Abstract: A control system for an electrical power system includes an electrical corrective device, a voltage measuring device coupled to each phase of the electric power system, a current measuring device connected between each phase of the electric power system and the electrical corrective device, and a protective device connected to outputs of the voltage measuring device and the current measuring device. The protective device includes a controller configured to detect an imbalance using the measured voltages and currents output from the voltage measuring device and the current measuring device without using or independently of other recent voltage or current measurements for other points in the electrical corrective device and independently of a neutral-ground measurement at the electrical corrective device.

Abstract: An electrical phase checking apparatus includes a first voltage sensor, a first current sensor, a first binary indicator corresponding to the first voltage and current sensors, a second voltage sensor, a second current sensor, and a second binary indicator corresponding to the second voltage and current sensors. The first binary indicator is configured to indicate when a phase separation between a voltage waveform measured by the first voltage sensor and a current waveform measured by the first current sensor is not more than a first value, and the second binary indicator is configured to indicate when a phase separation between a voltage waveform measured by the second voltage sensor and a current waveform measured by the second current sensor is not more than a second value.

Abstract: A system detects the wiring phase of an unknown phase voltage at a remote location relative to a reference phase voltage at a reference location in an electrical power distribution system having a single phase or poly phase power line. A transmitter transmits a signal from the reference location to the remote location. The signal comprises a characteristic signal pattern. Moreover, a first circuit detects at the remote location the characteristic signal pattern of the signal and determines a first time interval between the characteristic signal pattern and the occurrence of a reference point in the unknown phase voltage. A second circuit determines at the reference location a second time interval between the characteristic signal pattern and the occurrence of a reference point in the reference phase voltage. The system determines the wiring phase of the unknown phase voltage from the first time interval and the second time interval.

Abstract: An apparatus for collecting characteristics of a power line in a broadband over power line system that comprises a power line characteristic measuring device for measuring power line characteristics and a collector unit for collecting data from the power line characteristic measuring device and sending the data over the broadband over power line system to a remote location where the collector unit is a regenerator. Further, the apparatus can comprise a coupler, to couple the power line to the power line characteristic measuring device and the collector unit and allows a broadband over power line signal to pass from the power line to the collector unit.

Abstract: A signal analyzer for calculating the power consumption and power factor of a three-phase power system driving a motor includes logic that determines whether the analyzer's own input terminals are wired in a proper or inverted manner. To do this, the signal analyzer observes a pattern of zero crossing slope values of the three line-to-line voltages of the three-phase power system and observes a pattern of zero crossing slope values of the current in the three power lines. The analyzer also compares the slope of a voltage signal as the signal passes through zero volts and the sign of a corresponding current signal that exists as the voltage signal crosses zero volts. Based on the observed voltage and current patterns and the voltage-to-current relationships, the analyzer can positively identify which of a plurality of inputs or signal wires are inverted.

Abstract: The rotation phase angle measuring device measures a voltage instantaneous value of an electric power system in a period of 1/(4 N) of one period of a reference wave and integrates voltage amplitude of a squared value of the voltage instantaneous value in arbitrary timing for measuring the voltage instantaneous value. The rotation phase angle measuring device calculates chord lengths of the voltage rotation vectors in the above two timings by the integral arithmetic calculation with respect to a difference between two measured adjacent voltage instantaneous values in one pitch period including the above timing. The rotation phase angle measuring device also has a rotation phase angle calculator for calculating a phase angle of the voltage rotation vector in one pitch period including the above timing on the basis of the voltage amplitude value and the chord length value calculated by the above calculations.

Abstract: One embodiment includes a system comprising a switching power supply comprising at least one switching phase configured to provide a corresponding phase output at a respective phase node thereof, the respective phase node being coupled to an output through a filter for providing a corresponding output signal. At least one resistor interconnects the respective phase node of each of the at least one switching phase with a test node, the test node being configured to provide a test signal representing the phase output at each phase node.

Abstract: It is determined which of six continuous sections having different magnitude correlation of signal amplitude of each phase of an input three-phase signal a section is. Predetermined subtraction is performed between respective phases in the section, to obtain a normalized amplitude value normalized in the section, using the subtraction result. The normalized amplitude value is converted to a vector phase for one cycle based on a predetermined phase and output corresponding to the determined section.

