875 results about "Ground current" patented technology

A logic signal isolator comprising a transformer having a primary winding and a secondary winding; a transmitter circuit which drives said primary winding in response to a received logic signal, such that in response to a first type of edge in the logic signal, a signal of a first predetermined type is supplied to the primary winding and in response to a second type of edge in the logic signal, a signal of a second predetermined type is supplied to said primary winding, the primary winding and the transmitter being referenced to a first ground; and the secondary winding being referenced to a second ground which is galvanically isolated from the first ground and said secondary winding supplying to a receiver circuit signals received in correspondence to the signals provided to the primary winding, the receiver reconstructing the received logic signal from the received signals.

An antenna configuration includes two closely spaced antennas each positioned so as to be orthogonally polarized with respect to the other. The antenna configuration increases antenna isolation and reduces electromagnetic coupling between donor side antenna and repeat side antenna. The antennas include printed dipoles connected to respective transceivers through respective baluns to balance the non-symmetrical portions of the antenna feed paths to reduce unwanted radiation therein. Printed features such as chokes and non-symmetrical and non-parallel structures are preferably included in the ground plane of a multi-layer circuit board to reduce or eliminate circulating ground currents.

This invention discloses a method and a device for selecting single-phase fault of small earth current nets, which integratedly processes multiple kinds of fault signals based on the earth situation of the non-earth and arc-extinguishing coils, applies multiple kinds of line selention criteria to constitute quantification espressions showing that a line may be a fault one to get the final line selection result by integrated judgment, the selection device has good man-machine interface and is easily operated and installed, the hardware of the device is a PCI bus industrial control mainboard, and the selection algorithm is realized by virtual instrument technology to differentiate faults of single-phase earth, breakage of voltage mutual-inductors and ferromagnetic resonance and displayed by LCD.

The invention relates to an intelligent online monitoring and pre-warning system for cable operation condition. The intelligent online monitoring and pre-warning system comprises a monitoring terminal and a monitoring center master station, wherein the monitoring terminal acquires monitoring parameters of the cable operation condition, such as the grounding current of the metal protective layer of the cable, cable joint temperature, combustible gas content, poisonous gas content, oxygen gas content, smoke, water level and manhole cover security, in real time and reports the acquisition data to the monitoring center master station in a timing manner through a wireless network; the monitoring center master station is used for timely carrying out storage, statistic, analysis, display and processing on the reported acquisition data and has functions of acquiring synthetic data of cable operation, monitoring the operation state in real time, displaying image data, pre-warning a fault and giving an alarm, carrying out statistic analysis of information data and the like. The intelligent online monitoring and pre-warning system can provide an effective monitoring method for ensuring the cable trench line security, ensure that the high-voltage cable line runs stably and reliably and greatly improve the power supplying reliability.

The invention discloses on-line monitoring networking of a power transformer of an intelligent substation. The on-line monitoring networking synthetically considers all on-line monitoring projects of a current power transformer, namely on-line monitoring of gas dissolved in oil and micro water, on-line monitoring of casing pipes, on-line monitoring of winding fiber temperature detection, on-line monitoring of partial discharging, on-line monitoring of iron core grounding currents, on-line monitoring of infrared temperature detection, on-line monitoring of vibration, on-line monitoring of transformer load capacity and the like. Basic configuration, technical parameters and the like of each monitoring project are comprehensively studied and ruled. According to the on-line monitoring networking of the power transformer of the intelligent substation, on-line monitoring technology of the power transformer of the intelligent substation is studied in detail, and all the monitoring principles and monitoring technology indexes of on-line monitoring units of all current and national transformers are studied in an omnibearing mode. A monitoring unit of the load capacity of the transformer is firstly raised and applied, and detailed study is performed on software functions of an on-line monitoring system. A set of complete and formal technical standards of the on-line monitoring system of the power transformer are set up for the intelligent substation.

A wireless communication device is provided with a multipart case, having electrical interfaces that encourage the flow of radiation frequency ground current between case sections. The multipart case has a first planar groundplane section and a second planar groundplane section. For example, the multipart case design may be a slider, double slider, multiple hinge, flip, or swivel case. The second planar groundplane is substantially coplanar with the first groundplane in a case open position, and substantially bi-planar with the first groundplane in a case closed position. The wireless device also includes an antenna located adjacent the second groundplane section first end. A first and a second interface electrically connect the first groundplane section to the second groundplane section second end (the end opposite the antenna).

