Engineers who work with pressure and vacuum chambers usually reach for off-the-shelf sealed bulkhead connectors when they need to pass power and signal wires through the chamber wall. And while these connectors may seem like the best or only way to breach the chamber walls, they can actually drive cost, impose unnecessary mechanical design constraints and trigger electrical problems. So what’s the alternative? Wire feedthroughs hermetically sealed with epoxy.
If your application doesn’t need frequent disconnects on one or both sides of the sealed chamber, it pays to consider continuous wire feedthroughs before ordering an off-the-shelf connector. If you do, you can benefit from:
- Design flexibility. Even a large offering of standard bulkhead connectors may accommodate just four wire gauges, each typically with 10 pin configurations per wire gauge. Additionally, mixed wire gauge connectors are often unavailable or special order. Bottom line is that it’s often difficult to find an off-the-shelf connector that’s exactly right for the job at hand, which leads to compromises and over-engineering as engineers try to adapt the application requirements to available connectors rather than the other way around. Continuous wire feedthroughs, by contrast, can literally contain thousands of conductors—or just a handful if that’s all the application requires. Equally important, continuous wire feedthroughs give you the ability to mix and match conductors in ways that off-the-shelf connectors do not.
- Increased connector density. Wire feedthroughs have a huge conductor density advantage. Compared to connectors, well-designed feedthroughs can easily double the number of conductors that can squeeze through a given opening. This density advantage often allows a single wire feedthrough that combines all the application’s power and signal wires to take the place of multiple bulkhead connectors.
- Performance enhancements. Even the best electrical connectors have more losses that a continuous wire harness. For instance, connectors typical voltage greater than 1 mV per crimp and another 1 mV or more across the mated pin and socket. Contact resistance for the same connector would typically be as 100 mΩ. That’s enough to make a difference in thermocouple and other sensing applications that benefit from signal integrity. Wire feedthroughs also can also provide an edge in mechanical performance. Unlike bulkhead connectors, a wire feedthrough is not a wear item whose lifecycle depends on a finite number of mating and un-mating cycles. In non-flex applications, the lifecycle of a wire feedthrough equals that of the wire harness itself. There’s no extra failure mode as there would be with a connectorized feedthrough.
- Reduced Cost. It’s tempting to think that bulkhead connectors from a catalog or website will cost less than a custom engineered wire feedthrough. Yet nothing could be further from the truth if you consider the total installed cost of the two feedthrough technologies. Remember that a single continuous wire feedthrough can often replace multiple bulkhead multiple connectors. The resulting reduction in the number of wire harnesses that need to be engineered and manufactured produces a significant cost savings relative to connectors. In many cases, the feedthrough costs just half as much as a comparable connector-based designs.
For more information on best practices for wire feedthrough design, download our latest white paper, When Wire Feedthroughs Make Sense.