RU193830U1 - Power supply of measuring and recording equipment from a high voltage network - Google Patents

Abstract

The utility model relates to lifting equipment and can be used primarily for powering control systems and overload protection of electric hoisting machines from an industrial high voltage network. The power source of the measuring and recording equipment from the high voltage network contains a device for converting a high voltage current into a low voltage direct current. This device is an AC / DC and DC / DC converter, made in the form of a switching power supply (UPS), equipped with the first and second protective units connected respectively to its input and output. The first protective unit includes a first fuse included in the open of one of the line wires, a high-frequency interference filter, an input voltage suppression device, a rectifier, a key limiting device, and a rectified ripple voltage filter. The second protective unit includes a filter for smoothing the output voltage ripple and high-frequency interference and a device for protecting the output circuit from overload, short circuit, and unintentional connections of external power sources to it, including a second fuse that is included in the gap of one of the output wires. EFFECT: creation of a power supply with an extended range of permissible input voltages, capable of operating in a real industrial network both 220 V 50 Hz and 380 V 50 Hz, as well as in a real industrial DC network with a voltage of 220 V, and providing high-quality and trouble-free power supply measuring and recording equipment in conditions of unstable, constantly changing industrial network parameters. 4 s.p. f-ly, 8 ill.

Description

The technical field to which the utility model relates. The utility model relates to lifting equipment and can be used primarily for powering control systems and overload protection of electric hoisting machines from an industrial network of both alternating and direct current high voltage.

State of the art

The measuring and recording equipment installed at industrial facilities is powered in the vast majority of cases from the same industrial network 380 V 50 Hz, from which all industrial equipment is powered. Due to the high degree of loading of such a network, which constantly changes during operation from turning on or off a particular powerful load and with significant reactive components (inductive, capacitive), the voltage of the industrial network is constantly changing. These changes are both short-term in nature (surges and voltage dips within a fraction of a second), and long-term in nature (decrease and increase in voltage relative to the nominal value within a few seconds and up to several hours), and have an extremely adverse effect on the industrial equipment itself ( up to failure), as well as measuring and recording equipment containing sensors, sensitive elements and electronic components, which differ, along with high sensitivity to vapors Tram Measured and recorded processes are very sensitive to the parameters of its power. And those significant changes in the parameters of the industrial network that industrial equipment can withstand for measuring equipment in most cases turn out to be unacceptable: they lead not only to a distortion of the parameters of the recorded processes, but also most often to failure of the entire measuring and recording system, without which modern industrial equipment simply cannot work. And the cost of modern measuring systems is often comparable to the cost of equipment, and in some cases it can exceed it.

Typically, industrial automation devices receive power from an industrial network of three-phase alternating current with a voltage of 380 V 50 Hz. Obtaining a low voltage voltage (12-24 V) from a three-phase voltage is very attractive from the point of view of obtaining a constant voltage with a relatively low ripple due to the rectification of all three phases of the alternating voltage. However, this increases the frequency of the pulsations of the first harmonic. And the most important thing that limits the application of this method is the need to manufacture a step-down three-phase low-power transformer (50-200 W). The manufacture of such a low-power transformer is quite laborious and practically not mastered by the industry, its dimensions, as well as the cost of development and manufacture, significantly exceed the similar parameters of low-power single-phase transformers. Therefore, practically obtaining low-voltage direct voltage of low power from a three-phase voltage of 380 V 50 Hz did not find application in industry. Although schemes of this kind are known and described in the technical literature. In practice, when creating power sources for industrial automation units and safety systems of hoisting cranes, single-phase voltage is used, i.e. or one of the phases of a three-phase network, i.e. 220 V 50 Hz, or, which is especially typical for hoisting cranes, where in most cases there is no neutral fourth wire, the linear voltage of a three-phase network is used, i.e. 380 V 50 Hz, i.e. voltage between wires of any two phases.

Recently, in industry (and in household appliances) to obtain a low-voltage constant voltage (12-24 V) from a high voltage supply network, pulsed power supplies (IIPS) are widely used. They are also known in the technical literature as AC / DC and DC / DC converters or SMPS - Switch Mode Power Supply). This widespread use is due to a number of obvious advantages of IIP over conventional transformer analog power supplies (AIP).

This is, first of all, due to the conversion frequency not of 50 Hz, as in the AIP, but of tens and hundreds of kHz and even units of MHz, a significantly lower weight and dimensions of the IPS compared to the AIP due to the much smaller dimensions and weight of the transformer, a simplified half-wave rectifier circuit and dimensions of the output voltage filter.

