Emergency protective circuit arrangements (H02H)

Current protection method of three-phase network from single phase-to-ground faults

In this method negative-sequence current of the lines under protection is used as controlled electrical quantity, it is educed by measurement and calculation as a symmetrical component of three-phase currents in the system lines. Negative-sequence current is measured continuously before and upon occurrence of ground fault for all lines under protection. Increment of negative-sequence current is used as an input parameter for the protection operation, it is determined at once upon fault occurrence by subtraction of pre-recorded value of negative-sequence current from its actual value.

Remote ground fault protection method and device

Invention is related to electric engineering and may be used in remote ground fault protection systems in power transmission lines. The remote ground fault protection method consists of the following stages: measurement of a local source impedance on the basis of fault component at both ends (M, N) of a power transmission line when ground fault occurs; dispatch of the local source impedance from the first end of the line to the second one; setting the protection criterion at the second end of the line on the basis of measured impedance of the local source; assessment of ground fault as internal or external fault in compliance with the set criterion of the protection.

Method to lock ac rectifier with distributed energy accumulators

Application: in the field of electrical engineering. Invention relates to the method to lock an AC rectifier (2) with distributed energy accumulators (CSM) with at least two modules (41, 42, 43) of phases, which have appropriate upper and lower branches (P1, P2, P3, N1, N2, N3) of valves, which have appropriate multiple electrical serially connected bipolar submodules (SM1, SM2,…, SMn), which have an appropriate unipolar accumulating capacitor (CSM), with which electrically in parallel the circuit of serial connection is connected, from two disconnected semiconductor switches (S1, S2) with an appropriate antiparallel connected diode (D1, D2). In accordance with the invention submodules (SM1, SM2,…, SMn) of upper and lower branches (P1, P2, P3, N1, N2, N3) of valves of the module (41, 42, 43) of the phase of the AC rectifier (2) are controlled in cascades in time for switching into a switching state III.

Method to recognise contamination and/or formation of dew on components of ac frequency converter with intermediate voltage circuit

Invention relates to the field of electric engineering and may be used to recognise contamination and/or formation of dew on components of an AC frequency converter with an intermediate voltage circuit. In the method to recognise contamination and/or formation of dew, at least, during the process of preliminary charge of the intermediate circuit capacitor, having at least one capacitor, the AC frequency converter with the intermediate voltage circuit, a time characteristic is determined for the pulse current of partial discharge, besides, using this current pulse, a frequency spectrum is calculated, and depending on the result a warning is activated on contamination and/or a warning on dew formation.

Controlling power outage and faulty state of electrical power system

When executing an intelligent application associated with power outage, event messages are received, said messages indicating events associated with different devices in an electrical power system. The intelligent application associated with power outage determines the state of different devices based on said event messages. Based on the event messages, the intelligent application associated with power outage can determine and confirm the state of the power outage associated with a certain device. An intelligent application associated with a fault receives synchrophasor data for each phase in a multiphase electrical power system. The synchrophasor includes information on the value of the phasor vector and the angle of the phasor vector for each phase.

Method of initiating lightning discharges

Method of initiating lightning discharges comprises a remote definition of the pre-discharge state and coordinates of storm cells, as well as creation of a plasma conductive channel. At that the plasma conductive channel is created by synchronised blasting of series of artillery ammunition of plasma-optical action. The blasting points are located so that the ionised fields arising in the atmospheric air at triggering of the ammunition of plasma-optical action are arranged to overlap in the chain in the direction from the storm cell to the ground surface or to neighbouring storm cell. The overlapping of the ionised fields in the atmospheric air from triggering of the ammunition of plasma-optical action can be performed by changing the direction of flight of each subsequent ammunition in series in relation to the previous one. The overlapping of the ionised fields in the atmospheric air from triggering of the ammunition of plasma-optical action can also be performed by changing the triggering time of each subsequent ammunition in series in relation to the previous one. In addition, the overlapping of the ionised fields in the atmospheric air from triggering of the ammunition of plasma-optical action can be performed by simultaneous changing the direction of flight of each subsequent ammunition in series in relation to the previous one and the change in the triggering time of each subsequent ammunition in series in relation to the previous one.

