Sealed tube test method for evaluation of hermetic motor insulation performance with refrigerant systems

A sealed tube test procedure has been adopted for the efficient and expedient screening of "compatibility" between hermetic motor insulation materials and various refrigerant systems. This test procedure enables the measurement of retention of magnet wire dielectric strength, varnish bond strength, and film tensile properties under accelerated conditions in the refrigerant/lubricant environment. This test method also enables observations to be made on how the presence (or absence) of specific materials affect lubricant and other compressor components (metallic or nonmetallic). This test method has been applied to compare the effect on motor insulation of new HFC refrigerants and synthetic lubricants vs. conventional refrigerants and lubricants, and to estimate reliability life of specific insulation components, such as polyester film, when exposed to different refrigerants and temperatures.