What are Instrumentation Cables & their types?

Overview:Signal transmission has become easier due to modern wireless data transfer mediums. Data is transmitted and received seamlessly through wireless mediums and such mediums are spread across all the electronic gadget and computer based applications. Wireless transmission in many electrical equipment has partially reduced some part of physical wiring placed inside or around an equipment. Apart from the modern wireless methods, wires and cables are also very well capable of transmission of electrical signals in an electric circuit.

Cables and wires in industrial applications can shoulder different responsibilities such as transmission of power or transmission of signals and data. Cables used in power transmission applications are built to sustain damage and environmental impacts where as the cables used as signal transmission cables are built to shield the cable from outside signal inference. Cables are designed according to the application at hand and are provided with proper protective elements for e.g. insulation, sheath, braiding, shielding etc.

Instrumentation cables and instrumentation wires are the type of cables which consist of multiple conductors which help in conveying signals with low energy signature mainly used for monitoring and controlling electrical systems, power control and other processes associated with it. Such cables which are used in applications apart from power transmission also carry out important functions which help in smooth functioning of the process industries. Instrumentation cables are also typically used in microprocessor based or computerized instrumented systems. These cables are basically designed to transmit signals without interruption and interference from external sources.

Instrumentation Cables

Applications of Instrumentation cables: Instrumentation cables find application majorly in control and communication applications. Mainly these cables are used in process industries where a lot of systems are involved. Instrumentation cables are involved in process control, communication of analog signals or digital signals and voice transmission, signalling in industrial and process control circuitry.

Typical application industries: Instrumentation cables are used mainly in process industries, oil and gas industries, petrochemical industries, fertilizer industries, cement and steel industries.

Instrumentation cables typically tend to have a PVC outer coating. Polyvinyl Chloride (PVC) is one of the most popular materials used in cable and wire manufacturing. This material is basically a thermoplastic resin produced by polymerization processes. Due to polymerization and other processes this material tends to be resistant towards fire, flames, frequent abrasion and moisture containing environment. PVC can be considered to have fair toughness and mechanical strength so as to be used in outdoor environments. Due to properties like light weight, resistance to corrosion, weathering and chemicals this PVC material is an ideal choice for instrumentation cables and other power cables too.

PVC coating can be found over many instrumentation cables. The conductor used in instrumentation cables is similar to that of power cables which happens to be Copper. Instrumentation cables are generally designed and manufactured according to various standards for e.g. BS-EN-50288, EIL 6-52-46 etc.

Control cables are a type of instrumentation cables which are up to certain degree similar to power cables but there are considerable functional differences. Control cables are utilized to transmit signals to equipment in order to control its working. Control cables can be a part of autonomous systems which have automated controls and consist of copper conductors. A braiding of galvanized steel is also present in the cable construction. Control cables have a resistive covering which resists external interference. Due to these properties, low voltage signals can be sent across the system.

Instrumentation cables can face high amount of Electro magnetic interference which can lead to inaccurate transfer of instrumentation signals. To avoid such unwanted interference certain rules can be followed so that cable experiences less effect due to EMI.

Instrumentation cables or instrument wires need to be as far away from power cables as possible, they can be housed in separate trays to avoid crosstalk. If it is not possible to keep a distance between power cables and instrument cables, then both cables should be arranged in such a way that they cross each other at right angles. Loops formed on instrument wiring can cause interference, hence should be avoided while installing the cables. Now buy instrumentation cables at the best price online.

Braided copper cable: Copper wires can be of various types and construction. Some cables may have solid construction, stranded or braided construction. Each type of construction has its own set of advantages and functions. Braided copper cables or braided copper wires are preferred in applications where flexibility is of prime importance. Such cables can be found in various applications like automotive connections, in indoor electronic devices etc.

Braided Copper Cables

Advantages of braided copper cables: Advantages of braided electrical cables can be understood so that one can choose the correct wire for the application at hand. Solid copper wire is rigid and strong, but not flexible whereas braided copper wire has multiple stands of copper twisted or braided to form a wire. Due to the braided construction, these types of wires are flexible and can bend according to the application at hand. Copper has excellent malleability due to, which makes it resistant to bending, wear and tear as well as resistant towards rust. Resistance to rusting in turn increases the life cycle of the cable. Braided cables can be used in applications involved in processes, creating vibrations and high frequency movements. As these braided wires are tremendously flexible they can withstand vibrations and continue functioning. Braided copper cables if compared to other stranded cables has thin copper strands twisted together, which makes it easier to install and use.

Apart from the construction based advantages these braided copper cables are cheaper than other cables like co-axial cables. Both these cables can transfer power certain functions make them suitable for a particular application. Shop for flat braided copper wires and braided wires online at reasonable price.

