ORGANIZATION OF POWER SUPPLY FOR AUTOMATION AND TELEMECHANICS DEVICES
 

ORGANIZATION OF POWER SUPPLY FOR AUTOMATION AND TELEMECHANICS DEVICES

Requirements for power supplies for automation and remote control devices

Signaling devices are electrical devices that require electricity to operate. To ensure uninterrupted operation of signaling devices, it is necessary to organize their continuous power supply, and the quality (parameters) of electricity must comply with established standards and technical conditions for specific devices.



According to the Electrical Installation Rules [37], all consumers of electricity (power consumers), depending on the requirements for power supply, are divided into three categories. Category I includes consumers whose power supply failure can lead to an emergency, disruption of technological processes, create a threat to human life, or cause significant economic damage. Category I receivers must be supplied with electricity from two independent sources (independent sources are called sources of electricity, the termination of one of which does not lead to preferential action of the other). A break in the power supply can only be allowed for the duration of the automatic transition from the main power supply system to the backup one, which should not exceed 1.3 s.

In accordance with the PTE, power supply devices must provide reliable power to signaling devices as consumers of category I electrical energy.

Electrical centralization posts for stations with more than 30 switches and traffic control centers are allocated to a special group of category I. Receivers of a special group of category I must be supplied with electricity from three independent sources, and for some devices that directly ensure the safety of train traffic (relay circuits of electrical centralization, track circuits, entrance traffic lights, etc.) interruptions in the power supply are generally unacceptable.

Organization of power supply for ZhAT devices

The sources of electrical energy necessary for the operation of any electrical devices, including railway transport facilities, are power plants (thermal, hydro, nuclear) integrated into a unified energy system (UES). The transmission of electricity to consumers located at a considerable distance from the sources is carried out via power transmission lines (PTL). To reduce electrical losses in power lines, electricity is transmitted over distances at high voltage. Transformer substations are used to increase and decrease voltage.

The power supply system for railway transport is an integral part of the Unified Energy System. The power supply lines are divided into separate sections - power arms are usually no more than 50 km long. Electricity is supplied to each power arm from two sides - from two mutually redundant power points (PP). Traction substations are used as power points in electrified areas, and district substations in non-electrified areas. If the length of the supply arm exceeds 50 km, then a sectioning point is switched on in the middle of the arm, dividing the section into two half-arms. In normal mode, each half-arm is supplied with power from its “own” power point, and when one of the PPs is disconnected, the entire arm is connected to the second.

According to the PTE, the rated alternating current voltage on signaling devices should be 110, 220 or 380 V. Deviations from the specified rated voltage values are allowed in the direction of decrease of no more than 10%, and in the direction of increase - no more than 5%.

The basic requirements for the power supply system of signaling devices are as follows: do not allow deviations of voltage values in electrical networks from the established standards; if necessary, ensure automatic switching of power from the main source to the backup one; ensure shutdown completely or in sections of power supply lines for repair work.

For the principles of organizing power supply for distillation and station signaling devices, see [4,29]. The main source of power supply for automation and telemechanics devices are high-voltage signaling lines (VSL SCB), constructed along the railway tracks, with a voltage of 6 or 10 kV. Electricity from the VSL signaling system is supplied to consumers through step-down linear transformers.

Each signal point (signal installation) of automatic blocking must be supplied with power from two sources - the main and backup. There are two power supply systems for automatic blocking devices - alternating current and mixed.

With an alternating current system, which is the main one for Russian railways, automatic blocking devices receive main and backup power from high-voltage lines. The following are used as a backup power source: in areas with autonomous traction and DC electric traction - high-voltage longitudinal power supply lines (OHL PE) with a voltage of 10 kV; in areas with alternating current electric traction - wires of the two-wire-relay (DPR) system with a voltage of 27.5 kV or a PE overhead line with a voltage of 35 kV. Electricity from backup lines is supplied to consumers through step-down linear transformers or complete transformer substations.

With a mixed system, the relay circuits of the auto-blocking signal installations receive power from the VSL signaling system, and the track circuits - from local batteries, which are also a backup power source for the relay circuits. During new design and construction, a mixed automatic blocking power supply system is not used, since the process of technical operation of batteries located at signal points requires significant resource consumption.

The power supply of automatic crossing alarm devices is carried out according to the power supply circuit of automatic blocking devices with a mandatory third source (with an alternating current power system) - a rechargeable battery.