The invention discloses a direct-current converter station based on a bipolar structure. The direct-current converter station consists of two convertor units connected in series, the serial connection point of the two convertor units is grounded by a neutral bus, and each convertor unit consists of a plurality of MMC (Modular Multilevel Converter) which are connected in series and in parallel. With the structure, when direct current fails, only the fault pole is affected, and a perfect pole is hardly affected, so the system reliability is improved; meanwhile, according to the direct-current converter station, the neutral bus is led out to be grounded, the stage construction and capacity-increasing construction of a system can be conducted easily, and a single pole is firstly put into operation, then double poles are put into operation, so that investment benefits can be obtained early; and simultaneously, the neutral bus is grounded by a grounding pole guide line to provide a current backflow access to a system in a single-pole ground loop operation mode, and when the system is in balance operation, the grounding current is extremely low.

A method and apparatus including indicators and a Ground Fault Current Interrupter (GFCI) are provided to test the marina's power and the boats electrical system load to make sure that both are proper and safe to be inter-connected. A low voltage high impedance ground current path including an oppositely connected pair of typically four silicon diodes in series in each of the pairs, sufficient to raise the voltage to a safe level encompassing the typical combined AC ground fault and DC galvanic currents in a Marina is incorporated. This protects against low level AC ground faults present in the marina, as well as DC current due to the harbor safety ground interconnect between boats in the harbor.

A rotating machinery monitor provides a warning that is indicative of a developing problem with the rotating machinery. The rotating machinery monitor has at least one current sensor for detecting shaft grounding current and / or at least one voltage sensor for detecting shaft voltage in the rotating machinery; a monitoring device for monitoring real-time shaft grounding current values and / or real-time shaft voltage values over time; a detector for determining the change and / or determining the rate of change, in the shaft grounding current and / or in the shaft voltage; an evaluation system for producing a warning as a function of the change and / or rate of change, in the shaft grounding current and / or the shaft voltage wherein the warning generated is indicative of a developing problem with the rotating machinery.

The invention discloses an intelligent integrated online monitoring system and method for underground cable operation. The online monitoring system comprises a monitoring center as well as a cable anti-stealing detection unit, a cable video monitoring unit, a cable joint temperature monitoring unit, a cable metal sheath grounding current monitoring unit, an environment gas monitoring unit, a cable tunnel water level monitoring unit and a cable tunnel smoke monitoring unit which are connected with the monitoring center respectively. According to the system and the method, various sensors and mutual inductors are adopted to monitor cables and cable environments, the monitoring center masters the operation conditions of the cables in real time and gives an alarm when a normal condition happens, a worker is reminded to clear a fault in time, and large potential safety hazard is avoided; with the adoption of anti-stealing monitoring, the possibility of stealing of the cables is eliminated, in combination of video monitoring, the missing report caused by visual fatigue is prevented, one all-weather dead-zone-free monitoring platform is established, so that visual monitoring of important positions in cable tunnels is realized, manual inspection is replaced, the labor cost is reduced, the time is saved, further, videos can be stored and taken, and later maintenance is facilitated.

The invention discloses a high-voltage crosslinked polyethylene cable grounding current mechanism and fault analysis method. The method mainly includes the steps of carrying out modeling on a crosslinked grounding method connection diagram, building a mathematic model for cable crosslinked grounding current calculation, programming by means of the mathematic model for cable crosslinked grounding current calculation, calculating cable sheath grounding currents after programming, analyzing high-voltage cable sheath grounding currents on the basis of the calculation result of the cable sheath grounding currents, and analyzing faults of a grounding current system on the basis of the analysis result of the high-voltage cable sheath grounding currents. The high-voltage crosslinked polyethylene cable grounding current mechanism and fault analysis method overcomes the defects that in the prior art, the application range is small, precision is low, and utilization is inconvenient to achieve, and has the advantages of being large in application range, high in precision and convenient to use.

A camera assembly for a vehicle includes an end connector with a first connection point that carries a video+signal, a second connection point that carries power, and a third connection point that receives a video−signal, video shield current and ground current. The camera assembly may connect to a conduit assembly of the vehicle that includes a first conduit that carries the video+signal from the end connector to a display in the vehicle, a second conduit that carries power from a power source (such as a battery) to the camera assembly, and a third conduit that connects between the third connection point and a ground point for the display in the vehicle. The camera may include a radio frequency identification element operable to wirelessly communicate between a remote device and the camera to identify the camera module and / or to program the camera.

Disclosed are apparatus and methodology for providing land grid feedthrough capacitor designs having broad applicability to signal and power filtering technologies. Such capacitor designs provide characteristics for use in decoupling applications involving both signal level and power level environments. Low equivalent series inductance (ESL) is provided by current cancellation techniques involving opposite current flow in power or signal and ground current paths through the device.

