A voltage stabilizer is a device that stabilizes the output voltage. The voltage stabilizer is composed of a voltage stabilizer circuit, a control circuit, and a servo motor. When the input voltage or load changes, the control circuit samples, compares, and amplifies, and then drives the servo motor to rotate to change the position of the carbon brush of the voltage stabilizer. The coil turns ratio is automatically adjusted to keep the output voltage stable.

I What is Voltage Stabilizer?

A voltage stabilizer is a device that stabilizes the output voltage. The voltage stabilizer is composed of a voltage stabilizer circuit, a control circuit, and a servo motor. When the input voltage or load changes, the control circuit samples, compares, and amplifies, and then drives the servo motor to rotate to change the position of the carbon brush of the voltage stabilizer. The coil turns ratio is automatically adjusted to keep the output voltage stable.

II Voltage Stabilizer Working Principle

Because some electrical appliances contain coil components, eddy currents that hinder the current will be generated at the initial stage of energization. The eddy currents will not only weaken the instantaneous voltage when the appliance is started, resulting in a slow start, but also strengthen the instantaneous voltage generated after the circuit break, which may cause a spark that damages the circuit. At this time, a voltage regulator is needed to protect the normal operation of the circuit.

The voltage stabilizer is composed of a voltage regulating circuit, a control circuit, and a servo motor. When the input voltage or load changes, the control circuit samples, compares, and amplifies, and then drives the servo motor to rotate to change the position of the carbon brush of the voltage regulator. By automatically adjusting the coil turns ratio, we can keep the output voltage stable. The voltage regulator with a larger capacity also works on the principle of voltage compensation.

III Technical Parameter of Voltage Stabilizer

1. Input Voltage Adaptation Range

The IEC standard is that the input voltage changes within ±20 of the rated value. If the value exceeds the range, it will automatically start the sound and light alarm, and the output voltage cannot be stabilized within the required range.

2. Output Voltage Regulation Rate

It is the effect of the change in the input voltage caused by the change in the output. When the load is rated, adjust the input voltage from the rated value to the upper limit and the lower limit according to the voltage source range, then measure the maximum amount of change in output voltage (±).

The smaller the value, the better. It is an important indicator to measure the performance of the AC voltage stabilizer.

3. Load Regulation Rate

It is the effect of the change in output caused by the change of load. Change the load current and measure the change in output voltage (±). The smaller the value, the better. It is also an important indicator to measure the performance of the AC regulator.

4. Relative Harmonic Content of the Output Voltage

It's also called output voltage distortion, usually expressed in THD, which is the ratio of the total effective value of the harmonic content to the effective value of the fundamental wave. When the load is rated, and the input voltage distortion meets the base conditions (generally less than 3), measure the output voltage distortion when the input voltage is the lowest, rated, and highest value, and take the maximum value. The smaller the value, the better.

5. Efficiency

The voltage regulator efficiency the ratio of the output active power P0 to the input active power Pi (percentage),

6. Load Power Factor

The capacity of the voltage stabilizer is expressed in volt-ampere (VA) or kilovolt-ampere (KVA). In addition to the pure resistive load, there are also inductive and capacitive loads. In addition to the active power, there is reactive power. This indicator reflects the ability of the AC regulator to carry inductive and capacitive loads.

In general AC stabilized power supply, the load power factor cosφ is 0.8. When the product is 1KW, the maximum output active power (that is, the capacity to carry the resistive load) is 800W. If the product is 1KW (cosφ is still 0.8), the output active power is 1KW, and the output power S=1000/0.8=1250VA at this time. When the load power factor value is small, it means that the power supply equipment has a strong ability to adapt to reactive loads.

7. Other Parameters

Other Parameters of AC voltage stabilizer include output power, input frequency, source frequency effect, random deviation (time drift), no-load input power, source power factor (this value is different from the load power factor. The greater the value, the better, The maximum is 1), the relative harmonic content of source current, audio noise, etc., three-phase AC power supply, and three-phase output voltage unbalance, etc.

IV Types of Voltage Stabilizer

There are large-scale AC voltage stabilizers of several tens to several kilowatts for large-scale experiments, industrial and medical equipment. There are also small AC stabilizers of several watts to several kilowatts, which provide high-quality power supplies for small laboratories or household appliances.

According to the different output properties of the voltage stabilizer, the voltage stabilizer is generally divided into two categories: AC voltage stabilizer (AC stabilized power supply) and DC voltage stabilizer (DC stabilized power supply). The following focuses on the DC stabilized power supply.

According to the working state of the regulator tube, the stabilized power supply is often divided into two categories: linear stabilized power supply and switching stabilized power supply. Also, there is a small power supply that uses a voltage stabilizer.

