Continued from article Sizing of power cables for circuit breaker controlled feeders (part 2) 3. Criteria Starting and running voltage drops in cable This criterion is applied so that the cross sectional area of the cable is sufficient to keep the voltage drop (due to impedance of cable conductor) within the specified limit so that …
Sizing of power cables for circuit breaker controlled feeders (part 2)
Continued from article Sizing of power cables for circuit breaker controlled feeders (part 1) 2. Criteria-2 Continuous current capacity (Ampacity) This criterion is applied so that cross section of the cable can carry the required load current continuously at the designed ambient temperature and laying condition. Ampacity is defined as the current in amperes a conductor …
Sizing of power cables for circuit breaker controlled feeders (part 1)
The following three criteria apply for the sizing of cables for circuit breaker controlled feeders: This criteria is applied to determine the minimum cross section area of the cable, so that cable can withstand the short circuit current. Failure to check the conductor size for short-circuit heating could result in permanent damage to the cable …
Measurement of insulation resistance (IR) – Part 1
Introduction The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables. As a production test, this test is often used as a customer acceptance test, with minimum insulation resistance per unit length often specified by the customer. The results obtained from IR Test are not intended …
Copper or aluminium? Which one to use and when?
Apart from their electrical conductivity, the other technologically important properties of copper and aluminium differ so significantly (density is an obvious example) that their areas of application are and have always been clearly distinct. And not a lot has changed or is likely to change in that respect. The only really novel development in recent …
Discussing About LV And HV Electrical Cables
Space is really a critical criterion when discussing electrical cables and wires. In a low-voltage (LV) plastic-sheathed cable with conductor cross-sections of up to 10 mm2 per conductor or in high-voltage (HV) cables (Figure 2), the lion’s share of the cross-sectional area is occupied by the insulating material. If aluminium rather than copper is used …
EHV/HV Underground Cable Sheath Earthing (part 2/2)
Continued from previous part: EHV/HV Cable Sheath Earthing (part 1/2) Accessories for HT Cable Sheath Bonding 1. Function of Link Box? Link Box is electrically and mechanically one of the integral accessories of HV underground above ground cable bonding system, associated with HV XLPE power cable systems. Link boxes are used with cable joints and …
EHV/HV Underground Cable Sheath Earthing (part 1/2)
In urban areas, high voltage underground cables are commonly used for the transmission and distribution of electricity. Such high voltage cables have metallic sheaths or screens surrounding the conductors, and/or armour and metallic wires surrounding the cables. During earth faults applied to directly earthed systems, these metallic paths are expected to carry a substantial proportion …
Fire Properties Of Cables
This is an area of increasing public and legislative concern, and therefore of increasing interest to engineers. There have been major advances in the fire performance of cables in recent years, and table below lists some of the relevant standards. Standards relating to fire properties of cables (IEC, BS) Standard Description IEC 60331 Fire resisting …
Direct high voltage testing of cable insulation systems
DC testing has been accepted for many years as the standard field method for performing high-voltage tests on cable insulation systems. Whenever DC testing is performed, full consideration should be given to the fact that steady-state direct voltage creates within the insulation systems an electrical field determined by the geometry and conductance of the insulation, …