Protection of parallel lines of power supply grid

Invention is attributed to the field of electric engineering and can be used for protection of power supply grids. For protection of parallel lines of the power supply grid the first protective instrument (13a) is connected to the first line (11a) of the power supply grid for registration of measured values, which characterise working condition of the first line (11a). The first protective instrument (13a) via a communication connection (15) is connected to the second protective instrument (13b) located nearby. In order to increase reliability and selectivity during monitoring of parallel lines, a method is proposed, in which the second protective instrument (13b) is connected to the second line (11b) of the power supply grid stretching in parallel to the first line (11a). Both protective instruments (13a, 13b) exchange measured data recorded by them relative to their appropriate line (11a, 11b), and/or signals produced from these measured values. Each protective instrument (13a, 13b) is made as capable of performing a protective function for its appropriate line (11a, 11b) when performing the main logic (25) of protections. Each protective instrument for performance of its main logic (25) of protection involves measured values registered on its own line (11a), and also measured values and/or signals accepted from another protective instrument (13b).

Method to monitor resource of insulation of high-voltage ac equipment

Absolute maximum value is identified at each half-cycle of voltage curve, and residual resource is assessed by subtracting a part of resource from it, identified in each half-cycle of voltage curve as a ratio of duration of voltage half-period duration to value of permissible time of equipment insulation staying under voltage with maximum value of half-cycle. At the same time they measure electric voltage at evenly fixed moments of time, and counts of rectified signal are generated by detection of absolute values of measurements, counts of the rectified signal are compared with the specified threshold, and a section is identified, arranged between two counts below the threshold, and the counts of which are higher than the specified threshold, the count with the maximum value is found among counts of the identified section, and then they select the specified number of counts at the left and right from it. Via found counts they draw an interpolation curve with a single maximum, and its maximum is accepted as the absolute maximum value of electric voltage at the life-cycle.

Method to control three-phase valve electric motor of implanted rotary electric pump of cardioprosthesis with provision of liveness property (versions)

By a signal from current sensors, a failure is detected in a chain of one of three phases of an anchor winding. Then by means of a microcontroller device a signal is sent for actuation of a protective element of the failed phase, the process of automatic switching of two operating phases is carried out, providing for development of a motor torque. The protective element is represented by power switches of that inverter stand, to which the failed phase is connected. Remaining switches, forming a single-phase bridge inverter, are switched by means of a microcontroller device, carrying out serial selection of previously recorded control codes from memory cells corresponding to the condition of the anchor winding and position of the rotor. The criterion of available fault, as well as sound and light signals announcing the available fault and time of its occurrence, are generated by means of the microcontroller.

Device to control and ensure durability of double-fed motor

Device to control and ensure durability of a double-fed motor comprises an induction motor, a frequency converter made of a controlled rectifier and an inverter, a three-phase transformer. The rectifier is made as a grid thyristor converter, and the inverter - as a rotor thyristor converter arranged in accordance with a bridge three-phase circuit. The device additionally comprises current sensors, protective elements, two reserve half-bridges, each comprising three symistors and two reserve thyristors, and a microcontroller, which is connected to all thyristors and symistors. The specified elements are connected as specified in application materials.

Protective circuit breaker with detection of aperiodic current variation

Application: in the field of electrical engineering. A protective circuit breaker (11) comprises opening contacts for set disconnection of a grid, which are controlled by at least one start unit (10), to reduce risk of fire due to faults in electric networks. Additionally the protective circuit breaker comprises a detector (1) to detect aperiodic, substantially spasmodic variations of amplitude of at least one electric parameter in the electric network. The start unit (10) is functionally connected to the detector (1).

Device to monitor operation and protection of three-phase electric motor

Device comprising current sensors, a comparator with a threshold level setter, a contactor unit with contacts in a power supply circuit of an electric motor is equipped with two rectification and highest voltage release units, a differential amplifier and an analogue voltage divider. At the same time each of rectification and highest voltage release units is made on three operational amplifiers with diode-resistive feedbacks, and outputs of rectified voltage of one of polarities are combined and connected with the output of the highest voltage of the unit.

