Method for reducing inrush current of single-phase transformer when re-enabling in idle mode
SUBSTANCE: method comprises a switch contact closure when connecting the transformer to the network at the time of the maximum instantaneous voltage value in phase 90°. Herewith, prior to the switch contact closure when the transformer is connected to the network, demagnetization of the transformer magnetic circuit is completed by removing the residual magnetization of the transformer magnetic circuit by supplying direct current to the primary transformer winding of the amount sufficient to bring its magnetic circuit to saturation. Then, current is switched off and damped oscillatory discharge of the transformer current produces remagnetization of the magnetic system through the discharge capacitor with a gradual decrease of the magnetic induction amplitude to zero, and the switch contact closure with the transformer connected to the network, is performed by switching the device to the specified voltage phase comprising a switch control circuit, while the switch contacts are closed at the given phase after constant voltage supplying to the switch control circuit for synchronization with network voltage.
EFFECT: increasing efficiency of the inrush current reduction .
SUBSTANCE: system for spark-proof power supply to measurement sensors is intended for connection of sensors with high self-capacitance, which are located in an explosion hazard zone. The system includes spark-proof direct-current sources with different output voltages and spark protection barriers, clamps of one polarity of power sources are connected to a common point, feed circuits of the sensors, which are made on voltage stabilisers, are shunted with suppressors, for communication to informative main outputs of sensors there used is a receiving-transmitting device separated from recording equipment with an optoelectronic isolator.
EFFECT: possibility of parallel connection of several sensors has been obtained due to the fact that to a feed circuit of each of the parallel connected sensors there introduced are in-series chains of diodes from one to three, the number of which is determined by an explosion protection level, each of the two informative outputs of the sensors is shunted to a common bus of power sources with one, two or three suppressors, the number of which is determined by the explosion protection level, and the receiving-transmitting device with an optoelectronic isolator is fed from a spark-proof chain of the corresponding power source with a spark protection barrier.
SUBSTANCE: invention is referred to the method, device and system for protection of connection points for power supply from electrostatic discharge. The device comprises a timer unit having the connection point with the first power supply signal and intended to generate the first timer signal based on the first power supply signal; and a memory unit connected to the timer unit and having the second point with the second power supply signal and designed to limit the second power supply signal in response to electrostatic discharge (ESD) at the point of connection to the second power supply signal for the period, which duration is based on the level of the first timer signal.
EFFECT: increasing efficiency of power supply control.
28 cl, 12 dwg
SUBSTANCE: device comprises a command unit and an inductive component consisting of a primary load member and a control unit for the latter, and there is an additional integrating filter; the controlled current source is used as the primary load member, which first and second powered terminals are the control input respectively as well as the first and second powered terminals of the above primary load member, a multiplier with two input terminals and output terminal being the first and second input terminals and output terminal of the control unit is used as the control unit. The first and second input terminals of the above integrating filter are connected respectively to a neutral unit of the electric mains and to the ground, and the first and second output terminals of this filter are connected respectively to the second input of the control unit of the primary load member and to the ground.
EFFECT: improving specifications of the claimed device due to reduction of weight, power and noise level of the control unit, increasing its operating speed and efficiency factor, improving noise emission and Q-factor of the primary load member in comparison with performance of primary load members made as reactors with smooth regulated air gap.
4 cl, 11 dwg
SUBSTANCE: invention is intended for use at line circuit-breakers at compensated power transmission lines (PTL). The device consists of a launcher comprising at least one voltage relay, a selective component fixing occurrence of open phase conditions, a time delay component as well as output relays actuating shutdown of the circuit-breakers neighbouring the switched-on line circuit-breaker in open phase mode with low time delay at significant increase of voltage at PTL.
EFFECT: limitation in development of resonant voltage increase at switched off phases of PTL equipped with shunt reactors in different open phase conditions at single joint of this line to distribution switchgear coupled, in its turn, to the electric system.