This is also a higher efficiency (up to 90-98%) due to the fact that the main losses in the IIP are associated with transients at the moments of switching the key element. Since the key elements most of the time are in one of the stable states (i.e., either on or off), energy losses are minimal.

This is, finally, lower cost, thanks to the mass production of a unified element base and the development of key high-power transistors. In addition, it should be noted the significantly lower cost of pulse transformers with comparable transmitted power, and the possibility of using less powerful power elements, since their key operation mode.

And, of course, IIPs, at least, are not inferior to AIPs in the reliability of operation due to fairly simple protective circuit solutions for constructing various protections (from overvoltage, from overload, from overheating, from short circuit, etc.).

All these advantages of the IIP more than cover their certain disadvantages, in particular, the relatively high level of interference arising from the operation of the IIP. In cases where the equipment receiving power from the IIP works stably, this disadvantage can be ignored. In particular, microprocessor technology, when powered by an IIP, works, as a rule, steadily and without fail. Restrictions on the use of IIPs in industry appear only in equipment using analog-to-digital converters (ADCs). But even in such cases, the problem is usually solved by additional filtering of the rectified voltage.

With all these advantages, at present, with the existing level of availability of the element base for building IIPs, there are some restrictions on the construction and use of IIPs.

Almost the entire elemental base for IIPs currently allows them to be used only up to the level of the input AC voltage of 220 V + 20% = 264 V.

This limitation is due, first of all, to the fact that the capacitors of the IIP rectifier filter are electrolytic. And industry, both domestic and world, produces electrolytic capacitors for a voltage of not more than 450 V. That is, a capacitor with such an operating voltage works even at this voltage with almost no margin. In fact, with the current value of the alternating voltage of 264 V, its amplitude value reaches 372 V, and the voltage margin of the capacitor is clearly insufficient, since manufacturers usually recommend using at least twice the voltage margin for these capacitors. But in order to obtain a twofold margin, it is necessary to have a capacitor with an operating voltage of more than 744 V, but really not less than 1000-1200 V. To obtain a capacitor with such an operating voltage, two or more identical capacitors must be connected in series, with the resulting capacitance the capacitor will be n times smaller, where n is the number of capacitors. To equalize the voltages on the capacitors, they have to be shunted with resistors, which also negatively affects their characteristics. That is, the scheme becomes more complicated, becomes more expensive, and additional losses occur. If you create an IIP with a nominal input operating voltage of 380 V, then the problem is only further greatly complicated.

The second problem is related to the operating voltage of the key element. If at an input voltage of 220 V in the IIP a key element should be used (as a rule, this is a MOSFET transistor) with an operating voltage of at least 700-900 V, then at an input voltage of 380 V (and taking into account tolerances this can be 500 V or more ) the key element must remain operational up to voltages of 1500 V or more. At present, the industry practically does not produce key elements with such voltage, and what is produced, firstly, has a very high cost, and secondly, high-voltage key elements have increased internal resistance in the open state (1-3 Ohms), which leads to additional power losses, reduced efficiency and increased heating of the key element with all the ensuing consequences.

These problems have led to the fact that at present the industry produces almost exclusively IIPs for operation on a 220 V network. For operation on a 380 V network, single IIPs are produced, they have a very high price, are issued only for street LED lighting, and create significant interference output and have mediocre characteristics for most IIP parameters. At the same time, as indicated above, there is a problem of supplying industrial automation devices from an industrial network voltage of 380 V 50 Hz, where 220 V is absent and its receipt is associated with significant technical difficulties.

Known in particular is the flyback IIP, which includes a rectifier, a filter for smoothing the ripple of the rectified voltage, a key device on the MOSFET transistor IRF30BQ040, a PWM controller on a MAX5052 chip (PWM - pulse-width modulation (PWM) - the control process energy transfer using pulsed on and off method)), a transformer, a low voltage rectifier and a capacitive filter for smoothing rectified voltage ripples (Mack R. Switching power supplies. Theoretical design basis and a guide for practical use / Transl. from English - M.,: Dodeka-XXI Publishing House, 2008. - 272 pp., ill. (Power Electronics Series), pp. 111-118).

This IIP is intended for operation from a network with a voltage of 100-240 V, for supplying a load with a current of 1 A with a stabilized output voltage of 12 V ± 0.2 V. The ripple level is not more than 100 mV. This is a universal power source, typical for a large number of equipment powered by a 220 V household AC network.

