We offer a large selection of fully automatic devices of low and high power from the leading manufacturer ETK Energy, designed for high-speed elimination of poor-quality power supply by leveling surges and sags in single-phase and three-phase networks alternating current and tension. In most cases, our Energy and Voltron models belong to the group of premium class network devices, but there are also regular series that are designed to solve problems in non-critical conditions of continuous operation. And today we have a good range of relay, hybrid, electromechanical and electronic (thyristor) devices worthy of your attention. It is possible to buy a voltage stabilizer with current protection in Moscow, St. Petersburg and the regions. In addition to this main task of smoothing out differences, these stabilizing devices for 220V, 380V power networks will help suppress interference, qualitatively support the good operation of office or household appliances during short-term overloads and ensure complete safety modern consumers in case of short circuit. For this purpose, the best and most reliable operating elements are used in the design of 1-phase and 3-phase electrical equipment Energia and Voltron. The range of successful performance for many brands is 100 ... 280 Volts. There are also universal high-precision (accuracy ±3, ±5 percent) devices with a smooth adjustment system (Energy Classic and Ultra 5000, 7500, 9000, 12000, 15000, 20000) capable of stabilizing the power supply from 65V without much difficulty.

High-quality voltage stabilizers with current protection in our online store are presented in the most popular capacities (2, 3, 5, 8, 10, 15, 20, 30 kW), which are ideal for round-the-clock use in the office, country house, home and industrial objects. Hybrid and thyristor high-precision models have a pure sinusoidal signal shape, due to which they successfully operate with simple and highly sensitive electrical equipment for various purposes. Among the domestic certified products for variable network stabilization, technology-improved frost-resistant devices are also available for purchase, which allows trouble-free operation at subzero temperatures. You can buy a voltage stabilizer with current protection in Moscow, St. Petersburg through our official website at minimum price from a reliable manufacturer. Due to the special structure of the housing, some single-phase Russian brands can be installed as a standard floor-mounted option or use a more compact and convenient mounting method - on the wall (wall-mounted). In those highly efficient lines where smooth equalization of under- or critically over-powered power is provided, there is absolutely no flickering of light bulbs, which sometimes causes minor inconvenience in residential buildings, apartments or cottages. In terms of the noise level emitted during operation of the equipment, there are absolutely silent and inexpensive low-noise network electrical appliances. The warranty for Russian-made devices recommended for purchase, which are widely in demand in Russia, is 1-3 years. Absolutely all series are energy-saving and equipped with an automatic self-diagnosis function.

To power some radio devices, a power source with increased requirements for the level of minimum output ripple and voltage stability is required. To provide them, the power supply must be made using discrete elements.

Shown in Fig. 4.7 circuit is universal and on its basis you can make a high-quality power supply for any voltage and current in the load.

Rice. 4.7. Electrical diagram power supply

The power supply is assembled on a widely used dual operational amplifier (KR140UD20A) and one power transistor VT1. Moreover, the circuit has current protection, which can be adjusted over a wide range.

The operational amplifier DA1.1 is used as a voltage stabilizer, and DA1.2 is used to provide current protection. Microcircuits DA2, DA3 stabilize the power supply of the control circuit assembled on DA1, which allows improving the parameters of the power source.

The voltage stabilization circuit works as follows. Voltage feedback is removed from the source output (X2). This signal is compared with the reference voltage coming from the zener diode VD1. A mismatch signal (the difference between these voltages) is supplied to the input of the op-amp, which is amplified and sent through R10-R11 to control transistor VT1. Thus output voltage maintained at a given level with an accuracy determined by the gain of the op-amp DA1.1.

The required output voltage is set by resistor R5.

In order for the power supply to be able to set the output voltage to more than 15 V, the common wire for the control circuit is connected to the “+” terminal (X1). In this case, to fully open the power transistor (VT1) at the output of the op-amp, a small voltage will be required (based on VT1 Ube = +1.2 V).

This design of the circuit allows you to make power supplies for any voltage, limited only by the permissible value of the collector-emitter voltage (Uke) for a specific type of power transistor (for KT827A maximum Uke = 80 V).

In this circuit, the power transistor is composite and therefore can have a gain in the range of 750...1700, which allows it to be controlled by a small current - directly from the output of op-amp DA1.1. This reduces the number necessary elements and simplifies the diagram.

The current protection circuit is assembled on op-amp DA1.2. When current flows in the load, voltage is released across resistor R12. It is applied through resistor R6 to the connection point R4-R8, where it is compared with the reference level. As long as this difference is negative (which depends on the current in the load and the resistance value of resistor R12), this part of the circuit does not affect the operation of the voltage stabilizer.

