Whether designing casualty power connectors for shipboard use, high power connectors for electric submersible pumps in oil wells, or high temperature connectors for use under railway cars, manufacturers must ensure that the parts function in these environments at all times. Materials selection is critical, and whether the connector is designed for submersible, high shock and vibration, high pressure or extreme temperature environments, customers need to know the connector they’ve selected is proven for such use.
It’s imperative to engage with a connector company that is experienced in designing for these harsh environment applications and that is also familiar with testing parameters from a regulatory and standard bodies standpoint.
Connectors for Ship, Oil and Rail
Ship, oil, rail and even energy applications require highly robust connectors that operate properly at all times while conforming to stringent qualifications. For example, casualty power connectors employed on navy ships and aircraft electrical servicing cables used on navy carriers not only must meet all MIL qualifications, such as MIL-DTL-24552, MIL-DTL-32180 and VG95234, but they are also ITAR (International Traffic in Arms Regulations)-controlled and subject to further qualification testing.
Connectors are also often employed in energy applications such as electric submersible pumps in oil wells. Used at the surface and deep within the well, these connectors, as well as connectors and splices for metal-clad cables used in permanent down-hole gauges in oil and gas wells, must provide safe penetration for electrical power at all times.
Regardless if the application is for navy carriers, oil wells, passing electrical energy through pressure barriers or even railway applications such as electronically controlled pneumatic (ECP) brakes, connectors in these applications will be exposed to high shock, vibration, pressure and temperature conditions, as well as fluctuating environmental factors. As such, there are critical component parameters that must be met when designing connectors for ship, oil, rail and energy use.
Critical Component Parameters
When sourcing connectors for these harsh conditions, voltage specifications, size and resistance to environmental elements are just a few of the critical design parameters that must be considered.
Temperature is a concern, particularly in rail applications where components must be flame-retardant. While materials like neoprene are suitable for temperatures ranging from -55°C to +25°C, connectors utilizing silicon are capable of operation from -55°C to +200°C. Further still, some connectors are designed to meet European CEN/TS 45545 standards governing railway fire safety, and thus must be capable of withstanding a high temperature exposure period of at least 15 minutes at the ISO 834-1 heating curve, where maximum temperature is 800°C.
High-temperature connectors are often constructed with machined copper alloyplated contacts, a machined stainless steel shell and ceramic inserts. Conventional connector inserts are constructed with plastic or rubber, but these materials melt under the extreme temperatures of a fire. Ceramic, however, is resistant to fire and brittleness caused by moisture evaporation, and the rigidity of the material makes it less susceptible to vibration and breaking. A ceramic insert is kept in place in the shell by the use of a metal retention ring. As a result, the connector is easy to disassemble, allowing for quick, simple field maintenance and service.
Sealing for ship, oil and rail applications requires more than meeting IP69 or IP69K standards. Because of the applications, oftentimes connectors must be waterproof to 10 meters for up to 12 hours. Including wire sealing silicon rubber grommets on the plug and receptacle interface further enhances the robustness of the connector by sealing the wires against humidity, water and fluid penetration. Additionally, shock and vibration resistance is often specified to 50G and 20G, respectively. Once again, the use of a metallic retention clip provides a high integrity contact that will not release under extreme shock and vibration conditions. Designing a connector with bayonet coupling further ensures robustness, high vibration resistance as well as the ability to withstand moisture ingress.
Finally, as in many markets, size is a critical factor in component designs. While many connectors are small in size, especially given the amount of power they are often capable of delivering, customers continually seek smaller designs. Energy applications, such as passing electrical energy through pressure barriers, often requires connectors capable of 5000VAC at up to 200A (that’s about 800KW – enough energy to power 200 homes!).
Because of advancements in materials – such as the use of thermosetting elastomeric materials and PEEK (polyaryletheretherketone) engineered plastics, smaller, circular connector solutions are available down to 3" in diameter for many harsh environment applications, even for those requiring higher power and where resistance to high temperatures, high pressures, corrosive liquids and gases are imperative.
Sourcing Connectors, Testing and 3rd Party Approvals
Worldwide standards for ship, oil, rail and energy applications differ from country to country. This is particularly true for DIN rail specifications. NACE (National Association of Corrosion Engineers) International and API (American Petroleum Institute) set standards for materials and corrosion resistance, as well as suitability of products for service in hazardous locations, while military and ITAR specifications further define connector designs.
Engaging with a connector manufacturer that is experienced in each of these areas takes the guesswork out of designing for high temperatures, high-pressure interfaces, and a myriad of other design challenges. Because these parts are being used in oftentimes critical applications and situations, customers’ do not want to be part of the suppliers’ learning curve; to maintain high levels of quality and performance, and avoid dangerous results, they want parts from a manufacturer with a proven track record. Working with a manufacturer who is familiar with meeting the testing parameters of regulatory and standard bodies further streamlines design and development processes, while ensuring the connectors meet all necessary regulations. Inhouse testing capabilities such as hydrostatic testing to 19,000 psi, down-hole environment testing to 450°F at 7,000 psi, as well as continuous quality improvement programs, further reinforce a connector manufacturers’ position as an expert ship, oil and rail connector source.