Question

A uniform two-wire DC distributor that is 200 m long is loaded with 2 amperes/meter. Resistance of single wire is 0.3 Ω/km. Calculate the maximum voltage drop if the distributor is fed from one end.
1. 12 V
2. 6 V
3. 24 V
4. 36 V

Answer 1

Correct Answer - Option 1 : 12 V

Concept:

In a uniformly loaded distributor fed at one end, the maximum total voltage drop = IR/2

In a uniformly loaded distributor fed at both ends, the maximum total voltage drop = IR/8

The maximum voltage drop in the case of uniformly loaded distributor fed at both ends is one-fourth of the maximum voltage drop in the case of uniformly loaded distributor fed at one end.

Calculation:

Length of distributor = 200 m = 0.2 km

Current supplied by distributor = 2 amperes/meter

Total current supplied by distributor (I) = 200 × 2 = 400 A

The resistance of single wire = 0.3 Ω/km

Total resistance = 0.3 × 0.2 = 0.06 Ω

Maximum voltage drop \( = \frac{{IR}}{2} = \frac{1}{2} \times 400 \times 0.06 = 12\;V\)