Electrical machines voltage tests

Routine tests are conducted on subsequent similar machines. The purpose of a routine lest is to ascertain that the machine is assembled correctly and will be able to withstand the appropriate high-voltage test, and will be in sound working eondition, both electrically and mechanically. As a minimum requirement these tests will consist of ... 

Rotating electrical machines shall be tested at standstill and running with 0.9X 1.0X their rated speed. The rotor causes a certain turbulence of the test gas, resulting mainly in a considerably increased dp/dt value [2] and enhanced peak pressure. Cage induction motors may be fed from outside with an adjustable voltage and frequency via a frequency convertor, motors with sliprings or commutators need an auxiliary drive, e.g. a small cage induction motor powered by said frequency convertor. 

Specimens were strained in a push-pull mode by an Instron machine, Model TF-DM, which has cross head speeds from 0.05 to 0,5 cm/min and a load capability up to 10" kg. Details of the apparatus for the mechanical and electrical tests are reported elsewhere Only a brief description of the electrical portion is given here. The resistivity was measured by the typical four-probe dc method. A set of voltage leads were soft-soldered across the gauge length of the specimen surface. 

Under wet conditions, automatic controls for reducing no-load voltage should be used. Electrodes are to be removed from the holders when not in use. It is required that electric power to the welder be shut off when no one is in attendance. Suitable Are extinguishing equipment must be available for immediate use. The welder shall be forbidden to coil or loop welding electrode cable around his or her body. Wet machines must be thoroughly dried and tested before being used decreasing the risk of electrical shock or electrocution. 

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