An overview on the safety requirements which are to be carried out on cables and wires to ensure safe and efficient transportation of electricity
First and most important consideration of an efficient and safe transmission and distribution of electricity is the choice of material of conductor in electric cables. Copper and aluminium are the most commonly used metals in the conductor. Therefore, in order to ensure safe and efficient transportation of electricity, the metal should be of good quality, resistant to corrosion, and strong.
“Transmission of electricity with cables is undoubtedly much safer as compared to bare lines. But, underground cables are limited by their thermal capacity, which permits less overload or current rating then overhead lines. So, it is desirable to have adequate protection to the cable system against overloading. Long underground AC cables have significant capacitance, which may reduce their ability to provide useful power to loads,” says Sanjeev Vyas, Senior General Manager, Havells India Limited.
Additionally, Vyas explains the major safety concern in electric cable transmission as lack of safety guidelines to workers doing excavation work in cable route. Under such conditions, there is always a possibility of damage to nearby power cables already present in the route during digging. While penetrated by a sharp object such as tool or cable is crushed severely to cause contact between the sheath and conductors. This is most common circumstances and might cause severe burns to the hands, face and body. Therefore, basic safety guidelines must be provided to workmen at site who are doing excavation work in the cable route. Cable route must be clearly marked throughout.
Randeep Narang, President – International (T&D, Solar) & Cables, KEC International Ltd says, “At KEC, cables and wires are designed and manufactured complying with the requirements of relevant standards and are tested fully at our manufacturing units located in Vadodara and Mysore, before shipment. All the products are manufactured using raw materials of the highest purity, using state-of-the-art plant and machinery and under supervision of competent and skilled engineers and technicians. Additionally, they also pass through rigorous, in-process checks at each and every stage of manufacture.”
The cables are designed suiting to specific requirements of application of voltage grade and power transmission capacity with safety design factor. While designing the cables, environmental conditions such as such as changes of water ingress, chemical resistance, severe cold climate, and additional flame-retardant properties are taken into consideration. Cables are also marked with ISI marking, wherever applicable, which gives further assurance towards quality and reliability of cables.
The most important requirement for safety is good quality raw material with 100 per cent electrolytic grade copper having 99.97 per cent purity delivering 101 per cent conductivity and FR grade PVC insulation for a maximum rated conductor temperature and high insulation resistance, which is up to 70°C. On the methodologies front, there are automated and latest manufacturing processes that have electronic/ PLC based machines, which ensures a high degree of quality and improved consistency in wires.
Tetsuyasu Kawamoto, Joint Managing Director, Anchor by Panasonic states, “The insulation and packing lines are equipped with online HV spark tester (6KV to 10KV) in order to detect insulation failure. Also, we have a fully equipped QC lab in place, which is equipped with latest instruments and is capable for testing our wires and cables as per the National (BIS) and International (IEC, BS) standards. These cables are continuously tested in air and water for almost five times and more (6KV) for a higher voltage than standard insulation, which is (1:1). This in turn, makes the product way more safe and reliable.”
Cyclic maintenance on cables and wires
Cyclic maintenance of cable installation includes inspection, routine checking of current loading, maintenance and care of all cables and end terminations to avoid failure. Periodical inspection of cables and wires should be made in order to avoid any kind of interruption to service.
Vyas informs, “Cables laid direct in the ground are not accessible for routine inspection, but such cables are often exposed when the ground is excavated by other public utilities for installing or repairing their own properties. Therefore, preventive maintenance in the form of regular inspection of alSl digging operations by other utilities or persons, carried out in areas is of utmost importance to avoid any kind of mishap.”
Vyas adds, in a city where the roads are congested with services of other utilities, the likelihood of damage to electric cables is very high. Therefore, cable inspectors should patrol the various sections of the city and should examine cables and wires for any signs of damage; such as deformation or dents or damage to earthenware troughs or ducts. Such condition based maintenance is helpful to predict when and what kind of repairs might be needed in the future to avoid electrical failure.
Reliability is the prime requirement and cables and wires do not fail unless there is any external damage. Cable selection should be done considering all the de-rating, so as to ensure that there is no overloading. Narang claims, “Frequent overloading affects the life of cables and wires and may lead to pre-mature failures. If handled carefully and installed following standard guidelines and tested during pre-commissioning, cables will generally remain maintenance free, in specific operating conditions. However, it is a good practice to do periodic health check-up on old installations to take preventive actions if required.”
According to Kawamoto once the wire is put inside the conduit, essentially, any standard cyclical maintenance is neither possible nor prescribed; however, the overall installation can be reviewed. But, in any case, the installation has to be tripped off as we now use circuit breakers. To prevent any electrical failure, a few tips should be kept in mind that are to ensure moisture-free surroundings; being vigilant about water leakage near electrical and plug points, proper concealing, strong and safe wire joining, tight connections predominantly.”
Stopping the counterfeiting
Counterfeiting/supply of non-standard cables is one of the serious concerns for cable and wire industries. These non-standard cables may lookalike standard cables, but fail in addressing quality benchmarks and often cause serious safety hazards and network problems with considerable losses.
Vyas suggests, “In order to authenticate the quality of cables and wires, new methods needs to be devised such as barcoding, QR scanner like state-of-the-art technologies. Quality communication and information to stake-holders can also track non-compliant cables in the market.”
Cables and wires should be procured from reputed manufacturers and brands. Buyer should always check for the manufacturer’s identification mark on cables and check its genuineness. Narang suggests, “Cables and wires should be procured directly from the manufacturer, to discourage counterfeiting.”
Kawamoto explains, “At Anchor by Panasonic, manufacture wires are extremely vigilant, following the guidelines mentioned in IS 694 in 2010. Our licence is renewed as per the requirements and guidelines prescribed by BIS.”
In order to discontinue counterfeit of cables and wires, there has to be a stringent regulatory body that can keep a watch and periodically investigate each and every product available in the market and review its making, implementation laws to eliminate such misdeeds.
Quality communication and information to stake-holders can also track non-compliant cables in the market
Sanjeev Vyas, Senior General Manager, Havells India Limited
Cable selection should be done considering all the de-rating, so as to ensure that there is no overloading
Randeep Narang, President – International (T&D, Solar) & Cables, KEC International Ltd
Electronic/ PLC based machines ensures a high degree of quality and improved consistency in wires
Tetsuyasu Kawamoto, Joint Managing Director, Anchor by Panasonic