Permissible voltage in installations

Electrical installations are susceptible to several problems that can damage electrical and electronic devices, such as variations in voltage and frequency. We will address why fluctuations in the installation voltage may occur, how we can correct this voltage variation and what the value of the voltage variation is acceptable. Come on, guys!

As we know, electrical and electronic equipment basically needs two quantities supplied by the concessionaire to be able to function, which is the voltage and frequency, and both quantities cannot be varied, however small.

It is important to highlight that the electric energy concessionaires have the obligation to deliver voltage and frequency of good quality, within the specifications required by the standards, one reason being that these quantities cannot vary, they must be constant. Otherwise, the elements connected to this installation will present malfunctions and consequently damage them.

Main causes for voltage drops

The variation in electrical voltage in electrical installation can occur due to several factors, such as:

We know that over the entire length of a distribution network it is not possible to maintain the same voltage in all installations, because overall installations there will be a voltage drop, however small. Adding all these losses along with the distribution network, we can obtain a significant loss at the end of the network in relation to its beginning.

We can highlight another factor for the voltage drop at a distance, this is due to the resistance of the cables, which cause the voltage to drop from the source, such as the transformer in the distribution lines.

This same fact can occur inside the installation, be it residential, building or industrial if the distance between the loads and the QDC are relatively large and the conductor is not properly dimensioned.

Another cause for a low voltage within the installation is directly related to the utility, as the voltage delivered to the installation by the power utility is not within the standards. To identify this fault, just measure the voltage directly on the dealer’s meter.

Maximum and minimum mains voltage.

Effects of voltage drop.

The variation or voltage drop can undoubtedly harm the electrical and electronic devices of the installation, but the minor variations in most equipment and devices do not cause problems, because most of them are designed to withstand a variation in their supply voltage of up to maximum 10%.

However, in cases where the devices are being connected to a voltage below their limit, the possibilities of “burning” are rarer, but it does not mean that they cannot present problems, due to a poor installation, it is very common for lamps LEDs malfunction when turning on the shower, as the lamp is operating at a voltage below its limit.

However, the equipment that is subjected to a voltage above the limit, for which it was designed, suffers an overload and in this situation there is a great chance of the equipment being damaged, because certainly its internal circuit will be damaged and being burned.

In order to maintain their operation with a low supply voltage, certain appliances end up being forced to start, such as appliances with motors, as the starting voltage is not enough

Without being able to start in normal conditions, the motor has a very low impedance, which ends up requiring a much higher current than necessary, so there is a heating that is harmful to the equipment.

Maximum and minimum voltage

As previously mentioned, energy concessionaires have an obligation to deliver a certain voltage and frequency, without major variations in their values, here in Brazil all concessionaires must deliver a frequency of 60Hz, with very little variation, it must be extremely close to 60Hz, this variation in frequency occurs due to some network characteristics.

On the other hand, the voltage may vary according to your region and concessionaire, so establishing which maximum and minimum voltage will depend on the energy concessionaire, as each one has a tolerance range, so we must consult these values ​​in the account itself . The image below shows the maximum and minimum voltage that the Cemig concessionaire supplies and also Eletropaulo.

Maximum and minimum voltage according to our

How to correct these errors?

There are some devices on the market that are capable of protecting electronic equipment from possible damage due to variations and voltage drops, such as stabilizers and nobreaks, both of which protect equipment against voltage drops and fluctuations in the network, as they are able to maintain supply voltage at the stabilized output, in addition to preventing equipment burning.

To correct problems when the voltage is not within the conditions that the utility has to guarantee, the first step is to check the voltage directly on the utility’s meter, where the energy is coming from. If the problem is found directly in the standard, the responsibility is entirely of the concessionaire, who in this situation must be notified, and from then on the appropriate measures will be taken.

However, if variations or voltage drops are occurring within the installation, tests and measurements must be made for all circuits, for this type of service hire a trained professional so that you can identify the problem and consequently solve it.

The video below talks about what is the maximum voltage variation in the power grid allowed by ANEEL, besides presenting some important tips on how to identify these problems and what is the best solution.

We finished one more article and we hope to have helped to clarify doubts related to the allowed voltage variation. If you have any questions or curiosity about the subject, leave it in the comments and we will answer it!