However, this device cannot operate from an industrial AC network with a voltage of 380 V 50 Hz. And even more so, it cannot work in such a network in case of changes in the voltage in it, either downward or upward. It lacks: a voltage surge suppression device and a high-frequency (HF) input filter, safety devices (against overload, short circuit, overheating, etc.), the ripple smoothing filter contains only capacitors, and there is no high-frequency noise filter output, there is no voltage indicator of the output circuit.

Closest to the proposed utility model, the set of essential features is a power source for measuring and recording equipment from a high-voltage alternating current network, comprising a device for converting high-voltage alternating current to low-voltage direct current, including a step-down transformer, a rectifier, and a first electric filter for smoothing ripple at the output of the rectifier, a parametric stabilizer made on a zener diode and transistor, and a second electric filter to smooth out ripples at the output of the parametric stabilizer. The primary winding of the transformer is connected to the AC mains, and the secondary winding is connected to the rectifier, from the output of which the rectified ripple voltage is supplied to the first electric filter and from it to the input of the parametric stabilizer, from the output of which voltage is supplied to the second electric filter and then to load (MA Shustov. Practical circuitry.) Book 2. “Power supplies and stabilizers. 2nd ed., eras. - M.: Dodeka-XXI Publishing House, Altex, 2007, p. 72- 73).

This device is a general-purpose direct current source that provides a load with a stabilized voltage during fluctuations in the AC network that meets generally accepted standards (from -15 to + 10% relative to the nominal value of 220 or 380 V). There is no evidence to refute this claim in the description. A typical stabilizer circuit is designed to maintain a stable output voltage with minor fluctuations in the supply voltage. However, even a home network often gives significantly large deviations from the nominal, which lead to failure and failure of the power source. If we talk about an industrial network, where the power consumed by many machines, mechanisms, lifting devices exceeds tens and hundreds of kW, and these mechanisms do not work constantly, but turn on and off unpredictably, they change the operating mode and power consumption, where they act as the load significant reactive elements (capacitance, inductance), then under such conditions the described circuit of the power supply will work inefficiently, it will not be able to provide the accuracy necessary for measuring equipment Nia output voltage, its stability and low ripple output voltage variable component. And with significant changes in the voltage of the supply network, the current flowing through the zener diode will exceed the value acceptable for the selected zener diode, as a result of which the zener diode, and after it the transistor, will fail. Similarly, with significant increases in input voltage, a step-down transformer may fail due to breakdown of insulation and inter-turn circuit in the primary or secondary windings. That is, this device does not contain any measures and circuit solutions to combat significant input voltage spikes. But the stabilizer itself cannot cope with this problem.

The known device is also not able to fully perform its functions and with significant drops in the input voltage. The range of permissible currents flowing through the zener diode is small. As a rule, at a zener diode, the ratio of the maximum stabilization current to the minimum current does not exceed 20-30. This at 24 V of the rated voltage at the output of the power supply allows this device to efficiently perform the stabilization task when the input voltage changes from 28 to 42 V, which corresponds to the voltage range of the mains 310-140 V (at a nominal value of 380 V), i.e. 380 ± 20%. This range is clearly insufficient for equipment powered by a real industrial network, in which voltage changes are much larger. The real network of an industrial enterprise can produce at a nominal value of 380 V minimum voltages of 270-290 V and maximum 560-580 V, and these are not short-term pulses with a duration of tens of microseconds, but rather long-term changes that can last from hundreds of milliseconds to tens of minutes or even up to several hours.

The known device also does not contain solutions to combat short-term pulse emissions, which are almost always present in the industrial network due to frequent switching on and off of industrial equipment. It also does not contain circuitry to protect against overloads and short circuits in the load.

In addition, in the conditions of the workshop, erroneous unintentional connections to the output of this device of other voltage sources are possible, which can also lead to the failure of this device and an emergency in the workshop.

And finally, working with such a device and its diagnostics are really difficult due to the lack of any indication of the normal functioning of the device.

Disclosure of a utility model The task to which the proposed utility model is directed is to create a power supply with an expanded range of permissible input voltages, capable of operating in a real industrial network, both 220 V 50 Hz and 380 V 50 Hz, as well as in a real industrial network current voltage of 220 V without forced switching of its operating mode, and providing high-quality and trouble-free power supply of measuring and recording equipment in conditions of unstable, constantly me schihsya industrial network parameters when containing both short and long term voltage deviation from the nominal value, and with a power supply protected against unintentional connection to the output of the voltage source in the forward or reverse polarity from other external power sources.