Abstract: To identify a phase in a multi-phase electrical system, the following method is proposed: transmission, on a defined phase (L1, L2, L3) of a line of the system, of a message with a known synchronization with respect to the phase voltage (V1, V2, V3); reception of the message on an undefined phase (X, Y, Z) of the line; identification of the phase on which the message has been received according to the displacement between the voltage on said undefined phase and the message received.

Abstract: The present invention relates to detecting the wiring phase of an unknown phase voltage relative to a reference phase voltage in an electric power distribution system having a polyphase power line. In order to reliably detect the wiring phase at the remote location relative to a reference wiring phase even if the remote location is at a larger distance from the reference location, at least one relay location is arranged between the reference location and the remote location and connected to the wiring phase of the polyphase power line. A first phase relation is detected between the reference wiring phase voltage at the reference location and the wiring phase voltage at the relay location. A second phase relation is detected between the wiring phase voltage at the relay location and the wiring phase voltage at the remote location. The wiring phase of the remote location relative to the wiring phase at the reference location is detected based on the first phase relation and the second phase relation.

Abstract: A process and apparatus for identification of the direction of rotation of two periodic electrical signals present on two electrical conductors, particularly of a three-phase power system. In this process, the signals are sampled from two conductors by two wires of the test apparatus provided with a connection to ground via a user of the apparatus. The direction of rotation is determined from information provided by the two signals. The direction of rotation is determined during the zero-crossing of the voltage between the two phase signals. The invention can be used in a apparatus for testing of the direction of rotation of the phases of a three-phase network.

Abstract: The present invention provides a phase voltage circuit. In one embodiment, the phase voltage circuit includes a line voltage stage coupled to at least three input voltage lines and configured to provide at least two corresponding line voltages. Additionally, the phase voltage circuit also includes a difference voltage stage coupled to the line voltage stage and configured to provide at least one phase voltage from the at least two corresponding line voltages.

Abstract: An unbalanced current detection circuit determines when a multi-phase, normally-balanced load is unbalanced. The detection circuit of the present invention includes a plurality of current-squaring circuits, each squaring a sensed current of one of the phases. A summing circuit produces a sum of the squares of the currents. If the load is balanced, this sum should be relatively constant, perhaps changing only slowly over time, with little or no ripple from that relatively constant value. In an unbalanced current condition, the sum of the current squares would consist of an average (dc) component plus a ripple (ac) component. If the amplitude of the ripple current exceeds a threshold, it is determined that the currents are unbalanced.

Abstract: A solid state power controller (SSPC) (100) includes a power switching controller (30) and power switching devices (PSDs) (20A, 20B, 20C) for controlling each phase of a multiple-phase load to switch-on or -off at a zero-crossing point of a corresponding phase of a multiple-phase power source. The power switching controller (30) may include an ASIC (25A, 25B, 25C) for controlling each PSD (20A, 20B, 20C) to switch the corresponding load phase on or off. The ASIC (25A, 25B, 25C) may be configured to control the PSD (20A, 20B, 20C) to switch-on the load phase at a detected zero-crossing point of the voltage supplied by the corresponding phase of the power source, and to switch-off the load phase at a detected zero-crossing point of the load current supplied by the corresponding phase of the power source.

Abstract: A steering angle ?t detected by the torque sensor is read at S900. Then, an electrical angle ?m corresponding to a motor rotational angle is read at S902. At S908 through S922, motor rotational numbers are calculated based on ?t, ?m and the rotational number of a handle, and a correct rotational number of the handle is calculated from the motor rotational number which is the nearest to an integer of all of the calculated motor rotational numbers. Thereafter, an absolute steering angle which is not influenced by various errors is calculated based on the calculated rotational number of the handle and the steering angle ?t detected by the torque sensor.

Abstract: The method is for testing an electrical component. The sender unit 12 may be applied to an electrical plug 24 that has a first line 28, a second line 32 and a ground line 36. It is determined which of the lines 28, 32, 36 that has a voltage potential relative to the surrounding. The phase configuration of the electrical plug 24 may be determined. The unit 14 is applied to a remote electrical unit and the sender sends a synchronization signal 41 to the receiver unit 14 that starts a counter providing a measurement of the time difference between corresponding phase positions of the alternating current of the plug 24 and that of the remote electrical unit. This time difference can then be converted to a phase difference value. The system may also be used to identify a specific fuse that is associated with the plug and for testing ground fault interrupting devices.

