Power Electronics

Power Connector Pushes Current Density Higher

Tribotek's LowR Contact Design is Power Electronics Technology's Prodcut of the Year for 2005.

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Power distribution and interconnect components tend to evolve rather slowly when measured against the general pace of development in power supply technologies. And as power supplies reach higher levels of power and current density, the need for greater power and current density in the power connector grows. Earlier this year, a startup connector company called Tribotek (Burlington, Mass.) unveiled a new contact design that promises to help power connectors catch up with power supply advances. The company's LowR contact design increases the current-carrying capacity achievable in power distribution systems at costs said to be competitive with existing power interconnect solutions.

The LowR contact design decouples the electrical and mechanical functions of the connector. It uses pure copper conductors with many parallel points of contact to achieve a submilliohm-level contact resistance capable of very high current density. Tribotek's contact system combines a conventional pin with a woven socket in which gold-plated copper wire conductors are woven with an engineering fiber such as Kevlar (Fig 1).

The engineered fiber is tensioned to produce the normal force between the socket and the mating pin (Fig 2). The free ends of the copper conductors are terminated into a ferrule, and the engineered fibers are crimped into a mechanical spring. As the mating pin is inserted into the socket, the fibers are tensioned to generate the required normal force. This design results in very low insertion forces for contact mating and minimizes contact wear.

Current ratings depend on contact size, but may be as high as 700 A for the largest contact, a size #4/0 (0.5-in diameter) pin. For the smallest-sized pin (0.040-in diameter) available, the rating is 70 A. These ratings assume one mated pair terminated to bus bars, though pc-board and cable-type terminations are also possible.

Using its LowR contacts, Tribotek has developed several connectors that demonstrate the benefits of the new technology. For example, a series of blind mateable bus bar-to-bus bar connectors includes a connector with four #1/0 contacts capable of handling 325 A per contact with 60 µΩ of resistance per pin. According to Tribotek, this represents a 20% to 30% increase in current density over existing connector technology. And a member of the company's LowPro product line incorporates four 30-A contacts in a mixed data-and-power connector with right-angle terminations. Standing just 7.5 mm high, this component is half the height of a comparable connector built with conventional fork-and-blade power contacts. The reduced height permits greater airflow in the application.

In addition to the connectors described above, the company is offering its LowPro connector with cable terminations and multiple combinations of both ac and dc power contacts. Another product line is the InBoard Socket, which utilizes the LowR contacts and 3-mm, #10 or #8 socket sizes. The socket is embedded in a compliant press-fit lead frame suitable for backplane mounting.

Breaking into the connector business with a new technology is a difficult task given that customers are very concerned with connector reliability. And as Matt Mazdeh, Tribotek's sales manager, remarks, it takes time to go through a customer's qualification process and become an approved vendor. However, Mazdeh notes that the company has had design wins in military and commercial applications involving power supply interfaces and bus bar-to-bus bar interconnects. While cost is often an issue with new technologies, Mazdeh comments, “We've not had any setbacks due to cost. The connector was designed to be cost competitive.”

For more information, see www.tribotek-inc.com.

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