Cable Loss Calculation
The cable loss calculation is a very important parameter used by the designer while selecting a power cable for a particular electrical installation. The power loss in the cable is known as cable loss.
Generally, the power cable conductors are made of aluminum or copper material. The copper and aluminum have certain resistance according to the specified specific resistivity. The resistivity of the copper is about 59 % less than the resistivity of aluminum. Therefore, the copper conductor has less resistance as compared to the aluminum conductor.
When current flows through the conductors of the cable the heat loss I2R takes place. The heat loss in the cable depends on the current & the resistance of the conductor. The resistance of the cable depends on its length and cross-section area. Thus, the heat loss in the cable depends on the following operating & design data of the cable.
- Cable length
- Cross-section area of conductor
- Specific resistivity of the material
- Current
- Number of cores
Cable Power Loss Formula
For a Single Core Cable
For N cores Cable
Thus, the cable power loss Ploss in kilowatts is equal to 1000 times the square of the current(ampere), the resistivity(Ohm-meter), the number of the cores divided by the cross-section area (square mm) of the conductor.
Cable Loss Calculator
Fill the required data below in the fields and press calculate button to find the cable loss. For a fresh calculation, reset the previous data, and feed the fresh data for power loss calculation.
From the above calculator, we can calculate the power loss in a multicore cable by multiplying the number of cores by the power loss of a single-core cable if both types of cable carry the same current.
Generally, we use copper and aluminum cables in electrical installation. The resistivity of the copper and aluminum cable is;
Copper – 1.68×10−8 ohm-meter
Aluminum – 2.82×10−8 ohm-meter
Solved problem on power loss of cable
A cable has the following data.
No of cores – 3
Cross-section area – 70 Sq.mm
Cable conductor Material – Aluminum ( Resistivity -2.82×10−8 ohm-meter)
Length of cable – 1000 meter
The cable carries a 60-ampere current. Calculate the power loss in the cable.
Important Point- The cable resistance varies with an increase in temperature. If the cable carries more than its rated current, it increases the temperature. Consequently, the resistance of the conductor increase & further it increases the cable loss.