SUBSTANCE: method consists in: detection of short-circuit in a three-phase electrical network; determination of the value of directional phasor in the measurement point of the three-phase electrical network and comparison of determined value of directional phasor with pre-set boundaries on the complex plane. According to the invention, on the basis of the above-stated comparison, a neutral state of ground connection of the electrical network is determined, and one or more configurations of ground-fault protection system are applied on the basis of the above-stated determined neutral state of ground connection of the electrical network.
EFFECT: improvement of precision and sensitivity of the protection system.
13 cl, 4 dwg
FIELD: information technology.
SUBSTANCE: apparatus for protecting microcircuit leads from electrostatic discharges, which includes an n-channel and a p-channel switching transistor, an n-channel and a p-channel control transistor, two load resistors, an input bus, a power bus and an earthing bus, also includes a first and a second additional inductor, wherein the drain of the p-channel switching transistor and the source of the p-channel control transistor are connected to the first lead of the first inductor, the second lead of which is connected to the input bus, and the drain of the n-channel switching transistor and the source of the n-channel control transistor are connected to the first lead of the second inductor, the second lead of which is also connected to the input bus.
EFFECT: high reactive impedance of the protection apparatus at high frequencies.
SUBSTANCE: device for short-circuit current limitation in power transmission lines contains transformer, which primary winding W1 is connected in series to the line; it represents a cable section. The line includes also a block of logic circuits which output is connected to switching element control device connected in series to secondary winding of transformer. Switching element is made as in-series bidirectional thyristors and resistor with surge suppressor connected in parallel to them; limitation level of surge suppressor is equal to thyristor class. Control device is connected to exterior power supply source located at potential of power transmission line; it is made as tertiary winding of transformer connected to input of non-controlled rectifier which output is connected to control device.
EFFECT: reducing losses in the device in standard operation mode for power transmission; reducing weigh and overall dimensions of the device and preventing repair after each actuation.
SUBSTANCE: in the method to monitor stability margins, modules and phases of voltages are measured in a synchronised manner on buses of synchronous machines, active or reactive powers released or consumed by synchronous machines under naturally or artificially created variances of their mode of operation. Using values of voltages on buses of power plants and released active and reactive powers, available internal resistances of synchronous machines, they calculate EMF values and angles of synchronous machine rotors, a system of equations is made for stabilised modes of operation of synchronous machines, which connect internal and mutual conductivities of EMF of synchronous machines with measured released powers, a system of equations is made for the stabilised mode of synchronous machines, modes are calculated for the stabilised mode of synchronous machines, a limit is fixed on stability, and the produced limits are used to calculate margins and limit capacity of synchronous machines.
EFFECT: increased reliability and validity of detection of synchronous machine mode stability margins.
SUBSTANCE: in a source of power supply instead of an intrinsic safety barrier there is a unit used, comprising a semiconductor switch, which disconnects the power supply source output from the load in case of the stabiliser failure. Limitation of voltage is carried out with the help of the stabiliser, and intrinsic safety is provided by duplication or triplication of semiconductor elements.
EFFECT: increased reliability and reduced power scattered inside a power supply unit.
2 cl, 3 dwg
FIELD: electrical engineering.
SUBSTANCE: electric protective device contains two disc-shaped PTC-thermistors (1) positioned within a common housing (2). The housing (2) contains a hole (3) on either of the two opposite sides, the said hole (3) size matching (3) that of the PTC-thermistors (2) so that the PTC-thermistors (1) may be inserted into the housing through the holes (3). The two PTC-thermistors (1) are electrically insulated from each other inside the housing (2). Each PTC-thermistor (1) contains at least two connective wires (4) by means whereof the PTC-thermistors (1) are attached to the housing (2).
EFFECT: increasing efficiency and economy.
16 cl, 4 dwg
FIELD: electric engineering, possible use for protection of electric devices and electricity transfer lines in high voltage networks with isolated neutral.