The invention provides a transformer monitoring device and a fault diagnosis method. The device comprises an oil dissolved gas chromatography on-line monitoring unit, an oil trace moisture tester, a temperature monitoring unit, a partial discharge monitoring unit, a grounding current on-line monitoring unit, a transformer and on-load voltage regulation switch vibration monitoring unit, and a main station computer. Based on the transformer monitoring device and method provided by the invention, the fault of a transformer can be monitored and diagnosed by a variety of monitoring units and monitoring methods. Therefore, the monitoring accuracy is improved.

The invention discloses a network-side circuit of an electric locomotive unit, which comprises two network-side circuit bodies with pantographs. Each network-side circuit body consists of a high-voltage transformer, the pantograph, a high-voltage isolating switch, a main circuit breaker, a grounding switch, a lightning arrestor, a primary-side high-voltage current transformer, a transformer, a primary-side grounding current transformer and a shaft end grounding device. The high-voltage circuit of the electric locomotive unit further comprises a high-voltage circuit body without a pantograph, the high-voltage circuit consists of a main circuit breaker, a grounding switch, a lightning arrestor, a primary-side high-voltage current transformer, a transformer, a primary-side grounding current transformer and a shaft end grounding device. The three high-voltage circuit bodies are connected by roof high-voltage buses and high-voltage connecting cables. The network-side circuit of the electric locomotive unit can meet the requirement of heavy-load and high-power traction, an optional network-side high-voltage electric component can be isolated when breaking down, and power loss of an integral locomotive is minimized assuredly after fault isolation.

The invention discloses a medium-high voltage single-core crosslinked cable induction voltage and circular-current online detection method and a device. The method comprises the following steps: a load-current sensor is sheathed on a cable body under the charged operation condition so as to couple cable load current; a grounding current sensor is sheathed on a cable metallic protecting layer grounding outgoing line so as to couple grounding current of the metallic protecting layer; and the induction voltage of the cable metallic protecting layer is obtained by an induction voltage pickup probe clamped between a fracture of the cable metallic protecting layer grounding outgoing line and a grounding electrode or between the metallic protecting layer outgoing line of a cable line protection grounding side and the grounding electrode. The induction voltage and circular current values of the medium-high voltage single-core crosslinked cable metallic protecting layer can be obtained by optical fiber, an upper computer and a lower computer under the charged operation condition, thus providing effective reference for diagnosing and evaluating the health condition of the cable metallic protecting layer and an outer protecting layer, and providing a technical basis for adjusting and optimizing the grounding mode of the cable line and selecting the types of protects of protecting layers by a cable operation unit.

The invention belongs to the field of online monitoring of transformers, and particularly relates to a device and a method for monitoring the grounding current of a transformer core / clamp based on wireless communication. A straight-through current transformer and a device working circuit board are arranged in a shell. The upper part of the shell is connected with a housing top cover. A display screen is arranged on the housing top cover, and is connected to a controller. An external wireless communication module antenna is led from the shell. The device and the method can be used for monitoring data in real time, have functions of current ultralimit alarming, data information storage, system clock synchronization, parameter configuration and the like, and can be widely applied to the online monitoring of the grounding current of a core / clamp of electric equipment such as a transformer and a reactor, possible failures can be timely discovered, and the routing inspection work of an operator can be reduced or replaced.

The invention discloses a distinguishing, protective method and a protective system of single-phase grounding faults of a neutral point non-effectively grounded power network in view of the judgment wrong regions of the single-phase grounding faults of a neutral point non-effectively grounded system; wherein, the distinguishing method of the single-phase grounding faults distinguishes the fault phase according to the relationship between the zero sequence voltage and phase voltage as well as the relationship between the phase voltages to provide bases for right throwing and withdrawing of grounding protection, and the distinguishing method can particularly distinguish the weak signals of unobservable high resistance grounding faults to eliminate the faults in the bud; a grounding comprehensive protection method and a grounding comprehensive protection system combine a voltage limiting and bypass protection method of fault phase voltage and a current compensation protection method of inductance-current compensation grounding capacitor and current so as to achieve the ideal effects of reliably eliminating the faults such as arc grounding without being influenced by ground current as well as reducing the grounding fault current without accurately tracing and adjusting the compensation current values. The method and the system of the invention have the advantages of strong practicality, simple measurement and control and reliable protection.