As soon as the voltage at the specified point becomes positive, a negative voltage will appear at the output of op-amp DA1.2, which, through the diode VD12, will reduce the voltage at the base of the power transistor VT1, limiting the output current. The level of output current limitation is adjusted using resistor R6.

Parallel connected diodes at the inputs operational amplifiers(VD3...VD7) protect the microcircuit from damage if it is turned on without feedback through transistor VT1 or if the power transistor is damaged. In operating mode, the voltage at the inputs of the op-amp is close to zero and the diodes do not affect the operation of the device.

Installed in the negative circuit feedback capacitor C3 limits the band of amplified frequencies, which increases the stability of the circuit, preventing self-excitation.

A similar power supply circuit can be made on a transistor with a different conductivity KT825A (Fig. 4.8).

Rice. 4.8 Second version of the power supply circuit

When using the elements indicated in the diagrams, these power supplies make it possible to obtain a stabilized output voltage of up to 50 V at a current of 1.5 A.

The technical parameters of the stabilized power supply are no worse than those indicated for a circuit similar in principle to operation, shown in Fig. 4.10.

Rice. 4.10. Electrical diagram

The power transistor is installed on a radiator, the area of ​​which depends on the load current and voltage Uke. For normal operation of the stabilizer, this voltage must be at least 3 V.

When assembling the circuit, the following parts were used: tuning resistors R5 and R6 type SPZ-19a; fixed resistors R12 type C5-16MV for a power of at least 5 W (power depends on the current in the load), the rest are from the MLT and C2-23 series of the corresponding power. Capacitors C1, C2, C3 type K10-17, oxide polar capacitors C4...C9 type K50-35 (K50-32).

The DA1 dual operational amplifier chip can be replaced with an imported analogue MA747 or two 140UD7 chips; voltage stabilizers: DA2 on 78L15, DA3 on 79L15.

The parameters of the network transformer T1 depend on the required power supplied to the load. For voltages up to 30 V and current 3 A, you can use the same one as in the circuit in Fig. 4.10. In the secondary winding of the transformer, after rectification on capacitor C6, a voltage of 3.5 V should be provided greater than what is required to be obtained at the output of the stabilizer.

In conclusion, it can be noted that if the power source is intended to be used in a wide temperature range (-60...+100°C), then to obtain good technical characteristics additional measures must be taken. These include increasing the stability of reference voltages. This can be done by selecting zener diodes VD1, VD2 with a minimum. TKN, as well as stabilization of the current through them. Typically, current stabilization through a zener diode is performed using field effect transistor or by using an additional microcircuit operating in current stabilization mode through a zener diode, Fig. 4.9.

To power some radio devices, a power source with increased requirements for the level of minimum output ripple and voltage stability is required. To provide them, the power supply must be made using discrete elements.

Shown in Fig. 3.23 circuit is universal and on its basis you can make a high-quality power supply for any voltage and current in the load. The power supply is assembled on a widely used dual operational amplifier (KR140UD20A) and one power transistor VT1. Moreover, the circuit has current protection, which can be adjusted over a wide range. The operational amplifier DA1.1 is a voltage stabilizer, and DA1.2 is used to provide current protection. Microcircuits DA2, DA3 stabilize the power supply of the control circuit assembled on DA1, which allows improving the parameters of the power source.

The voltage stabilization circuit works as follows. The voltage feedback signal is removed from the source output (X2). This signal is compared with the reference voltage coming from the zener diode VD1. A mismatch signal (the difference between these voltages) is supplied to the input of the op-amp, which is amplified and sent through resistors R10...R11 to control transistor VT1.

Thus, the output voltage is maintained at a given level with an accuracy determined by the gain of the op-amp DA1.1. The required output voltage is set by resistor R5. In order for the power supply to be able to set the output voltage to more than 15 V, the common wire of the control circuit is connected to the “+” terminal (XI). In this case, to fully open the power transistor (VT1) at the output of the op-amp, a small voltage will be required (based on VT1 ibe = +1.2 V). This design of the circuit allows you to make power supplies for any voltage, limited only by the permissible value of the collector-emitter voltage (UK3) for a specific type of power transistor (for KT827A maximum UK3 = 80 V).

In this circuit, the power transistor is composite and therefore can have a gain in the range of 750... 1700, which makes it possible to control it with a small current - directly from the output of the op-amp DA1.1, which reduces the number of required elements and simplifies the circuit.