Abstract: A method for diagnosing induction motor broken bar faults using the resultant magnetic field pendulous oscillation phenomenon is disclosed. Broken bar faults cause the resultant magnetic field of an induction motor to possess a pendulous oscillation modulating its inherent rotation at synchronous speed, and the range of this angular pendulous oscillation, referred to as the swing angle, increases with an increase in the number of broken bars. The angular pendulous oscillation is determined by calculating the space vectors derived from motor terminal voltages and currents. The variation in the angular difference between these two space vectors versus time is used to observe the resultant magnetic field's pendulous oscillation, and thus provide on-line rotor fault diagnostics.

Abstract: An apparatus (14) for detecting a zero-crossing of an alternating current after occurrence of a fault in a current path (2) for determining a suitable time for opening an electric switching device (2) arranged in the current path for breaking the current in the current path comprises members (15) adapted to detect the current in the current path. An arrangement (19) is adapted to calculate the dc-level of the current and the decay of the dc-level with time on the basis of values of the alternating current detected and also predict the time for a future zero-crossing of the alternating current on the basis of at least current values obtained through said current detection, the dc-level calculated, the dc-decay calculated and information about the period time of the alternating current.

Abstract: An input signal is a complex vector whose phase is a coherent measurement of the phase rotation occurring between two separated symbols of a received CDMA signal. A processing block (30) provides a first signal showing the magnitude and the sign of the imaginary part of the input signal, and a second signal showing the magnitude and sign of the real part of the input signal to an initialisation block (31). A quadrant determination block (32) examines the signs of the signals to determine the quadrant in which the phase of the input signal exists. A comparator block (33) determines if the magnitude of the first signal is greater than or equal to the magnitude of the second signal. If a negative determination is made, the magnitude of the first signal is doubled in a multiplication block (35) to form a multiplied signal, and a counter incremented, initially from zero. The comparator block (33) then determines if the multiplied signal is greater than or equal to the magnitude of the second signal.

Abstract: A magnetic field sensor including an amplifier and a magnetic field element for outputting a signal to a switch circuit according to the strength of an applied magnetic field. The switch circuit outputs a signal selected by an external two-phase signal to an amplifier that amplifies the signal and outputs a resulting voltage to a first end of a memory element. A switch, having one end connected to a second end of the memory element, is controlled by the two-phase signal. The switch closes in a first phase of the two-phase signal causing the memory element to store the output voltage of the amplifier, and opens in a second phase causing a vector sum of the output voltage the amplifier to be stored in the memory element and providing the output voltage to a signal output terminal connected to the second end of the memory element.

Abstract: A method and apparatus for measuring quantities of a multi-phase electric line, the apparatus comprising a control unit and a measurement unit in connection with each phase conductor of the electric line, wherein each measurement unit is arranged to measure a first phase quantity of the phase conductor in connection with which it is located and to transfer the measured quantity value to the control unit, the measurement unit located in connection with one phase conductor being further arranged to measure phase angles between the first phase quantity of said phase conductor and first phase quantities of other phase conductors and to transfer the measured phase angle values to the control unit.

Abstract: A line phase identification system and method identifies the phase of a power line at a remote unknown-phase line (160) in a three-phase power distribution network (100). The instantaneous phase of a known-phase line (150) is measured and saved each GPS second using a 1-pps time mark of a GPS receiver (660). The instantaneous phase at the unknown-phase line (160) is measured at a single GPS second using the 1-pps time mark of a GPS receiver (660) and compared to the phase measurement taken from the known-phase line (150) at the same GPS second. The differential phase between these simultaneously taken known and unknown instantaneous phases will be close to either 0, +120, or −120 degrees, thus identifying the line phase at the line under test (160).