Synchronisation method for differential current protection

Method involves the following stages: point is chosen in a transmission line protected by differential current protection; current and voltage is measured on each of the poles of the transmission line; compensating voltage is calculated at the chosen point according to the measured current and voltage on each of the poles; a synchronisation error is detected and calculated by comparing compensating voltages. Current and voltage on each of the poles are measured before or after a fault occurs, and they can be measured in the form of vector random values, phase values or sequence values. The point can be chosen in any place of the transmission line, preferably in the middle or on ends of the transmission line, or at the point of a T-shaped connection of multipole transmission lines. In addition, the synchronisation method involves a detection stage of a cause of a synchronisation error: strong change in the parameter of the line or symmetric switching of the channel; detection is performed by calculation of a rate of change of difference of a phase angle or a wave shift of the above compensating voltage.

Safety relay

Invention relates to a safety relay including an input circuit that detects the state of an external device in compliance with the fact whether external input voltage exceeds the pre-set threshold voltage or not. The safety relay includes an input circuit and an actuation unit that reads off a detection signal detected by the input circuit and performs a safety relay actuation operation. The input circuit includes a switching device that becomes current-conducting when divided voltage is supplied to it, which is obtained by means of voltage division resistors that divide external input voltage when external input voltage is higher than or equal to threshold voltage, and an opto-relay that is actuated by stabilised current of the output circuit and outputs an actuation signal to the actuation unit when the switching device becomes current-conducting.

Protection device for crane

Invention relates to crane protection device which can be steadily used at temperatures not exceeding minimum operation temperature of electronics. Heaters (22c) and two thermostats (22a, 22b) with different operating temperature are installed in control panel, jib length sensor (22), jib angle sensor (23), jib raising and lowering cylinder pressure sensor. The heaters (22c) are switched on by means of switching on the first thermostat (22a) when electronic devices (22, 23) temperature does not exceed the first preset temperature (0°C), and electronic devices (22, 23) are heated to the first preset temperature. Additionally, crane operation is limited and lamp is turned on by means of the second thermostat (22b) switching off when electronic devices (22, 23) temperature does not exceed the second preset temperature (-10°C).

Overvoltage protection element

Invention describes overvoltage protection element with a case and at least one overvoltage limiting component installed inside the case, primarily gas-filled discharger (1), spark discharger, protective diode (2), or variable resistor. According to invention, monitoring of functioning and state of overvoltage protection element during operation is enabled by correlation of overvoltage limiting component with monitoring component registering current (i) flowing through overvoltage limiting component, and by installation of result processing unit evaluating signal from the monitoring component.

Apparatus for protecting microcircuit leads from electrostatic discharges

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.

Voltage switch with over current protection

Device includes electronic switch with MOS structure, supplying power to load unit. A sequence of reference voltage source, second electronic switch unit, resistor and thermal resistor ensures actuation of relay element with hysteresis almost independent from temperature. Electronic switch unit connected to the common point of switch and load unit, with its output connected to adder input, enables exclusion of current sensor requiring significant heat removal, from the circuit. In case of current overload, power is disconnected from load unit.

Voltage switch with over current protection

Device includes electronic switch with MOS structure, supplying power to load unit. Electronic switch device and a sequence of resistor and thermal resistor connected to common point of switch and load unit reduce error of relay element actuation level generation with hysteresis that control switching load power supply unit on and off with the help of first and second AND elements. In case of current overload, power is disconnected from load unit.

Method to control double-phase short-circuit and to inhibit second cycle of automatic reclosing for master circuit-breaker in line feeding transformer substation

