Here is an essay on the ‘Installation of Power Cables’ for class 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on the ‘Installation of Power Cables’ especially written for school and college students.
Essay on the Installation of Power Cables
- Essay on the Installing of Power Cables
- Essay on Energy Costs in Power Cables
- Essay on IEE Regulations for Choosing Power Cables
- Essay on Optimum Cable Size
- Essay on Cost Considerations
- Essay on Best Conductor Material
Essay # 1. Installing of Power Cables:
While the installation and use of much energy-efficient equipment is being well considered and taken care of, the energy losses in undersized power cables are frequently ignored. If cables are installed with a conductor size that is the minimum allowed to avoid overheating, energy losses can be very significant.
Mandatory regulations specify minimum conductor sizes for thermal safety but are not intended to be the most economical if energy losses throughout the life of the power cable are taken into consideration. Until the recent world-wide economic downturn, it was common practice to install cables that were two standard sizes larger than the minimum recommended simply in order to allow for increased demand.
There was an immediate benefit from a reduction in I2 R losses and long, reliable lifetimes for the cables due to their running at less than their maximum rated temperature. Now, new costing policies may demand lowest first cost by installing the minimum permitted cable size and result in these benefits being lost. It is therefore necessary to calculate running costs to ascertain the most economic size of cable to install.
Where environments have to be controlled ventilation of air conditioning, the extra cost of removing waste heat from inefficient cables must also be calculated. The cost of electricity is more likely to rise than fall; this too must be considered as far as is predictable.
If the energy demand of a system subsequently increases to a level above the safe cable rating, the installation of extra power cables can be a very significant extra expense. Initial specification of cables that are an optimum economic size is a recommended practice encouraged by a new British Standard.
Essay # 2. Energy Costs in Power Cables:
Energy cost in cables has to be generated. A reduction in losses brings about not only a reduction in fuel costs, but also in plant capacity needed to provide the losses at times of peak generation. The cost of energy is generally increasing with inflation and the depletion of natural resources.
Energy-efficient considerations are becoming increasingly important. The use of conductor cross-sections that have been chosen with the cost of energy losses in mind can be shown to save money now and will probably show increased savings with time.
Essay # 3. IEE Regulations for Choosing Power Cables:
Recommended procedures for choice of cable size are frequently followed without a full understanding of the implications. IEEE regulations 19, now BS 7671 (equivalent to IEC 364 and European Standard HD 384), can be used to ascertain the minimum permissible safe conductor size.
These ensure that, when used at rated current flow, the cable does not overheat dangerously but do not give the optimum size for lowest cost over the life of the cable, nor even over a stipulated payback period.
Cable sizes should be specified larger than the IEE regulation minimum for any combination of a variety of reasons, including:
i. Allowing cables to run cooler and save energy.
ii. Nearest standard size up.
iii. Standard fuse rating requiring larger cable for safety in overload conditions.
iv. Allowing for future expansion in demand.
Essay # 4. Cost Considerations:
In costing the installation, many factors have to be considered:
i. Maximum rating when installed.
ii. Resistance to possible short circuits.
iii. Rate of growth of demand.
iv. Cost of losses of power due to cable resistance.
v. Cost of removal of excess heat.
vi. Installation cost.
vii. Maintenance costs.
viii. Cost of performance losses of equipment running at reduced voltage.
ix. First cost of cable.
x. Future costs of energy.
xi. Interest and discount rates.
Essay # 5. Optimum Cable Size:
Cable installations should be specified according to the guidance of British Standard 7450:199120, equivalent to IEC 1059:1991, ‘Economic Optimization of Power Cable Size’, which gives useful guidance on the optimum costing of cable installations. This standard needs to be a requirement of management procurement policy and included in contractual documents in order to avoid the false economy of ‘lowest first cost’ attitudes.
The standard points out that:
‘Rather than minimizing the initial cost only, the sum of the initial cost and the cost of losses over the economic life of the cable should be minimized. For this latter condition a larger size of conductor than would be chosen based on minimum initial cost will lead to a lower power loss for the same current and will, when considered over its economic life, be much less expensive’.
For the values of the financial and electrical parameters used, the saving in the combined cost of purchase and operation is of the order of 50%. Calculations for much shorter financial periods can show a similar pattern. It is difficult to give an accurate forecast of some of the time-dependent variables given above.
However, the methods chosen have the result that the impact of errors in financial data, particularly those that determine future costs, is small. While it is advantageous to use data having the best possible accuracy, considerable savings can be made using data based on reasonable estimates.
Laying cost for cables does not increase proportionately to cable size since most of the operations are common. For conductor sizes up to 100 mm2, the laying cost for buried cables is higher than the cable cost.
The cost of waste heat removal cans more than double the cost of 12 R losses in cable ducts. In modern office and industrial buildings with a heavy demand for power, air conditioning plant has to be used to export surplus heat for much of the year. This cost must be taken in to account.
While cables are now being made with insulation that can withstand regular running at higher temperatures, it is false economy to save on conductor size and waste more energy throughout the lifetime of the cable.
The benefits of modern high temperature cable materials are best realized in installations where space limitations, ambient temperatures and possible over current conditions are such that a high conductor temperature cannot be avoided at any reasonable cost.
Upsizing of copper conductors can reduce energy losses significantly at a marginal premium cost. This can be evaluated using standard calculation techniques or software and can result in savings in energy losses of the order of 50%. Such calculations also add to the justification of upsizing cable sizes to allow for standard fuse ratings and the likelihood of increased future demand.
Besides power cables in industry, consideration should also be given to optimum sizing of installations in commercial buildings such as offices and retail outlets.
Essay # 6. Best Conductor Material:
The conductivity of copper is 65% higher than that of aluminium which means that the conductor size of similarly rated cables is proportionately smaller. Correspondingly less expense is then incurred in providing for insulation, shielding and armouring the cables themselves. Transport of the less-bulky cables is easier and so is installation. In limited spaces in cable ducts, the smaller volume and better ductility of copper cables can have an even larger benefit.
Copper cables are easily jointed because copper does not form on its surface a tough, non-conducting oxide. The oxide film that does form is thin, strongly adherent and electrically conductive, causing few problems. Cleaning and protection of copper is easy and if joints are made as recommended they will not deteriorate to any great extent with age, which saves on maintenance costs.
For the same nominal current rating, the cable with the aluminium conductor is significantly larger in diameter, carries a proportionally greater volume of insulation and is not so easily installed because of being less flexible. Aluminium is notoriously difficult to joint reliably.