Frequency Response Analysis (FRA): This is currently the most mainstream method. The instrument injects a sinusoidal sweep signal (typically ranging from 10 Hz to 10 MHz) into the transformer winding and measures its response signal. Since the inductance, capacitance, and resistance of the transformer winding form a complex distributed parameter network, its frequency response characteristics (amplitude-frequency curve and phase-frequency curve) are closely related to the geometric structure of the winding.
Electric energy comprehensive analyzer is a professional device specially designed for monitoring and analyzing the power quality in the power network. It can collect key parameters such as voltage, current, power factor, and frequency in real time, and conduct in-depth analysis of power quality issues such as harmonic distortion, flicker, and three-phase unbalance. Through these data, users can fully understand the operating status of the power system and formulate corresponding improvement measures accordingly.
Basic concept: The ultra-low frequency withstand voltage test detects the insulation performance of the equipment under test by applying a high voltage at a lower frequency (typically 20Hz to 200Hz). Compared to traditional power frequency withstand voltage tests, the ultra-low frequency test uses a lower voltage but lasts longer.
Detection: Measure the response characteristics (amplitude and phase) of the winding to signals of different frequencies, generating a "frequency response curve".
Judgment: If the winding is deformed, its internal distributed inductance and capacitance parameters will change, causing the frequency response curve to change. By comparing the lateral data among the three phases or the longitudinal comparison with historical data, the degree and location of deformation can be determined.
The following is a detailed analysis of this technology:
1. Why is Very Low Frequency (VLF) testing needed?
In the field of power cable testing, traditional methods have obvious drawbacks, and VLF technology has emerged as the best solution:
Disadvantages of DC withstand voltage test:
During a maintenance process of a large substation, the XX brand Model XYZ winding deformation tester was used to perform winding deformation tests on all main transformers. Through frequency response analysis, technicians quickly discovered slight winding deformation issues in several transformers and promptly carried out repairs. This measure effectively avoided potential safety hazards and ensured the stable operation of the substation.