Invention is related to automatic equipment of electric mains and intended for control of a double-phase short-circuit and inhibition of the second cycle of automatic reclosing for the master circuit-breaker (MCB) in the line feeding the transformer substation. The technical result includes expansion of functionality by receipt of data on the double-phase short-circuit and inhibition of the second cycle of automatic reclosing for the MCB in the line. According to the invention since loss of the linear voltage at the transformer the first countdown is started, which is equal to the operation delay time of the in-line MCB protection, at that loss of two other linear voltages is controlled and when they are lost at the first countdown completion then the conclusion is made about cut-off of the MCB and since its cut-off moment the second countdown is started equal to the operation delay time of the first cycle of the MCB automatic reclosing, at that the linear voltage is controlled and when the two linear voltages appear when the second countdown is over and the first linear voltage does not appear then the conclusion is made about the second automatic reclosing in result of short-circuiting and since the moment of its actuation the third countdown is started, which is equal to the operation delay time the in-line MCB protection with acceleration, at that loss of two appeared voltages is controlled and when they are lost at the moment of the third countdown completion the conclusion is made about automatic reclosing of the MCB and a signal is sent to inhibit the second cycle of the MCB automatic reclosing in the line feeding the transformer substation.

Method for automatic reclosure of overhead transmission line at glaze ice melting

Short-circuited section of an overhead transmission line is defined, the total load and time period since the melt starting up to the fault interception is measured for the wire at this section and automatic reclosure for the line is permitted when certain conditions are met.

Damaged section determination method for sectionalised line of ring network

Since tripping of a short-circuit current surge in a line of the main power supply unit the countdown is started, which is equal to the operation delay time of an automatic transfer switch (ATS). Availability of the operating current is monitored in this line, and when it is equal to zero, and at the moment of the countdown completion the operating current surge occurs in the line of the main power supply unit with the value defined by a load of this line section adjacent to the ATS point, then conclusion is made about a damage of the master section in this line, and if the operating current is not equal to zero and defined by the load connected to the master section in the line of the main power supply unit and at the moment of the countdown completion the short-circuit current surge occurs in the line of the main power supply unit, then conclusion is made about a damaged section in the line of the main power supply unit adjacent to the ATS point.

Method of insulation service life monitoring for alternating current high-voltage equipment

Method evaluates remaining life by means of subtraction from it of the life part determined at each voltage half-period as the ratio of a half-period duration to the permitted time of insulation stating under effective voltage. The initial service life of insulation is accepted as 1. The novelty of the method lies in operations allowing increase in accuracy of determination of the effective voltage value (nonsinusoidal, in the general case) against voltage measurements at equal time intervals. In order to achieve the above goal, the voltage measurements are converted to intermediate signal samples by their squaring, the intermediate signal is subject to additional averaging, weighing with a coefficient of ј the sum of its current sample and three previous samples shifted in regard to the current sample to the fixed time intervals equal to 1/6, 1/2, and 2/3 or 1/4, 1/2 and 4/5 of the sample number within the rated frequency period of the measured voltage, if the above number of samples is divided evenly by 6 or 20 respectively. The effective value of voltage is defined by square-rooting of the averaged amount of the intermediate signal samples for the number of measurements during the period of electrical voltage.

Relay protection of csr power winding

Single-system differential current protection of a reactor power winding includes two insaturable current sensors connected between two outputs of the power winding neutral point and a point of their connection to the earthing network, at that a current relay (a measuring element of the protection) is activated by the current difference of the above sensors upon separation of the main component of the first harmonic by filters, which passes through each current sensor and applies when the preset value is exceeded for a shutdown of the reactor switch without time delay.

Device of protection aerial and cables lines of distributed network 6-35 kv from single line-to-earth fault

Device contains a directional element consisting of matching current and voltage converters of transformer type, two frequency filters, two emergency component filters, two current and voltage signs comparator circuits, two univibrators, two inhibit circuits and a starting element consisting of a commercial frequency filter, an inhibit circuit, a voltage relay, AND element, a time element and two output relays, there are also auxiliary inhibit circuit, a commercial frequency filter, two threshold elements, two time elements and two output relays.

Method for fast three-phase reclosure of transmission lines with compensation by shunt reactor

Invention relates to the field of electric engineering and suggests an adaptive switching method to control overload in result of three-phase reclosure of transmission lines with compensation by shunt reactor. Since an automatic circuit breaker (ACB) cuts the line off interaction between shunt admittance of the transmission lines and inductance of the reactive power compensator makes voltage between the ACB poles taking an oscillation form (beat). An optimal section for ACB reclosure corresponds to the section where voltage beat amplitude between the ACB contacts is minimum. It also allows a bigger time span for ACB operation after detection of the optimal section for reclosure, at that there are still several period of the main frequency ahead. The algorithm of the method is included into the control logic device for a digital relay of the three-phase reclosure of transmission lines thus creating a new digital relay for adaptive three-phase reclosure of transmission lines with compensation by shunt reactor.