Abstract: The system of the present invention includes transformers 12-1, 12-2 and 12-3 for detecting voltages received at a power receiving point in the power system, a negative-phase-sequence component voltage detector 18 for arithmetically operating the voltage of a negative-phase sequence component from the received voltages and amplifying the voltage of a negative-phase-sequence component to output the amplified voltage of a negative-phase-sequence component, and a negative-phase-sequence voltage compensation input unit 14 for injecting the outputted voltage of a negative-phase-sequence component into a system as an object of compensation to compensate for the received voltages at the power receiving point. The voltage of a negative-phase-sequence component is cancelled for a load 17 as an object.

Abstract: A wireless alternating current phasing voltmeter multimeter that uses modular wireless based components in order to provide indications of highly desirable parameters of interest, such as AC voltage, phase rotation, and the number of degrees difference between phases. The use of wireless technology eliminates the cable customarily used to interconnect the test probes and the metering circuitry, which may effectively eliminate the concern regarding the distance separating the power lines that are to be tested. The wireless alternating current phasing voltmeter multimeter has two base modules, but, because of the flexibility of the design, modifications can be readily incorporated into the present invention modules that allow for numerous operational and functional permutations to be implemented in order to meet an individual user's needs including the use of one of the modules as a hand-held base module that can be remotely located away from the electrical power lines (or test points).

Abstract: A cable phase identification system and method identifies the phase of a power cable at a remote location in a three-phase power distribution network. The instantaneous phase at a known phase location is measured and saved each GPS second using the 1 pps time mark of a GPS receiver. The instantaneous phase at an unknown phase location is measured at a single GPS second using the 1 pps time mark of its GPS receiver and compared to the phase measurement taken at the known phase location at the same GPS second. The differential phase between these simultaneously taken known and unknown cable instantaneous phase measurements will be close to either 0, +120, or −120 degrees, thus identifying the cable phase at the unknown phase location.

Abstract: An apparatus and method are disclosed that may be used to determine equivalent individual phase voltages and phase currents from an alternating delta power source and load configuration. A delta-wye input transformer and a wye-delta output transformer are interconnected between the delta power source and the delta power load. Each phase of the delta power source is effectively connected across a corresponding wye configured coil. The delta-wye input transformer and the wye-delta output transformer are electrically connected to each other in a manner thereby providing three conductors through which the individual phase currents through the wye coils may be directly measured.

Abstract: An electrical monitor circuit in which star points of taps on a first and a second side of a three-phase current limiting device are voltage compared. Possible applications are combinations with electrical switches, especially for power supplying and protecting circuits for electrical motors.

Abstract: A method for identifying a rotation direction of a three-phase network includes the steps of sampling the individual phases at given times and using an evaluation algorithm to evaluate the measured values or interpolated approximate values, or only the mathematical signs of the values, in order to determine the rotation direction. In addition to the basic method for an ideal signal profile, half-wave-rectified signal profiles of individual phase conductors can preferably be evaluated. The method can advantageously be used to detect the rotation direction with a digital overload relay, using a digital signal control and/or signal processing which is already provided in the digital overload relay.

Abstract: An apparatus and method for determining, in real time, the key parameters of a three phase system electrical generator's output. A pair of reference vectors in quadrature (orthogonal) is phase-locked to a selected input open delta line to line voltage vector. Preferably, the cosine reference vector is locked 45° out of phase from the selected input vector whereby a best projection of the input vector onto the quadrature pair is provided and increases accuracy in subsequent magnitude and phase calculations. The phase-locked reference vectors provide a basis for computing the magnitude and phase angle for the remaining open delta line to line voltage vectors and three line to neutral current vectors.

Abstract: A power supply negative-phase detecting circuit (10) for electronic equipment (12) using a three-phase AC power supply source includes a pulse generator (13) for generating a first pulse indicating the phase difference between any pair of two phases of three-phase AC power to be supplied to the electronic equipment and a second pulse indicating the phase difference between another pair of two phases of the three-phase AC power, a differentiating circuit (25) for generating a third pulse from the second pulse in synchronism with the rise-up of the second pulse so that the third pulse has a pulse width smaller than the phase difference between the first and second pulses, and a switching unit (14) for subjecting the first pulse and the third pulse to OR operation and turning on/off the power supply to be supplied to the electronic equipment on the basis of the OR operation result of the first and third pulses.

