Life Recorder of Dielectric Based on Microcontroller
Jun Liu · Gao dianya jishu · 2007
A life time recorder is required in the ageing life testing of dielectric material because parallel testing of multi-samples is allowed within less time costing and more exact data.A recorder based on the thermal resistors is used to monitor and record the state of the dielectric sample which is put into HV square wave life testing.The temperature of the limiting resistors installed in series in the HV test circuit is almost the same as the condition before the samples are broken down.Once one of the samples was broken down, the temperature of the limiting resistor connected to that sample will rise rapidly responding to the large energy loss on it.When the thermal resistor is placed near to the limiting resistor,the variation in temperature of the limiting resistor will be detected safely without connecting HV circuit by this way and can be used as the broken down criterion of the dielectric samples.The temperature signals will be transferred into analog electric signals by the thermal resistors,the analog signals will be transferred into digital signals by A/D converter,and the digital signals will be calculated by time differential algorithm in microcomputer AT89C55.The exact life recording with time percentage error less than 2% and quick cutting within 1~3 seconds of the broken down channel can be both achieved by this device.The life time recorder presented in this paper has been put into practical operation.