Overload relay

Invention relates to overload relays for protection of an electric motor or other device from thermal overload. The overload relay consists of the following components: a variety of shunting resistors and control means connected to each shunting resistor. At that each shunting resistor is installed in the current pathway of the respective feed line from the power supply source for an electric motor or any other device. Control means may generate a signal to cut-off power when it detects overload conditions on the basis of one or several signals representing current passage through the shunting resistors. The power supply unit consists of a rectifier to generate direct current from the feed lines of alternating-current power supply source connected to an electric motor or any other device protected by the overload relay and at least one transformer connecting the power supply source with the overload relay.

Device for longitudinal differential current protection of power transmission lines

Invention is related to the field of electric engineering and may be used in relay protection power transmission lines designed for implementation of current protection of power transmission lines. In device for longitudinal differential current protection of power transmission lines a microprocessor terminal is placed at one end of the power transmission line and contains two current measuring and transforming elements.

Method for determination of damaged point at short-circuiting in aerial cable lines of direct-current power transmission

Method lies in registration of voltage curve shape for the damaged transmission pole, determination of temporary voltage reduction at the pole below the setting U set up to 0, comparison of this time interval with the preset value t cl, when this value is exceeded an output signal is shaped at the first protection channel signalling damage at the aerial segment and when the time interval is less or equal to t cl an output signal is shaped at the first protection channel signalling damage at the cable section of the direct-current power transmission line; calculation of frequency component of voltage change with the biggest amplitude against the first points of the voltage curve transition through 0, comparison of this frequency component with the preset value fmincl, when this value is exceeded an output signal is shaped at the second protection channel signalling damage at the cable section and when values of the frequency component are less or equal to fmincl, but bigger than fminal, then an output signal is shaped at the second protection channel signalling damage at the aerial segment of the direct-current line. The protective output signal is shaped for cut-off of the respective half-circuit without automatic reclosure at simultaneous delivery of the signals from the first and second channels that register detected damages at the cable section of the line. The protective output signal is shaped for cut-off of the respective half-circuit with automatic reclosure at simultaneous delivery of the signals from the first and second channels that register detected damages at the aerial section of the line.

Device for balancing open-phase modes in 10kv line for remote consumers

Device for balancing open-phase modes in the line 10kV for remote consumers contains a current-limiting inductor, arresters and a converting unit consisting of a three-phase rectifier, which inputs are connected through the current-limiting inductor and arresters to a three-wire network and which outputs are connected to a capacitance divider; a three-phase five-level inverter is connected in parallel to it and its control electrodes are connected to the control unit connected through the battery to a photoelectric converter.

Neutral wire earthing method

Invention is related to the field of electric engineering and can be used for reduction of overvoltage level and single-phase current in electric network. The method lies in earthing of the neutral wire by means of capacitors and a reactor. At that active resistance of the reactor branch is selected as the maximum value ensuring the preset single-phase closing current and the total capacitance of capacitors by the following condition: C ≥ E ω ⋅ R ⋅ U , where ω is pulsation of the network; R is the selected active resistance for the branch of the reactor winding; U is the current value of voltage of the reactor at resonant current value; E is the current value of the phase electromotive force of the network.

Line damage detector

Invention is related to the field of electric engineering and can be used in the fault detection system in order to detect a fault or damage at an electrode line in HVDC system. Technical result lies in improvement of the system reliability at damage detection. The electrode line contains the first and second branches connected in parallel. The fault detection system contains the first and second pulse generation schemes intended to generate electric pulses for the first and second branch respectively and also the first and second current measurement devices capable to generate signals specifying the electric signals in the first and second input lines respectively.

