Voltage deviation in the network according to GOST - permissible values

Inconsistency of the parameters of the electrical network adversely affects the operation of electrical equipment. In everyday life, this is most often reflected in the life of the bulbs (they burn out faster), as well as the operation of household appliances, in particular, refrigerators, TVs, microwave ovens. In this article we will consider the permissible and maximum voltage deviation in the network according to GOST, as well as the reasons for such a problem.

Norms in accordance with GOST

So, we will be guided by GOST 29322-92 in the current edition (for 2014), according to which the maximum deviation (both positive and negative) in Russia should not exceed 10% of nominal. In total, we get the following values:

• for a 230v network - from 207 to 253 Volts;
• for a 400V network - from 360 to 440 Volts.

As for the permissible voltage deviation among consumers, the GOST indicates that this value at the points of common connection is established directly by the network organization, which in turn must meet the standards specified in these standards.

In addition, I would like to note that during normal operation of the network, the permissible voltage deviation at the terminals of electric motors is in the range from -5 to + 10%, and no more than 5%. At the same time, after the occurrence of an emergency mode, it is allowed to reduce the load by no more than 5%.

By the way, I would like to additionally note that at the power supply in 0.4 kV power grids, according to the standards, the deviation should not exceed 5%, in fact, like the consumers themselves. Total, 5% at the source + 5% for consumers, we have 10% of the maximum allowable.

It is important to know about the causes of the voltage deviation. So the main reason is the seasonal or daily change in the electrical load of the consumers themselves. For example, in the winter time, everyone abruptly turns on the heaters, as a result of which the parameters of the power grid drop noticeably. About, what to do if the network voltage is low, we told in the corresponding article!

Negative influence of deviation of parameters

So that you understand the whole danger of voltage deviations in the network, we provide you with the following facts for reading:

1. When the value falls below the norm, the service life of the electrical equipment used is significantly reduced and at the same time, the likelihood of an accident increases. In addition, in technological installations, the duration of the production process itself increases, which entails an increase in production costs.
2. In the household network, as we have said, voltage fluctuations will shorten the life of the bulbs. When the voltage rises by 10%, the service life of conventional bulbs is reduced by 4 times. In turn, energy-saving lamps begin to flicker when the voltage drops by 10%, which also negatively affects the duration of their operation. About the rest causes of flickering of fluorescent lamps you can find out from our article.
3. With regard to electric drives, the current consumed by the motor increases due to the decrease in voltage. This in turn reduces the life of the engine. If the voltage is even at a seemingly insignificant 1% higher than the norm, the reactive power consumed by the electric motor can increase up to 7%.

Moving towards the end, I would like to note that there are several modern ways to solve the problem: reduction of voltage losses in the electrical network, which we wrote about in the corresponding article, as well as load regulation on outgoing lines and substation buses.

So we examined the norms for the deviation of the voltage in the network according to GOST. Now you know how low or high this parameter can reach in a three-phase and single-phase AC network!

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