The electric and electronic design of appliances continues to change as manufacturers work to create products that include enhanced features and provide more energy and cost-efficiencies. Yet, through all of these design modifications, there are some components that remain essential to any electric or electronic design: connectors.

Similar to other devices that require electric or electronic current in other industries, connectors continue to play a larger role in the creation of nearly every appliance available to the market. With the potential for multiple interconnect points within a given appliance, it begs the question, “How should a designer determine which connector or connectors to use?”

From round-pin connectors, flat-tab style connectors and insulation-displacement technology connectors, there are several choices for a design engineer to consider, depending on the application.

Low-cost, round pin

Round-pin connectors can be best described as generalized power connectors. These connectors are not only a low-cost option, but they are also a proven solution, as they have been used for several decades in appliance applications. Along with their reliability and versatility, round-pin connectors use a simple crimp, poke and plug application for easy assembly. The terminals are designed to crimp to specific wire gauge sizes and are inserted in the housing (insulator) by hand. The terminal and housing combination typically has a built-in locking element to retain the terminal and wire within the housing. Round pin connectors are well-suited for low-volume applications. Round-pin connectors can also be used outside of the appliance industry in lighting and electronics.

Flat-tab style

The Versablade flat-tab style connector system is based on three components: 1.80 mm (0.070 in.) width, flat-blade tab terminals, multi-configured modular housings and terminal position assurance inserts. The system accepts AWG 14-22 wire and can carry 4 A to 15 A and 300 V.

Appliance designs differ from one global location to the next and have influenced connector development on a regionalized basis. For instance, North American manufacturers have shifted some connector demand from round pin to an expanding market for 0.125 in. (3.17 mm) or 0.250 in. (6.35 mm) flat-tab style connectors. While in Asian appliance markets, 0.070 in. (1.80 mm) wide flat-tab style connectors are popular. Flat-tab connectors offer the multi-circuit similarity to round pin connectors, or may also be available as a single termination, commonly known as a Quick Disconnect. They are also similar in that the terminals are crimped to wire and are inserted into the housing by hand.

Whether it is 0.250 in., 0.125 in. or 0.070 in., the advantages of a flat-tab system over a round-pin system is three-fold:

• Greater electrical and mechanical reliability.
• Higher amperage capability.
• Improved physical features that enhance the assembly process.

Flat-tab style connectors have multiple points of contact interface for a more reliable electrical connection. Mechanically, the housing and terminal combination design provides greater assurance against terminal back-out. Depending upon terminal and wire size and circuit count, flat-tab systems are capable of carrying up to 30 A of current, which is significantly greater than round pin systems.

On the physical side, flat-tab style housings have harness assembly protective elements such as anti-tangle walls to prevent wires from being tangled under the latches and breaking. Some flat-tab connector designs include inexpensive Terminal Position Assurance inserts, which ensure the terminals to be fully seated and prevent terminal back-out in high shock and vibration applications.

Flat-tab style housings also include ergonomic considerations, such as pull-tabs to simplify mating and to prevent un-mating. Their male tab and female box style contacts resist deformation due to handling. Additionally, flat-tab style connectors have terminals that are keyed to specific housing silos to allow multiple wire gauges for use within the same housing. Finally, the flat-tab style modular system enables power and signal to be combined in to one common, panel-mount plug.

This multi-module housing system can help manufacturers overcome problems associated with clustering multiple, relatively low-pin count assemblies on one interface. This makes the flat tab style connectors well suited for HVAC, major appliances and consumer electronics applications. They are also used for specialized applications, where it is necessary to bring multiple connections from devices in various locations within a unit, such as washers or other situations when different wire gauges are located in far locations.

Standardizing with RAST

Molex’s RAST IDT connector system, Appli-Mate, offers high specification products that are tested under the most severe conditions. The Appli-Mate system has two distinct connector families RAST 5, RAST 2.5 and RAST Power, and has a field life of over 10 years.

RAST is an industry standard connector. The acronym roughly translates to “pitch connector plug technology.” The RAST standard governs the connector’s interface. RAST, which originated in Europe and is gaining momentum in North America, was developed to eliminate mis-mating and accomplishes this with a standardized keying system.

Unlike North American consumers in the 1980s, European consumers were willing to pay a high cost for appliances that used less water and energy. Yet the sensors, controllers and actuators that help to deliver these efficiencies, brought on increased mismatched and crossed wiring issues. To alleviate this situation, appliance OEMs and electronic manufacturers created the RAST standard, which typically uses IDT connectors.

IDT connectors have preloaded internal contacts that displace the wire’s insulation. This eliminates the need to strip wire, crimp terminals to the wire, and insert terminals by hand in a multi-circuit housing. The most obvious benefits of using IDT are reducing assembly labor costs and full automation.

For instance, using fully automated tooling drastically increased the number of terminations annually, with one operator doing the work of many. Because IDT terminals can be mass-terminated in a single step, fully automated tooling can be used, which can be outfitted with a full array of testing capabilities that virtually eliminates the possibility of a bad harness making its way to the production floor. Full automation makes these connectors ideal for high-volume applications, such as major appliances and other automated assembly products.

Many options

As appliance manufacturers continue to make technological advances in design, connectors will serve as an important part of the equation. Even though they are all designed for use in appliances, round-pin connectors, flat-tab style connectors and IDT connectors each have unique traits that matches them with different applications. When choosing a connector for an appliance, design engineers should start by examining the appliance’s application, assembly method and appliance category. Then, they can choose the connector type that best meets these needs. Fortunately, with round pin connectors, flat-tab style connectors and IDT connectors, they have plenty of options.


For more information email: donna@jaisinc.com