278results about "Voltage polarity indication" patented technology

A system and method is provided for detecting an island condition using active detection. The active detection involves biasing the voltage, frequency, current or phase of a distributed resource connected to a utility network. Biasing the distributed resource involves inducing a change of voltage, frequency, current or phases above or below the normal operating values. The impact of this biasing on the system operating parameters can then be measure to determine if an island condition exists. Once an island condition has been detected, the system can initiate an anti-islanding procedure to remove the distributed resource from the utility network such as opening a breaker connecting the distributed resource to the network. Additionally, the system and method can include a passive element for detecting frequency and voltage (or other parameters) shifts above certain points.

A remote battery monitoring system and sensors are disclosed in which a plurality of telesensors are connected to batteries in a battery string. The telesensor measure battery data such as voltage, current, and temperature and wirelessly transmit the battery data to a control and collection unit. The control and collection unit receives, processes, analyzes, and stores the battery data. Remote monitoring software running on the control and collection unit can be configured to provide warning alarms when the battery data is outside present limits.

A semiconductor leakage current detector of the present invention includes a first analog switch which causes a current to be measured to flow or to be cut off, a second analog switch which causes a reference current to flow or to be cut off, an integral capacitance element which is connected by the first analog switch and the second analog switch and is charged with the current to be measured or the reference current, a discharge unit which discharges the integral capacitor, and a comparison unit which compares the reference voltage with each of an integral voltage generated in the integral capacitor by a reference current after the discharge of the integral capacitor and an integral voltage generated in the integral capacitance element by the current to be measured after the discharge of the integral capacitor

A fault indicator for indicating the occurrence of a fault in an electrical conductor is automatically configured for an overhead application or for an underground application. The fault indicator has a housing, a battery, a display for indicating the occurrence of a fault, a current sensor for sensing the load current in a monitored conductor, and electromagnetic field sensor to sense the electromagnetic field about the conductor, and a microcontroller for determining whether a fault condition occurred, for determining the magnitude of the electromagnetic field, and for configuring the fault indicator in the overhead configuration if the electromagnetic field is above a predetermined magnitude or configuring the fault indicator for the underground mode if the field is below the predetermined magnitude. In the overhead configuration, voltage inrush restraint is enabled, the fault response time is set within a range of 1 to 50 ms, and the display is operated in bright or dims modes depending upon ambient lighting levels. In the underground configuration, inrush current restraint is enabled, the fault response time is set within a range of 1 to 24 ms, and the display is operated in only the dim mode. Related methods are also disclosed.

A three-phase faulted circuit indicator adjustable to accommodate a variety of three-phase power cables is disclosed. In one embodiment, faulted circuit indicator comprises a flexible holder that encircles the monitored conductor slightly more than one time. The flexible holder includes a plurality of magnetic sensors for monitoring the current within the internal conductors of the power cable, a logic circuit for determining the occurrence of a fault, and an output device for providing an indication of a fault. In a second embodiment, the faulted circuit indicator comprises a plurality of sensor compartments, each disposed about a central point, and each coupled to two other sensor compartments.

A testing system includes a hand-held transmitter that plugs into a receptacle electrically coupled to a selected branch circuit. The transmitter includes a circuit effective to test an arc fault circuit interrupter electrically coupled to the branch circuit by creating a first pulse on the branch circuit that is effective to trip the arc fault circuit interrupter. The transmitter can perform at least one additional test including: determining whether the receptacle is wired properly; determining a location of a circuit interrupting device electrically coupled to the branch circuit by creating a second pulse on the branch circuit that can be sensed by a receiver located proximately to the respective circuit interrupting device and broadly tuned about a frequency of the second pulse; and testing a ground fault circuit interrupter electrically coupled to the branch circuit by creating a third pulse on the branch circuit that is effective to trip the ground fault circuit interrupter.

The invention discloses a charging circuit and a method for preventing charging power supply from reversely connecting in an electronic cigarette or electronic cigarette case. The charging circuit comprises a direct current input terminal, an unit for preventing charging power supply from reversely connecting, a charge management unit and a rechargeable battery. The unit is electrically connected to the direct current input terminal; the charge management unit is electrically connected to the unit and the rechargeable battery. The charging circuit and method according to these embodiments of the invention can effectively avoid the risk caused by the reverse connection of the charging power supply for the electronic cigarette or the electronic cigarette case; it also has the advantages such as low voltage drop and low power consumption.

In an inverter circuit including switching devices and diodes connected in parallel with the switching devices which are provided in pairs of upper and lower arms, and also including resistances for detecting phase currents in a motor connected to the lower arms, during dead time periods when both a switching device in an upper arm and a switching device in a lower arm are off, a voltage across a phase-current detection resistance induced by a phase current flowing through a diode is sampled.