An additional problem, which the proposed utility model is aimed at, is the creation of a power source for measuring and recording equipment with the possibility of primary diagnostics of this source in the place of its installation.

The stated technical problems are solved by the fact that in the power supply of the measuring and recording equipment from the high voltage network containing a device for converting a high voltage current into a direct current of low voltage, according to a utility model, said device is an AC / DC and DC / DC converter made in the form of a switching power supply (UPS), equipped with the first and second protective blocks connected respectively to its input and output, while the first protective block includes the first fuse included in the breakdown of one of the line wires, a high-frequency interference filter, an input voltage suppression device, a rectifier, a key limiting device and a rectified ripple voltage filter, and the second protective unit includes a filter for smoothing the output voltage and high-frequency noise ripples and a protection device output circuit from overload, short circuit and inadvertent connections of external power sources to it, including the second one will protect spruce included in the gap of one of the output wires.

The achievement of the technical result is also facilitated by the private essential features of the utility model.

In the first protective unit, the high-frequency interference filter and the input voltage emission suppression device are combined into a single unit containing resistors common to the filter and this device.

Preferably, the high-frequency interference filter at the input of the power supply and the input voltage surge suppression device are multi-stage.

The protective blocks are made with indicators of input and output voltage.

The indicated indicators are made on LEDs.

The essence of the utility model is as follows.

The presence of an AC / DC and DC / DC converter, made in the form of a UPS, allows the use of domestic and foreign UPSs commercially available from industry, which can overwhelmingly operate as AC 220 V 50 Hz (90-264 V) in the power supply. , and from a network of direct (pulsating) current voltage of 220 V (127-370 V), since they include a rectifier at the input, which rectifies the input high alternating voltage (turns it into a pulsating voltage) and passes through it almost without loss Constant high voltage. This greatly simplifies the implementation of this power source and reduces its cost.

The first fuse in the first protective block, included in the break of one of the line wires, allows you to protect both the first protective block and the UPS, and the second protective block, both from possible overloads, short circuits in the power supply and the load, and from possible large voltage surges in the industrial network.

The introduction of a high-frequency interference filter at the input of the power source into the first protective unit provides suppression of interference coming to the source from the power supply network and from neighboring units of industrial equipment operating in the workshop and powered by switching power supplies. This filter protects the electronic load blocks and measuring circuits of the sensors from failures and errors in operation. At the same time, the input voltage surge suppression device suppresses powerful impulse noise coming to the power supply from the mains and from neighboring units of industrial equipment operating in the workshop, and also protects all power supply units from failure and damage from interference energy, and even electronic load units.

The introduction of a rectifier into the first protective unit allows, in the case of an alternating high input voltage, to obtain a constant (ripple) voltage at the rectifier output, which can significantly simplify the circuit of a key limiting device and increase the reliability and accuracy of its operation. In the case of a constant high input voltage, the rectifier simply passes it through itself with negligible losses.

Introduction to the composition of the first protective device of the key limiting device allows us to solve the main problem - to normalize the input voltage, i.e. bring its effective value, which in the network is 380 V 50 Hz (the actual range of variation of the effective values of the alternating voltage 280-560 V) can vary from 480 V to 970 V (rectified ripple voltage) to a level not exceeding the maximum allowable input value DC voltage of the UPS (370 V).

The inclusion of a rectified ripple voltage filter in the first protective device allows obtaining a continuous ripple voltage from the voltage at the output of the key limiting device, i.e. voltage without breaks and gaps. This is necessary to ensure stable and reliable operation of the UPS.

The inclusion in the composition of the second protective block of the filter of smoothing the output voltage ripples and high-frequency noise allows to reduce high-frequency ripples - the result of the UPS, the main operating frequency of the conversion of which can lie in the range from ≈ 50 kHz to several MHz, and make it possible to work powered by electronic equipment . Some of the existing industrial UPSs include such filters at the output, but for the most part these filters are very simple, cheap and suitable only for very unpretentious household applications, such as household appliances, kitchen appliances, LED lighting, etc.

Introduction to the second protective unit of the device for protecting the output circuit against overload, short circuit and inadvertent connections of external power sources to it, including a second fuse included in the break of one of the output wires, can improve the reliability and reliability of the power source in adverse industrial conditions production.

