In preventive testing of zinc oxide arresters, measurement results of the DC 1 mA reference voltage and the leakage current at 0.75U1mA often show excessive dispersion. During troubleshooting, first confirm the contact and shielding of the test circuit, then check whether the instrument's range and resolution cover the test object's parameters. The KDX-9700 zinc oxide arrester tester is designed for this application and is suitable for DC parameter measurement of zinc oxide arresters (varistors) and overvoltage protection components such as metal-ceramic two- and three-electrode discharge tubes. It can measure the DC breakdown voltage Vsdc, with a measurement range of 20–1700 V and an operating error of no more than 3%.
Common split-type solutions require an external high-voltage source, microammeter, and voltmeter to be read separately, involving many wiring steps, and the leakage current is easily affected by lead arrangement; integrated solutions combine DC high-voltage output and microamp-level current measurement in the same enclosure, shortening the test leads and correspondingly reducing the influence of distributed parameters on readings. The KDX-9700 adopts an integrated measurement approach, in which the test voltage and leakage current are acquired synchronously in the same circuit, reducing manual conversion steps.
On site, the PT low-voltage side signal of the arrester test voltage can be taken, ranging from 0–250 V, to assist in judging the condition of the test object. Before use, verify that the PT ratio matches the instrument setting and confirm the correspondence between the low-voltage side signal and the actual voltage applied on the high-voltage side, so as to avoid misreading the reference voltage due to a ratio setting deviation.
Before each test, check the insulation layer of the test leads and the grounding connection, and confirm reliable grounding before raising the voltage; after measurement, discharge fully and disconnect the high-voltage output. Store the instrument in a dry environment, and perform a no-load voltage rise check before reusing it after long-term storage. When the leakage current reading fluctuates abnormally, first check the shielding wire and the surface leakage path of the test object rather than directly judging the test object as deteriorated.
