During transformer handover tests or routine maintenance, operation and maintenance personnel sometimes encounter phenomena such as abnormal sounds during on-load tap-changer switching, or sudden current changes during the switching process, but it is difficult to judge the contact operation sequence and transition resistance status by visual inspection alone. At this time, a test device capable of recording the waveform of the entire switching process and measuring transition time and transition resistance is needed.
The switching process of an on-load tap-changer lasts only tens of milliseconds, and the transition resistance and transition time need to be captured during the dynamic process. Ordinary multimeters have insufficient response speed, cannot reproduce the transition waveform, and cannot distinguish the sequential differences in three-phase contact operation. If the upper limit of the measurement device's transition time range is insufficient, the long switching process waveform of large-capacity transformers will be truncated; if the synchronism error is too large, it is difficult to determine which phase contact operates later. Therefore, when selecting a model, attention should be paid to the transition time range, synchronism measurement accuracy, and waveform recording completeness.
The HCR-6200 On-Load Tap-Changer Tester adopts computer control and, through a specially designed measurement circuit, achieves measurement of parameters such as transition time, transition waveform, transition resistance, and three-phase simultaneity of on-load tap-changers. The instrument has a built-in data acquisition and processing unit that can continuously record the resistance change curve during the switching process and automatically calculate the transition time and transition resistance values of each phase. The measurement results are presented in both waveform and numerical forms, making it convenient for design and selection personnel to judge the switch status by comparing with factory test data.
The transition time measurement range covers the switching duration of conventional on-load tap-changers, meeting the recording requirements for long switching processes of large-capacity transformers; the transition resistance measurement range covers common transition resistance values, and the resolution meets the requirements for distinguishing low-resistance sections; three-phase synchronism measurement is used to compare the differences in three-phase contact operation moments and help locate the phase that operates later. For specific range and accuracy indicators, refer to the product technical manual; during selection, matching should be carried out according to the rated parameters of the tested switch and the requirements of test standards.
This tester is suitable for handover acceptance, preventive testing, and post-maintenance operation characteristic inspection of on-load tap-changers in power transformers. In factory tests at manufacturing plants, it can be used to record switch switching waveforms; at substation sites, it can be used to diagnose abnormal phenomena during the switching process. The instrument operation interface is mainly based on waveform display, and measurement data can be stored and exported for subsequent analysis and comparison. Design and selection personnel can confirm whether the instrument has the corresponding measurement channels and recording length according to the requirements of the test project.