SUBSTANCE: device for compensation of one-phased capacity closing currents and for limiting internal overvoltages in high-voltage networks, contains three-phased force transformer, primary winding of which is connected in accordance to "star" circuit to external neutral and by means of commutator is connected to powering system of buses, while secondary one - in accordance to circuit "open triangle", one-phased voltage transformer and reactor between neutral and grounding device, current transformer, resistors, main and bridging commutation devices, each one with individual control circuit. Device additionally contains second reactor, connected serially to first one with simultaneous parallel connection to clamps of secondary winding and bridging commutation device, while reactors are connected by means of main commutation device to the neutral, and through current transformer to grounding device, and are bridged by resistors connected in parallel, one resistor has linear characteristic, another one - nonlinear characteristic, circuit for controlling main commutation device contains current relay and intermediary relay in secondary circuit of current transformer, control circuit of bridging commutation device contains voltage relay and intermediate relay in secondary circuit of one-phased voltage transformer.
EFFECT: increased efficiency of operation of protective device, provision of magnetic compatibility with previously installed electric equipment on sub-stations and electricity transfer lines.
4 cl, 1 dwg
FIELD: electrical engineering.
SUBSTANCE: proposed device designed for limiting parameters of electromagnetic processes in electrical installations and power transmission lines of 6- to 220-kV insulated-neutral and 110- to 220-kV effectively insulated neutral networks has power transformer whose star-connected primary winding with neutral brought out is connected through switching unit to power supply bus system and open-delta connected secondary winding; reactor connected to secondary-winding open circuit and through high-voltage lead, to ground circuit. Device also has series-connected switching apparatus with control circuit and resistor designed for shorting out the reactor; potential transformer whose high-voltage winding is connected through one lead to neutral and through other lead, to ground circuit; switching apparatus control circuit is connected to its low-voltage winding.
EFFECT: enhanced operating reliability of networks, improved power characteristics, reduced loss and cost of protective gear.
5 cl, 1 dwg
FIELD: power engineering; power supply to users.
SUBSTANCE: proposed method for no-break power supply includes conversion of unstable source energy into AC power and storage of the latter in storage device, voltage frequency of supply mains being regulated by means of adjustable capacitor matrix with bidirectional switches whose capacitor ratings are chosen from ratio of 8-4-2-1 controlled by analog-to-digital phase-frequency AFC circuit of supply mains to frequency of commercial-frequency reference generator; amplitude is regulated by modulating supply frequency with aid of pulse-width modulator; capacitor matrix and supply mains are switched over to DC power supply by means of two thyristor switching bridges whose diagonally opposite DC terminals are connected to storage device through transistor controlled by pulse-width modulator; diagonally opposite terminals of AC bridges are connected to AC supply mains and to capacitor matrix, respectively.
EFFECT: enlarged range of unstable-source useful power capacities at high use factor of their energy, reduced capacitance of storage device.
1 cl, 1 dwg
FIELD: power supply systems for consumers disposed at long distances from power centers.
SUBSTANCE: proposed single-wire distribution network that has power supply, three-wire network connected thereto, single-phase step-down transformer, intermediate converter installed on three-wire network submain that incorporates power rectifier bridge whose inputs are connected to three-wire network and outputs, to ripple capacitor, power supply, and primary winding of single-phase intervening transformer one of whose secondary-winding leads is grounded and other one is connected through single-wire line to one of primary-winding leads of single-phase step-down transformer; other lead of the latter is grounded and its primary winding is connected in series with power thyristor assembly whose control input is connected to anode of rectifier diode; cathode of the latter is connected to secondary winding lead of disabling matching transformer whose primary winding integrated with parallel-connected protective diode is inserted in collector circuit of disabling transistor; connected to base of this transistor through current-limiting resistor is output of 2AND gate one of whose inputs is connected to pulse-width modulated generator and to rectangular-pulse generator and other one, to rectangular-pulse generator through inverting component; connected to cathode of second rectifier diode whose anode is connected to secondary winding lead of enabling matching transformer whose primary winding incorporating parallel-connected second protective anode is inserted in collector circuit of enabling transistor whose base is connected through current-limiting resistor to output of second 2AND gate; inputs of the latter are connected to pulse-width modulated generator and to rectangular-pulse generator; secondary-winding second leads of disabling and enabling transformers and leads of non-polar voltage regulator diode are connected to power thyristor assembly cathode.