The invention provides a current full compensation method and a system based on single-phase earth fault. When zero sequence voltage is not in a preset voltage value range, namely, the happened single-phase earth fault is instant ground connection, an arc extinction coil device with high flexibility in high-resistance ground connection can compensate ground connection capacitive current. When thezero sequence voltage is in the preset voltage value range, namely, the happened single-phase earth fault is not instant ground connection, a breaker in a fault phase transfer ground connection deviceconnected with a fault phase is turned off, fault current is converted into earth current, and a compensable compensation device is further utilized to output full compensation fault residual current. The fault current is converted into the earth current, the earth current can serve as tracking compensation signals of the compensable compensation device, and judgment reference is provided for a compensation effect of the compensable compensation device. In addition, the earth current can be determined by measurement; furthermore, measurement is convenient, and complex calculation is avoided;thus, compensation quickness and accuracy are ensured, compensation precision is improved, and fault points are shielded.

An electric motor with an adjustable speed drive includes a bearing current reduction assembly including a charge concentrator providing a higher electric field concentration through a clearance between an inner bearing cap and a rotor shaft than occurs within a bearing. Accordingly, damaging rotor to ground currents through a bearing are reduced or eliminated. The charge concentrator is disposed on either the rotor shaft or the inner bearing cap, or both.

The invention discloses a high-accuracy implement method of an element for measuring a grounding distance unrelated to the loading current and the grounding resistance. When a high-voltage / ultra-high-voltage / extra-high-voltage has a single-phase grounding fault, the current in a relay location is IPhi, and the voltage is UPhi; the distance from the fault point to the relay location is x; the voltage at the fault point is UPhif; the grounding current is IPhif; and the break current DeltaIPhin of positive sequence and negative sequence in the relay location is measured. Since the grounding is ohmic, UPhif is in the same phase with IPhif; and since DeltaIPhin has the same phase angle as IPhif, UPhif has the same phase angle as the DeltaIPhin, thereby further obtaining a fault distance formula which is unrelated to the loading current and the grounding resistance, wherein Phi is equal to a, b or c, and n is equal to 1 or 2. Since the formula itself is unrelated to the loading current and the grounding resistance, and DeltaIPhin and IPhif have the same phase angle, as a distance protective impedance measuring element, the element has high measuring accuracy, and is not affected by the loading current or the high resistance grounding fault. Theoretical analyses and simulation results show that the proposed principle has very high practicability and computational accuracy.

The invention discloses a tunnel cable grounding current safety alarm expert analysis method. The tunnel cable grounding current safety alarm expert analysis method includes setting alarm threshold values and filtering conditions in a monitoring platform; loading serial numbers and name information of monitoring terminals in the monitoring platform; dividing grounding current abnormalities into three categories including jumping abnormality, absolute value abnormality and inter-phase comparison abnormality; sequentially judging whether grounding current acquired by the monitoring terminals are abnormal or not; filtering current abnormality analysis results and alarm when all the filtering conditions are met; outputting the filtered grounding current abnormality analysis results in the monitoring platform. The tunnel cable grounding current safety alarm expert analysis method has the advantages that alarm analysis of the tunnel grounding current can be achieved, so that current abnormalities can be monitored effectively; through the set threshold values of the filtering conditions of the abnormal current, the abnormal current meeting the filtering conditions can be alarmed, false alarm is prevented and alarm accuracy is improved.

The invention relates to a small earth current grid single-phase grounding fault wire-choosing method, which comprises: 1) Collecting the zero order voltage and the zero order current signal on the voltage sensor and the current sensor of each wire and computing the zero order voltage amplitude, if the amplitude is over the limit, it quotes that it occurs the fault and collects the zero order current after four period of the fault; 2) computing the second, third and forth period effect value I1, I2 and I3 when each line zero order current fault starts and computing the gradient factor K1, K2 of each line zero order current; 3) quoting weather it satisfies K1ú¥KSET and K2ú¥KSET, wherein KSET is the gradient factor setting value with the range 1.2-2.0; 4) if it satisfies K1ú¥KSET and K2ú¥KSET, the wire is earth fault wire. The wire-choosing system comprises a microcomputer including a fault detecting open unit, a zero order current gradient computing unit and a transient gradient wire-choosing unit.

An earth clamp for testing contact voltage, comprising a measuring circuit formed of a voltage inducing transformer and a current measuring transformer, adapted to be mutually coupled by an earth conductor whose earth impedance is to be measured, a microcontroller to deliver an alternating voltage to the voltage inducing transformer and, in response, to receive a reference voltage generated in the earth conductor and an earth current iB+iF induced in the current measuring transformer, the microcontroller being configured to extract an amplitude E of the reference voltage, an amplitude IB and an amplitude IF of the earth current and a phase shift φ between the reference voltage and the loop current iB and to calculate the earth impedance Zb at a determined frequency, the microcontroller also computing the contact voltage Uc at said determined frequency by the product of the earth impedance times the amplitude IF.