The combination in the first protective block of the high-frequency noise filter and the input voltage emission suppression device into a single unit containing resistors common to this device and filter allows the filter to be more compact and stable as to each of the individual factors (interference, surge, failure ), and to their combined effect.

The implementation in the first protective block of a high-frequency interference filter and a device for suppressing input voltage emissions by multi-link (multi-stage), increases the efficiency of this filter, and also increases the reliability and stability of powerful interference suppression, since the interference energy is distributed between all parts of the filter, i.e. only one part of the total interference energy acts on one filter element.

The implementation of the first and second protective devices with indicators of the input and output voltage on the LEDs, respectively, provides the ability to visually determine the operability of the power source and, if necessary, accelerate the diagnosis of faults and localize these faults.

The technical result from the use of this utility model is to create a power source with an extended range of permissible input voltages, capable of working in a real industrial network of both 220 V 50 Hz and 380 V 50 Hz, as well as in a real industrial DC network with a voltage of 220 V, and providing high-quality and trouble-free power supply to the measuring and recording equipment in the conditions of unstable, constantly changing parameters of the industrial network.

The following description of the proposed power source and the accompanying drawings are intended only to illustrate the utility model and in no way limit the scope of the utility model formula.

A brief description of the drawings. In FIG. 1 is a functional diagram of one example of a proposed power supply; in FIG. 2 - input voltage emission suppression device with an RFI filter; in FIG. 3 - rectifier; in FIG. 4 is a key limiting device and a rectified ripple voltage filter; in FIG. 5 and 6 - changes in the values of the ripple voltage at the input to the key limiting device, at its output and at the output of the filter of the rectified ripple voltage when the value of the voltage at the input to the key limiting device, respectively, is lower than its threshold and exceeds its threshold; in FIG. 7 - filter smoothing ripple output voltage and high-frequency interference; in FIG. 8 - device for protecting the output circuit from overload, short circuit and connections of external power sources. In the figures shown, the same elements are denoted by the same positions.

Utility Model Implementation

The power source of the measuring and recording equipment, for example, a load limiter of a bridge-type crane (hereinafter referred to as the limiter) from an industrial alternating current network of 380 V 50 Hz, contains a high voltage to DC low voltage converter 24 V, made in the form of UPS 1, equipped with the first and second protective devices 2 and 3 connected respectively to the input and output of UPS 1.

The first protective device 2 includes a fuse 4, included in the breakdown of one of the line wires, an input voltage emission suppression device 5 combined with a high-frequency interference filter 6, a rectifier 7, a key limiting device 8, and a rectified ripple voltage filter 9.

The second protective device 3 includes a filter 10 to smooth out the ripple of the output voltage and high-frequency interference and a device 11 for protecting the output circuit from overload, short circuit, and inadvertent connections of external power sources to it, including a fuse 12, included in the gap of one of the output wires .

The protective devices 2 and 3 are equipped with indicators 13 and 14 of the input and output voltage of the power supply, respectively, made on the LEDs.

One of the possible embodiments of the input voltage surge suppression device 5 with a high-frequency interference filter 6, made in the form of a combined 4-stage assembly, is shown in FIG. 2. Generally speaking, the input voltage emission suppression device 5 and the high-frequency interference filter 6 are different devices made on different radio elements. The input voltage surge suppressor may be implemented on one or more gas arresters. In particular, as shown in FIG. 2, it is made on two gas arresters 15 and 16, a varistor 17 and three protective symmetrical diodes 18, 19 and 20, connected in series to ensure operation with a high voltage pulse (more than 800-900 V) and in parallel with resistors 21, 22 and 23 , equalizing the voltage across the diodes, and separated by resistors 24-27 to bring together the moments of operation of these elements. The high-frequency interference filter 6 consists of ceramic or film capacitors 28-31 of various capacities (0.1-0.01 microfarads), also separated by resistors 24-27 for the separation of the cutoff frequencies of the individual filter steps. That is, the voltage surge suppression device 5 and the high-frequency interference filter 6 combine the fact that they are generally multi-stage for reliability and increase their functionality, preferably including up to 4 stages. And these steps for the voltage surge suppression device and for the filter are separated by resistors. Those. the same resistor can act as a stage separator, an interference filter and a delay for a voltage surge suppression device. Therefore, the resistors of these devices are the same, and the capacitors of the filter stages are connected in parallel with the elements of the emission control device. Two gas arresters 15 and 16 are used here for greater reliability and stability of the suppression of powerful interference.

