The DLX-80 ultra-low frequency withstand voltage test device adopts a closed-loop frequency feedback circuit, with an output voltage frequency instability of ≤1%, meeting the technical requirements of DL/T 849.4-2004 for ultra-low frequency high-voltage generators. The device has a built-in 0.1Hz sine wave generation module, which dynamically adjusts the output frequency by sampling the load current and voltage phase in real time, avoiding frequency drift caused by cable capacitance effects. Before conducting withstand voltage tests on long-distance cables, technical engineers should confirm that the device is reliably grounded and check that the high-voltage output cable is correctly connected to the test object.
The maintenance of the device focuses on the high-voltage output unit and the cooling system. After each test, clean the surface of the high-voltage bushing with a dry soft cloth and check for discharge traces; the cooling fan filter should be cleaned quarterly to prevent dust accumulation from affecting cooling efficiency. The fuse and relay contacts in the control unit are recommended to be checked annually to ensure reliable operation. When not in use for a long period, the device should be stored in an environment with humidity ≤85%RH and temperature -10℃~50℃, and powered on for 10 minutes each month to maintain stable performance of the capacitor components.
According to GB 50150-2016 and DL/T 596-2021, before testing, it must be confirmed that the test object has been fully discharged and grounded. After connecting the high-voltage output terminal of the device to the test object, safety fences should be set up and warning signs hung. During voltage rise, operators must maintain a sufficient safe distance from the high-voltage circuit and monitor changes in leakage current. After the test, first cut off the power supply, wait for the device to automatically discharge to zero, and then discharge the test object with a grounding rod. If abnormal sounds or sudden current changes occur, stop raising the voltage immediately and identify the cause.
This can be judged through the voltage/current measurement circuit built into the device. Under no-load conditions, set the output voltage to 50% of the rated value and observe whether the deviation between the measured display value and the set value is within ±3%. If the deviation is too large, check the voltage divider connection and the grounding of the measurement cable shielding layer. During load testing, pay attention to the correspondence between peak voltage and measurement range. The DLX-80 has a peak voltage of 80kV, and the measurement range covers 0.1Hz and above. Regularly comparing measurement accuracy with a standard voltage divider can effectively ensure the reliability of test data.
