CURRENT STATE OF SURGE TESTING （增加测试的当前状态）.pdf

CURRENT STATE OF SURGE TESTING INDUCTION MACHINES John Wilson Baker Instrument Company ABSTRACT Surge testing of motor coils has been an industry practice since J. L. Rylander published “A High Frequency Voltage Test for Insulation of Rotating Electrical Apparatus” in Transactions of the AIEE, in February of 1926. Since that time the use of surge testing to diagnose failing or damaged insulation in motors has advanced greatly. In 1926, the indication of a turn-turn insulation failure was the drop of the coil voltage amplitude as determined by a vacuum tube rectifier circuit using an apparatus the size of a large work bench with rotating spark gaps for switches and large step up transformers to charge large high voltage capacitors. Today’s instrumentation uses high-speed digitizers to observe the entire waveform. Instead of a work bench, a 50lb portable enclosure contains the entire instrument which includes small high voltage power supplies, power semiconductors for switching elements, small efficient high voltage capacitors and a complete Pentium class computer with color display. The principles of surge testing, the strength of the turn -turn insulation being tested, the motivation to perform the surge test, the required test voltages necessary to succeed with the test, the industry standards surrounding the technology and the modern diagnostic algorithms will be presented. PRINCIPLE OF THE SURGE TEST If a rapidly increasing current is applied to a coil, a voltage will be generated across the coil by the principle of induction. The voltage across the coil is given by V=L*di/dt Where V is the terminal voltage across the coil, L is the coil’s inductance, and The time rate of change of current pulse is di/dt. The terminal voltag