Method for dynamic detection of accidental electric discharge and device for its implementation

Application: in the field of electric engineering. According to the method a recorded signal i(t) of load current is supplied into two channels, each channel has three processing steps, at that at the first step of the first channel deviation of current signal from the periodic function is assessed, a regular component being the determinate part of the source signal is then defined by means of the source signal averaging in a short period of time - more than ten times less than the reporting period T and its mean-square value is calculated; at the second step high frequency components are defined excluding signal components slowly varying during several reporting periods T; at the third step the signal is filtered in order to exclude influence of certain pulses with large amplitude and history of its previous values is considered for the long-term period of time with reduction of each value contribution into the result depending on its time limitation; at that at the first step of the second channel an irregular component is defined by means of a regular component deduction from the signal i(t) and its mean-square value is calculated; at the second step high frequency components are defined and at the third step the signal is filtered, signal levels obtained at the outputs of the first and second channels are compared with the preset threshold values and when they exceed these values an alarm command is generated in order to cut off the controlled mains.

Method for limitation of short-circuit currents and transient recovery voltage in high-voltage electric mains

Increase in current passing through the connection switch is fixed up to the value exceeding switching capacity of the switch, the connection is shunted, then the switch is switched off and the connection is deshunted. After the above fixation action of the relay protection on the switch is locked, its disconnection and deshunting of the connection is made after testing of shunting current availability and non-availability of current passing through the switch respectively.

Method for protection of integrated switchgear cubicles from arcing fault

Invention relates to electric engineering, and namely to method for relay protection and may be used for protection of integrated switchgear cubicles from arcing fault. Technical result leads to reducing of damage in case of arcing fault in integrated switchgear cubicles. In this invention currents are measured in the cubicle cable phases comparing them to the first reference value. The cable switch is switched off with time delay when these current values in at least one phase are bigger than the first reference value. Zero-phase sequence currents are measured additionally close to the switch outputs and close to the sealing end from the cable side. The difference between them is calculated and compared with the second reference value and when the difference is bigger the cable switch is cut off without time delay.

Method of protection from currents of remote short circuits

Application: in the field of electrical engineering. The method lies in measuring current in power line and assessment of its nature change. According to the method harmonic composition of current is measured and at that distortion coefficient of current curve KIi harmonicity is calculated on permanent basis. Each moment when the current value of the main harmonic component in the power line exceeds value of minimum fault current Ifcmin or value of starting current Isc for asynchronous engine the actual value of distortion coefficient of current curve KIi harmonicity is compared with the previous value. The signal about fault current occurrence in the power line is generated when distortion coefficient of current curve KIi harmonicity decreases.

Switchgear for interruption of bidirectional direct current and installation with photocells equipped with such switchgear

Invention is related to direct current interrupting switchgear. Switchgear (1) for interruption of bidirectional direct current in the electric line (3) contains at least two connection leads (E1, S1) and even number (Np) of plug contact pairs (11, 12) for arch-quench chambers (14, 15) connected to certain pairs of plug contacts and tripping mechanisms connected to certain pairs of plug contacts and interconnected mechanically, at that each arch-quench chamber is equipped with arc blow chamber (43, 44) and permanent magnets (47, 48) with polarity allowing electric arc (52) shift in the arc blow chamber when current passes in the electric line in the target direction, at that the target direction is different for one half of arch-quench chambers.

Arrester with guide strips for protection of electric equipment from overvoltage at lightning and insulator of power line equipped with such arrester

Invention presents arrester with guide strips for protection of electric equipment or power line that contains insulating body made of solid dielectric, two main electrodes connected mechanically with insulating body and two or more intermediate electrodes placed between the main electrodes with mutual displacement at least along longitudinal axis of the insulating body; they can be formed between the main and intermediate electrodes of streamer discharge. Intermediate electrodes are placed inside the insulating body and are separated from its surface by insulation layer, at that between the first and second adjoining electrodes there are exposed discharge chambers. At least three discharge chambers are equipped with guide strips made of insulating material fixed to external surface of the insulating body and installed to prevent spreading of plasma cloud formed inside chambers during discharge from one discharge chamber towards the neighbouring discharge chamber by means of plasma cloud streaming to outside air.

