AVR type
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Relay. Such devices have a transformer with a set of contacts, each of which is responsible for a certain voltage value. Thus, the adjustment is carried out stepwise. And for switching between groups of contacts, a specialized relay is responsible, in full accordance with the name. Being simple and fairly inexpensive devices, relay regulators have high speed (see “Response speed”) and a wide input voltage range (see below). At the same time, the relay gives a rather large error (see "Output voltage accuracy") and is poorly adapted to work with high currents and sudden voltage surges (for example, when using a welding machine) — the contact group is highly likely to burn out. Therefore, models of this type are mostly designed for simple conditions where neither high accuracy nor power is required — for example, they are well suited for connecting individual household appliances. In addition, we note that the operation of the relay is often associated with a significant level of noise (primarily due to the characteristic "click"); this can cause serious inconvenience in residential use.
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Thyristor. The device of thyristor stabilizers is in many ways similar to the relay stabilizers described above: in particular, there is the same transformer with a set of separate outputs for step adjustment. However, switching between the windings is carried out not with the help of a relay, but with the help of
...semiconductor devices — thyristors. The principle of their operation is also similar to a relay: a thyristor is able to close and open a circuit with powerful currents, receiving control commands using weak signals. The main design difference of thyristor stabilizers, which gives them an advantage over relay ones, is the absence of a contact group. This allows you to connect a fairly powerful load to such devices, the accuracy of their work is very high, and the noise during switching, unlike relay circuits, is practically absent. On the other hand, thyristors are sensitive to overheating and require the installation of active cooling systems (see below), which accordingly affects the price and dimensions of the device.
— Triac. Stabilizers built on triacs (symmetrical thyristors). In fact, they are a variety of the thyristor devices described above, and from the practical point of view, they do not noticeably differ from them in any way — neither in advantages nor in disadvantages.
— Electromechanical. The operation of such stabilizers is based on the operation of an electric motor (sometimes called a servomotor), which moves a special carbon contact directly along the transformer windings. Depending on the position of the contact, the number of turns of the winding included in the work changes; This is how the voltage is adjusted. Such models are considered one of the best in terms of price / quality ratio, they combine low cost with excellent accuracy and smoothness of adjustment. At the same time, the response speed in them directly depends on the degree of change in the input voltage: the stronger the jump, the greater the distance the brush must travel along the windings. Accordingly, electromechanical stabilizers are poorly suited to work with sharp drops in the network, and therefore, in order to avoid unpleasant consequences, the input voltage range (see below) is usually rather narrow. In addition, the brush is erased with constant movement, which requires periodic cleaning of the transformer and replacement of the brush itself; however, such a need does not arise often and usually does not cause difficulties. The operation of the servomotor creates some noise, but in general models of this type are quieter than relay ones (although noticeably louder than solid-state ones).
— ferroresonant. One of the first types of stabilizers mass-produced. The design of such a device is based on a pair of coils, reminiscent of a classic transformer. The characteristics of the coils are selected in such a way that when the input voltage is exceeded, the “extra” part of the magnetic flux from the input coil is diverted into the so-called magnetic shunt, and the magnetic flux through the output coil (and, accordingly, the voltage at its outputs) remained constant. Due to this, ferroresonance models have high speed and smooth operation, good accuracy, as well as a simple and inexpensive design. On the other hand, such stabilizers are not capable of delivering a smooth sinusoidal current, they are highly dependent on the frequency of the input current, they create noise on the line (which requires the use of filters when connecting sensitive electronics), they have a small range of input voltages and load powers (they are unable to operate idle or with overload). In addition, devices of this type are heavy and bulky. As a result, they are considered obsolete and are used relatively rarely.
— Combined. A kind of stabilizers that combines elements of relay and electromechanical models in the design. Usually, for small voltage surges, they use tuning with an electric motor; the relay, in turn, plays the role of insurance and is activated in case of significant deviations that the electromechanical part cannot cope with “alone”. Thanks to this, in one device it was possible to combine the advantages of both options — high tuning accuracy and a wide range of input voltages. However this type of stabilizer also inherited some disadvantages — in particular, the need to clean the brush and noise when the relay is triggered (although the latter happens less often than in purely relay models). In addition, the cost of such units is usually quite high.
— Double conversion. The principle of operation of this type of stabilizer is to convert AC to DC (using a rectifier) and then back to AC (using an inverter). The inverter is set up to provide a near reference voltage and a sine wave over the entire operating range of the input voltage. Thus, the main advantage of double conversion stabilizers is the high accuracy of the output signal, such devices are suitable even for delicate components such as TVs or speakers. In addition, the input voltage range turns out to be quite wide, the reaction to power surges is almost instantaneous, and due to the absence of moving parts, the stabilizer operates quietly and “lives” for a long time. The main disadvantages of such devices are high cost and relatively low efficiency (about 90%).Input voltage range
The voltage range at the input of the stabilizer, at which it is able to operate in normal mode and supply a constant voltage of 230 or 400 V to the load (depending on the number of phases, see above). The wider this range — the more versatile the device, the more serious power surges it can extinguish without going beyond the standard operating parameters. However, note that this parameter is not the only, and not even far from the main indicator of the quality of work: a lot also depends on the accuracy of the output voltage and the response speed (see both points below).
Also note that some models may have several modes of operation (for example, with 230 V, 230 V or 240 V output). In this case, the characteristics indicate the "general" input voltage range, from the smallest minimum to the largest maximum; the actual ranges for each particular mode will vary.
In addition, there are stabilizers that can operate outside the nominal input voltage range: with a slight deviation beyond its limits, the device provides relatively safe output indicators (also with some deviations from the nominal 230 or 400 V), but if the drop or rise becomes critical, it works appropriate protection (see below).
Output voltage accuracy (±)
The largest deviation from the nominal output voltage (230 V or 400 V, depending on the number of phases), which the regulator allows when operating in the normal input voltage range (see above). The smaller this deviation, the more efficiently the device works, the more accurately it adapts to “changes in the situation” and the less voltage fluctuations the connected load is exposed to.
When choosing for this parameter, it is worth considering first of all how demanding the connected devices are for voltage stability. On the one hand, high stability is good for any device, on the other hand, it usually means a high price. Accordingly, it usually does not make sense to buy an advanced stabilizer for an unpretentious load like light bulbs and heaters, but for sensitive devices like audio systems or computers, it can be very useful.
Efficiency
The efficiency of the stabilizer is the ratio, expressed as a percentage, between the amount of electricity at the output of the device to the amount of energy at the input. In other words, efficiency describes how much of the energy received from the network the device transfers to the connected load without loss. And losses during operation will be inevitable — firstly, not a single transformer is perfect, and secondly, the control circuits of the stabilizer also require a certain amount of energy to work. At the same time, all these costs are quite small, and even in relatively simple modern models, the efficiency can reach 97-98%.
