In response to increasing demand for customer led research and development projects we have invested in a fully functional Voltage Endurance (VE) test lab for bespoke projects and internal product development.
VE is a test that quantitatively measures the capability of an insulation system to withstand partial discharge (corona) at operating temperature, which in turn is a measure of the quality of the design of the materials, and of the manufacturing process.
High voltage stress causes aging of stator winding insulation and eventually leads to insulation failures. This, widely accepted, accelerated life cycle test is used as a measure of quality by applying a much higher than normal machine-operation stress to coils/bars within a short period of time to accelerate insulation aging which occurs during machine service.
This means customers can be assured that coils are manufactured to maximise the lifetime performance of the coils and reduce any potential partial discharge which could cause premature failure.
We also carry out partial discharge testing on our coils.
Corona discharge activity at the exit of the core is designed out by using the highest grade of corona stress grading tapes applied using a proven process and the corona discharge activity at the slot portion is overcome by using hot pressed corona protection tape which provides a resilient continuous corona protection shield.
We control the PD to less than 300 pc (Pico Coulombs), this gives both ourselves and our customers the confidence that a much longer life expectancy can be achieved and the security that any PD emanating from the coils in the wound motors and generators can be eliminated.
We use a 20kV partial discharge free transformer and divider together with Lifeview QTD digital capacitance / loss factor (Tan ?) and partial discharge analyser, which is calibrated to UK national physical laboratory standards.
If required, we can PD test each coil as it is manufactured which gives increased confidence in the quality of the coils and their ability to maximise the life of the asset once rewound.
This, alongside all our other testing and quality processes, gives us the confidence to offer customers an extended warranty on our coils. To find out more and discuss your next project contact Stuart Whitfield on stuart.whitfield@houghton-international.com.