Machine protective device

Device includes a (+24 V) power supply circuit 1, directly connected to the output of the numerically controlled supply circuit of the machine, two parallel-connected safety relays, two protective diodes, three normally open contact switches and one normally closed contact switch, a resistor, the device is provided with at least two normally closed mushroom-shaped emergency switches, a feedback relay with a parallel-connected protective diode and a normally open contact, which can be connected to the numerically controlled system of the machine. The normally open contact is connected in series to the first safety relay; the supply circuit of the safety relay passes through a unit of normally closed emergency stop position switches, each at least made in form of one switch, connected in parallel by a jumper, having a normally open non-fixed contact with a key; the output of said contact switch of the first safety relay is connected in parallel to the coil of the second safety relay and the resistor of the device ON lamp. The safety relay is equipped with parallel-connected protective diodes, from the input of the supply circuit in parallel to the unit of normally closed emergency stop switches; the supply circuit is connected to the input of the numerically controlled system, connected in parallel to series-connected normally open contacts of the first and second safety relays, the output of which is connected to the output of the device for connecting to the numerically controlled system, and outputs of the safety relays and the feedback relay, protective diodes and ON lamp are connected to the "0" phase bus.

Method to connect three-phase transmission line

First phase is connected, voltage is measured on the second and third phases, it is checked how the first reference value exceeds each of the measured voltages, and if the check results are positive, they connect the second phase, measure voltage on the third phase, inspect how the second reference voltage value exceeds the voltage measured in the third phase, and if the result of the check is positive, they connect the third phase, and in case of negative check result in the first reference value exceeding voltages measured in the second and third phases, and the second reference value exceeding the voltage measured in the third phase, subsequent phases are not connected, and the ones connected previously are disconnected. When a signal is received on availability of an earth fault in the first phase during its connection, it is disconnected, and subsequent phases are not connected, after connection of the second and third phases they compare modules |U12(13)| of vector difference of voltages in the first and second phases |U12| and the first and third phases |U13| with low reference value 0.1|U pn|, where |U pn| - nominal phase voltage, and if the condition |U12(13)|<0.1 IU pn| is met, they fix the closure of accordingly the first and second and the first and third phases to each other, afterwards they disconnect the first and second and the third phases, accordingly.

Device for protection of railway hardware and line-cable structures of wire communication

Invention relates to protection of railway communication cable lines. Proposed device comprises protection units including protection first-stage module connected to communication cable and protection second-stage module connected to communication hardware. Besides, it comprises monitoring unit including comparator, microcontroller and current transducers connected to said comparator. Microcontroller is connected via Ethernet interface to weighman software-hardware device and portable monitoring device. Microcontroller software analyses the results of current comparison in measured circuits with threshold magnitudes in real time mode.

Resonance suppression system and method

System for reduction of resonance occurring as a result of non-linear harmonic distortions in a high-voltage power system includes a voltage surge damper connected to the above high-voltage power system between a cable and an earth circuit and having the possibility of preventing voltage surges. The system includes a frequency converter connected in parallel to the above voltage surface damper and having the possibility of shifting resonance frequency of the high-voltage power system.

Blocking device of power circuit built into equipment

Blocking device of a power circuit built into equipment refers to electric engineering and can be used in automatic protection schemes of electric lines built into racks, frames, housings, etc. of technical systems, equipment and actuated in case of unallowable deviations from normal working modes, and namely to prevent the possibility of actuation in case the same actuation can lead to undesirable electric modes or dangerous consequences for operating personnel. The device includes a power circuit disconnection scheme with a switching element and a connector, the contacts of which are connected by means of jumpers; with that, the disconnection scheme is made without any break in the form of an additional power circuit outline. The switching element has a power communication to a disconnected part of equipment, thus providing break of the power circuit at disconnection of its parts from each other; besides, in addition, the connection is provided with contactors-simulators made on both mating parts of the connector and connected with jumpers simulating the sections of the power circuit.