Electric centralization devices are powered from two (at stations with up to 30 switches) or three (at stations with more than 30 switches) independent sources. In the latter case, a local power plant is used as a third source. There are two power supply systems for EC devices—battery-free and battery-powered.

In a battery-free system, which is the main one for stations of the railway network, the main objects (traffic lights, switch electric drives, track circuits) are powered by alternating current directly from the network or through rectifiers (frequency converters). To avoid short-term interruptions in the operation of EC devices when switching power from the main source to the backup one and back, a control battery is used. The same battery is used as a backup power source for relay circuits and scoreboard lamps when all AC sources are turned off. Redundant power supply for the red and invitation lights of the entrance traffic lights is carried out from rechargeable batteries installed in battery cabinets at the entrance traffic lights.

With a battery system, two batteries are installed - a working one, intended for backup power supply of turnout electric drives and turnout control circuits, and a control one. During new design and construction, the battery power supply system for EC devices is not used.

Structurally, power supply devices at EC posts are power supply units (EPU), equipped with standard panels for various purposes. EPUs include devices for input, conversion, regulation, distribution and ensuring uninterrupted supply of various AC and DC voltages.

To back up the power supply to signaling devices, automated diesel generator sets of the types TsGA-12M, DGA-24M, DGA-48M, DGA-100 and E-8R, 2E-16AZ are used as local power plants (the number after the hyphen means output power in kW).

The DGA includes a diesel generator, a diesel generator control panel ShchDGA, an auxiliary automation panel ShchAV, as well as auxiliary equipment - fuel and oil tanks, fuel pumps, batteries, a battery charging cabinet ShZB, ventilation and heating devices.

DGAs produce three-phase alternating voltage 380 V with a frequency of 50 Hz. The generators are equipped with self-excitation and automatic voltage control system equipment, which ensures accuracy of maintaining voltage within ±2% of the average regulated value. Generators allow 10% power overload for 1 hour at rated voltage and power factor. The guaranteed motor life of the DHA is up to 4000 hours.

There are two ways to start the diesel generator: remote (by a telecontrol signal or by pressing the “Start” button on the control panel) and automatic (when the external network voltage disappears or decreases, during an emergency stop of another previously operating unit and when the room temperature drops to +8 °C - start-up for self-heating). There are two ways to stop the diesel generator - normal (when the unit is stopped remotely, the external network voltage appears and the room temperature rises to +20 °C, if the diesel generator was turned on for self-heating) and emergency (when overload protection devices are triggered).

In recent years, new diesel generator stations have been used as backup power sources: DGS of the “President-Neva” type (developed by the President-Neva Energy Center, St. Petersburg, Russia), for example, AD48-T400, AD60-T400 , AD 100—T400 with a rated power of 48, respectively; 60; 100 kW, generating three-phase alternating voltage 400/230 V with a frequency of 50 Hz, as well as diesel power plants produced by Gen Set (Italy) and FG Wilson (UK).

Operation principles and operation of batteries

A chemical current source (CHS) is a device that converts the chemical energy of active substances into electrical energy. The main elements of the HIT are two electrodes and an electrolyte placed in a housing. When the active substances of the electrodes and the electrolyte interact (electrochemical reaction), one electrode receives a positive potential, the other - a negative one. When a load is connected to the electrodes, due to the potential difference, a constant electric current flows in the load. This process is called HIT discharge. HITs are divided into two types - primary (single use) and secondary (reusable). In primary HITs, the active substances of the electrodes and electrolyte, consumed during the discharge, are not restored, in secondary HITs they are restored. To restore active substances, a direct current source is connected to the electrodes; this process is called a HIT charge.

A battery is a secondary HIT that has the ability to accumulate (accumulate) electrical energy and transfer it to the load. A series connection of several batteries is called a battery.

Depending on the composition of the electrolyte, batteries are divided into acid (the names “lead-acid” or “lead-acid” are also used) and alkaline. Acid batteries have a higher efficiency and less voltage drop during discharge, while alkaline batteries have higher mechanical strength. Therefore, acid batteries are mainly used as stationary power sources for signaling devices, while alkaline batteries can be used as portable or temporary sources.

Rechargeable batteries (batteries) are used as backup power sources for electrical center equipment (in power supply installations at electrical center posts), automatic crossing signaling devices, control equipment for entrance traffic lights at stations, DC track circuits, as well as for starting diesel generator sets (starter batteries). The Department of Automation and Telemechanics of JSC Russian Railways has approved the following types of batteries for use in power supply devices of signaling equipment: acid ABN-72, SSAP-76, SKZ-SK14, OP, OPSE, OpzS, VE (VE type batteries - only with PR2 type panels -ETs, PVP1-ETSK, PVV-ETs power supply units); alkaline nickel-cadmium KPL 70Р, 5KPL 70Р. The operational and technical characteristics of batteries are given in [4,17,29].

