Surge Protection

On the official website of Atlant, it is possible to download the instruction manual for household refrigerators, where it is written that the supply voltage is 220-230 V( the last digit is in favor of European standards) when the nominal deviation is 10% each way. If the voltage drops below 200 V, it’s not a fact that the equipment will work. Protection against voltage surges is needed not solely for the reason indicated. Short-term overloads are more dangerous, unhindered by the frequency of passing the filter. When such a tsunami reaches the e-filling, everything becomes possible. Any microcircuit marked limits, above which the functioning leads to failure. Protection of technology becomes the main task when it comes to power surges.

Why protect equipment from power surges

Let's try to find a protection device against power surges and study the instructions. I liked the information provided by the catalogs of the Spanish manufacturer RTR Energia. On the subject of a three-phase harmonic filter, it is written:

  1. Products are designed to filter harmonics with frequencies of 134 and 189 Hz.
  2. The transmission coefficient at the filtering frequencies is 14% and 7%, respectively.
  3. The purpose of the listed measures is explained. Due to these characteristics, it is possible to suppress the 5th harmonic( 5 x 50 = 250 Hz).As a result, there is no resonance between the inductive load impedance and the capacitor bank, which naturally protects the input circuits from overloads.

An overvoltage protection device

Let us clarify that reactive power in industrial networks is considered to be a parasitic effect, does not perform useful work, but requires a substation resource. As a result, the average man pays for the kWh active power, enterprises have to unfasten their jet power as well. This increases spending, and, we emphasize, does not benefit the consumer. To compensate for the reactive part of the load, large enterprises install blocks of capacitors at the input of consumers. Each is characterized by power in kVAR, capable of redemption.

As a result of such activities and there is a threat of overload. We struggle for reactive power compensation in order to reduce energy costs, and we obtain resonance at the above frequencies. As a result, the imaginary part of the resistance vanishes, and large energy runs here and there, which is emitted exclusively as heat in the active part of the load. This is again a loss. In addition, based on the manufacturer's data, it is possible that our saving capacitor blocks may already be out of order. To prevent additional blocks are put out of chokes( one per phase), omitting the limiting frequencies of transmission of the entire system.50 Hz of the useful voltage almost does not suffer.

What are harmonics and wave analysis of industrial voltage

Let's understand what harmonics are, how network protection against power surges depends on them. It turns out that the forms of various vibrations are difficult to analyze. And this is required by all means in order to predict the result of the system, including the forecast of the operation of the surge protection unit. Requires knowledge of parameters.

Physicists and mathematicians thought and decided that any fluctuation in nature is decomposed into a spectrum. Performs direct and inverse transform using Fourier methods. This is a set of mathematical formulas implemented in practice at home. True, you have to use the discrete Fourier transform. It is optimized just for the application of numerical methods( programming).As a result, it turned out that:

  • Any oscillation is represented as a set of sinusoidal signals. For example, for a pure sine wave consists of a single dash. On the frequency of the sinusoid. The mains voltage is ideally provided at 50 Hz. And the spectrum consists of a single harmonic.
  • In practice, the waveform is different from sinusoidal. Additional complexity: the final spectrum is determined by the Fourier functions exclusively for an infinite signal. Our voltage shows the start( power on) and terminate( power off).A number of harmonics appear in the spectrum. These frequencies are proportional to the main 50 Hz. For example, 100, 150, 200, etc. Now readers understand that from the information of the manufacturer RTR it is not difficult to know the importance of filtering the fifth harmonic of 250 Hz. To accomplish the task suppress frequencies of 134 and 189 Hz. Why? Only scientists will answer this question. This is somehow connected with the peculiarities of the equipment and the transition processes in the network.