Shielded cables: Some cable applications require shielding over the cable to cancel out external interference’s. Construction of shielded cables is fairly simple to understand.

Shielded Cables

Shielded cables consist of multiple conductors with insulation. These conductors are in a twisted pair configuration. A pair shield is applied over every twisted pair. Drain wire can also be a part of the construction.

In simpler terms shielded wires or shielded cables are the type of cables which have insulated conductors covered a layer. Typically, these shields can be made up of copper strands which are braided or a copper tape or some other polymer which is able to conduct. If unshielded cables are directly stacked against the shielded cables, shielded cables happen to be slightly thicker and more rigid in nature. Shielded cables are found in industrial environments where surrounding equipment has a tendency of emitting electromagnetic waves which might cause interference to the cables. Unshielded cables are light in weight, less costly, more flexible and have high utility, but are not always suitable for industrial use where requirements are more stringent.

Most important functions of shielded cables is to provide protection to the data that is being transferred by the cables from external Electro magnetic interference. Such cables are mainly used in large scale data centers, offices and facilities where computers are used on a massive scale. Electrical circuit can stop functioning due to the effect of external EMI or reduce its performance all together. Loss of data due to EMI is an undesirable effect and can be avoided by using shielded cables. Natural as well as electronic gadgets is capable of generating electric current which might induce EMI in cables causing unwanted effects. Electo magnetic radiation as well as electrical noise is reduced to a very low amount by the use of shielding in construction of the cables.

Insulation in cables protects the cable against various external factors like abrasion, electrical losses, moisture etc. but it is generally useless against Electro magnetic energy. Hence, as discussed, shielding is absolutely crucial for the cable to survive and function at its best in a zone where EMI is predominant. Cables are responsible for conducting the EMI as well as radiating it were shielding if applied restricts conduction as well as radiation of EMI related to cable.

If we consider production lines and industrial setups noise can be categorized into high, medium or low noise level generation sources. Industries which have large, heavy motors, generators, inductive heaters, transformers or power lines have a high noise level and mainly this equipment can be found in metal processing plants or metal foundries. Medium noise level relates to medium sized motors or relays typically found in average manufacturing facilities and places like labs, offices, assembly lines typically generate a very low noise. Now buy shielded power cables and shielded wires online that too at a click of a button.

Shielding inside the cable is capable of reflecting the energy of the cable as well as the pickup noise generated by the cable and conduct it to the ground. Due to such characteristics EMI does not infiltrate the shielding and cannot reach the conductor in any case. Shielded cables have a specific amount of shielding included in the construction which mainly depends on the type of application the cable is planned to be used. Length, weight, dimension of the cable is some of the factors that govern the choice of the shielding.

Types of shielding: There are two types of shielding that can be found on the shielded cables namely foil type shielding or braid type shielding.

A thin layer of Aluminium is used in case of foil shielding. These Aluminium layers are often used with a polyester carrier which imparts cable with strength. Due to these layers being thin it becomes difficult to deal with such cables, especially while application of a connector. Foil shielding covers the entirety of the conductor and hence instead of grounding the entire cable only the drain wire is used for termination and grounding of the shield.

Braided shielding is a mesh made up of tinned copper wires. This type of shielding is easier to crimp or solder while the connector is being attached to the cable. Due to the mesh pattern, braided shielding does not offer over all covering of the conductor and any gaps remain in between the braids. Tightness of the weave of the braid decided the coverage offered; typically, this shielding offers 70 to 95% coverage. Advantage of braided shielding over the foil shielding is the fact that Copper is used in the prior which is a better conductor than Aluminium.

In an environment where noise levels are extremely high multiple shielding layers are required to get the job done. Using foil and braid type shielding can be a possible option for preventing cross talk and interference in multicore cables.

A cable which contains a shield in its construction is not grounded will not be able to function in a proper manner. A low impedance path to ground is specially needed in shielded cables. Choosing the cable shielding for the application is most important for successful utilization of the cable in noisy areas. Type of shielding shield be determined and should be chosen according to the noise level. Connectors and termination of these cables play a very important role and hence need to be properly chosen. Summarizing the details about instrumentation wires and cables with copper braids and shielding one needs to be aware about the noise level of the application environment and expected requirement from the cable. Environment with high noise generated from electrical equipment and power cables is one of the factors that can retard the functioning of Instrumentation cables or control cables reducing its efficiency. Such cables need a proper layout to avoid loss of efficiency. Braided copper cables provide flexibility to the end user and hence can be used in applications where flexibility and high conductivity is the essence. Shielding on a cable is provided to reduce and eliminate the effect of EMI on the cable due to which these cables can function at full efficiency.

Leave a Reply

Your email address will not be published. Required fields are marked *