By Christian Taylor
Sustaining Engineering Team Leader
Bulgin
Cambridge, U.K.

While most of us live and work in relatively protected and safe indoor environments, much of the world’s most critical electronic systems and equipment operate in harsh conditions. Whether it’s water, dust, extreme weather, explosive atmospheres or pressure, a range of harsh environments can create challenging conditions where these systems and their connectors operate.

One of the most common points for damage in any electrical system is where cables get plugged in—the connector. Connectors are at the junction of system and cable, needing to have the flexibility to mate and disconnect easily yet securely, all while keeping the elements out. As the guardians of the entry points to both system and cabling, their integrity in harsh environments is critical.

Because they’re at the entry point to the system, connectors face the same hazards of any electronic system, including water, dust/dirt, extreme temperatures, potentially explosive “ATEX” environments, pressure/weight, shock/vibration and salinity.

What defines a harsh environment?

A harsh environment for humans can be defined as an environment in which prolonged exposure to the elements would pose a danger to survival without specialized equipment. A similar definition can be applied for electronics: a harsh environment is one that would ordinarily cause serious damage to an electrical system. Wet or dirty environments with water, high humidity/water vapor, dust or dirt can wreak havoc on electrical equipment, causing short circuits or malfunctioning equipment. If salinity is a factor, such as in a seaside environment, corrosion can also be a serious issue.

Electrical systems are also often sensitive to temperature extremes, which can cause components to fail or malfunction. For data connections, electromagnetic interference (EMI) can be an issue as it can disrupt wired communication.

Physical force is another hazard which can come in the form of mechanical shock and vibration, or pressure. To withstand shock and vibration, a robust mating method needs to be in place. Connectors in undersea, aerospace or pressurized environments also need additional ruggedization.

For connectors used in explosive environments, an additional requirement is that they do not have any way to set off a spark, either mechanically or electrically, and cause a hazardous explosion.

Rugged applications

The range of rugged applications is extremely varied, and crosses many industry lines. Ruggedized systems and connectors are used in industrial, marine, oil and gas, transportation and infrastructure, telecom, and more.

Industrial. In industrial environments, technology such as automation, machinery and measurement come together to create today’s hyper-efficient manufacturing systems. Industrial environments are often exposed to a variety of harsh elements including water, vibration, chemicals and temperature extremes. The move to greater automation and “Lights-out” manufacturing means environmental challenges will only increase as equipment now increasingly has the freedom to operate in inhospitable conditions.

Industrial equipment such as food slicers, saws, sand blasters, food processors and coating machines can generate significant shock and vibration, as well as create dust or airborne contaminants. Sealed, rugged metal or plastic housing connectors with IP66, IP67, IP68 and IP69K ratings can withstand these harsh conditions and keep power, signal and data connections secure.

Because of noisy EMI conditions in industrial environments and the dependence on sensors and communication, EMI is also a concern for data connections. In these cases electrically shielded connectors are ideal.

Marine. Marine applications are faced with challenging environmental conditions, both on the surface and underwater. Surface marine applications such as boating equipment, ship-deck systems, or marina facilities face threats from corrosion due to high salinity, as well as water ingress, making robust, sealed components essential.

IP rated components should be chosen depending on the level of water and dust protection needed, with IP66 and IP67 sufficient for many surface applications while IP68 or IP69K will be necessary when connectors may be submerged. For undersea applications such as diving electronics, depth loggers or undersea remotely operated vehicles, it is important to source independently tested systems purpose-designed for subsea pressures.

Oil & gas. The oil and gas industry faces many of the same environmental hazards of industrial and marine environments, but must also deal with explosive atmospheres which require the use of ATEX /IEC Ex rated equipment. For offshore platforms, both marine hazards and explosive atmospheres exist. In addition, the oil and gas industry makes extensive use of underwater ROVs for drilling and construction support as well as exploration.