The principle of operation of an acid battery is shown in Fig. 4.1 [4, 29]. The active substances participating in the electrochemical reaction are: on the positive electrode - lead oxide PbO2 (dark brown); on the negative electrode - sponge lead Pb (gray); electrolyte - aqueous (H20) solution of sulfuric acid H2SO4. In an aqueous solution, sulfuric acid molecules disintegrate into positively charged hydrogen ions 2H+ and negatively charged ions of the acidic residue S042-. When a load g is connected, the battery begins to discharge, and a discharge current /p flows through the load (Fig. 4.1, a). During the discharge process, due to the interaction of sulfuric acid with the active masses of the electrodes, molecules of lead sulfate PbS04 (on the electrodes) and water are formed. In this case, the density of the electrolyte decreases. During a deep discharge, lead sulfate turns into a solid, coarse-crystalline salt, which is poorly restored when charged. Therefore, if the electrolyte density has reached 1.15-1.17 g/cm3, the battery should not be discharged further.

To charge the battery, it is connected to a DC source (Fig. 4.1, b). During the charging process, under the influence of charging current /3, lead is reduced on the negative electrode, and lead oxidation is reduced on the positive electrode. In this case, additional molecules of sulfuric acid are formed. The electrolyte density increases. When the electrolyte density reaches 1.20-1.24 g/cm3 (depending on the type of battery), the process of recovery of active substances stops, and further exposure to charging current can cause the decomposition of water into oxygen and hydrogen, when mixed, an explosive mixture is formed (“explosive gas"). Therefore, if there are signs of electrolyte “boiling” (formation of oxygen and hydrogen bubbles), the battery charge must be stopped.

Alkaline nickel-cadmium batteries [4, 29] use an aqueous solution of potassium hydroxide (KOH) or sodium hydroxide (NaOH) with a density of 1.19-1.21 g/cm3 as the electrolyte with the addition of lithium hydroxide (LiOH) to increase service life . The active mass of the negative electrode consists of spongy cadmium, the positive one - of nickel hydroxide Na(OH)3. When the battery is discharged, the active mass of the negative electrode turns into iron hydroxide Fe(OH)2, and the positive electrode turns into nickel hydroxide Ni(OH)2. KOH (NaOH) is not consumed for the formation of these substances, so the density of the electrolyte does not change during discharge. Under the influence of the discharge current, part of the water decomposes into oxygen and hydrogen, which evaporate, so water must be periodically added to the battery. When the battery is charged, the active masses of the electrodes are restored.

The main way to turn on batteries is a buffer connection (Fig. 4.2), in which the GB battery is connected in parallel with a direct current source - a rectifier device (RD): during normal operation of the rectifier device, the battery smoothes out the ripples of the rectified voltage, and when the external power is turned off or the VD is faulty - provides power to the load. When using a buffer switch, two main modes of battery operation are used: continuous recharging and pulse recharging [4].

In continuous charging mode (Fig. 4.2, a) the AC supplies the RH load. The battery is in a charged state and is continuously fed from the AC with a small direct current that compensates for self-discharge. In the pulse charging mode (Fig. 4.2, b), the AC also powers the RH load and recharges the battery, but the value of the charging current depends on the voltage on the battery. To control the voltage value on the battery, a voltage relay RN is installed. When the battery is discharged to the set threshold (minimum) voltage value, the LV relay releases the armature, its rear contact closes, and the value of the current supplied by the rectifier device increases sharply. The so-called forced battery charge occurs. When the voltage value on the battery increases to the set normal value, the PH relay will turn on and break the forced charge circuit.

Battery maintenance work includes checking the condition (inspection and cleaning if necessary), checking the level and measuring the density of the electrolyte, and measuring the voltage on the batteries [53]. Safety requirements for the operation of batteries are set out in [31,48,53].

Batteries (batteries) in the buildings of EC posts are placed in special rooms - battery rooms, outside service and technical buildings (at automatic blocking signal points, at crossings, at entrance traffic lights, etc.) - in battery cabinets or battery boxes [3].

