Abstract: A device and a method are described for online monitoring the lifespan of switch contacts of a transformer on load tap changer (OLTC). The method includes connecting a current signal sensor of a voltage adjustment winding of the power transformer with a current signal processing circuit thereof; connecting the current signal sensor with an analog-digital converter of an industry control computer (IPC). When a switch signal is received, the switch current value and the number of switching operation of the OLTC are used for comparison with a lifespan relationship as a function of number of switch operations of a switch contact having similar specifications, wherein the relationship indicates a critical current value indicating the need for replacement. The device includes the IPC, the signal processing circuit, a monitor, and a keyboard.

Abstract: The all-purpose portable tester for isolation character of the surface of the composite bushing made from silicon rubber applies to detecting and estimating hydrophobicity and isolation performances, the length and width and density of the cracking, comprehensive assessment of the surface of the umbrella skirt and bushing and to detecting the tracking and the electric corrosion of silicon rubber, being made up of Master Control Unit, Principal Computer, Hydrophobicity Detection Unit, Crack Detection Unit, Tracking Detection Unit and Electric Corrosion Detection Unit and Image Capture Unit through which the comprehensive diagnosis and life assessment of the isolation character of the surface of the composite bushing made from silicon rubber shall be achieved.