ABB Turns to DuPont™ Zytel® Nylon Flame Retardant (FR) for Demanding DC Switching Application

K 2013 – Düsseldorf, Germany, October 16-23, 2013

DuPont Performance Polymers — Hall 6, Stand C43

Düsseldorf, Oct. 16, 2013 – ABB, a leader in power and automation technologies, selected DuPont™ Zytel® FR nylon for direct current (DC) switch disconnecter housings because the material can stand up to extremely high instantaneous temperatures should electrical arcing occur.

Easy-to-process Zytel® FR also offers good impact resistance, strength and a relevant Comparative Tracking Index (CTI) value.  CTI is used industry wide to measure the electrical breakdown (tracking) properties of an insulating material.

The ABB devices – called ‘OTDC 16 … 32’ – have been designed to suit the specific demands of photovoltaic applications, which include the significant arcing generated by high-voltage DC switching.

These small, DC rated switch-disconnectors can experience voltage levels as high as 1,000 volts even in solar applications.  The CTI value of the material has to be significant, especially in these small switches where there is not much space to create buffer zones.

"DC is more difficult and challenging than alternating current (AC)," said Oskari Uitto, product manager, breakers and switches, ABB Oy, Finland. "AC fluctuates and DC doesn't, so there are no natural zero points; as a result the breaking features have to be more powerful than an AC switch.

"Arcing concerns us," he said. "With DC there is always arcing when you break a load. This means that any material used in the switch's construction has to be able to withstand the extremely high instantaneous temperatures.

"We had to take a very hard look at the materials out there," Uitto explains, "due to the high CTI values we needed. In this case we had to see what we wanted and balance it against what was available. We have manufactured switches for a very long time; we know the materials and the ones we typically use, we really had to dig deep in the design of this switch range due to the required CTI value and the small space we had available."

With its UL rating, weldability, excellent flow and impressive mechanical properties, Zytel® also offers cost savings against other thermoset alternatives. Zytel® is an extremely flexible material, which has been put to use in a huge range of applications across the globe and it has undergone significant development by scientists at DuPont in order to create grades tailored to specific applications. Sustainability also is a high priority and DuPont has addressed industry needs with the development of non-halogen and renewably sourced variants.

OTDC switch-disconnectors

OTDC switch-disconnectors for 16 to 32 Amperes have various DC voltage ratings with the same footprint area. The application benefits from DuPont™ Zytel® FR performance in CTI, ductility and easy processing.

ABB has developed a whole range of products dedicated to photovoltaic applications and is able to meet all installation requirements, from the strings on the DC side to the AC grid connection point. Its product range includes circuit breakers, switch disconnectors, fuse disconnectors and fuses, residual-current-operated circuit-breakers, grid-connection relays, metering devices, surge arresters, consumer units and enclosures suitable for outdoor installation, all specially designed for these applications.

ABB ( is a leader in power and automation technologies that enable utility and industry customers to improve their performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 145,000 people.

DuPont Performance Polymers is committed to working with customers throughout the world to develop new products, components and systems that help reduce dependence on fossil fuels and protect people and the environment. With more than 40 manufacturing, development and research centers throughout the world, DuPont Performance Polymers uses the industry’s broadest portfolio of plastics, elastomers, renewably sourced polymers, filaments and high-performance parts and shapes to deliver cost-effective solutions to customers in aerospace, automotive, consumer, electrical, electronic, industrial, sporting goods and other diversified industries.

Image: Courtesy of ABB

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