In battery rooms, batteries are installed on special wooden racks, the number and dimensions of which depend on the type and number of batteries being mounted. The racks are located in such a way as to provide easy access to the batteries. The distance between the racks must be at least 1 m. The batteries are placed in such a way as to prevent a person from simultaneously touching two live parts whose potential difference exceeds 250 V. It is prohibited to place acid and alkaline batteries in the same room. Battery rooms are equipped with supply and exhaust ventilation, which must be turned on before charging and turned off no earlier than 1.5 hours after the end of charging. In the battery room, it is prohibited to store and eat food, smoke, enter a room with fire, use electric heating devices, as well as tools that can create a spark.

When preparing an acid electrolyte, the acid is slowly poured in a thin stream from a mug into a heat-resistant (ebonite, porcelain, ceramic, earthenware, etc.) vessel with distilled water. In this case, it is prohibited to use glassware. The electrolyte should be constantly stirred with a glass or hard rubber rod (tube) or a fireproof plastic stirrer. When preparing an electrolyte, it is prohibited to pour water into the acid; it is allowed to add water to the finished electrolyte. To prepare an alkaline electrolyte, you can also use iron or cast iron vessels; it is prohibited to use galvanized, tinned, aluminum, ceramic vessels, as well as vessels that were used to prepare an acid electrolyte. Crushed pieces of potassium hydroxide should be dipped into distilled water using steel tongs, tweezers or a metal spoon and stirred with a glass or hard rubber rod until completely dissolved.

When working with acid, it is necessary to wear a coarse wool or cotton protective suit with acid-resistant impregnation; when working with alkali - cotton. You should also wear rubber boots (under trousers) or galoshes, a rubber apron, rubber gloves and safety glasses. If acid or alkali gets into exposed areas of the body, it is necessary to wash these areas first with water, then with a neutralizing solution of soda or boric acid.

When installing and servicing batteries, it is prohibited to touch live parts (terminals, contacts, wires) and lead plates with bare hands (without rubber gloves). When working with alkaline batteries, use insulated handles on the tool.

Promising chemical current sources are sealed batteries, for example, acid batteries of the 24V SPzV, OpzV Block, OGiV HP series produced by BAE (Berlin, Germany) [5]. Such batteries are maintenance-free, which significantly reduces the cost of their operation, and have a long service life, 3-4 times longer than the service life of unsealed batteries. Sealed batteries do not release products of electrochemical reactions into the surrounding air, so special battery rooms are not required for their installation. In addition, such batteries operate more stably in low temperatures.

Converters and rectifiers in power supply devices of ZhAT equipment

To ensure the operation of railway automation and telemechanics systems, it is necessary to supply electricity with certain parameters (number of phases, voltage, current, frequency) established by the relevant technical conditions to the inputs of each individual device (element, device). In order to obtain the required nominal values of electricity parameters, the power supply equipment includes special devices that carry out the necessary transformations.

Converting alternating voltage (current) to direct voltage (current) is called rectification. The structure of the rectifier device and the voltage diagrams at the inputs and outputs of its elements are shown in Fig. 4.3. The main elements of the control unit are: transformer T, which performs level matching (lowering or increasing) the values of the input UhX and output Uh voltages; rectification circuit B, which directly converts alternating voltage into direct voltage; smoothing filter SF, designed to smooth out rectified voltage ripples; MV voltage stabilizer, which ensures that the load voltage Un is maintained within specified values when exposed to various destabilizing factors (changes in supply voltage, load resistance, ambient temperature, etc.). As part of any computer, the rectification circuit is a mandatory element, and other elements are included as needed.

Single-phase rectification circuits and diagrams explaining their operation are shown in Fig. 4.4. Let's consider the principles of operation of the circuits, assuming that an alternating voltage Sh is applied to the primary winding of the transformer T, and voltage V is removed from the secondary winding

The half-wave circuit (see Fig. 4.4) works as follows. During the time interval [0, i], the diode VD is under the influence of the positive half-wave voltage Ш (voltage polarity is shown by the signs “+” and “—” without brackets). A current pulse /0 flows through the circuit formed by the secondary winding of the transformer, the open diode VD and the load RH, the shape of which follows the shape of the voltage C/2. A voltage Uq is released at the load, the shape of which also follows the shape of the voltage £/2. During the time interval [l, 2l], the diode VD is under the influence of the negative half-wave voltage Ш (the polarity of voltage U2 is shown by the signs “+” and “—” in parentheses). Due to its property of one-way conductivity, the diode, being under the influence of reverse voltage £/rev, remains closed and no current flows through the load. Thus, in a half-wave circuit, the rectified current flows through the load only during one half-cycle of the supply voltage.

