As the word co-axial defines, concentric conductors separated by insulators, so the co-axial cables could be elaborated in wider sense of cables that have two conductors as well as insulators on alternating positions. The risk factors of co-axial cables associated with moistures are very significant and have the potential of its potent damages and deleterious effects.
The interesting part is that the risk factor for the co-axial cables doesn’t come up with the heavy rainfall or flooding etc. but it makes its way very slowly as per time scale through minute gashes in the jackets.
Moisture, that are micro droplets of water, are vigorously harmful for all types of electrical equipment if they enter by means of intrusion. Now if we talk about the co-axial wires, moisture may cause grievous damage to them deteriorating its performance, efficiency and requirement for its replacement. The basic effects one could find because of moisture is “attenuation” or “power-loss”.
Attenuation occurs by means of resistive loss by oxidation and rusting of braid (braid refers to braided outer conductor). Moisture when enters inside oxidizes the outer conductor slowly which in turn increases the resistance of conductor and decline the performance of cables.
Another effect of attenuation is when water absorbs in di-electric, it persist there and got heat up when power is passed along the co-axial cable. The heat produced is solely the consequence of moisture intake.
The most common method of moisture penetrating in the coaxial cable is ‘Termination’. A basic example is the small termination box which is usually provided with the many TV antennas. When these boxes are used externally; they provide a little protection against the moisture and the coaxial cable will quickly deteriorates. However, self-amalgamating tape is the best precaution for this aftereffect.
Another way of moisture entrainment is the pin-holes in the coaxial cable’s jacket. This happens at the time of the installation, especially when cables are exposed externally or installed inside the walls. However, the best practice is to install cables very effectively.
As we know all elements have a certain vapor transmission rate. If a coaxial is experiencing continues contact with water so the shielding material will definitely allow moisture content to permeate through it.
Co-axial cables are indeed a new renovation in the cable assemblies, still they are susceptible to moisture/water vapors, and this could seriously impair the co-axial cable and deprived them of their pure efficiency. Attenuation is the major repercussion one has to face because of moisture. Moisture can be entered through jacket grooves as well as loose port seals. Preservation ways can variate as per source of entrance of moisture.
In the recent time, there are many types of sealing tapes and fillers available to prevent them from moisture and corrosion. Now it’s up to us how to fortify co-axial cables from moisture to continue derive their benefits.