The current protection circuit is assembled on op-amp DA1.2. When current flows in the load, a voltage is released across resistor R12, which is applied through resistor R6 to the connection point R4, R8, where it is compared with the reference level. As long as this difference is negative (which depends on the current in the load and the resistance value of resistor R12), this part of the circuit does not affect the operation of the voltage stabilizer. As soon as the voltage at the specified point becomes positive, a negative voltage will appear at the output of op-amp DAL2, which, through the diode VD12, will reduce the voltage at the base of the power transistor VT1, limiting the output current.

The level of output current limitation is adjusted using resistor R6. Parallel-connected diodes at the inputs of operational amplifiers (VD3...VD6) protect the microcircuit from damage if it is turned on without feedback through transistor VT1 or if the power transistor is damaged. In operating mode, the voltage at the inputs of the op-amp is close to zero and the diodes do not affect the operation of the device. The SZ capacitor installed in the negative feedback circuit limits the band of amplified frequencies, which increases the stability of the circuit, preventing self-excitation.

When using the elements indicated in the diagrams, these power supplies make it possible to obtain a stabilized output voltage of up to 50 V at a current of 1...5 A.

The power transistor is installed on a radiator, the area of ​​which depends on the load current and voltage UK3. For normal operation of the stabilizer, this voltage must be at least 3 V

When assembling the circuit, the following parts were used: trimming resistors R5 and R6 of the SPZ-19a type; fixed resistors R12 type C5-16MV for a power of at least 5 W (power depends on the current in the load), the rest are from the MJ1T and C2-23 series of appropriate power Capacitors CI, C2, SZ type K10-17, oxide polar capacitors C4... C9 type K50-35 (K50-32). The DA1 dual operational amplifier chip can be replaced imported analogue tsA747 or two 140UD7 microcircuits; voltage stabilizers: DA2 on 78L15, DA3 on 79L15. The parameters of the network transformer T1 depend on the required power supplied to the load. In the secondary winding of the transformer, after rectification, capacitor C6 should provide a voltage 3...5 V greater than what is required at the output of the stabilizer.

In conclusion, it can be noted that if the power source is intended to be used in a wide temperature range (~60...+100°C), then additional measures must be taken to obtain good technical characteristics. These include increasing the stability of the reference voltages. This can be done by selecting zener diodes VD1, VD2 with a minimum TKN, as well as stabilizing the current through them. Usually, current stabilization through the zener diode is performed using a field-effect transistor or by using an additional microcircuit operating in the mode of stabilizing the current through the zener diode. In addition, zener diodes provide the best thermal stability of voltage at a certain point in their characteristics. In the passport for precision zener diodes, this current value is usually indicated and it is this value that must be set using trimming resistors when setting up the reference voltage source unit, for which a milliammeter is temporarily connected to the zener diode circuit.

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We bring to your attention a high-quality, practical, powerful power supply. To power some radio devices, a power source with increased requirements for the level of minimum output ripple and voltage stability is sometimes required. To provide them, the power supply must be made using discrete elements. The above circuit is universal and on its basis you can make a high-quality power supply for any voltage and current in the load.
Fig.1
The power supply is assembled on a widely used dual operational amplifier (KR140UD20A) and three power transistors VT1-VT3 N-P-N conductivity. In this case, the circuit has current protection, which can be adjusted over a wide range and which must operate quickly enough to prevent damage to the source itself in the event of a short circuit at the output. The operational amplifier DA1.1 is a voltage stabilizer, and DA1.2 is used to provide current protection. Microcircuits DA2, DA3 stabilize the power supply of the control circuit assembled on DA1, which allows improving the parameters of the power source. The voltage stabilization circuit works as follows. Voltage feedback is removed from the source output (X2). This signal is compared with the reference voltage coming from the zener diode VD1. A mismatch signal (the difference between these voltages) is supplied to the input of the op-amp, which is amplified and sent through R16-R17 to control transistors VT1-VT3. Thus, the output voltage is maintained at a given level with an accuracy determined by the gain of the op-amp DA1.1. The required output voltage is set by resistors R10-R15. In order for the power supply to be able to set the output voltage to more than 15 V, the common wire for the control circuit is connected to the “+” terminal (X1). In this case, to fully open the power transistors (VT1-VT3) at the output of the op-amp, a small voltage will be required (at the bases Ube = +1.2 V). This design of the circuit allows you to make power supplies for any voltage, limited only by the permissible value of the collector-emitter voltage (Uke) for a specific type of power transistors (for KT827A maximum Uke = 100 V, KT827B - 80 V). In this circuit, the power transistors are composite and, therefore, can have a gain in the range of 750... 18000, which allows them to be controlled with a small current - directly from the output of op-amp DA1.1. This reduces the number of elements required and simplifies the circuit. The current protection circuit is assembled on op-amp DA1.2. When current flows in the load, voltage is released across resistor R5. It is applied through resistor R11 to the connection point R9-R13, where it is compared with the reference level. As long as this difference is negative (which depends on the current in the load and the resistance value of resistor R5), this part of the circuit does not affect the operation of the voltage stabilizer. As soon as the voltage at the specified point becomes positive, a negative voltage will appear at the output of op-amp DA1.2, which, through diode VD9, will reduce the voltage at the base of power transistors VT1-VT3, limiting the output current. The level of output current limitation is adjusted using resistor R11. Parallel-connected diodes at the inputs of operational amplifiers (VD5...VD8) protect the microcircuit from damage if it is turned on without feedback through transistors VT1-VT3 or if (one of) the power transistors is damaged. In operating mode, the voltage at the inputs of the op-amp is close to zero, and the diodes do not affect the operation of the device. The capacitor C12 installed in the negative feedback circuit limits the band of amplified frequencies, which increases the stability of the circuit by preventing self-excitation. When using the elements indicated in the diagrams, these power supplies make it possible to obtain a stabilized output voltage of up to 50 V at a current of up to 5 A. Power transistors are installed on a radiator, the area of ​​which depends on the load current and voltage Uke (at least 1500 cm2). For normal operation of the stabilizer, this voltage must be at least 3 V. R1 is for discharging the capacitors after turning off the power supply. The second half of the power supply is made similarly based on 3 parallel-connected transistors of P-N-P conductivity 2T825A (KT825G).

