Voltage drop in DC of electrical conductors

voltage drop in DC

Cables are indispensable elements in every electrical installation. But in the field of power for telecommunications, they have very special characteristics. One of which we will analyze in this post titled Voltage drop in DC of electrical conductors.

In fact, voltage drop is a parameter that is much more critical in DC electricity than in AC power. This is because the former operates with very high current values.

Next, we will explain the meaning and importance of calculating voltage drop. Let’s see!

What is voltage drop in dc and why is it important in the selection of electrical conductors

Voltage drop is the most significant consequence of electrical resistance in an electrical conductor.

In simple terms, it’s a phenomenon where part of the energy flowing through the conductor is lost as heat due to the electrical resistance of the conductor.

As a result, the load receives a lower voltage than what is supplied by the source. Below, we present an image of this situation to help you understand it better.

voltage drop in DC circuit

From the previous diagram, we can see that the voltage reaching the equipment is:

Vequipo = Vdc – 2*Vrc

The value of voltage drop depends on the length and gauge of the conductor. If the length is longer and the gauge is smaller, the voltage drop will be greater because the resistance is higher.

On the other hand, depending on the load, it must receive a minimum voltage within its operating range. We clarify this with the following image.

voltage window to find voltage drop in DC

With the above, we want to tell you that for the equipment to operate. It must be powered with a voltage value that falls between VMIN and VMAX.

Importance of DC voltage drop calculation in electrical conductors

In telecommunications power systems, the selection of the appropriate conductors for this factor is critical.

A poor choice of a conductor due to voltage drop can result in disaster for a telecommunications power system, as it can cause problems with equipment under certain conditions.

An example of this scenario would occur when a failure shuts down the rectifiers, and the system continues to operate on batteries. If the voltage drop is too high, the voltage level will be low, causing the loads to shut down and resulting in a service interruption.

This would happen even if the battery voltage level is more than sufficient to maintain operations for a longer period.

It can be said that this is a negative parameter to consider when choosing a conductor.

In summary, this variable is highly influential to the extent that the reliable and stable operation of telecommunications services depends on it, both under normal operating conditions and during emergencies.

Calculation method for voltage drop in DC in electrical conductors

Voltage drop in DC can be calculated in two ways. The first method uses the electrical resistance values provided in tables for electrical conductors, applying Ohm’s Law or calculating based on resistivity.

The second method involves using technical data tables for DC, in combination with equations designed for this purpose.

In our post Calculation of voltage drop in dc in electrical conductors based on commercial conductivity factor we will explain another method. Don’t miss it!

Likewise, we invite you to read the content we have prepared for you on the energydcac blog.

We are also in the process of developing our Course on sizing and designing DC power systems for telecommunications and critical systems. Follow this link to learn more about its content.

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