Key Features of Industrial Control Cables

• System voltage and the type of system whether single phase, three phases, earthed or unearthed, etc.
• Suitable derating/ uprating factor should be used depending on the conditions of laying such as Depth of laying, ambient temperature of ground or Air, Soil resistivity, Whether one or more groups of cables are laid together, Any heating source near cable run.
• The mode of installation determines the type of cable to be used. Electricity regulators require the use of armoured cables for underground applications. In general, armoured cables are recommended where there is any chance of mechanical damage. If subsequent mechanical damage after laying cables is not likely, cheaper, unarmoured cables can be used.
• For longer length of cable run it is necessary to check that with the cable size selected the voltage drop does not exceed the prescribed regulations limit. A higher size cable may have to be used if the voltage drop limits are not to be exceeded.
• It is essential to ensure that the cable selected is capable of handing temporary overloads. The cables permit conductor temperatures of up to 130°C under temporary overload conditions.
• Short circuit rating depends on the expected level and the expected duration of the short circuit. In certain cases, a larger size of cable than be cable required for normal full load current may be needed. The cables with high KVA capacity are expected to carry short circuit current of high magnitude. The cables permit a short circuit temperature of 160°C.
• The most economical construction and size of cable persistent with current carrying capacity and laying conditions has to be selected. A detailed study of 3 or 4 approximate sizes is made. Actual running costs are worked out taking into consideration |2R loss and interest, depreciation of the total cable cost. The size which gives minimum running costs is to be preferred.