The rectifier 7 is made on a traditional diode bridge. In each arm of the bridge, two diodes are connected in series to increase reliability with significant surges in supply voltage.

The key restriction device 8 shown in FIG. 4 (it can also be called a voltage normalizer), is performed on a MOSFET transistor 32, which operates as a low-frequency (100 Hz) switch and comparator, which sets a given level of high-voltage output (in our case, 370 V). The comparator is built using a combination of an NPN transistor 33 and a zener diode 34 and includes a voltage divider across the resistors 35 and 36, a zener diode 37 and a protective diode 38 to limit the level of the control signal supplied to the gate of the MOSFET transistor 32, control resistors 39 and 40 the gate signal of the MOSFET transistor 32, as well as two protective diodes 41 and 42, connected in series to increase the level of protection operation. In parallel to the protective diodes, resistors 43 and 44 are included to equalize the voltages at each of the protective diodes.

The rectified ripple voltage filter 9, also shown in FIG. 4, is made on two series-connected electrolytic capacitors 45 and 46. Serial connection is made to increase the level and expand the range of operating voltages of the power source.

The filter 10 for smoothing the ripple of the output voltage and RF interference, shown in FIG. 7, this is a traditional three-link resistive-capacitive filter, consisting of two electrolytic capacitors 47 and 48 and one ceramic capacitor 49, interconnected by resistors 50-52. Here, a combination of electrolytic capacitors 47 and 48 with a ceramic capacitor 49 is used, since such a combination extends the effective filtering band. It is known that electrolytic capacitors filter well lower frequency ripples, especially mains ripples of 50 and 100 Hz, and ceramic capacitors better filter higher frequency noise. After the rectifier 7, the ripple has a value equal to the amplitude of the rectified voltage. After filter 10, the ripple amplitude decreases to 100-300 mV, depending on the values of the capacities included in the filter. This level of ripple is quite acceptable for microprocessor technology.

The output of the filter 10 to smooth out the ripple of the output voltage and RF interference is connected to the input of the device 11 for protecting the output circuit from overload, short circuit, and unintended connections to it of external power sources of the device. Its circuit is shown in FIG. 8. Diodes 53 and 54 are designed to protect the low-voltage output circuit of the UPS from possible overvoltages in the load. Diodes 55-58 and fuse 12 protect the low-voltage output circuit of the UPS from possible overvoltages in the load and from inadvertent connections of external power sources in the polarity opposite to this power source. If the voltage of an external power source in reverse polarity is accidentally connected to the output of the power source, the diodes 55-58 in this connection do not represent any resistance for it, the current caused by this external source will flow through them. Current will flow through diodes 55-58 and fuse 12. This circuit actually creates a short circuit for the external source, as a result of which the fuse 12 will trip, break the circuit and thereby protect the power supply circuit from undesirable external influences.

The structural design of the converter of high voltage to direct current low voltage 24 V, made in the form of UPS 1, is not the subject of this utility model. As this converter can be used, for example, UPS series LPV-60 company Mean Well (China), a block diagram of which is shown, in particular, on the website http://www.mean-well.ru/uploads/files/datasheets /LPV-60-24.pdf, or any other that can work both from an alternating 90-264 V 50 Hz, and from a direct network voltage of 127-370 V.

The LPV-60 series UPS contains at its input a high-frequency (RF) interference filter (EMI FILTER), a rectifier (RECTIFIERS), a key device (POWER SWITCHING), a transformer, a low-voltage rectifier (RECTIFIERS), and a filter for smoothing out rippled low-voltage ripples (FILTER). It also includes an overvoltage protection device (OVP - Over Voltage Protection - overvoltage protection), overload protection (DETECTION CIRCUIT - current detection and OLP - Over Load Protection - overload protection), as well as optocouplers for galvanic isolation between input and output.

This UPS is designed to operate from a household AC network with a frequency of 47-63 Hz with a voltage of 90-264 V, from a constant or pulsating voltage of 127-370 V. At the output of the unit, depending on its design, the voltage is 5 V, 12 V, 15 V, 24 V, 36 V or 48 V. The power given to the load is 40 W at 5 V and 60 W for other output voltage values. The output voltage is maintained with an accuracy of ± 8% at 5 V and with an accuracy of ± 5% for other values of the output voltages. The ripple level at the output is from 80 mV at 5 V to 150 mV at 48 V, which is quite acceptable for microprocessor technology. Overvoltage protection and overload protection are automatically turned off and put the UPS in working condition after the disappearance of the conditions that caused its operation. The efficiency of the device is from 76 to 86%, depending on the level of output voltage.

