Page 28 - 2019 How-to-Specify E-Book
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As the demand for more pins increases, some designers use multiple off-the-shelf connectors to more easily meet IEC requirements. However, this solution often results in several undesirable consequences.
 Multiple off-the-shelf connectors can be used to meet IEC requirements, but often cause other design issues.
The use of multiple off-the-shelf connectors means that operators are responsible for properly mating each plug to its respective receptacle and that the physical keying options intended to prevent mismating are limited, leaving operators to rely upon labeling and patients to rely upon caregivers with varying levels of equipment handling expertise to achieve multiple properly mated connections to ensure their safety. Cable harnesses also become more complex and unwieldy with the use of multiple connectors, leaving yet more room for operator error and undesirable consequences.
Standard High-density Connectors
In response to the growing need for higher density connectors across multiple markets, many manufacturers are developing standard, off-the-shelf high density connector solutions, which can be an effective and affordable choice when the connector meets the needs of a given application and production volumes are in the low to medium range (e.g., up to 20,000 or 50,000, depending upon complexity).
However, the development of standard high-density connector products involves some compromises as well. Connector manufacturers have to consider myriad characteristics in order to develop standard offerings that satisfy a broad range of both application requirements and budget demands, including material and plating characteristics and costs, pin-counts, creepage and clearance, lifecycle, operating voltages, and whether combining signal and power in the same layout or adding features like locking mechanisms, shielding, sealing, polarization, color- coding and more is likely to be required or cost-effective. Well-established connector manufacturers with access to key industry thought leaders can succeed with this strategy, but cannot possibly arrive at a single configuration that is so universal that it can be used by everyone.
This challenge is being addressed in two ways. The first is to develop standard high-density connector configurations that employ a modular contact system capable of satisfying various application demands with standard parts. The second, for when standard offerings still don’t meet the need, is to design a custom configuration based on an established contact system, as this both shortens time to market and reduces investment and risk.
This standard, high-density (79-pin) connector has a metal shell with an outer diameter of 45mm, a threaded, locking coupling nut, a waterproof seal, and a creepage/clearance dimension of 1.6mm. It is rated for 175°C and a high cycle life. When evaluating this standard offering, one thing designers should consider is whether the non-passive screw coupling is
the right locking mechanism for the given application.

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