Voltage tolerance according to GOST

Hello dear guests and subscribers of my channel. If you are asked the question: What voltage should be in the network? Then, of course, most of you will answer 220 or 230 volts.

But if you take a multimeter in your hands and measure the voltage in the nearest outlet, then for sure the voltage will differ from 230 Volts up or down.

In this material I will tell you why a strong deviation from the norm up or down is harmful, what it leads to, and what deviation is permissible according to GOST.

Why voltage deviation is harmful

So, any significant voltage deviation, no matter up or down, can negatively affect the operation of electrical appliances.

So in any enterprise where any technological process is taking place, a strong decrease in voltage can lead to a violation of the technology (time will inadmissibly grow). This means that a marriage will be made or the final product will greatly add in value.

Also, if the voltage is "raised" higher, then the connected equipment may not withstand the high voltage and fail, or it will also work with a strong overload.

A good example for understanding the importance of a stable voltage is a common incandescent lamp.

In the case of normal voltage, it (the lamp) will easily serve the entire declared service life. But if you and I lower the voltage by 10%, then the light will burn 40% dimmer.

And vice versa, if we overestimate the voltage by 10% of the norm upwards, then the lamp will light up much brighter and at the same time its operating life in this mode will be four times shorter than usual.

If we consider the most common asynchronous motor, then if the voltage on the stator winding is 15% lower than nominal, this will be a consequence of a decrease in the torque on the shaft by rather 25%. And, most likely, at such a low voltage, this engine simply will not start.

Also, at a reduced voltage, the current will increase. This will lead to a reason for the rapid heating of the stator windings, which means that the trouble-free operation time will be rapidly reduced.

It was calculated that if the motor operates at a voltage that is 10% lower than the nominal voltage, then its actual service life will be almost half the declared one.

What voltage is considered normal according to GOST

Of course, if the voltage is not 230 Volts, but, say, 215 Volts, this is not a reason to run and complain to the sales company. After all, there are both long-term permissible deviations from the norm and short-term deviations.

All these assumptions are written in GOST 29322-2014. So, according to this GOST, deviations of 10% both up and down are permissible in the short term. That is, if you measured the voltage in the outlet, and it is in the range from 207 to 253 Volts for a short time, this is a perfectly acceptable voltage.

The long-term permissible deviation is 5%. That is, if your voltage constantly fluctuates in the range from 218 to 242 volts, then this is the normal voltage in the network.

But what if you measured and your voltage is below or above the permissible limits.

How power engineers remove such deviations

So, if your voltage is below or above the established limits, then the first thing to do is contact either the sales organization or the management company.

They will be required to respond to your application and take control measurements during peak hours first. If the deviation is confirmed, then the power engineers have several ways to solve this problem.

The simplest is to raise or lower the voltage directly at the substation. So if the installed transformers are equipped with an on-load tap changer (under voltage regulation), then the attendant, after coordination, will simply change the voltage in the range from - / + 16% with an adjustment step of 1.78%.

If it is impossible to adjust, and you have deviations from the norm, then everything is much more complicated. In this case, perhaps you just have an outdated line that does not correspond to the increased capacity and needs to be replaced. Or an even more "difficult" option: you have a new line, but the transformer station has a low-power transformer, which will also have to be replaced.

You cannot influence the last two options in any way, but you can solve the problem yourself only by installing uninterruptible power supplies on important nodes.

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