A half-wave circuit with a midpoint (see Fig. 4.4) works as follows. During the time interval [0, l], diode VD1 is exposed to a positive half-wave voltage £/2. Through the circuit formed by the upper half-winding of the secondary winding of the transformer, the open diode VD 1 and the load RH, a current pulse flows and a voltage C/q is released to the load, the shape of which follows the shape of the voltage Sh. Diode VD2, being under the influence of the reverse voltage C/rev2, remains closed . During the time interval [l, 2l], diode VD2 opens, and diode VD1 remains closed. A current pulse /02 flows through the load, releasing voltage Uq. Thus, in a full-wave circuit, rectified current flows through the load during both half-cycles of the supply voltage.

A full-wave bridge circuit (see Figure 4.4) operates similarly to a midpoint circuit. In this case, during the positive half-cycle of voltage C/2, diodes VD1 and VD3 are open, and diodes VD2 and VD4 are closed. During the negative half-cycle of voltage £/2, on the contrary, diodes VD2 and VD4 are open, and diodes VD1 and VD3 are closed. Therefore, in a bridge circuit, the rectified current also flows through the load during both half-cycles of the supply voltage.

The half-wave circuit works as follows. The rectified current /q flows through a circuit formed by one of the secondary windings of the transformer by an open diode connected to its circuit and a load RH. At any given time, only one diode is open - the one that is exposed to the positive half-wave of the voltage that has the greatest value. So, during the time interval [0, the voltage i/^ has the greatest value, during the interval [/j, /2] - the voltage Shchf, during the interval [tj., /3] - the voltage Shchf. Therefore, during the time interval [0, r| J diode VD1 is open, during interval 12] - diode VD2, during interval [t2, /3] - diode VD3.



The bridge circuit works as follows. At each moment of time, two diodes are open, one of which is connected to the circuit of the secondary winding, which has the highest positive potential, and the second - to the circuit of the winding, which has the highest (in absolute value) negative potential. The voltage values on the secondary windings of the transformer and the corresponding open diodes are shown in table. 4.2. For example, during the time interval [0, /j], rectified current /0 flows through the circuit from the 1F winding through the diode VD2, load RH, diode VD3 to the 2F winding, during the interval tj\ - from the 1F winding through the diode VD2, load R ^, diode VD5 to the PF winding, etc.

Converting DC voltage (current) to AC voltage (current) is called inversion. The structure of the voltage converter - inverter and the voltage diagrams at the inputs and outputs of its elements are shown in Fig. 4.6. The main elements of the inverter are: key circuit K, which interrupts the direct voltage Uq arriving at its input at a certain frequency, resulting in the formation of a pulsating (pulse) voltage; transformer T, which converts the pulse voltage Shch into alternating voltage Shch (IF necessary, with an increase or decrease in value voltage).

Converting a DC voltage (current) to a DC voltage (current) of another value is called conversion. The structure of the voltage converter - converter and the voltage diagrams at the inputs and outputs of its elements are shown in Fig. 4.7. The main elements of the converter are: inverter I, which converts the constant input voltage Shch into alternating voltage Uy\ rectifier device VU, which converts the alternating voltage Sh into constant Uq2 with an increase or decrease in its value. Rectifier and converter devices are widely used in power supply devices for signaling equipment [18, 42]. are given in table. 4.3.

Battery rectifiers (BAC) are used to recharge batteries during a buffer connection, as well as to directly power relay circuits. The rectifiers VAK-11 A, VAK-1 ZA, VAK-14A and VAK-16A use cuprux rectifier elements (copper plates coated with a thin layer of copper oxide), while the rectifiers VAK-13B, VAK-14B and VAK-16B use silicon diodes, in rectifiers VAK-13, VAK-14 and VAK-16 - selenium rectifier elements.

The stabilized semiconductor rectifier VSP-12/10x2 has two independent outputs, each of which provides a rated voltage of 12 V with a maximum load current of 10 A. When the rectifier outputs are connected in series, a voltage of 24 V can be obtained; when connected in parallel, the load current can reach 20 A

VUDK rectifier devices are used to power frequency dispatch control devices.

The BPSh plug-in power supply is designed to power linear circuits of numerical code automatic interlocking, and the BPSN power supply is intended for supplying circuits for changing the direction of single-track automatic interlocking.

The selenium rectifier block BVS, the diode-resistor block BDR and the diode block BD are used in switch control circuits.

