The heat generated during the operation of a magnetic device – whether an electric motor, generator or transformer – naturally leads to degradation of the insulation over time. It is safety-critical to understand how this thermal ageing takes place as a failure in the insulation may lead to fire, injury or electric shock. Electrical insulation components are often issued their own individual thermal ratings – the maximum operational heat they can withstand – but it is the way these components perform in combination that is a true measure of the safety and reliability of the device.
This thermal ageing test may take a year or more to complete but UL is launching an accelerated 50-day program at CWIEME Berlin, which is tailored to the needs of electric motor manufacturers.
"Insulation materials behave differently in combination," explains Mark Raymond, principal engineer at UL. "And there are also many different combinations you can have so it is essential for manufacturers to carry out long-term thermal ageing tests on the integrity and performance of the entire electrical insulation system for their own confidence in the safety of the product as well as their customers’."
"A lot of our customers have been asking for a way to shorten the time needed to test their insulation systems," he says. "This 50-day program can help them bring their products to market quicker especially, for example, if they make a tweak to the motor design at a later stage in development with a new combination of insulating materials as they won’t have to wait a whole year to get the product certified."
UL can also help customers launch products quicker by issuing a provisional certification if, during a long-term test program, all trends are pointing towards the desired temperature rating. This would allow the manufacturer to start a production run under the understanding that the final rating may change.
The 50-day test for electrical insulation performance in electric motors, although new for UL, is not entirely new in the industry. The method has been described in the IEC (International Electrotechnical Commission) standard 60335 (annex C) for several years but this is the first time that UL is offering it. The move comes as part of UL’s growing use of IEC standards and increasing global outlook. Since March this year UL bases all of its UL1446 standard test methods on the IEC methods, where previously it had referenced ASTM (the American Society for Testing and Materials).
"UL has long been thought of as a gateway to the North American market for foreign manufacturers. While that is certainly true, our test data can be used to substantiate certification processes in any other country around the world. We’ve listened to the needs of the market and by working from international test methods, we are able to improve the transparency, relevancy and convenience of our tests," Raymond says.
UL experts will be on hand at the company’s booth (3.1 / E41) at CWIEME Berlin to help demystify safety testing and certification processes. Mark Raymond will also be holding a free seminar at CWIEME Central, entitled ‘Electrical insulation system performance and reliability’, on Tuesday 10th May 12:05 12:45. In addition, there will be a workshop on Wednesday 11th May 11:00 12:00 to elaborate on UL 1446 standard updates called, ‘UL 1446 standard of systems of insulating materials: updates and future plans’.
"For many years the electrical products industry was quite stagnant but a steady tightening of environmental legislation together with some exciting materials and design innovations have given rise to many new electrical insulation systems that need to be evaluated. Naturally this has generated a lot of questions for manufacturers on the best way to get products certified for markets at home and abroad. I am very much looking forward to meeting customers at CWIEME Berlin and discussing how we can help get their products to market in a safe and profitable way," he concludes.