By adopting large voltage feedback, the voltage stability is greatly improved, achieving high quality, portability, and the ability to withstand rated voltage discharge without damage. It features high output power and small size, and is widely used in power cable testing, arrester leakage current tests, and other power tests.
The other two phase conductors, metal shields or metal sheaths, and armor layers at both ends of the cable should be connected separately to each phase. For this test, it should be noted that the cable is a capacitive device, and the insulation resistance and absorption ratio should be understood. For example, fully discharge before and after the test, ignite before connection, and disconnect before powering off the vibration table.
Oil-paper insulated cables only undergo DC withstand voltage tests, not AC withstand voltage tests. In the hot state, the electric field distribution is uneven, and the cable is prone to damage. It should be noted that the cable core is connected to the negative electrode: after the cable is moistened, water carries positive charges. If the core is connected to the negative electrode, water will concentrate in the core, and the moisture in the insulation layer will increase. The leakage current increases, and defects are prone to appear. When the core is positive, water seeps into the lead sheath, the insulation water decreases, the leakage current decreases, and defects in the DC high voltage generator are less likely to appear.
Rubber-plastic cables are polyvinyl chloride, cross-linked polyethylene, and ethylene-propylene rubber insulated cables, with characteristics such as large capacity, high voltage level, light structure, and good flexibility. Currently, oil-paper insulated cables are gradually being replaced by cross-linked polyethylene cables. The difference between cross-linked polyethylene cables and common oil-paper wrapped cables is that their phase insulation is mainly cross-linked polyethylene plastic and a double-layer semiconductor adhesive layer. The outer surface of the core wire is coated with semiconductor adhesive, which overcomes corona and free discharge, providing a good transition between the core wire and the insulation layer. On the outer surface of the insulation between the core wire and the insulation layer, a second layer of semiconductor adhesive is coated in the copper tape shield layer. The copper tape shield layer is only 0 mm thick and 1 mm thick thin copper tape, forming an interphase shield layer.