To charge batteries in continuous charging and forced charging modes, the charger-buffer device ZBU12/10 (12 V is the battery voltage, 10 A is the maximum current supplied by the device), charge-buffer rectifiers ZBV 12/20, ZBV 24/ 30 and ZBV 220/3, automatic current regulators RTA and RTA1, automatic chargers UZA-24-10 and UZA-24-20, automatic three-phase chargers UZAT-24-ZO.

With backup power from a battery, semiconductor pointer converters PPS-1 with a power of 1 kW and PPS-1.7 with a power of 1.7 kW are used to turn on DC pointer electric motors (work together with rectifier devices VUS-1.3) to turn on pointer electric motors three-phase alternating current—semiconductor switch three-phase converter PPST-1.5M with a power of 1.5 kW.

The input voltage source for semiconductor converters PP-0.3 and PP-0.ZM with a power of 0.3 kW can be a battery or a three-phase rectifier (with a bridge rectification circuit).

The semiconductor plug-in converter PPSh-3 can operate in one of two modes - rectification of alternating current or conversion of direct current. Configuring the converter to one of three power modes (alternating current; direct current; normal - from an alternating current source, and when it is turned off - from a direct current source) is carried out by installing jumpers on the plug socket.


Semiconductor converter-rectifiers PPV-0.5M with a power of 0.5 kW and PPV-1 with a power of 1.0 kW are used to charge the battery (rectification mode) and backup power to signaling equipment with alternating current when the network is disconnected (battery direct current conversion mode).

Frequency converters type PCh50/25 (Fig. 4.8) are used to convert alternating voltage (current) with a frequency of 50 Hz into alternating voltage (current) with a frequency of 25 Hz [4.42]. Converters PCh50/25-100 with a power of 100 VA, PCh50/25-150 with a power of 150 VA and PCh50/25-300 with a power of 300 VA are used. The converters operate from a single-phase alternating current network with a frequency of 50 Hz and a voltage of 220 or 110 V.

Structurally, the IF50/25 consists of two blocks - a ferromagnetic one (magnetic system and diodes) and capacitors. The magnetic system of PCh50/25-100 and PCh50/25-150 (see Fig. 4.8, a) consists of two U-shaped steel cores, on the outer rods of which there are magnetization windings wnl and wna, and on the middle ones there is a contour winding wK. Windings wn | and wn2 are connected to an AC mains frequency of 50 Hz. Winding wK and capacitor Sk form an oscillatory circuit tuned to a resonant frequency of 25 Hz. The windings wnl and уун2 are connected counter-currently, so that the magnetic fluxes Фп1 and Фп2 created by them are also directed counter-directed and do not induce an alternating current with a frequency of 50 Hz in the wK winding. The VD diode provides full-wave rectification of the input current, as a result of which the magnetic fluxes in the cores will change at a frequency of 50 Hz (50 times per 1 s). The magnetic permeability of the cores will change with the same frequency, and therefore the inductance of the winding wK. A change in the winding inductance with a frequency 2 times greater than the natural frequency of the circuit causes oscillations to occur in the wK-Sk circuit with a frequency of 25 Hz.

The frequency converter PCH50/25-300 is distinguished by the design of the core (magnetic circuit), which has a cross-shaped shape (see Fig. 4.8, b). Two windings—magnetization wn and loop winding wK—are located at an angle of 90° to each other, which eliminates the transfer of energy from one winding to another by inductive means.

The output windings of the IF50/25 are sectioned to produce voltages from 5 to 220 V. The converters have good stabilizing properties - they operate stably when the input voltage fluctuates in the range from 180 to 270 V (when powered from a 220 V network). IF50/25 does not require protection against short circuits and overloads: if there is a short circuit or the load current exceeds the set value, the converter stops working, and when normal mode is restored, the operation of the converter is restored automatically.

The technology for servicing converters and rectifiers is described in [53]. The maintenance work for voltage converters installed in the backup power circuits of power supply installations includes external inspection, startup with load connected and measurement of alternating voltage at the output and direct voltage at the input with the load connected. The maintenance work for rectifiers includes external inspection, measurement of the rectified voltage value, and measurement of forward current. Checking the voltage values at the outputs of frequency converters PCH50/25 installed on the panels of the power supply installation of the electrical center post is part of checking the voltage values of all output circuits of the electronic control unit. Checking the voltage values at the outputs of the PCH50/25 frequency converters, which are the power sources for the running rail circuits (installed in the relay cabinets of automatic blocking and automatic crossing signaling), is part of the work on measuring and adjusting the voltage on the travel relay.