These underwater remotely operated vehicles are essentially remote-controlled robots. They require power, data, and often fiber-optic lines, have to operate in rough subsea conditions, and are often asked to go to depths beyond the possibilities of human divers. Bulgin’s ROV tether connector, for example, is designed to keep these robotic helpers working reliably in uncertain waters. Made from 316 marine-grade stainless steel, it is a Pressure Balanced Oil Filled (PBOF) cabling solution that uses oil as a compensating fluid for water pressure, allowing ROVs to submerge to depths of 7,000 m.

Other applications. From transportation and infrastructure to automotive and agriculture, a wide variety of electronic systems operate in the outdoors. They require connectors that can withstand extreme temperature changes, water and dust ingress, physical duress, and more.

No one-size-fits-all solution

One of the first challenges for the manufacturers who design connectors for rugged environments is the term “harsh” or “rugged.” These terms might lead customers to the assumption that there is a “holy grail” of rugged connectors that will be a one-size-fits-all solution for all applications. The truth of the matter is that this is impossible, simply because all applications have their own subtle differences and requirements, and all customers have different budgets.

The best approach will be for the designer to work as closely as possible with the client to find customized solutions. Design engineers will first gather as much information as possible to accurately scope out the project and ensure that the solution will be both wanted and fit for purpose. The engineers will then work against time, budget and scope drift to ensure that the solution is adequately tested and delivered by the project deadline.

Key features

IP rating. IP ratings define the level of protection from dust and water ingress of the component. The first digit indicates the level of dust protection and goes from 0 to 6, while the second digit indicates liquid ingress protection. For harsh environments, sealed connectors should always be dust-tight, with water ingress protection depending on the application.

IP66 (protection against powerful water jets), and IP67 (immersion up to 1 m), are suitable for many above-water applications where systems may be rained on, or otherwise repeatedly exposed to water. Connectors which may be continuously submerged should be at least IP68 (immersion to 1 m or more) or greater. For undersea applications, purpose-designed equipment with independently tested depth ranges is vital to ensure complete underwater protection.

IP68 and IP69K (protection against close-range high pressure and high temperature spray-downs) are extremely effective for medical and food processing environments as this allows the equipment to be regularly washed and sanitized without harming the electrical components.

Locking/coupling mechanisms. With many connectors being exposed to environments with shock and vibration present, a robust coupling mechanism is a must. There are many different types of connector couplings, including ring, twist locking, threaded, bayonet, push-pull and quick-disconnect couplings, all with different attributes for various types of applications. Some, like the bayonet connector provide better security against shock and vibration while others, like push-pull and quick disconnect, provide greater ease of use when connectors may need to be disconnected often.

Housing and insulation. The material that makes up a connector helps it resist environmental challenges. For applications with extreme temperatures as well as plenty of moisture and dust, a corrosion resistant metal housing may be appropriate. If lightweight and flexibility is key, temperature-resistant plastic composites will be more attractive.

Connector design. The connector’s shape, mating mechanism and pin positioning also play a part in its ruggedness. Circular connectors have the benefit of easy engagement/disengagement, as well as the capacity to fit a wide variety of contacts with the connector body. Circular connectors also are easy to seal and less likely to wear out. An intelligent “scoop proof” design can be used to avoid pin damage while trying to mate the connector.

Making the right connections

Our world is becoming increasingly connected. From outdoor cellular base stations to connected factories, to IoT sensors on oil and gas platforms, electronics are being placed in every environment imaginable. The electronic systems have to be guarded against all the forces of nature.

As the point of entry to the system, connectors must be robustly designed to seal off and protect against all environmental challenges present—from shock and vibration to dust and water, or EMI. Thankfully today’s connectors have evolved to provide strong ruggedization for just about any application in many markets, such as Bulgin’s Buccaneer range of power, signal and data connectors. Through choosing the right IP rating, locking mechanism, housing material and connector design, almost every rugged electrical system today can be made to work reliably with the right connector.

Bulgin
www.bulgin.com