Abstract: In order in an electronic apparatus (1a), in particular an electricity meter (1b), to afford a simple way of monitoring the failure of the reference phase (L2), it is provided that the angle (&agr;) between two detected interlinked voltages (UL2/L3 and UL2/L1) is measured. When a predeterminable limit value (&agr;G) for the angle (&agr;) is exceeded, a fault signal is produced, which represents failure of the reference or datum phase (L2). Preferably an Aron circuit is used.

Abstract: A method for generating a signal identifying a three-pole short-circuit occurring in a three-phase power transmission line in which the phase currents and phase voltages are sampled forming phase current and phase voltage sampling values and the signal is formed from the phase current and phase voltage sampling values. In order to reliably detect three-phase short-circuits with such a method, even during oscillations, a positive phase-sequence system effective power parameter that is proportional to the instantaneous value of the positive phase-sequence system effective power of the power transmission line is formed, from which a grid frequency component parameter and a swing component parameter are then determined. The signal is generated from the grid frequency component parameter and the swing component parameter.

Abstract: Line voltage and line current signals are sensed on a power line having at least one conducting path. The sensed line voltages and line currents are converted into a digital signal. A phase-to-neutral voltage signal and phase current signal are computed from the digital signal to thereby define a phase of the power line. An interval of orthogonality is determined from the sensed voltage and current signals, coinciding with passage of an integral number of cycles of a fundamental frequency reference signal which is computed from the computed phase-to-neutral voltage signal. A vector metering quantity is computed for the determined interval of orthogonality from the computed phase-to-neutral voltage signal and the computed phase current signal. The vector metering quantities to be computed may be identified and computed based upon an associated detent. The vector metering quantity is also computed based on an identified circuit topology.

Abstract: The present invention pertains to a device and method for determining the sign of a phase angle of a first and second, essentially identical, periodic electric signals on corresponding first and second electrical conductors L1, L2, in particular, to determine the phase sequence in a three-phase power system. The device according to the present invention has a sensing device for sensing of the first signal from the first conductor L1 and of the second signal from the second conductor L2; a trigger device 25 for receiving the sensed first signal and specifying a time reference point and/or a time reference window within the signal period of the first signal and outputting a corresponding trigger signal; and a determination device 31, 32, 33 for receiving the trigger signal and the sensed second signal and determining the sign of the phase angle under consideration of at least the value of the second signal at the time reference point and/or the waveform of the second signal within the time reference window.

Abstract: Disclosed is a method and arrangement for use in an electrical utility meter, the electrical utility meter operable to be connected to a plurality of electrical service types. The arrangement is operable to identify a present service type, the present service type being one of the plurality of electrical service types to which the electrical utility meter is connected. The arrangement comprises: conversion circuit for obtaining measured voltage magnitude and phase angle data for a plurality of phases in a polyphase electrical system; a memory; and a processor connected to said memory and said conversion circuit. The processor is operable to execute programming steps stored in the memory to receive the measured voltage magnitude and phase angle data from the conversion circuit and identify the present electrical service type based on the measured voltage magnitude and phase angle data.

Abstract: The present invention includes an electrical utility meter operable to measure power consumption. The method detects and compensates for one or more wiring errors that affects the power consumption measurement of the electrical utility meter. The method includes the steps of: obtaining measured phase angle data for a plurality of phases in a polyphase electrical system; periodically performing one or more diagnostic tests using the measured phase angle data to determine whether a wiring error is present, automatically adjusting the operation of the electrical utility meter to effect a compensation for the wiring error, said compensation increasing an accuracy of power consumption measurement of the electrical utility meter. The meter is operable to detect and compensate for wiring errors including polarity errors and cross phasing errors. According to another method of the present invention, the meter is operable to determine automatically the service type to which it is connected.

Abstract: In a first measurement step, the two test probes of a measurement apparatus are contacted with two of the three phase lines. The measurement apparatus determines the frequency of the three-phase voltage. In a subsequent second measurement step, one of the two test probes is brought into connection with the remaining third phase line. The other test probe is held in contact with the other line. In the second measurement step the voltage level or voltage profile on the third phase line is evaluated inside the measurement apparatus in comparison to the first phase line during one or more time windows of length .pi..