There are many known fuse designs. The simplest and most effective are self-healing and fuses. Resettable fuses are convenient in that they themselves repair a broken circuit after removing overload conditions. However, they have very large variations in the magnitude of the response current and, in addition, a significant delay in the response time, which can reach units of seconds. Fuses require replacement after operation and also have some variation in the conditions of operation, however, the parameters of their operation at the current level of development of fuse technology are much higher and more accurate than self-healing fuses. In addition, the phenomenon of “aging in time” and as a result of repeated tripping is inherent in self-healing fuses. For these reasons, fuses are more preferable for devices operating from an unstable network.

Structurally, the power supply is made in a separate metal case, equipped with a lid with a seal to protect the cavity of the body from external influences. UPS 1 and a printed circuit board are installed in the case, on which the assemblies of both protective devices 2 and 3 are mounted. Connectors are installed on the case for powering other limiter nodes and exchanging information signals between these nodes, as well as for transmitting information and command signals from the limiter control device to other peripheral nodes of the crane. On the front surface of the housing there are two LED indicators 13 and 14.

The design of the limiter is not the subject of this utility model. The limiter contains a control device installed in the crane cabin, a strain gauge force sensor installed in the hinge node of the hook suspension, and a combined communication line between the force sensor and the control device.

The power source of the measuring and recording equipment from the AC network operates as follows.

The alternating voltage of the supply network 380 V 50 Hz (for all possible voltage fluctuations of a real industrial network from 90 to 560 V) is supplied through a fuse 4 to the input of the voltage surge suppression device 5, combined with a filter 6 of the input high-frequency interference. The gas spark gap 15 (16) has the longest delay time, but at the same time absorbs the largest part of the ejection energy, varistor 17 has a slightly lower response delay, but is also able to absorb less energy, protective diodes 18-20 have the shortest delay time and are the first to operate , but they are also able to suppress a relatively small part of the emission energy. Resistors 24-27 will make it possible to bring the operation of these elements closer in time, to suppress the surge most efficiently and with the least losses for this device.

The voltage from the output of the voltage surge suppression device 5, combined with the filter 6 of the input high-frequency noise, is supplied to the rectifier 7. The voltage from the outputs of the rectifier 7 is supplied to the key safety device 8, which is essentially a voltage regulator, i.e. a device that brings the input voltage with wide ranges of variation (in our case it is 90-560 V) to the levels available for further conversions by other devices (in our case it is UPS 1) with a range of input constant (pulsating) voltages of 120-370 V, to the constant voltage necessary for the measuring equipment (24, 12, 5 V, etc.). The shape of the rectified ripple voltage supplied to this normalizer is shown in FIG. 5 under the inscription “Input” for the case when this voltage is less than the threshold value for UPS 1 (370 V) and in FIG. 6 for the case when this voltage is greater than the threshold value for UPS 1 (370 V).

As long as the input ripple voltage level is below the threshold value of 370 V, the voltage at point A (the junction of the resistors 35 and 36 of the voltage divider and the zener diode 34) is lower than the threshold level of the zener diode 34 - 6.3 V, the transistor 33 is closed, the current through it does not flow, on the collector of it, due to the presence of resistor 40, a high voltage of 15 V, which is limited by the zener diode 37 and the protective diode 38, is applied to the gate of the MOSFET transistor and ensures its open state and low internal resistance An ode to drain source, as a result of which an input high voltage with a level of <370 V is applied to a rectified ripple voltage filter 9, consisting of electrolytic capacitors 45 and 46, charges them and ensures stable operation of UPS 1 following the filter 9.