    Home Voltage

  • If you look at GOST 13109, you will see some interesting comments and requirements for the industrial network. For example, short-term deviations of the nominal from the norm can not exceed 10%.It reminds those values ​​for which the Atlant refrigerators were created. The fact simply says that the Belarusians adhered to the standards. Long-term withdrawal from the nominal cannot exceed 5%.The thresholds for each harmonic are determined. Are expressed by harmonic coefficients. This number is approximately equal to the ratio of the amplitude in the spectrum of the main signal of 50 Hz to the magnitude of the harmonic( frequency, 100, 150, 200, etc.).We see that the form of the voltage is clearly defined and it is written that the consumer has the right to demand the fulfillment of the specified parameters( try to sue the garage cooperative).
  • Finally, for individual pulses, the signal spectrum goes to infinity and becomes continuous. In this regard, most of the input filters are based on a low-frequency circuit. As through the gate passes 50 Hz and additionally a small area, and all the above is cut off. The reason is that power surges cause changes in the spectrum that are detrimental to the equipment.

How to check the effectiveness of measures of protection against voltage surgesThis is perfectly audible on the example of processor coolers. If the voltage form is unstable, the system unit is buzzing like a tank. This is caused by the instability of the rotational speed of the cooling fans. It is enough to eliminate the effect( partial) to close the ground lobe of the socket to the neutral wire. As a result, the filter of the computer’s power supply unit will enter the design mode, the voltage spikes at nominal values ​​will decrease, which will naturally cause a reduction in hum.

Devices and their effects on voltage

The complexity is solved, by the way, in an extravagant way. In addition to standard voltages of +5 V and + 12 V, to which a fan is allowed to be connected, computers often have a pair of sockets: this is a processor cooler( either for a hard disk, etc.).Please note that individual allow regulation of turns. As a rule, the bundle includes a 4 pin pin. Two: power and ground( yellow and black), the second two: tachometer signal( blue) and pulse-width modulation( to cut the voltage and reduce speed in this way).If you want to reduce the noise level, it is reasonable to use such complex coolers, depending on the needs of the system unit( CPU temperature, etc.), the speed will be adjusted.

The slower the blade rotates, the quieter it happens. As for our case, the output to the ground lobes of the neutral wire allows the harmonics filters to function correctly at the input of the power supply. Protection of equipment against power surges is carried out indirectly. It just turns on the regular filter, which would otherwise work incorrectly. At the same time, the shielding properties of the instrument case are clearly improved. Please note that the method is valid only if there is no grounding in the power supply network at home. Similar measures are prohibited for lighting lighting group circuits.

An effective method is the use of an uninterruptible power supply. This device is by definition designed to filter harmonics. Please note that imported versions usually contain filters that require grounding. The defense system collapses if the sockets are set against European standards. But how to protect household appliances from voltage drops of a relatively slow nature. In the case of uninterruptible power supplies, the voltage is maintained, in other cases failure occurs( rise).

Uninterruptible Power Supply

We draw the attention of readers to GOST 13109, according to which the consumer in the latter case has the right to demand the provision of quality services. Get ready for a small fee increase, but the tariffs are regulated by antitrust laws. Thus, in normal mode, when complying with the standards, protection of the refrigerator from power surges is not required. But! It will be necessary to provide the device with grounding. Otherwise, the input filter should work( if available).

Understand cause and effect. For example, protection from power surges in a washing machine is implemented by a special unit. It does not work if there is no grounding, a potential of 60 V is detected on the case( the harmonics described above are filtered).This is done not for a thick-skinned engine, but for a delicate electronic filling that includes a switching power supply unit, where the input stages are simplified in terms of pre-filtering. Imagine now if there is no grounding: we deprive ourselves of a system of protection against voltage surges.

If necessary, buy an automatic or manual type phase selector that monitors voltages. The use of such devices for the supplier is potentially beneficial. The overvoltage protection relay will stop the power supply if the supply voltage goes beyond the permissible limits. Do not confuse with consumption control, the elements of which are included in the meter: it simply cuts off the energy supply to “unimportant” consumers.

For industrial equipment we recommend the use of balun transformers. The meaning of devices in the elimination of phase skew. If a jump occurs along one line, it will be compensated for at the output by a balancing winding. Often, such device protection is more appropriate than others. Combined use with three-phase switches will allow to completely enclose the equipment from excesses.

They told how protection against power surges in the apartment is performed, and it is easier to check this with a screwdriver indicator. If the case is properly grounded, even in the high sensitivity mode, the non-contact trigger method is not observed.

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