Voltage stabilizer: device, principle of operation, purpose

Definition

A voltage stabilizer (MV) is a device designed to convert an input unstable voltage from the mains: underestimated, overestimated or with periodic jumps, in a stable value at the output of the device and connected to it electrical appliances.

Let's paraphrase for dummies: the stabilizer makes sure that the voltage for the devices connected to it is always the same and close to 220V, regardless of what it comes to its input: 180, 190, 240, 250 Volts or in general floats.

Note that 220V or 240V is the standard value for the Russian Federation, Belarus, Ukraine, and so on. But in some countries of the near and far abroad, it may be different, for example 110V. Accordingly, "our" stabilizers will not work there.

Stabilizers are different species: both for operation in DC circuits (linear and pulse, parallel and series types), and for operation in AC circuits. The latter are often called "mains voltage stabilizers" or simply "220V stabilizers". In simple terms, such stabilizers are connected to the mains, and consumers are already connected to it.

In everyday life, CH is used to protect both individual devices, for example, for a refrigerator or a computer, and to protect the whole house, in this case a powerful stabilizer is installed at the input.

Classification

The design of stabilizers depends on the physical principles on which they operate. In this regard, they are divided into:

• electromechanical;
• ferroresonant;
• inverter;
• semiconductor;
• relay.

According to the number of phases, they can be single-phase and three-phase. A wide range of capacities allows us to produce stabilizers for both home and small household appliances:

• for TV;
• for a gas boiler;
• for the refrigerator.

So for large objects:

• industrial units (for example, three-phase industrial stabilizers Saturn);
• workshops, buildings.

Stabilizers are quite energy efficient. Electricity consumption ranges from 2 to 5%. Some stabilizing devices may have additional protections:

• from overvoltage;
• from overloads;
• from short circuits;
• from frequency drops.

Operating principle

Voltage stabilizers are of different types, each of which differs in the principle of regulation. We will consider these differences later. If we generalize the principle of operation and the structure of all types, then the mains voltage stabilizer consists of 2 main parts:

1. Control system - monitors the input voltage level and instructs the power unit to increase or reduce it so that a stable 220V output is obtained within the specified error (accuracy regulation). This error is within 5-10% and is different for each device.
2. The power section - in servo-driven (or servo-motor), relay and electronic (triac) - is an autotransformer, with the help of which the input voltage rises or falls to a normal level, and in inverter stabilizers, or as they are also called "double conversion" - is used inverter. This is a device that consists of a generator (PWM controller), a transformer and power switches (transistors) that pass or turn off the current through the primary winding of the transformer, forming the output voltage of the desired shape, frequency and, most importantly, magnitudes.

If the input voltage is normal, then some models of stabilizers have a "bypass" function or "Transit", when the input voltage is simply applied to the output until it leaves the set range. For example, from 215 to 225 volts, the "bypass" will be turned on, and with large fluctuations, for example, with a drawdown of up to 205-210V, the control system will switch the circuit to the power section and start adjusting, increase the voltage and the output will be already stable 220V with a given error.

Smooth and most accurate adjustment of the output voltage for inverter MV, in second place - servo-driven, and in relay and electronic the adjustment occurs in steps, and the accuracy depends on the number of steps. As mentioned above, it lies within 10%, more often about 5%.

In addition to the two parts mentioned above, the 220V voltage stabilizer also contains a protection unit, as well as a source secondary power supply for control system circuits, the same protections and other functional elements. The general device is clearly shown in the picture below:

At the same time, the scheme of work in its simplest form looks like this:

Let's take a quick look at how the main types of voltage regulators work.

Relay

In a relay stabilizer, regulation occurs by switching the relay. These relays close certain contacts of the transformer, raising or lowering the output voltage.

The controlling body is an electronic microcircuit. The elements on it compare the reference and mains voltage. In case of mismatch, a signal is given by the switching relay to connect the increasing or decreasing windings of the autotransformer.

Relay MVs usually regulate electricity within ± 15% with an output accuracy of ± 5% to ± 10%.

The advantages of relay stabilizers:

• cheapness;
• compactness.

Disadvantages:

• slow response to voltage fluctuations;
• short service life;
• low reliability;
• when switching, a short-term power outage of the devices is possible;
• unable to withstand overvoltage;
• noise, clicks when switching.

Servo

The main elements of servo stabilizers are an autotransformer and a servo motor. If the voltage deviates from the norm, the controller sends a signal to the servo motor, which switches the required autotransformer windings. As a result of using such a system, smooth regulation and accuracy up to 1% of the total range are provided.

In servo-driven MV, one end of the primary winding of the transformer is connected to the rigid branch of the autotransformer, and the second end of the primary winding is connected to a movable contact (graphite brush) that moves servo motor. One terminal of the secondary winding of the transformer is connected to the input power supply, and the second terminal is connected to the output of the voltage regulator.

The control board compares the input and reference voltage. For any deviations from the set ones, the servo drive comes into operation. He moves the brush along the branches of the autotransformer. The servomotor will keep running until the difference between the reference and output voltage is zero. This whole process, from the inflow of poor quality electric power to the output of a stabilized current, takes place in tens of milliseconds and is limited by the speed of the brush movement by a servo drive.

Servo-driven mains voltage stabilizers are produced in various designs.

1. Single phase. Consists of one autotransformer and one servo drive.
2. Three-phase. They are classified into two types. Balanced - have three transformers and one servo drive and one control circuit. Regulation is carried out on all three phases at the same time. They are used to protect three-phase electrical devices, machine tools, devices. Unbalanced - have three autotransformers, three servomotors and three control circuits. That is, stabilization occurs in each phase, independently of each other. Scope: protection of electrical equipment of buildings, workshops, industrial facilities.

Advantages of servo stabilizing devices:

• high-speed performance;
• high stabilization accuracy;
• high reliability;
• overvoltage resistance;

Disadvantages:

• need periodic maintenance;
• require minimal skills in setting up the device.

Inverter

The main difference between this type of MV is the absence of moving parts and a transformer. Voltage regulation is carried out by a double conversion method. In the first stage, the input AC current is rectified and passed through a ripple filter consisting of capacitor. After that, the rectified current is fed to the inverter, where it is again converted into alternating current and supplied to the load. In this case, the output voltage is stable both in magnitude and in frequency.

In the next video, you will learn about the principle of operation of one of the options for implementing a voltage converter from 12V DC to 220V AC. Which differs from the inverter voltage stabilizer primarily in the input voltage, otherwise the principle of operation is very similar and the video will allow you to understand how this type of device works:

Advantages:

• speed (the highest of the listed);
• large range of regulated voltage (from 115 to 300V);
• high efficiency (more than 90%);
• silent work;
• small dimensions;
• smooth regulation.

Disadvantages:

• reduction of the regulation range with increasing load;
• high price.

So we examined how a voltage stabilizer works, what it is for and where it is used. We hope the information provided was useful and interesting for you!

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