Electrical energy passes through various types of voltage in order to be transported efficiently and safely to where it is needed. During this process, there may be some variation or loss of voltage. When this is very small, it goes unnoticed and does not pose any major risks. However, if the voltage drop is high, it can have consequences for the operation of devices connected to the power supply.
Knowing how to calculate voltage drop is extremely important to ensure the proper functioning of electrical circuits. The following article will explain some of the most relevant aspects of this topic, from what it is to how to prevent voltage drop.
What is voltage drop?
It can be defined as the difference in electrical power between each end of a conductor. In other words, it refers to the loss of energy that occurs when electricity is transported.
This is due to electrical resistivity, a property of materials that is defined as the ability to withstand the flow of electricity. Most materials that carry electricity have a good level of resistivity, although there are factors that can affect them and cause a voltage drop.
Calculating voltage drop is important mainly in systems where high voltage is required. For example, when transporting energy over long distances, voltage-sensitive electrical systems, medical or safety devices, or power supply systems.
Some effects of voltage drop may include the following:
- Reduced performance. When equipment does not receive the proper amount of voltage, it may stop working or become intermittent during use.
- Power loss. A reduction in voltage results in less electrical power available to connect any device.
- Overheating. A voltage drop causes equipment to work harder to compensate for the lack of power, thus causing excessive heating.
- Operational interruptions. Some equipment is very sensitive to voltage changes and may restart or shut down completely. In industry, this leads to significant economic losses.
How to calculate voltage drop?
In 1827, physicist George Ohm experimentally demonstrated the relationship between voltage and current. This gave rise to Ohm’s Law, which is widely used in all electrical calculations. It states that the intensity of current passing through a conductor is directly proportional to the voltage and inversely proportional to the resistance.
The voltage drop can be calculated using the following formula: V=I × R. Since the resistance of the conductor is directly proportional to the distance, the voltage drop in the conductor can be calculated, so the final voltage reaching the load would be the source voltage minus the conductor drop. It is important to mention that, depending on the type of circuit, there may be some variations in this calculation:
- Series circuit. The current remains constant and the voltage varies with respect to the resistance of the circuit.
- Parallel circuit. For these circuits, the voltage remains constant, while the current changes according to the resistances.
- Alternating current circuit. This type is influenced by the load current, the power factor, and the electrical impedance of the conductor. The formula varies as follows: V = I × Z, where Z is the impedance value.
Generally, a 2% variation is acceptable in any electrical installation. However, if this percentage increases, it will be necessary to increase the conductor size to lower the voltage drop.
Causes of voltage drop
As already indicated, voltage drop is mainly due to the resistivity of the conductive material. However, there are several factors that can cause such drops.
External situations
Voltage drops can be caused by situations related to factors external to the electrical installation. Here are a few:
- Component overload. This occurs due to an excess of current flowing through the conductors. If a circuit was designed to operate at 100A and the current is, for example, 150A, the voltage drop in the conductor is greater and a voltage drop in the load occurs that may exceed the maximum 2% of the design.
- Power outages. These can be caused by short circuits in the electrical network, electrical discharges, the connection and disconnection of power switches, etc. When this occurs, some systems have the ability to modify the electricity supply or shut it down to prevent damage.
- Accidents or faulty connections. There are situations in which electrical installations can be compromised due to accidents or poor installation.
Type of material
The material used in electrical installations is a decisive factor in voltage drop, so it is extremely important to know all the characteristics of the wiring when choosing it. Some points to consider are as follows:
- Material used. The resistivity of the material has a direct influence on the voltage drop. Some conductors such as iron cause a greater drop, while copper is usually a better conductor.
- Cable size. Cables with a larger diameter have less resistance, so the voltage drop is lower than that of cables with a smaller cross-section. In the case of the metric indicator, the number is 10 times greater than the diameter. For example, a cable with a diameter of 5 mm is 50 gauge.
- Wire length. For wires of the same gauge, shorter wires have less voltage drop than longer ones. For home electrical installations, distance is not a major issue. However, when it comes to commercial circuits, it is important to choose the right gauge for the length required.
- Amount of current. The amount of electricity carried affects voltage drop values. This is where the ampacity of a cable comes into play, which is the maximum amount of current it can carry under normal conditions. At the same time, ampacity is affected by factors such as the type of insulation and temperature.
How can voltage drop be avoided?
Voltage drop during the use of electrical energy is normal, although ideally it should be kept to a minimum. To ensure that the necessary levels are maintained, you can follow some recommendations:
- Reduce distance. Minimizing the distance between electrical circuits as much as possible allows for the use of shorter wiring.
- Thicker wiring. Analyzing the type of wiring required for the electrical installation in question will help you choose the right one.
- Increase voltage. One way to reduce voltage drops is to increase the input voltage to the circuits. This option can be used when the electrical wiring distance is long.
- Quality of connections. It is essential to ensure that the entire installation is in good condition and suitable for withstanding the voltage.
- Regular maintenance. Related to the previous point, scheduling regular maintenance helps to minimize voltage drops.
What are the advantages of calculating the correct voltage drop?
The safety and efficiency of electrical circuits depends on the calculations made before installation. When working with electricity, it is important that all elements function properly.
Some advantages of calculating voltage drop are:
- It allows for proper design and planning of electrical installations.
- It helps improve system efficiency by reducing energy losses.
- It guarantees a constant and safe electricity supply.
- Using the right materials helps reduce costs for maintenance and replacement of components.
- It improves the performance of electrical systems.
- It ensures that electrical installations comply with the regulations that govern them.
- It allows faults in systems to be found and analyzed more quickly.
- Minimizes power outages and helps improve the performance of connected equipment.
- Having all the information about the design and installation of the electrical system makes it possible to make the most appropriate decisions.
In general, knowing the voltage drop values increases the usefulness of electrical systems, as it guarantees both their efficiency and safety. Not doing so properly can be counterproductive.
In the home, excessive voltage drops can result in malfunctioning appliances and even damage. At the industrial level, it leads to economic losses due to downtime or overheating of machinery and production losses.
In turn, there are other sectors in which a voltage drop can endanger the physical integrity of people. An example would be the impact on communication and security systems in industries such as healthcare and transportation.
Voltage drop is a very important factor in the installation of electrical systems, as its calculation helps to maintain the proper functioning of all the circuits used.
