According to the GB/T 10230.1 standard, the transition time deviation of an on-load tap-changer must be controlled within the millisecond range. The ZDR-9200 transformer on-load tap-changer tester is designed for technical engineers to measure parameters such as transition time, transition waveform, transition resistance, and three-phase simultaneity. Compared with earlier testing methods that required an external oscilloscope circuit, this instrument adopts computer control and a dedicated measurement circuit, supports three-phase constant current output (1A for each phase), achieves a transition time measurement accuracy of 0.1ms and a transition resistance measurement accuracy of 0.1Ω. The wiring method is flexible: measurements can be taken directly from the tap-changer leads, or directly from the transformer's three-phase bushings and neutral point.
When voltage sag or abnormal noise occurs during voltage regulation, maintenance personnel need to locate the faulty phase. Limited by sampling rate and channel count, ordinary data loggers often can only capture the overall trend of transition resistance, making it difficult to distinguish subdivided stages such as contact separation, arc duration, and bridging switching. For such scenarios, the ZDR-9200 expands the three-phase simultaneity sequentially in the transition waveform, using abrupt change points on the waveform time axis to help determine the faulty phase. When selecting a model, it is recommended to compare five indicators: sampling rate, number of signal channels, transition time measurement range, transition resistance measurement range, and simultaneity measurement error. For example: if the upper limit of the transition time range is insufficient, measuring the long switching process of a large-capacity transformer will truncate the waveform; if the simultaneity error is too large, it will be impossible to effectively distinguish which of the three phases has a contact operating later.
The transition resistance measurement resolution is 0.1Ω, suitable for comparing resistance changes of the same switch across different test cycles. Three-phase simultaneity data is given in the form of transition time differences among phases. Combined with the positions of the rising and falling edges of the waveform, it can determine whether the contacts are bridged synchronously. When the resistance value of a certain phase remains high or the simultaneity deviation exceeds the range specified by the manufacturer, it indicates that the contact wear or loose transmission mechanism of that phase should be checked.
The instrument can be wired directly from the tap-changer leads, or from the transformer's three-phase bushings and neutral point, adapting to both substation maintenance and factory testing conditions. Measurement data can be recorded and stored for subsequent comparison with historical waveforms. Applicable scenarios include: routine maintenance of on-load tap-changers, fault location after voltage regulation anomalies, and sampling inspection of transition parameters during handover acceptance.