1. Switching Voltage Stabilizer

Figure 1. Switching Voltage Stabilizer

The switching regulator uses the output stage to repeatedly switch the "on" and "off" states, and produce an output voltage with the energy storage components (capacitors and inductors). It adjusts the switching timing according to the feedback sample of the output voltage.

In a fixed frequency regulator, the timing is adjusted by adjusting the pulse width of the switching voltage. This is the so-called PWM control. In a gated oscillator or pulse regulator, the width and frequency of the switching pulse remain constant, but the "on" or "off" of the output switch is controlled by feedback.

According to the arrangement of switches and energy storage components, the output voltage generated can be greater or less than the input voltage, and a voltage regulator can be used to generate multiple output voltages.

In most cases, under the same input voltage and output voltage requirements, pulse (buck) switching regulators are more efficient than linear regulators to convert power. Compensation type---high-precision AC compensation regulated power supply (single-phase 0.5kVA and above, three-phase 1.5kVA and above) has a compensation transformer and 110V output.

2. Parameter Voltage Stabilizer

LDO(low dropout regulator) is a kind of linear regulator. A linear regulator uses a transistor or FET operating in its linear region to subtract the excess voltage from the input voltage to produce a regulated voltage. The so-called drop voltage refers to the minimum difference between the input voltage and the output voltage required to maintain the output voltage within ±100mV of its rated value.

LDO with positive output voltage usually uses power transistors (also called transfer apparatus) as PNPs. This kind of transistor allows saturation, so the regulator can have a very low drop voltage, usually around 200mV. In comparison, the voltage drop of a traditional linear regulator using NPN composite power transistors is around 2V. Negative output LDO uses NPN as its transmission device, and its operating mode is similar to that of positive output LDO PNP device.

Newer developments use CMOS power transistors, which can provide the lowest drop voltage. With CMOS, the only voltage drop through the regulator is caused by the ON resistance of the load current of the power supply. If the load is small, the voltage drop produced by this method is only tens of millivolts.

3. Voltage Stabilizer for Laser Cutting Machine

When the power supply voltage of the distribution network fluctuates or the load changes, it can automatically ensure the stability of the output voltage. It must have a large capacity, high efficiency, wide voltage regulation range, no additional waveform distortion, and phase shift, fast strain time, and stability. Besides, it also has perfect alarm protection functions such as short circuits and mechanical failure, and the volume should be as compact as possible and easy to use.

V Voltage Stabilizer Application and Function

1. Voltage Stabilizer Application

Voltage stabilizers can be widely used in industrial and mining enterprises, oil fields, railways, construction sites, schools, hospitals, posts and telecommunications, hotels, electronic computers, precision machine tools, computer tomography (CT), precision instruments, test devices of scientific research, elevator lighting, imported equipment, production lines and other places that require stable power supply voltage.

Figure 2. Computer Voltage Stabilizer

It is also suitable for users at the end of the low-voltage distribution network where the power supply voltage is too low or too high, and the fluctuation range is large, that is the electrical equipment with large load fluctuations. The high-power compensating power stabilizer can be connected to thermal, hydraulic, and small generators.

2. Voltage Stabilizer Function

A voltage stabilizer is a power supply circuit or power supply device that can automatically adjust the output voltage. Its function is to stabilize the power supply voltage that fluctuates greatly and does not meet the requirements of electrical equipment within its set value range so that various circuits or electrical appliances can work normally under the rated working voltage.

The original power regulator relied on the jump of the relay to stabilize the voltage. When the grid voltage fluctuates, the automatic correction circuit of the power stabilizer is activated to start the internal relay, forcing the output voltage to remain near the set value. This circuit is simple, but the voltage regulation accuracy is not high, and every time the relay jumps and shifts, it will cause an instantaneous interruption of the power supply, generating spark interference.

This greatly interferes with the reading and writing of computer equipment, and it is easy to cause wrong signals on the computer, and in severe cases, it will damage the hard disk.

High-quality small voltage stabilizers mostly use a motor to drive the carbon brushes to stabilize the voltage. This type of voltage stabilizer has little interference to electrical equipment and has relatively high voltage stabilization accuracy.

VI Precautions

1. Daily Attention

(1) Avoid violent vibration, and prevent corrosive gas and liquid from flowing in; prevent from being irrigated and place it in a ventilated and dry place; do not cover with fabric to obstruct ventilation and heat dissipation.

(2) Please use a three-plug (grounded) socket, and the grounding screw on the machine should be properly grounded, otherwise, we'll find the case is with charges when testing. It is a normal phenomenon caused by the distributed capacitance-induced electricity and can be eliminated after connected to the grounding wire.

If there is a serious electric leakage on the case, and the measured insulation resistance is less than 2MΩ, the insulation layer may be damp or the circuit and the case are short-circuited. You should find out the cause and eliminate the fault before using it.

