More tasks need more versatile, varied wire, cable types

Selecting cable used to be easy. Users picked wire for communications and control or to supply power. They added accessories, trays and tracks, and connectors to fit their layout and facilities, and specified environmental protections, such as chemical/oil resistance and shielding/interlocking armor.

06/01/2000


Selecting cable used to be easy. Users picked wire for communications and control or to supply power. They added accessories, trays and tracks, and connectors to fit their layout and facilities, and specified environmental protections, such as chemical/oil resistance and shielding/interlocking armor.

Because standard hook-up wire or multiconductor twisted-pair is still by far the most used wiring, these basic criteria remain crucial. However, more sophisticated sensors, I/O devices, data acquisition, and communications, as well as varied power requirements, and multiplying robotics and machining center applications, are making wire and cable selection increasingly complex. Still, specifying the correct cable doesn't have to be a mystery.

There are eight main choices when it comes to non-stationary, communication, or more traditional wire and cable. These include continuous flex; torsional robotic; servo; control; data bus; European wire, cable, and cordage; European Unitronic; and crane and conveyor system cable. Variable frequency drive, fiber-optic, and more specialized cable types and combinations are also widely used depending on specific applications.

  • Continuous flex cable, for example, is designed for high-speed automated applications, such as industrial robots, pick-and-place machines, handling systems, machine tools, and conveyor systems. Standard control cables are also used in these applications, though they're unable to match continuous flex's usual minimum performance of 5-10 million cycles. Continuous flex cable should also be able to travel at 6.5-13 ft/sec and accelerate at 25 ft/sec.

Continuous flex cables are made of resilient materials, so they can immediately return to an unstressed state after each flexing cycle. Their copper conductors must be made of finely drawn (no more than 34 gauge) strands rather than coarse ones, which aids movement and reduces wear.

When selecting and installing continuous flexible cable, users must also be aware of its bend radius. This is an evaluation of how tight an angle (usually 12x diameter or less) that it can follow without loss of elastic memory or other damage. Users must also project the flex life their cable will need by calculating the approximate number of cycles it will need to travel.

  • Torsional robotic cable is designed to perform in twisting and bending applications without failure or fatigue, generally for more than 2 million cycles. It must also meet the flame, voltage, and aging requirements of standard cable.

  • Servo cable can combine up to three types in one cable for power, signal, and control of servo motors to achieve exact movement over large or small distances. Certain servo systems require high flex-cycle life cables, and may contain several different gauge conductors. Power conductors drive the motor, while control conductors direct desired movements. Servo motors often operate in environments that require them to be shielded from electromagnetic interference (EMI), which can distort control and feedback signals.

  • Control cable allows data transmission throughout applications and facilities. This cable traditionally operates at 115 V ac or 24 V dc over small and medium gauge, shielded cable. This type is sometimes known as "electronic wire."

  • Data bus cable transmits information in high-speed, high-bandwidth applications via device level networks that connect plant floor devices to control systems, without the need for input/output (I/O) interfaces. Fieldbus wiring also performs many of the same tasks, though it may also deliver low power to some applications.

  • European wire, also known as "harmonized" cable, is used in equipment intended for export to European countries adhering to European Committee for Electrotechnical Standardization (CENELEC) guidelines, while complying to CE directives. Harmonization cable standards apply to power supply cable and hook-up wire.

  • European Unitronic electronic cables are multipair cables that likewise satisfy European standards such as VDE and DIN. They are used in electronics, communications, process control, and instrumentation applications.


Author Information

Richard Buchicchio, marketing director, Olflex Wire & Cable, Fairfield, N.J.


Wire and Cable Types Common uses

Standard twisted pair: All types of communication applications in normal ambient conditions.

Accessories, tracks, connectors: All types depending on specific industries and applications.

Flexible variable frequency drive: Drives, motors, and related applications.

Fiber optic: Many types, including high speed, data integrity, and noise immunity.

Chemical/oil resistance: Harsh, potentially corrosive environments.

Shielded/interlocking armor: Heavy EMI, RFI environments

Continuous high flex: Robotics, motion systems, machine tools, gantries, torsional robotic, servos

Source: Control Engineering