EFFECT: enhanced reliability of power supply.
1 cl, 1 dwg
FIELD: electrical engineering.
SUBSTANCE: windings of three type NOL single-phase potential transformers are connected in star within proposed device; integrated XYZ neutral leads of high-voltage windings and terminals connecting them should withstand test voltage specified for them; primary winding of fourth type NOL potential transformer is connected between neutral lead of these transformers and ground and its secondary winding is used for connecting insulated-neutral network ground-fault detection relay.
EFFECT: enhanced operating reliability of molded potential transformers and electricity metering efficiency.
1 cl, 2 dwg
SUBSTANCE: device contains element (1) with threshold voltage and current characteristics and thermal fuse (2) which is connected in series between damping resistor (R1) and additional secondary winding output of one of one-phase transformers.
EFFECT: decrease of ferroresonance oscillations and device dimensions.
5 cl, 5 dwg
SUBSTANCE: method consists in three condensers star-connection to network phases. Condenser common point is grounded via resistor and reactance connected in parallel. In this case condenser, resistor and reactance parameters are selected from condition of arc extinction insuring when forced closing current is crossing zero, that provides the least multiplicities of overvoltage.
EFFECT: electric network reliability and safety improvement.
3 dwg, 1 tbl
SUBSTANCE: invention can be used in electrical engineering. The system contains first, second and third windings, magnetically connected to the transformer core of a power supply. The system also contains a first low-voltage contactor and a second low-voltage contactor. The system further contains a first low-voltage impedance element, connected between the first low-voltage contactor and the first winding, a second low-voltage impedance element, connected between the second low-voltage contactor and the first winding, a third impedance element, connected between the first low-voltage contactor and the second winding, and a fourth low-voltage impedance element, connected between the second low-voltage contactor and the second winding.
EFFECT: more reliable protection from inrush current.
20 cl, 6 dwg
SUBSTANCE: there proposed is current limiting device (mainly three-phase) of electric network in the form of two parts with earth neutral wire, each of the phases of which contains linear current limiting reactor and capacitor battery. Current limiting reactor is in-series connected to network and one of its ends is connected to one part of network. In addition, capacitor battery and two controlled shunt reactors are introduced to the device. The second end of linear current limiting reactor is connected to the second part of network, one capacitor battery and shunt reactor are connected in parallel and connected to one reactor end and to earth neutral wire, the other capacitor battery and the other shunt reactor are connected in parallel and connected to the other reactor end as well as to neutral wire. Recommended ratio of sizes and parametres of current limiting reactor, power of capacitor battery of each electric network part, and nominal power of controlled reactor of each electric network part are described. Any high value of inductive resistance of current limiting reactor can be chosen so that short circuit current is not more than standard one because reactive power sources allow compensating voltage decrease.
EFFECT: increasing technological capabilities.
2 cl, 2 dwg
SUBSTANCE: invention is related to the field of electronic engineering and may be used in redundant control systems, where switching of redundant motor control windings is required, and their connection to voltage commutator is executed according to bridge circuit. Voltage commutator comprises input bas bar (1), two channels, every of which comprises device for generation of control signals (2), model-analog (3) of control signal generation device, the first (4) and second (5) commutators of positive voltage potential, the first (6) and second (7) switches, the first (8) and second (9) commutators of negative voltage potential, the first element OR (10), comparator with hysteresis (11), indicator (12), current sensor (13), the first (14) and second (15) outlets of voltage commutator, the third (16) and fourth switches, busbar of positive (18) and busbar of negative (l9) voltage potential, load (20), the first commutator (21) and the second commutator (22) of voltage. Proposed voltage commutator may be used in various control systems, in particular, in systems of spacecrafts control.
EFFECT: improved reliability of control system and provision of its serviceability in case of any failure in unit of voltage commutator.
2 cl, 3 dwg