By Randy Sadler
Circular DIN connectors are being tested for use in fuel cell applications for power and signal connections.
Circular connectors fit almost any application available today, from harsh industrial environments to high-reliability aerospace system applications. There are literally thousands of applications across a variety of industries and new projects are developing everyday.
The primary industries are:
- Industrial automation — as electronics becomes even more widely incorporated into industrial controls and peripheral equipment, the need for robust connectors is an absolute requirement.
- Medical products — as technology for this field advances daily, reliable, high-density connectors are becoming an increasingly important part of equipment design.
- Military/aerospace — light, space-saving, highly reliable connectors are required for aircraft and mission-critical equipment.
- Communications — one of the fastest growing industries; networking and transmission equipment requires reliable interconnection products for installation and troubleshooting.
- Transportation/automotive — highly reliable and durable connectors are required for the tough environmental conditions found in railway cars and automotive plants throughout the world.
Another application for circular connectors is in hazardous locations. Several manufacturers have products certified for use in these locations. They are primarily intended for use in instrumentation and control applications on offshore drilling platforms, in chemical plants and in petrochemical refineries.
Fuel Cell Market
Circular DIN connectors are also being tested in emerging markets, such as fuel cell technology for transportation applications, including buses, cars and trucks. Not on the plant floor, but inside the vehicle, the connectors are being used for power and signal connections. With all of the new electronics, global positioning systems, sensors and so on being installed in cars and trucks, there is an absolute need for highly reliable and durable connectors that can provide a solution for automobile manufacturers.
California's zero-emission vehicle law states that by 2004, 10 percent of automakers' cars sold in the Golden State are to be zero-emission vehicles. Several Northeastern states have also adopted this law. Even the cleanest internal combustion engines cannot cut the mustard. Battery-powered vehicles, which can meet these stringent zero-tolerance emission requirements, are struggling to achieve acceptable levels of performance, range and recharge cycles. Component suppliers need to investigate the materials, systems and processes needed to build these zero-emission engines and their drive systems, or risk being left behind by more innovative suppliers. With fuel cell technology, pollutant emissions are practically zero.
Fuel Cell Technology
 Figure 1. Conceptual operation of a fuel cell. |
What is fuel cell technology? The basic principle was discovered in 1839. Fuel cells are electrochemical devices that convert a fuel's energy directly to electrical energy. Fuel cells operate much like continuous batteries when supplied with fuel to the anode (positive electrode) and oxidant (e.g., air) to the cathode (negative electrode). The cells forego the traditional extraction of 1) energy in the form of combustion heat, 2) conversion of heat energy to mechanical energy (as with a turbine) and 3) turning mechanical energy into electricity (e.g., using a dynamo).
Instead, fuel cells chemically combine the molecules of a fuel and oxidizer without burning, thus dispensing with the inefficiencies and pollution of traditional combustion. Fuel cells function on the principal of electrolytic charge exchange between a positively charged anode plate and a negatively charged cathode plate. When hydrogen is used as the basic fuel, reverse hydrolysis occurs, yielding only water and heat as byproducts, while converting chemical energy into electricity (see Figure 1).
Production and distribution of energy affects all sectors of the global economy. The increasing industrialization of the world requires sustainable, highly efficient energy production. Without a major technology advance, projected insufficient energy production will dramatically impact the quality and sustainability of life on earth. For this reason, the application of fuel cell technology may be the most important technological advancement of the next decade.
Circular DIN vs. Military-style
 Figure 2. "Smart" connectors incorporate fiber optic electronics within the connector housing. |
Circular connectors can be broken down into two distinctive types. The predominant circular connectors used in the United States are military-style or MIL-Spec-type connectors. The second type is standard European industrial circular DIN connectors. The product differences are analogous to U.S.-style barrier strip terminal blocks and International Electrotechnical Commission (IEC)-style DIN rail-mounted terminal blocks. Military-style connectors are larger and less expensive than industrial circular DIN connectors. Circular DIN connectors are much smaller, and smarter. They are available with "electronics" inside (see Figure 2).
Circular DIN connectors are being tested for fuel cell applications because of their reliability and functionality. Circular DIN connectors have both power and signal contacts in a single housing that is robust and provides electromagnetic compatibility (EMC) shielding. Applications for circular DIN connectors in fuel cell technology range from military to civil, from submarines to taxis and from forklift trucks to boats.
Circular DIN connectors have made their way into fieldbus technology as well. Because decentralization and standardization play such integral roles for fieldbus manufacturers, so do the connections. Circular DIN connectors are also becoming popular in fiber optic applications because standardized connectors make fiber optics more cost-competitive.
Other considerations are high-protection applications, such as IP67, EMC screen shielding for safer data transfers, higher transmission speeds, and smaller and lighter designs (such as plastic) that can be located closer to, or on, the machinery.
Why Circular DIN Connectors?
Why circular DIN connectors for the fuel cell technology vehicle prototypes? Automotive manufacturers are being very hush-hush about the applications for circular DIN connectors with fiber optic and copper conductors inside the car itself. No one wants any trade secrets to leave the research and development area before the testing is finished and the details have been worked through.