A constant current driving circuit for a field emission device has a ground current of an anode electrode measured in real time and the measured ground current is fedback to vary the frequency and duty ratio of a voltage applied to gate and cathode electrodes of the field emission device, thereby causing the ground current of the anode electrode to be constantly maintained. The field emission device has an anode electrode formed on a front substrate, gate and cathode electrodes formed on a rear substrate disposed opposite to the front substrate to be spaced apart from the front substrate by a predetermined distance, and an emitter formed on a top surface of the cathode electrode. The constant current driving circuit includes current detection circuit for detecting a ground current of the anode electrode; an input power unit for applying a driving AC voltage for emitting electrons from the emitter to the gate and cathode electrodes; and a feedback circuit unit for comparing the ground current of the anode electrode detected by the current detection circuit with a predetermined reference voltage to obtain a current variation and providing the input power unit with a frequency signal for varying a frequency of the driving AC voltage or a duty ratio signal for varying a duty ratio of the driving AC voltage in accordance with the current variation.

The invention discloses an arc suppression coil device and method for compensating for an active component in single-phase grounding fault current. The device comprises a Z-type grounding transformer module with a secondary winding, a single-phase arc suppression coil module, a low-voltage reactor module controlled by a thyristor, a single-phase full-bridge inverter module, a three-phase PWM rectifier module and a controller module. The method includes the steps that the active component in the grounding current is compensated for by the arc suppression coil in the mode that a three-phase PWM rectifier is combined with a single-phase full-bridge inverter, when a single-phase grounding fault happens in a power distribution network, the single-phase full-bridge inverter module is controlled to compensate for the active component in the grounding current with the formula (please see the formula in the specification) as instruction current, an appropriate PWM control strategy is adopted for generating driving signals to adjust and control corresponding electric and electronic devices so that the electric and electronic devices can be controlled to output compensation current same to the active component current in magnitude and opposite to the active component current in phase, the active component in the grounding current is optimally compensated for, reliable and stable operation of the arc suppression coil is guaranteed, and the operation safety of the power distribution network is improved.

The invention provides an online monitoring method of grounding current of an iron core of a transformer, and the method comprises the following steps: (1) sheathing a straight-through current transformer on a grounding wire of the iron core of the transformer for getting a primary iron core grounding current signal; (2) utilizing the straight-through current transformer to convert the acquired primary current signal into a secondary current signal and converting the secondary current signal into a voltage signal; (3) performing gear position switching and amplification treatment on the voltage signal, and further sending the signal to an AD (analog / digital) circuit arranged in a controller via a voltage signal conditioning circuit; and comparing with a pre-set alarm threshold, and using the controller to control a display screen to display an alarm signal when the signal is abnormal; and (4) on the one hand, displaying the signal after calculation treatment in the step (3) through the display screen, on the other hand, storing measurement result and measurement time in a FLASH memory. The method is widely suitable for online monitoring of the grounding current of the iron cores / clamping pieces of the transformers, reactors and other electrical equipment.

A device and method to determine the presence of a ground fault that distinguishes between the capacitive portion of the currents to ground, and the resistive portion of the currents to ground by ascertaining aspects of the voltage and residual current waveforms.

The present invention provides a power cable intersect cross connection grounding system grounding current monitoring and evaluating method which is implemented by a power cable grounding current monitoring system. The method comprises the steps of calculating a cable sheath self-impedance, calculating a sheath induction voltage caused by a to-be-tested cable wire core load current, calculating a cable sheath induction voltage caused by a to-be-tested cable sheath grounding current and a large ground leakage current, calculating an induction current of a to-be-tested cable, calculating a cable capacitive current, predicting a grounding current fluctuation value caused by the load change, predicting the grounding current fluctuation caused by the load change, analyzing and determining the current condition of a power cable intersect cross connection grounding system cable sheath, etc. The power cable intersect cross connection grounding system grounding current monitoring and evaluating method of the present invention is different from a method of analyzing and calculating a grounding current from a circuit model purely, introduces the ideas of prediction, analysis and cable parameter characteristic calculation, enables the grounding current monitoring and evaluating accuracy of a power cable intersect cross connection grounding system to be improved effectively, and provides a more effective analysis method for cable external insulation state evaluation.