Comparison Luxeon EDC-500 0.5 kVA / 350 W vs Forte TDR-500VA 0.5 kVA

— 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.

— 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%).

The maximum active load power allowed for this model.

Active power is the power that in AC appliances is spent on useful work or on heat generation. In addition to it, such devices also consume reactive power — it goes to the operation of specific components, primarily capacitors and inductors. Apparent power, denoted in volt-amperes (kilovolt-amperes), is the sum of active and reactive, see below about it. Here we note that in simple everyday situations, there is enough data on active power indicated in watts for calculations. In particular, it is this parameter that is considered the key when choosing stabilizers for washing machines and dishwashers : in the first case, power from 2 to 5 kW is considered optimal, in the second — from 1.8 to 2.5 kW.

Anyway, the total active power of the connected load should not exceed the figures indicated in the characteristics of the stabilizer. For a full guarantee, it's ok to take a certain margin, but this margin should not be too large — an increase in the allowable power significantly affects the dimensions, weight and price of the device. Also note that there are formulas that allow you to convert the active power consumption into total power, taking into account the type of connected electrical appliance; these formulas can be found in special sources.

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).

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.

The rate at which the regulator responds to changes in input voltage. It is determined by the time that passes from the moment of a power surge until the moment when the device fully adjusts to the new parameters and the output current corresponds to the standard 230 or 400 V (depending on the number of phases, see above). Accordingly, the shorter the response time, the better the stabilizer works, the lower the likelihood that a power surge will significantly affect the connected equipment. On the other hand, not all types of electrical appliances are sensitive to speed — for some, smooth adjustment or voltage accuracy is more important (see above); and the high speed itself can significantly affect the price of the device. Therefore, when choosing by this parameter, it makes sense to consider which devices are planned to be connected through the stabilizer.

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%.

- From overheating. Protection that prevents the critical temperature rise of individual components of the stabilizer - for example, in case of overload, short circuit or failure in the cooling system. When a certain temperature value is exceeded, it turns off the device in order to avoid breakdowns and fires. Such systems are especially important for semiconductor types of stabilizers - thyristor and triac(see above). And in some models, this function can be supplemented by a temperature increase signal - it works at a temperature close to critical.

- From high-frequency interference. This protection dampens incoming high-frequency interference, preventing them from affecting the operation of devices connected to the stabilizer. Such interference can occur, for example, from electric motors, welding machines, etc. So, in audio systems, high-frequency distortion causes an unpleasant background from the speakers. RFI protection filters out these distortions, providing a smooth sine wave output.

- Against short circuit. A system that protects the stabilizer in the event of short circuits in the connected load. A short circuit is a situation when the resistance in the circuit becomes close to zero; this leads to a sharp increase in current strength, overloads the power grid and the stabilizer itself, and also creates a ri...sk of breakdown or even fire. In order to avoid unpleasant consequences, appropriate protection is provided: it disconnects the load in case of a significant excess of the current in it. This feature is almost mandatory in modern stabilizers.

- From overload. Safety system in case of stabilizer overload - that is, a situation when the total power of the connected load becomes greater than the corresponding indicators of the device itself (see "Power"). The reason for this situation may be, for example, the inclusion of an additional consumer or a change in the operating mode of one of the existing ones. Unlike the short circuit described above, when overloaded, all electrical appliances work normally, the stabilizer itself is abnormal, which can lead to its failure or even fire. To avoid this, overload protection is applied. Its specific implementation may be different. In some models, the load is turned off immediately, in others - after a certain time after the warning signal, which gives the user the opportunity to reduce power consumption and avoid system tripping.

- From over / under voltage. A system that protects the device from too low or too high input voltage. A significant overshoot of the input voltage range (see above) is dangerous not only by the risk of damage to the stabilizer itself: under such conditions, the device’s capabilities are not enough to fully protect the connected load, which can result in trouble for it. And this function prevents such consequences: if the input voltage goes beyond the permissible values (they may be wider than the operating values, see “Input voltage range”), the stabilizer is disconnected from the network. At the same time, some of its functions may remain operational - for example, a voltmeter that allows you to assess the "state of affairs" in the network at the input. And in some models there is a function to automatically turn on when the voltage returns to operating limits.

The degree of protection of the internal components of the stabilizer from various undesirable influences from the outside — first of all, from the ingress of moisture and foreign objects. The IP (ingress protection) standard is used to describe the protection provided by an enclosure.

In marking according to this standard, two digits are usually used — for example, IP54. The first digit describes the degree of protection against various solid objects (up to and including sand and dust). Its specific meanings may be as follows:

1 — protection against objects measuring 50 mm or more (for comparison: the average male fist will no longer pass even through the largest hole in such a case).
2 — from objects with a size of 12.5 mm or more (comparable to the thickness of a finger on a hand).
3 — from objects with a size of 2.5 mm or more (we can talk about protection against accidental contact with most standard tools).
4 — from objects with a size of 1 mm or more (for example, most wires).
5 — medium degree of protection against dust (it is allowed to get inside a certain amount of dust that does not affect the operation of the device).
6 — the maximum degree of protection against dust (its ingress is practically excluded).

The second digit, respectively, describes the resistance to moisture:

1 — minimum degree of protection — the device, placed in the working position, is resistant to individual drops falling vertica...lly on it.
2 — vertical drops are allowed when the device deviates from the working position by less than 15 °.
3 — splashes flying at an angle of up to 60 ° from the vertical are allowed; rain protection.
4 — resistance to splashes from any direction; wind and rain protection.
5 — resistance to water jets; protection from heavy rains, storms.
6 — short-term ingress of large volumes of water is allowed — for example, when a wave hits.
7 — the possibility of short-term immersion under water to a shallow depth (up to 1 m).
8 — the ability to work at a depth of 1 m and for a longer time.

One of the numbers can be replaced by the letter X — this usually means that the device does not have official certification in the corresponding direction of protection. In some cases, this suggests that there is no such protection at all — for example, the IP2X case is most likely not designed for any water ingress at all. However, it can be the other way around — for example, IPX7: a housing with the ability to submerge under water will certainly be well protected from dust, even if this is not officially announced.

Of course, it is worth choosing an option for this parameter, first of all, taking into account the expected operating conditions: for example, for a dry utility room, water protection is useless (it will only cost extra money), but in a damp basement, such a case can be very out of place. However, note that no protection provides absolute guarantees and does not eliminate the need to comply with safety rules.

The presence in the design of the stabilizer of a special handle for carrying the device from place to place. This feature is useful primarily for powerful and, accordingly, heavy devices, which would be inconvenient to hold directly by the case. And in the most "weighty" models, which are not designed to be carried alone, there are several handles.