How to Select a DC Power Jack for Harsh Operating Environments

It’s easy to treat DC power jacks as an afterthought during product design. But if that jack sits unplugged on the outside of equipment destined for a factory floor or outdoor installation, what happens when it is exposed to dust or water? Environmental considerations for jack selection can be as important as electrical ratings or connector compatibility.

Let’s look at how DC jacks can be compromised when exposed and how to protect them. We’ll then explore some solutions from Switchcraft and see how they support robust power connections.

Protecting DC power connections in harsh environments

Imagine, for example, an industrial programmable logic controller (PLC) with its DC jack unplugged during a routine maintenance operation. While the enclosure itself might be well protected, removing the power plug may create an entry point for contaminants such as water or dust, damaging the device.

Similar equipment may remain disconnected from external power for extended periods, so designers may need to maintain high ingress protection (IP) even when the jack is unmated. This is where the connection's IP rating becomes important, as defined by IEC 60529 (Figure 1). For example, IP68 indicates complete protection against dust ingress and protection against continuous water immersion under conditions specified by the manufacturer.

Figure 1: Shown are the IEC 60529 IP ratings. (Image source: Engineer’s Toolbox)

This level of protection is useful for many applications. For a multi-device charging station, unused ports may remain exposed for extended periods, so you can't choose the environmental seal assuming a plug is always present. Similarly, outdoor devices such as agricultural sensors or lighting control systems may be exposed to rain, floodwater, and dirt when DC ports are disconnected.

Once you start thinking of the DC jack as part of the enclosure, rather than simply an electrical connection, the importance of IP becomes much clearer.

Robust DC power jacks with unmated ingress protection

Designed to maintain environmental protection even when no plug is inserted, Switchcraft IP68 sealed unmated DC power jacks are rated IP66, IP67, and IP68, primarily through a robust silicone housing and a high-quality epoxy seal. The family includes 1.3, 2.0, 2.1, and 2.5 millimeter (mm) center pin sizes and remains compatible with standard DC power plugs. For a more secure connection, threaded bushings accept locking plugs that mechanically secure the plug to the jack rather than relying on friction alone.

Another useful feature of these jacks is the normally closed internal shunt switch. Inserting a power plug opens the switch, allowing you to disconnect another circuit or power source. This supports portable or industrial equipment designs that run on internal batteries until external power is connected. The jacks also specify a durability of at least 5,000 insertion and withdrawal cycles, making them suitable for applications where connecting and disconnecting power may be part of everyday operation, such as charging stations.

For its standard models, Switchcraft specifies an electrical rating of 24 volts DC (VDC) and 5 amperes (A), with an operating temperature range of -55 to 85°C. High-temperature and higher-current variants are also available for more demanding application requirements. With these specifications in mind, let’s consider how these jacks fit into a design.

Matching Switchcraft DC power jacks to different design requirements

Say you were tasked with designing an industrial controller that requires a 24 VDC power input through a jack with a 2.0 mm center pin. The electrical interface is clear, but you still need to consider how the jack will be soldered inside the enclosure. Switchcraft’s PC722AU (Figure 2, left), 722RAU (Figure 2, center), and 722AU (Figure 2, right) 2.0 mm DC power jacks offer different termination options to support a variety of scenarios.

Figure 2: The PC722AU (left), 722RAU (center), and 722AU (right) provide different mounting and termination options for 2.0 mm DC power jacks. (Image source: Switchcraft, modified by author)

For direct printed circuit board (pc board) integration, the PC722AU provides a through-hole soldering option. This supports applications where DC jacks are mounted directly on a pc board near the enclosure panel, such as PLCs and industrial controllers.

However, a straight connection may not work for every layout. When pc board orientation or enclosure depth gets in the way, the 722RAU retains the same 2.0 mm interface and electrical rating but switches to a right-angle through-hole mounting option with board lock features for added mounting stability.

For even greater mounting flexibility, the 722AU uses solder eyelets, making it suitable for wired assemblies that do not require the jack to be soldered directly to a board.

These options show why selecting a DC power jack isn't simply about meeting the required electrical rating. You can keep the same 2.0 mm interface, environmental protection, and 24 VDC, 5 A rating while choosing a mounting and termination option that best suits the equipment's physical design requirements.

Conclusion

Voltage and current ratings are only part of selecting a DC power jack for systems in harsh environments. Designers must also consider what happens when the plug is removed and how the jack integrates into the overall design. Switchcraft's IP68-rated unmated DC power jacks offer a range of center pin sizes, mounting styles, and termination options to help designers meet environmental, electrical, and mechanical requirements.