870 results about "Ground current" patented technology

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.

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.

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.

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 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 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.

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 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 i_B+i_F induced in the current measuring transformer, the microcontroller being configured to extract an amplitude E of the reference voltage, an amplitude I_B and an amplitude I_F of the earth current and a phase shift φ between the reference voltage and the loop current i_B 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 I_F.

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.