Why We Use…

Self-Clinching Fasteners

Bus bars, in general, serve to distribute high currents of 10 to 2000A. They provide power distribution solutions for the computer, power conversion, telecommunications, energy management, power supply, military, medical, transportation, and automotive industries. According to Reuven Koter, director of marketing and new business development at Eldre Corporation, Rochester, NY, bus bars can reduce system costs (decreased assembly time and parts count); eliminate potential wiring errors (compared with standard cable harnesses); improve system reliability and quality; and provide the widest possible variety of interconnection methods for customization. Every bus bar designed by Eldre is custom-made to meet application requirements, ranging from single-layer bus bars to multi-layer laminated structures incorporating discrete components into an integrated power electronics package of virtually any size and shape. All design and manufacturing are done in-house, with a focus on cost-effective and easy-to-assemble products.

Today’s power distribution systems impose particular demands on engineers, who constantly must make the most efficient use of space (more power in smaller packages) and deal with the potential negative effects of vibration in an assembly. The method most favored by Eldre begins with a self-clinching fastener mounted on the bus bar. Says Koter, “The clinch fastener simplifies assembly of bus bars into applications, because it eliminates one piece of loose hardware stock at the time of each termination.” A robust fastener also reduces the potential for problems in installations that will experience vibrations, and it improves assembly procedures in areas of restricted physical access. Some application examples:

• Digital Switches. A three-layer laminated bus bar distributes power within a central telecommunications office switching system. Multiple conductors are soldered together (one thin and one thick) to carry required 400A currents while contributing to desired flexibility. A self-clinching threaded stud mounted into each flexible tab provides the means for simple attachment to a backplane and minimizes installation time.

• Internet Routers. A two-layer epoxy powder-coated bus bar carries DC power (load of 48 VDC and 50A) from a power supply onto plated pads on a mid-plane for an internet router. (The epoxy powder coating is ideal when tight forms are required to clear other components.) Each layer is individually insulated and then assembled into a pair. Four self-clinching threaded studs are installed directly into the bus bar to enable easy assembly and a cost-effective approach for installation. (A mirror-image assembly is used for redundancy.)

• Power Trays. Mounted inside a circuit breaker tray, individual Eldre bus bars are nested in a machined FR-4 frame to provide output connections. Two self-clinching studs and a self-clinching nut installed in each bus bar offer effective interconnection without requiring costly custom connectors. The assembly’s design further promotes proper safety separation and single-component installation. (Loads are 48V and 280A.)

• Backplanes. In a rack system for a computer application, a laminated bus bar distributes +5V and return to a backplane. Four self-clinching nuts installed into the bus handle 230A.

In every bus bar application where clinch hardware could prove advantageous, Eldre specifies and installs standard self-clinching nuts and studs manufactured by PEM Fastening Systems, Danboro, PA. “Our engineers are very much familiar with all PEM fastener products,” Koter comments, “which helps us to deliver power distribution assemblies and total bus bar solutions supported by efficient hardware technology.”

—RM

PEM Fastening Systems
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