Fig. 2 When assembling the circuit, in addition to those indicated, you can use: rectifier diodes (diode bridge), designed for a current of at least 10A, voltage more than 200V (for radiators), VD5-VD8-1N4148, VD9-VD10 - any for a current of 1A, voltage 100V , variable, tuning resistors R11 (later replaced by a biscuit switch with current-limiting resistors installed and pre-selected during setup), R10 and R15 type SP3-19a, SPO-0.5, etc. (the circuit uses multi-turn wire ones to smoothly change the output voltage with an accuracy of 0.1V; fixed resistors R2-R5 type C5-16MV (wire or imported) for a power of at least 5 W (power depends on the current in the load), the rest from series MLT, BC, S2-23 of appropriate power. Capacitors C4, C5, C14 are preferably of high quality, for example polypropylene (imported with the MKR marking). The dual operational amplifier chip DA1 can be replaced with an imported analogue mA747S or two K(R)140UD7 chips (respectively according to the pinout, the correct printed circuit board is required); voltage stabilizers: DA2-DA3 - any domestic, imported at + -15V (78L15,79L15, etc.). C12-type K10-17, C10-C11-film (K73-17 etc.).Zener diodes VD1, VD2 with a minimum TKN - D818 (with any letter index). The parameters of the network transformer Tr1 depend on the required power supplied to the load (in this case, OSM-0.4 kW). In the secondary winding of the transformer after rectification capacitor C2 should provide a voltage 5-7 V higher than what is required at the output of the stabilizer (41 V AC). The powerful secondary winding is wound in two wires with a cross-section of 0.85 mm2 each, a single wire must have a cross-section of at least 1.5 mm2. As Tr2, any power of about 20 W, having two double windings 2x 17 V (each half of the power supply has its own separate windings with a common point for powering the stabilizers) with a load current of 200 mA. Output transistors must be selected with similar parameters, namely: gain. To do this, during setup, selection fixed resistors instead of R11, use multimeters to connect to resistors R2-R4 located on the radiator (you can take turns, if there are not enough multimeters), connect a load, for example, with a current of 1 A and record the values ​​of the voltage drops (DC) on each of the resistors, compare them, they should be as close to each other as possible; if there is a significant difference on some resistor, then it is necessary to replace this transistor with another and repeat the measurements. Such a number of used powerful transistors caused by a more even distribution of heat generation across them under heavy load, which will ensure stability and stability of the operation of the power supply unit as a whole, although one transistor is quite resistant to operation in extreme conditions. During tests at a current of 5A, two transistors out of three KT827A leaked between the ECs (not a breakdown, Rke = 9 kom), apparently due to a strong scatter of parameters. Ammeter with a full deflection current of 5 amperes or more (with a shunt where necessary). Please take into account that if the load is in the form of a spiral (a powerful wire resistor), then over time it (it) will heat up and, accordingly, the resistance will increase, and the current, on the contrary, will decrease, so it is advisable to carry out measurements quickly. Sorry for the poor quality printed circuit board by hand (rectifier and power filtering elements, +-15V power stabilization boards are not indicated, although in reality they are located on the same printed circuit board.).
Chapter:

Current stabilizer with short circuit protection

Current stabilizer overload protection

Current stabilizers are widely used in various devices. Their schemes are simple and not so simple. But in any case, it will be better if it has overload protection. The problem that we will consider is the following, we have a voltage stabilizer with load current limitation. That is, such a stabilizer is not afraid short circuits at his exit.

