Understand The Cause Of Control Cable Wire Failure

Five Control Cable Wire Failure Modes

1. Conductor failure

Open Conductor - The conductor may break or break, resulting in a loss of continuity. Causes can include repeated bending in a narrow bend radius or ticking motion, incorrect or too-tight bend radius, or extreme tension on the cable.

High resistance of conductors - Stranded conductors will most likely initially see a single-strand break before the conductor is cut. As a single strand break, the resistance of the conductor increases. This can lead to two possible failure modes: 1) the conductor strands will continue to break until a complete break occurs, or 2) the higher resistance will begin to generate heat and eventually overheat, causing localized burning points to break the conductor.

2. Insulation failure

Cracks/Perforations - Types of insulation failures may include cracks or perforations in the insulation. Cracks in insulation can be caused by constant bending over narrow radii. The insulating material becomes fatigued and eventually fails. Perforation of the insulation can occur if the conductor strands begin to break or cut and perforate the insulation wall.

3. Shield fault

Foil Guards - Foil guards tend to break down over time when subjected to repeated bending/bending movements. Foil shields started to crack, eliminating their use in cables.

Copper Braided Shields - Copper braided shields can become mechanically fatigued, especially when placed under twisting or twist-type motion.

4. Jacket failure

The jacket protects the inner conductor and cable assembly from the external environment. It is subject to the greatest abuse by mechanical, chemical, and weather influences.

cable expansion

Cracking/Expansion - Exposure to certain oils, chemicals or fluids may cause the jacket material to react negatively. Depending on the chemical, this can cause the sheath to swell and become soft and tear easily, or hard and brittle leading to cracking.

Wear - When the outer jacket wears from exposing the cable core, the outer jacket fails due to wear. This type of failure occurs when the cable is used in an application that wears down the cable. This can happen if the cable is dragged across the ground, in an application that constantly rubs against the cable, or if it is improperly installed on the equipment.

Cuts/Punctures - Bumping or contact with sharp objects can cause cuts to the jacket. Small cuts that appear only on the surface of the jacket usually do not affect cable performance. Cuts that impair the performance of the jacket or penetrate into the shield or cable core are reasons to repair or replace the cable.

5. Electrical failure

Open Circuit or Loss of Continuity - An open circuit (or loss of continuity) of a conductor will result in a loss of power or signal data.

Short Circuit - A short circuit can occur if a conductor strand breaks and penetrates the insulating wall and comes into contact with the shield or other strands of the broken conductor. Conductor-to-conductor or conductor-to-shield shorts may occur. Depending on the location and application of the short, this can result in loss of signal or data, or transient overcurrent resulting in conductor or cable damage.

Shielding Loss/EMI-RFI Issues - Cables may be more susceptible to EMI/RFI noise issues if foil and/or braided shields are damaged. This may result in data loss or corruption.

Current Overloading - If the ampacity is not handled properly, the cable can overheat at the conductors. This can lead to extreme heat build-up that compromises the integrity of the insulation and sheathing materials. In extreme cases, cables can burn and become flammable.