Understanding Cable Sizing & Voltage Drop Calculations

Detail Understanding for Key Concept and calculations for Cable sizing & Voltage drop

What you’ll learn:
What is Cable Sizing, Why it is required
What is Ampacity, Continuous Current Carrying Capacity
Short Circuit rating
How to calculate short circuit level
K Factor
Cable Derating / Correction Factor

Requirements
Basic Understanding of Electrical

Description
•Introduction Cable Sizing

•Understanding Basic Terminologies

–Continuous Current Carrying Capacity

–How to Calculate Continuous Current Capacity for any electrical item.

–Short Circuit Capacity

–Why short circuit capacity changes

–What is voltage drop

–How to Calculate Voltage drop

–Phase-Phase Vs Phase-Ground Voltage

•Understanding Basic Terminologies

–Correction Factors K

–Temperature Correction Factor in Air :K1

–Ground Temperature Correction Factor:K2

–Ther.Resi Correction Factor: K4

–Soil Correction Factor:K4

–Cable Depth Factor (K5)

–Cable Distance Correction Factor(K6)

–(Cable Grouping factor K7 )==No of Tray

•Admissible current as a function of nominal cross-sectional area of conductors

•Increase the cross sectional area , Current carrying capacity (ampacity) will increase.

•Ampacity is a portmanteau for ampere capacity defined by National Electrical Codes, in some North American countries. Ampacity is defined as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating

How to Calculate Voltage Drop and Size of Electrical Cable

Calculation Example for voltage drop and size of cable for 80KW, distance between source and load is 200 meters, system voltage 415V three phase, power factor is 0.8, permissible voltage drop is 5% and demand factor is 1.

•Continuous Current Carrying Capacity

•The ampere rating at which a cable can operate continuously without exceeding its thermal limits.

•The over current rating depends on the thermal conditions of the cable. The value of maximum continuous current ratings of cables is supplied by manufacturers. The rating valid for the specified conditions of installation (depth of laying, ground temperature, air temperature, etc.)

•What is Short-Circuit Current Rating? Short-circuit current rating (SCCR) is the maximum short- circuit current a component or assembly can safely withstand when protected by a specific overcurrent protective device(s) or for a specified time.

Short circuit current rating for PVC & XLPE cables

•Short Circuit Rating are based on the assumption that duration of the short circuit is to small and apparently that there is no transmission of heat, produced during short circuit, through the insulation and the whole of it is absorbed by the conductor. With a high increase in KVA, capacity in power distribution system, cables are expected to carry short circuit to carry short circuit current of high magnitude. Normally rated at 70 C,PVC insulation material permit a short circuit temperature of160 C.

Who this course is for
Student, Engineer, Professionals