But in short-circuit mode, a large amount of power will be released on the regulating transistor of such a stabilizer; this will require the use of an appropriate heat sink, which will entail an increase in the size of the device and, well, its price. Otherwise - thermal breakdown of the structure of a powerful transistor.

For example, let's take simple diagram current stabilizer on the microcircuit shown in Figure 1.

Everything is in general terms. The stabilization current, in accordance with formula 1, is 1A. Let's say the normal load resistance is 6 ohms. Then, at a current of 1A, the voltage on the microcircuit will drop equal to: U = IxR - IxRн = 12-1.25-6 = 4.75V. Accordingly, the power P = UxI = 4.75 W will be released on the microcircuit. If you close the output of the current stabilizer, then the voltage on the microcircuit will already drop 10.75V and, accordingly, the power released on the microcircuit will be equal to 10.75W. It is this power that the radiator must be designed for, then the reliability of your device will be at its best. But what to do if it is not possible to install a larger radiator? Right! It is also necessary to limit the power allocated to the chip. It is possible to install a tracking stabilizer in front of this circuit, which in the event of a short circuit would take on part of the released thermal power, but this is a bit complicated. It would be better to completely turn off the stabilizer in the event of a short circuit at its input. Knowing that power is equal to the product of current, and we set the current ourselves and it is stabilized, then we will monitor the voltage drop on the current regulator.

The circuit of an adjustable current stabilizer is taken from the article. You can read more about the operation of this adjustable current stabilizer in the article.

Operation of the over-power protection circuit

To ensure protection of the current stabilizer, we introduce only five parts into the circuit. Transistor VT1, which acts as a key and completely turns off the stabilizer during short circuit mode. A MOSFET transistor with channel P is used here. For small currents, on the order of one or two amperes, the IRFR5505 is suitable

At high currents, it is better to use a transistor with a large operating drain current and lower open channel resistance. For example - IRF4905

Thyristor optocoupler, you can use a domestic one - AOU103 with any letter, you can choose an imported one, for example - TLP747GF

Zener diode, any low-power one, read the article to the end and, if necessary, choose the one you need. R1 is a resistor through which a negative opening voltage is supplied to the key gate. R2 is a resistor that limits the current of the thyristor optocoupler LED. Yes, if the input voltage is more than 20V, then in parallel with the optocoupler thyristor it is necessary to install another 12V zener diode, which will protect the gate-source transition of the key transistor. Since most MOSFET transistors have a maximum allowable voltage of this junction of 20V.

For example, let's take the case of charging a twelve-volt battery with a stable current of 3A. When supply voltage is applied to the circuit, transistor VT1 will be open, since a negative voltage is supplied to its gate and the circuit operates in normal mode. We will not take into account the voltage drop across the switch due to its small value. Under such conditions, the power P = (20 - 12) ∙ I = 8 ∙ 3 = 24 W will drop on the current stabilizer itself. During a short circuit, the power will increase to 60W, if without protection. This is too much, and it is not safe for the VT2 transistor, so after 30W we will turn off the stabilizer by placing a zener diode with a stabilization voltage of 10V in the protection circuit. Thus, we get a circuit with protection not only from short circuits, but also from exceeding the permissible power dissipation on the current stabilizer. Let's say that for some reason, completely unnecessary to us, the load resistance begins to drop. This will cause an increase in the voltage drop across the stabilizer and, accordingly, the power dissipation on it. But as soon as the voltage between the input and output exceeds 10 volts, the zener diode VD1 will “break through” and current will flow through the LED of the optocoupler U1. The emission of the LED will open the photothyristor, which will bypass the gate-source transition of the key transistor. It will, in turn, close and turn off the stabilizer circuit. It will be possible to return the circuit to working condition either by turning off the power and reconnecting it, or by short-circuiting the photothyristor, for example with a button. Thus, by monitoring the voltage between the input and output of the current stabilizer, you can set the power limit threshold you need using zener diodes for different stabilization voltages.

This circuit is applicable to almost all stabilizers, whether for current or voltage. It can be built into a ready-made stabilizer that does not have short-circuit protection.
Good luck and good luck. K.V.Yu.