If the input voltage to the key limiter 8 exceeds a level of 370 V, as shown in FIG. 6 on the graph on the left, the voltage at point A becomes higher than 6.3 V. In this case, the zener diode 34 opens, current flows through the base of the transistor 33, as a result, the transistor 33 also opens, the voltage at its collector, at the zener diode 37 and, therefore, at the gate of the MOSFET transistor 32 drops to the level of shutting off its drain-source transition. The MOSFET transistor 32 closes and does not pass current through itself and the voltage at the output of the key limiting device 8 drops to zero, as shown in the middle graph of FIG. 6 (assuming no filter 9). But the output of the key limiting device 8 is connected to the filter 9 of the rectified ripple voltage, which is less than 370 V, the filter capacitors 45 and 46 are not charged, but only a discharge is provided to ensure the operation of UPS 1. The voltage graph at the output of filter 9 for the case when the voltage at the input to the key limiting device 8 exceeds 370 V, is shown in the right graph of FIG. 6. Thus, the key restriction device 8 freely passes through itself a pulsating voltage lower than the threshold level of 370 V (less than the upper allowable limit for UPS 1) and limits the level <370 V of the voltage at the input to the UPS 1 when the input of the key restriction device 8 becomes more than this level.

A low rectified voltage of 24 V from the outputs of UPS 1 is supplied to the filter 10 to smooth out the ripple of the output voltage and RF interference of UPS 1, and the device 11 protects the output circuit and fuse 12 from short circuit and unintended connections to it of external power sources.

The main circuit of the proposed power source is described above. It produces a stabilized voltage of 24 V. However, other voltages are required to power microprocessors, electronic circuits, and limiter sensors. Microprocessors and electronic circuits usually require 5 and 3.3 V. For load cells, in particular, a very high-quality stabilized voltage of 10 V. is required. Separate blocks and nodes of the limiter are located in different places at a sufficiently large (several and tens of meters) distance. Therefore, it is extremely undesirable to generate all these voltages in one power source, because when transmitting small voltages over considerable distances, noticeable losses in the resistance of the connecting cables occur. In addition, low voltages are more susceptible to interference and disturbances inherent in any electric lifting machine. Therefore, it is advisable to distribute a relatively high voltage of 24 V from the power supply to the blocks and nodes of the limiter through the cables, which will give less and less interference. And already in each block and node specifically form from this voltage the other voltages necessary there: 10 V, 5 V, 3.3 V. Then these voltages will be less susceptible to disturbances and disturbances, and all blocks of the limiter will receive a high-quality stabilized voltage.

In particular, to power the microprocessor of the limiter control device and electronic circuits, a linear voltage stabilizer can be used, the input of which is supplied with 24 V DC, and the voltage of 5 and 3.3 V is removed from the outputs of the linear stabilizer.

To power the limiter strain gauge, you can use a precision voltage stabilizer with a power amplifier on the transistor and a precision voltage reference source, equipped with a filter to smooth out the ripple of the rectified voltage. At the same time, 24 V DC voltage is supplied to the input of a precision voltage stabilizer, and 10 V DC is removed from the filter output.

The distributed structure of the proposed power source, in which the primary conversion of the high alternating voltage of the supply industrial network to an intermediate value of constant stabilized voltage is carried out in a separate independent unit, the casing of which can be mounted on the construction of an electric crane outside its cabin, eliminates the possibility of a crane operator being struck by high voltage and other maintenance personnel, and ensures the transfer of this intermediate stabilizer th e voltage connecting cables to other individual blocks limiter with further conversion of this intermediate voltage in each of the blocks into a voltage with parameters necessary and sufficient for the operation of the unit.

Industrial applicability The declared source of power supply for measuring and recording equipment from alternating current can be manufactured industrially at an instrument-making enterprise using modern electronic components and technologies.

Claims (5)

1. The power supply of the measuring and recording equipment from the high voltage network, comprising a device for converting a high voltage current into a direct current of low voltage, characterized in that said device is an AC / DC and DC / DC converter made in the form of a switching power supply ( UPS), equipped with the first and second protective blocks connected respectively to its input and output, while the first protective block includes a first fuse included in the gap of one of wires, a high-frequency interference filter, an input voltage suppression device, a rectifier, a key limiting device and a rectified ripple voltage filter, and the second protective unit includes a filter for smoothing the output voltage and high-frequency noise ripples and a device for protecting the output circuit from overload, short circuit and inadvertent connections to it of external power sources, including a second fuse, included in the gap of one of the output wires. 2. The power supply according to claim 1, characterized in that in the first protective unit, the high-frequency interference filter and the input voltage emission suppression device are combined into a single unit containing resistors common to the filter and this device. 3. The power source according to claim 2, characterized in that the high-frequency interference filter and the input voltage emission suppression device are multi-stage. 4. The power source according to claim 1, characterized in that the protective blocks are made with indicators of input and output voltage. 5. The power source according to claim 4, characterized in that said indicators are made on LEDs.

Images