Implications for Sensors and Actuators
IDC connector technology, a fast and simple termination method that requires no tools, lends itself to installation, testing, and maintenance of industrial cables.
John Moore, Harting, Inc., of North America
Bill Robinson, The Interface Group
Wherever any electrical system is installed, and especially in sensor/actuator systems where the integrity of low-power signals is critical, electrical terminations must provide high-quality, low-resistance connections between conductors and the termination device. Industry has placed great emphasis on reducing the time required to make terminations while maintaining integrity of the system.
Conventional screw, solder, and cage clamp termination devices require removal of the insulation from the conductor to ensure electrical contact. Stripping to the correct length without nicking or damaging the conductor takes time and must be accomplished properly.
Insulation displacement contact (IDC) technology, an alternative to conventional methods, is a termination method in which individual conductors keep their insulation while being pressed between two blades. The blades cut through the insulation to make contact with the conductor, saving a lot of time because the insulation is not removed. The first U.S. applications of this technology were during the 1950s in the telecommunications industry, where large numbers of small conductors needed to be quickly and reliably connected. It is still used extensively in different forms in telecom applications, achieving high-quality terminations in the field and throughout the telecommunications infrastructure.
Photo 1. HARAX is a detachable insulation displacement connector system for heavy industrial use.
IDC technology’s greatest benefit is placement speed. As the demand for cost savings, modularization, and connectorization fuels the trend toward faster, more reliable connections, IDC connectors are gaining widespread acceptance throughout a variety of industries. Installation and maintenance costs are major factors when commissioning plant machinery, and downtime can be very expensive. IDC connectors readily lend themselves to industrial applications for initial installation, testing, and maintenance because they require no tools. Since the installer doesn’t need to strip or crimp the wire, these connectors take as little as 25% of the time required by conventional connector methodologies. Screw clamps, while offering high connection quality, take longer to terminate. Spring cages are much easier to terminate than screw clamps but the insulation must still be stripped from the conductor. IDC connectors also eliminate much of the human error in connector installation. Strip too much insulation, and wire is left exposed; strip too little, and connections are sometimes compromised. This approach also prevents bare wires from coming into contact with one another. Incorrect tightening torque on saddle or screw clamps has been the culprit in many field device failures where loose connections caused high resistance burn-up of the termination.
Harting, Inc., developed the HARAX insulation displacement connector (see Photo 1, above) as a field-attachable device with widespread industrial applications, including those that use sensors and actuators. The connector can be assembled in three simple steps (see Photos 2, 3, and 4)
Photo 2. Strip the outer jacket from the cable.
Photo 3. Assemble the screw cap, rubber seal, and splitter block onto the cable.
Photo 4. Slide the contact carrier over the splitter block and tighten the screw cap.
The resulting gas-tight connection qualifies for an IP67 rating, making the system well suited to heavy industrial applications. HARAX is intended for round cables containing a low number of strands, optimal for areas where sensors and actuator boxes are used.
Industrial 3- and 4-pole connectors are most common in automated machinery incorporating many sensors and actuators. The time when an IDC industrial (field attachable) connector is very useful is when a molded connector must be cut from the end of a cable assembly. After the cable jacket is trimmed away, an IDC connector can be immediately assembled onto the end of the cut cable. In addition, those who need custom cable lengths can use spooled cable and HARAX connectors to build their own cables. The connectors can be reused up to 10 times without suffering degradation of the connection. The rubber seal acts as a cable strain relief when properly tightened. HARAX provides termination components for panel feed-through, M8 and M12 connectors, and passive sensor/actuator boxes, as well as customer-specific solutions. Typical applications involve systems with working voltages up to 230 VAC/16 A.
Several panel feed-through products are available:
- With fast-on contacts
- With solder lugs for hand soldering
- With solder pins for PC board connection
HARAX connectors are typically used by industries that require sensors, actuators, and I/O boxes. These include packaging, robotics, plastics, metal forming, materials handling, wood and paper, pharmaceutical, textile, food processing, and automotive assembly and conveying.
HARAX is a registered trademark of Harting, Inc., of North America.
John Moore is Marketing Manager, Harting, Inc., of North America, 1370 Bowes Rd., Elgin, IL 60123; 877-741-1500, fax 847-717-9420, firstname.lastname@example.org.
Bill Robinson is Vice President, The Interface Group, 425 Huehl Rd., Ste. 4A, Northbrook, IL 60062; 847-498-6133, fax 847-498-6170, email@example.com.