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This much is known. Circular DIN connectors are being seriously considered because of their relatively small size, proven reliability on plant floors in the harshest environments, and capability to mix power and signal connections inside one product instead of two separate connectors (one for power and the other for signal). A recent circular DIN connector development allows plastic fiber optic contacts, and their associated electronics, to be mounted right inside the same connector with the "normal" copper conductors (see Figure 3 and Table 1). This "hybrid" connector offers real benefits to fuel cell system design engineers, including:
- Prevention of EMC interference
- Electrical isolation
- High rates of data transmission
- Ideal solution for fieldbus systems
- Low signal damping and distortion
- Saves space and components (one connector and one cable)
- IP67 rating
Conclusion
 Figure 3. Hybrid connectors integrate electrical and fiber optic contacts in a single housing. |
Today, both styles of circular connectors, DIN and military-style, are used in almost every industry in a range of applications. Circular DIN connectors are emerging and gaining more acceptance over the larger, less-frills military-style connectors. As everyone knows, things are quickly getting smaller and smarter. Connector suppliers must move as fast or faster to stay ahead. Circular DIN connectors offer higher performance, shrink the size and weight of the connector, and reduce the number of components (one connector and one cable for both power and signal). With all of these benefits, it is no wonder the automobile industry is testing and designing-in circular DIN connectors for use inside future vehicles.
RANDY SADLER is Vice President, Sales and Marketing, Contact Electronics, 38 Fairfield Place, West Caldwell, NJ 07006; (973) 575-7660; Fax: (973) 575-7208; Web site: www.contactelectronics.com.
SPEC SHEET
End Applications:
Harsh environments, such as automotive, military, marine, industrial and medical
Related Products:
Circular, circular DIN, military-style, fiber optic and fieldbus connectors
Main Point:
Circular DIN connectors are emerging and gaining more acceptance over larger, less-frills military-style connectors. Circular DIN connectors offer higher performance, shrink the size and weight of the connector, and reduce the number of components needed (one connector and one cable for both power and signal). It is no wonder the automobile industry is testing and designing-in circular DIN connectors for use inside future vehicles.
Designing to Meet Requirements
By Bill Barbera
 Miniature circular connectors and splices. |
Designers of electronic and electrically based systems for aerospace, automotive, marine and advanced industrial applications all face the same challenge — reduce the weight, trim the size and lower the production cost. Not long ago, lighting engineers employed by a U.S.-based airframe manufacturer rolled up their sleeves and responded to such a challenge. They configured a complex lighting system that could provide the desired level of brightness throughout the passenger area of a plane while its power circuitry remained hidden away within the confined area between the airframe wall and back of the decor paneling.
To produce the new lighting system, design engineers needed miniature circular connectors and splices that could meet the weight, size and cost requirements. The connectors also had to stand up to the punishing conditions of shock, vibration and moisture that typically occur while a plane is in flight, as well as during take-off and landing. A high degree of manufacturing sophistication and quality control would be essential to meet the stringent design specifications and to assure the integrity of the product.
Accepting the Challenge
WPI/Viking accepted the task of developing these miniature circular connectors and splices for the airframe manufacturer. The company applied its capabilities to produce a product that satisfied the requirements set forth by the design engineers. The final result was miniature circular connectors and splices that are lightweight, rugged and flame-retardant, and that exhibit a high degree of resistance to moisture. They also have a positive-latching system, and the capability to mix power and signal contacts in the same housing.
Secure, Reliable Connection
The miniature circular connectors and splices consist of a receptacle that receives removable pin-type contacts, and a mating plug that receives removable crimp-type socket contacts. Insertion and removal of the individual screw-machined contacts is accomplished by using industry-standard tools.
The connectors and splices have thermoplastic (polyester elastomer and nylon) housings that protect the electronic components against vibration and shock. The plug and receptacle housings are molded with keying features that are specific to each polarity configuration so that only plugs and receptacles of the same polarity can fit together, eliminating the risk of mismatching. Three polarizing options are available. During a typical lighting or power circuit installation, technicians may very well be using two or all three of the polarity configurations.
Moisture Resistance
The miniature circular connectors and splices are manufactured with a silicone rubber wire sealing grommet on both plug and receptacle housings. The receptacle cavity of the miniature circular connector is also fitted with a silicone rubber facial seal that compresses the connection to the plug, providing a seal against moisture and dust.
Latching Features
Latching features have been incorporated into the design to ensure that the connectors and splices provide a reliable electronic interconnection in applications where strong vibration typically occurs. The mating halves are latched together by means of two integrally molded latch features on the plug that engage complementary features on the receptacle. The maximum force needed to engage or separate the plug and receptacle is 10 lb. When the plug and receptacle are latched together, the resulting mechanical contact retention is 20 lb in both directions (axial displacement not to exceed 0.020").
Conclusion
The miniature circular connectors and splices are made from materials that withstand extremes of heat and cold and other harsh conditions without increasing the weight of the connector assembly. By incorporating the additional features of keyed fitting of plug and receptacle and a silicone rubber seal, the connectors offer protection from shock, vibration, moisture and dust. This combination of material and product design provides the connector market with an affordable solution to the demand for products that withstand harsh conditions in spite of size and weight restrictions.
BILL BARBERA is Director of Marketing, WPI/Viking, 5455 Endeavor Court, Moorpark, CA 93021-8009; (805) 553-9633; Fax: (805) 553-9655; E-mail: info@wpi-interconnect.com; Web site: www.wpi-interconnect.com.
