Register to reply

Voltage drop calculation in 3 phase unbalance circuit

by ben1000
Tags: calculation, circuit, phase, unbalance, voltage
Share this thread:
ben1000
#1
Jan1-10, 06:42 AM
P: 1
Dear All,

Iím facing some problem when I try to determine the total voltage drop (%) from the source to the load.

Assume the condition as follow:

1. DB-A is serving 3 number of individual load (#1,#2 and #3) , each 100m away from DB-A, single phase, 5kw, pf=0.85, V=240V,by using individual cable 2Core, 16mm2 PVC/SWA/PVC copper cable (2.7mV/m/A).

2. The incoming power supply (415V, 3 phase) to serve DB-A is also 100m away, using 4Core, 16mm2 PVC/SWA/PVC copper cable (2.3mV/m/A).

For calculate total voltage drop from the source to the load #1. Iím using formula as follow:

Assume all three loads are on.
Total connected load under DB-A = 15kw = 15/0.85/0.7188= 26.085A

Load #1 = 5kw = 5/0.85/0.24 = 26.04A

VD (source to DB-A) = [(100m x 2.3mV/m/A x 26.085)/1000/415V] x 100%
= 1.45%

VD (DB-A to load #1) = [(100m x 2.7mV/m/A x 26.04)/1000/240V] x 100%
= 2.93%

VD total = 1.45% + 2.93 % = 4.38%

My question is how to determine the total voltage drop (%) at load #1 if the load #2 & #3 are off. Or let said load #2 and #3 is disconnected from DB-A
Iím confused which VD factor of cable and applied voltage should I applied when calculate VD (source to DB-A). 2.3mV/m/A or 2.7mV/m/A? 415V or 240V? The serving cable is 4 Core, but it just like using 4 Core as 2 Core by only serving load #1.

My second question is how about when there is unbalance load. Assume load # 1 now is 10kw, #2 and #3 are 5kw each. All single phase. How am I going to determine the V.D (%) from the source to DB-A? (Three load are on) should I assume it as balanced? If I do so, does it actually reflect the total V.D (%) suffer at load #1?

Thanks for your help

From
Kelvin
Phys.Org News Partner Engineering news on Phys.org
Hoverbike drone project for air transport takes off
Student develops filter for clean water around the world
Developing the next evolution in underwater communication

Register to reply

Related Discussions
Voltage Drop (Three phase) Electrical Engineering 9
Calculating Voltage Drop in an AC circuit Introductory Physics Homework 7
RLC Circuit - Voltage drop across Inductor Introductory Physics Homework 2
Why must voltage drop across a resistive circuit? Electrical Engineering 8
Series circuit lab problem: voltage drop? Introductory Physics Homework 9