How to Specify Rectangular Connectors for Automotive Applications
Rectangular connectors are commonly used in automotive applications, but the industry has unique requirements. Phoenix Contact offers tips on how to specify rectangular connectors for automotive applications.
Rectangular connectors have long been used in industries where a harsh environment is standard operating procedure. These connectors need to meet a variety of specifications, including a high Ingress Protection (IP) or NEMA rating; resistance to chemicals, cleaners, oils, or salt spray; and EMC shielding.
Rectangular connectors are commonly used in automotive applications, but the industry has its own unique requirements. Some cases will require routing data along with power, signals, or even pneumatics through the rectangular connector, while some connectors need to handle shock and vibration but also be flexible enough to maintain the connection.
Size and Type
To determine the size of the rectangular connector required, the engineer needs to know some basic information, such as the number of contacts, the wire’s AWG, the cable’s outer dimension, and the voltage and amperage for each contact. The preferred connection technology, whether it is screw, crimp, or even push-in, will affect the housing size. Crimp contacts provide high-density capabilities, but push-in technologies may be used to save production assembly time. Inserts can be “fixed,” with a known number of contacts, or modular, which lets the engineer determine the configuration that meets the specific design need.
Some rectangular connectors are compatible with a competitor’s products, so they can be installed on older machines. Size and contact positions will need to match, but this capability lets the engineer use multiple suppliers. In the automotive industry, where programs or line upgrades need to meet specific production time frames, having an industry-compatible connector is an immense advantage.
Typical I/O applications will require low voltage ratings (24VDC) with the current levels usually less than 2A. The heavy-duty rectangular connectors typically used in high-voltage applications (600V) can easily meet these low voltage and current levels. But with low current and voltage, a bigger concern is the errors that can occur inside the cabling or connector. Effort must be made to shield the interconnect from signal interference: Currents that are less than 1A or in the milliamp range may require gold plating; the housing must provide a conductive shielding path from the cable to the enclosure; and the housing’s sealing material will need to be conductive, so the entire assembly is properly shielded.
Some applications have high voltage requirements, such as 120V or 480V for motor control, welding, or power panels. Here, an engineer must ensure that transient voltages are not introduced into the signal and data lines. Hybrid inserts or modular inserts can route both power and signal contacts, and even Ethernet, through the rectangular connector. But again, the engineer must take care to eliminate signal errors generated by the power lines.
A sealed rectangular connector is imperative to protect the electrical contacts. Any degradation or breakdown of the contacts could cause error signals to the transmitted data, or worse, lead to a catastrophic failure. You must be sure that dust, water, or any outside contaminants cannot enter the connector housing. The cable gland, cord grip, or bayonet-locking gland must fit securely to the outer diameter of the cable to provide proper sealing.
Rectangular connectors have a multitude of locking mechanism options that attach the connector to the enclosure – single- or double-locking latches as well as bayonet- or screw-locking latches. If the application requires a high number of rectangular connectors to be mounted side by side, double-locking latches are desired and preferred, as the double latches allow easy access to unlock the connectors. One important note: the rectangular connectors should never be connected or reconnected under power. They are not a disconnect device.
Some manufacturers have developed rectangular connectors that do not require the traditional mounting base, which can reduce costs by up to 30%. These designs are mounted to the enclosure via a Philips or hex head screw, with the hex head providing IP69k sealing protection. Of course, another important aspect of this design is to confirm that the cable gland meets the IP69k requirement also. Typically, housings can be made of plastic (polyamide), aluminum die-cast, salt-water-resistant, or chemical-resistant materials.
Stocking numerous housing part numbers and configurations can be expensive and inconvenient, but one design on the marketplace eliminates this hassle. Instead of carrying eight different housing part numbers in stock, just one is required. The design accepts any one of the four glands that are offered, as well as modular or fixed inserts.
Like many other electrical devices, rectangular connectors require Underwriter Laboratories (UL) certifications. The UL seal means the product will meet the application safety specifications.
Some application environments will also require a NEMA or IP rating. A rectangular connector certified to NEMA 4/4x/12 or with an IP65 or 69k protection rating will help determine if the connector will survive in its environment.
Steven Obert is a product marketing lead specialist for industrial field connectivity at Phoenix Contact USA in Harrisburg, Pa.