed Inquiry
Download
Get the IEE Business Application
Use the IEE-Business app to find equipment, obtain solutions, connect with experts, and participate in industry collaboration anytime, anywhere—fully supporting the development of your power projects and business.
App Store App Store App Store App Store App Store App Store App Store App Store
App Store