Protection method of synchronous generators against fault to ground at one point of excitation circuit

Poles of an excitation winding are shunted by resistors, some part of which is shunted from time to time with controlled switches for the purpose of changing the state of a measuring circuit; voltages are measured on certain elements of the circuit and insulation resistance is calculated as per the formula given in the invention description. A flow chart of the method includes excitation winding (1); controlled insulation resistance (3); two shunting resistors (6) and (8); two controlled switches (5) and (9) of shunting resistors (6) and (8) respectively; ballast high-ohmic resistors (2) and (4) connected between poles of the excitation winding and switches (5) and (9); switch control unit (10); measuring unit 11; output relay unit (12); control unit (13) of good state of switches; earthing resistor (70). The technical results is achieved by decreasing the level of voltages on the shunting switches by their separation with outputs of the excitation winding by means of high-ohmic resistors, and the switches themselves for control of their good state are connected in parallel to the resistors on which voltages are measured.

Phase differential protection method of power transmission lines

Invention refers to phase differential protection of 110-220 kV power transmission lines with three-phase control of switches. The invention solves a problem of detection of a complicated type of damage: single-phase short circuit with simultaneous break of a wire. In order to solve a problem, additional units controlling an actual break and direction of power are used.

Protection device against short circuits in dead zone of open distributing devices of electric power engineering sites of high or ultrahigh voltage - in sections between current transformers and switches

On a potential of high or ultrahigh voltage for each phase there are two transmitting modules installed on ends of the protected section and connected between themselves with a fibre-optic communication line. On the earth potential there is a retransmission module connected by means of radio channels to both transmitting modules and connected by means of a fibre-optic communication line to a combined control station. Each of the transmitting modules includes a power supply unit, a measuring converter, a modem, a comparison unit and a radio transmitter. The retransmission module is common for transmitting modules of all the phases of the protected section.

Automatic adjustment method of arc-suppression reaction coil

Method consists in creation on a network neutral in its normal operating mode of an artificial potential from a generator of variable non-industrial frequency and measurement of parameters of the outline of zero network sequence based on the found frequency of resonance of fixed inductance of a reaction coil with the network capacity, and at occurrence of single-phase fault to ground - in recording of a measurement result, deactivation of the variable frequency generator and resonant adjustment of an arc-suppression reaction coil in compliance with the results of the last measurement, supplemented by the fact that as an arc-suppression reaction coil there used is a single-phase controlled reaction coil of a transformer type with short-circuit voltage of 100% between windings, and its resonant adjustment in the single-phase short-circuit mode in compliance with the earlier found values of capacitance current of the network is performed by selection of the required inductance resistance at outputs of secondary winding by means of a switchboard and a set of sufficient amount of resistances with values pro rata to the first numbers of ascending power series 2n, which can be connected to outputs of secondary winding of the reaction coil in series with possibility of shunting with the corresponding switch of the switchboard of any of them.

Device to control excitation of ac motor

Device to control excitation of an AC motor including: an inverter (INV), having multiple switched elements exposed to control by connection/disconnection, to convert DC voltage into AC voltage with required frequency, in order to excite an AC motor (6); an opening contactor (MMK) of the motor connected between the inverter (INY) and the AC motor (6); a unit (55) of preliminary detection of a switching operation for detection of the switching operation of the opening contactor (MMK) of the motor to the contact or disconnection of the main contacts and release of a signal of preliminary detection of the switching operation; and a control unit (10A), comprising a unit (70) of inverter control for control of connection/disconnection for multiple switching elements and control of disconnection for an opening contactor (MMK) of the motor and control of the inverter (INV) on the basis of the signal of preliminary detection of the switching operation.

Method for elimination of overvoltage

Invention refers to the sphere of electrical engineering. Method lies in that neutral is earthed to capacitive and resistive components connected in series and additional capacities are connected between phases. Parameters of components are selected on condition of elimination of oscillation transient processes after earth fault of phase and quenching of arc.

Device for protection of three parallel lines

Invention refers to electric engineering, and namely to relay protection, and it can be used for short-circuit protection of three parallel lines. For this purpose the declared device contains one maxi-selector for the same phases of each line, one comparator for each phase, current relay and transductor, logic unit common for all lines; at that current relays and transductors are connected to primary windings of respective current transformers while inputs of maxi-selectors and first inputs of comparators are connected to secondary windings of respective transductors of the same phases and outputs of maxi-selectors are connected to the second inputs of comparators, outputs of comparators and current relays are connected to inputs of logic unit and outputs of the latter are connected to trip circuit of circuit breakers of the first, second and third line.