The invention provides a novel overhead transmission line lightning stroke current monitoring method and a novel line lightning stroke fault recognition method which are easy to implement. The technical scheme comprises an inversion algorithm for lightning stroke current of the tower top and a ground wire at the center of the tower span of a lightning struck overhead transmission line, a lightning stroke fault type recognition method and a line lightning stroke probability observation and lightning leading width calculation method. The technical scheme provided by the invention has important application values for improving the lightning performance and the risk evaluation level of the overhead transmission line, optimizing the line lightning protection design and improving the line lightning protection level.

A clamp meter is provided for measuring consumption of current and power of an electrical appliance. The clamp meter includes a power inlet port and a power outlet port that are in controlled connection with each other. A current detection element is arranged between the power inlet port and the power outlet port. When the power inlet port is connected to a power source and the power outlet port is connected to an electrical appliance to be detected, with the electrical appliance turned on, the current detection element detects and converts the current flowing through the power outlet port into a digital signal, which is displayed on a display device mounted on the clamp meter, whereby, through the data and information displayed on the display device, a user may get aware of the power consumption of the electrical appliance and abnormality of power consumption thereof.

The invention discloses a self energy supply lightning current detection system, which is used for being matched with a lightning rod device for use to realize the defection on relevant parameters of lightning current. The self energy supply lightning current detection system comprises a signal sampling maintaining device, an energy taking device, a single chip control unit, a hardware clock unit and a data storage unit, wherein the signal sampling maintaining device comprises a current sensing unit, a first voltage limiting protection unit and a positive/negative peak value maintaining unit which are connected in sequence, and the energy taking device comprises an energy taking coil, a front end protector, a rectifying and wave-filtering unit, a second voltage limiting protection unit, a voltage stabilizing unit and a DC/DC unit which are connected in sequence. The self energy supply lightning current detection system of the invention can continuously realize the monitoring on whether a transmission line or a building lightning rod suffers with the lightning strike or not, and can accurately record the time, the amplitude value in the occurrence of the lightning strike and the polarity, a special triggering circuit is not needed, and the invention has the characteristics of high precision, simple structure, small size, low cost, high safety and the like.

The invention discloses a method for rapidly judging a wiring error of a power distribution transformer monitoring terminal. The method is characterized by comprising two steps of voltage detection and current return accuracy detection, wherein the intelligent judgment on the wiring error of the power distribution transformer monitoring terminal is realized according to the phase relationship between a three-phase voltage and a current. According to the method, the method is embedded into the terminal in mode of embedded software directly; the automatic operation can be realized when the terminal is powered on, and then the wiring error of the terminal is judged automatically; and the installation personnel are prompted through a liquid crystal interface and a buzzer; the accuracy rate of the installation is improved; and the labor waste caused by secondary construction is avoided.

A device for switching a semiconductor-based switch includes a terminal that is configured to be connected to a control terminal of the semiconductor-based switch. A controllable activation voltage source is configured to provide a time-varying activation voltage potential. A controllable resistive circuit includes at least two ohmic resistances connected in parallel that are controllable such that at least three resistance values of the parallel connection result. A control device is configured to control the controllable activation voltage source and the controllable resistive circuit independently of one another. The controllable activation voltage source and the controllable resistive circuit are connected to a series connection connected to the terminal. The control device is configured to control the controllable activation voltage source and the controllable resistive circuit in a time-varying manner to obtain time-varying resistance values of the controllable resistive circuit and the time-varying activation voltage potential of the controllable activation voltage source.

The present invention provides an improved method of identifying which electrical conductor is supplying a signaling-point that is located on that conductor, in the electrical grid. The present invention makes the identification by measuring currents flowing into and out of a common connection-point, such as a power bus, and analyzing concurrent portions of these currents to determine whether they are ingress-current or egress-current over the analysis-intervals, and by a subsequent intra-bus and inter-bus analysis of the ingress/egress patterns. This is in contrast to prior art systems that rely on the measurement of signal strength, an approach that does not take best advantage of information in the signal because it fails to consider polarity of instantaneous voltages, reflective of the direction of current flow, or the intra-bus and inter-bus ingress/egress current-relationships.

The invention relates to a mode recognition-based current transient state quantity direction protection method for a power transmission line with a unified power flow controller, and belongs to the technical field of power system relay protection. When the power transmission line with the unified power flow controller has a fault, data, which is obtained at a line measurement end, of line mode current containing a fault phase is subjected to principal component analysis, and a forward direction fault is distinguished from a back direction fault according to the projection of sample data on a first principal component axis. According to the invention, principal component cluster analysis directional protection of the line mode current containing the fault phase can reliably distinguish the forward direction fault from the back direction fault, also can judge that the forward direction fault is positioned at the left side or the right side of the unified power flow controller, and can reliably recognize a fault section. Therefore, criterions about property recognition of the forward direction fault and the backward direction fault have high reliability.