(3) The 0.5-1.5KVA low-power voltage stabilizer uses the fuse for overcurrent and short circuit protection, and the 2-40KVA voltage stabilizer functions as the circuit breaker for overcurrent and short circuit protection. If the fuse often blows or the circuit breaker frequently trips, check whether the electricity consumption is too large.

(4) When the output voltage exceeds the protection value (the phase voltage protection value is adjusted to 250V±5V at the factory), the stabilized power supply is automatically started. If the output voltage of the stabilized power supply is cut off, and the overvoltage indicator is still on, the user should immediately shut down and check the grid voltage or the voltage stabilizer. If the voltage stabilizer is automatically powered off (with input but no output), check whether the mains voltage is higher than 280V. If it is lower than 280V, check whether the regulator is malfunctioning. Use after finding out the reason.

(5) If the output voltage of the voltage stabilizer deviates much from 220V, please adjust the potentiometer on the control panel until the output voltage becomes normal(if the input voltage does not reach the voltage regulation range, it cannot be adjusted).

(6) When the mains voltage is often at the lower limit (<150V) or upper limit (>260V) of the voltage stabilizer input voltage, the limit microswitch is easily touched and control failure is likely to occur. At this time, the voltage regulator cannot adjust the voltage or can only be adjusted up (or can only be adjusted down), and the microswitch should be checked first.

(7) Please keep the inside of the machine clean, dust will hinder the rotation of the gear and affect the accuracy of the output voltage. Please clean and maintain the coil contact surface clean in time. When the carbon brush is severely worn, the pressure should be adjusted to avoid flashover on the contact surface of the carbon brush and the coil. The carbon brush should be replaced when the length is less than 2mm. And when the coil plane is burnt black, fine sandpaper should be used to polish it.

(8) The input end of the 3 phase voltage stabilizer must be connected to the neutral line, otherwise, the voltage stabilizer cannot work normally with load, and the voltage stabilizer and electrical equipment will be damaged. Do not use the ground wire to replace the neutral wire (but the neutral and ground wires can be connected in parallel), and the neutral wire must not be connected to the fuse.

Figure 3. 3 Phase Voltage Stabilizer

(9) When the output voltage of the regulator is lower than the rated voltage (220V or three-phase 380V), check whether the input voltage is too low. When the rated voltage is reached at no load and the output is lower than the rated voltage under load, this is due to the input line load surface is too small, or the load end exceeds the rated capacity range of the regulator, the line voltage drop is too large when the load is used, and the input voltage is lower than The lower limit of the regulator's adjustment range, at this time, you should replace the thicker input wire or increase the product capacity.

(10) When a single load has a large power (such as an air conditioner, etc.), the input line is long, and the load surface is insufficient, the voltage is severely reduced when the load is working, and the load may be difficult to start. When the load is stopped temporarily while working, overvoltage power failure will occur in the output moment. If such a phenomenon occurs, it is not a voltage regulator failure, and the input line should be improved (the line should be thickened and the length of the input line should be shortened as much as possible to reduce the voltage drop in the line).

(11) When the output voltage of the voltage stabilizer deviates seriously from 220V, check

① whether the input voltage is within the voltage stabilization range;

② whether the motor gear is severely worn and whether the rotation is flexible;

③ whether the limit switch is damaged;

④ whether the coil plane is smooth;

⑤ whether the control board is damaged.

2. Safety Matters

(1) When the stabilized power supply is powered on, please do not disassemble the stabilized power supply or pull the input and output lines of the stabilized power supply at will to prevent electric shock or other electrical safety accidents.

(2) The input and output lines of the stabilized power supply must be arranged reasonably to prevent trampling and wear, which may cause leakage accidents.

(3) The stabilized power supply must be reliably grounded, and the user is responsible for the electric shock or human injury caused by the operation of the ungrounded wire.

(4) The ground wire of the stabilized power supply cannot be connected to public facilities such as heating pipelines, water supply pipelines, gas pipelines, etc., to avoid infringement of third-party rights or causing harm.

(5) The input and output lines of the stabilized power supply should be checked regularly to avoid loosening or falling off, thereby affecting the normal use and safety of the stabilized power supply.

(6) The selection of the connecting wire of the voltage stabilizer should be able to carry sufficient current capacity.

(7) The voltage stabilizer should be handled gently to avoid severe vibration in working;

(8) Ensure that the carbon brush spring of the voltage stabilizer has sufficient pressure to avoid flashover on the contact surface of the carbon brush and the coil;

(9) Non-professionals can not disassemble or repair the stabilized power supply.

VII Failure Analysis

Friendly reminder: If the voltage stabilizer fails and you cannot deal with it or stop powering the back-end equipment, please contact a professional company.