Abstract: Line voltage and line current signals are sensed on a power line having at least one conducting path. The sensed line voltages and line currents are converted into a digital signal. A phase-to-neutral voltage signal and phase current signal are computed from the digital signal to thereby define a phase of the power line. An interval of orthogonality is determined from the sensed voltage and current signals, coinciding with passage of an integral number of cycles of a fundamental frequency reference signal which is computed from the computed phase-to-neutral voltage signal. A vector metering quantity is computed for the determined interval of orthogonality from the computed phase-to-neutral voltage signal and the computed phase current signal. The vector metering quantities to be computed may be identified and computed based upon an associated detent. The vector metering quantity is also computed based on an identified circuit topology.

Abstract: A circuit for detecting the phase angle of a three-phase alternating current includes a plurality of low-pass filters installed at each input port for removing noise and high-frequency signals mixed in an alternating current input signal, a plurality of multipliers each for multiplying the signal output from each of the low-pass filter by a feedback signal, a subtracter for receiving the signals output from the plurality of multipliers and calculating an error between two signals, a loop filter for receiving the signal output from the subtracter and filtering the same, an integrator for receiving the signal output from the loop filter, time-integrating the same, and outputting an estimated digital phase angle signal, and a phase delay compensator installed between the subtracter and the loop filter, for compensating for phase delay of the input signal caused by the low-pass filters.

Abstract: A quadrilateral characteristic relay system for determining a fault associated with a multiple-phase electric power transmission system is disclosed. The system dynamically adapts one line of the quadrilateral trip region to account for the interaction of load current and fault resistance. As a result of the adaptation, the system exhibits better overreach and underreach performance characteristics. The system employs impedance and voltage plane quadrilateral characteristics using negative sequence current as a proxy for fault current. In the voltage plane, the fault determination is made through a series of comparisons, avoiding computationally inefficient mathematical divisions.

Abstract: Apparatus for performing a variety of tests, including phase matching, detection of open phases and energized/not energized verification, on primary distribution cables. The apparatus is operable from a location which is physically remote from the primary distribution cables under test and does not require an ohmic contact to such lines, thereby substantially enhancing the safety of such testing.

Abstract: A system for automatically detecting whether a power converter or inverter is correctly connected to a three-phase AC power source consisting of first, second, and third phases, the system comprising: a zero-crossing comparator (1) for determining whether the phase of the first-phase voltage (current) is in a positive half cycle or a negative half cycle and generating a first discrimination signal (C.sub.U); a zero-crossing comparator (2, 3) for determining whether the phase of the second- or third-phase voltages (current) is in a positive half cycle or a negative half cycle and generating a second discrimination signal (C.sub.V or C.sub.W); and a D-type flip-flop (5) which detects, in response to the first discrimination signal, that the second discrimination signal is in a predetermined half cycle.

Abstract: An apparatus for detecting the amplitude and phase of an a.c. signal detects the a.c. signal with signal detection means (4), calculates an a.c. signal that is phase-shifted by the amount of the phase characteristic .phi. of the calculation circuit (14) at the frequency of the detected a.c. signal, multiplies the detected a.c. signal by cos .phi., and multiplies by 1/sin .phi. the multiplication result subtracted by the phase-shifted a.c. signal.

Abstract: A missing phase detector circuit which monitors the ac three-phase output voltages of power equipment or sources and produces an output signal in the event a missing ac phase is detected. The circuit reduces the monitored phase voltages to low values and produces an ac ripple voltage waveform where each ripple represents a phase. An analyzer circuit examines the ac ripple voltage waveform for its zero crossings and produces a pulsed dc waveform where the width of the pulses is normally small. If any of the pulses is found to be wide, indicating a missing phase, a positive high signal is output by an AND gate. This output signal may be used to initiate illumination of a "Missing Phase" indicator or it may be used for equipment control purposes. Provision is made to prevent a false output signal when there is no input power. The circuit is not sensitive to frequency, power factor or unbalanced loads.

Abstract: A transmitting box is connected to a first electrical outlet in a building. The phase of the first electrical outlet is used as the reference phase. The transmitter box senses each of the zero-cross-overs of the reference phase and injects a data packet of the data carrier frequency at each zero-cross-over. A receiving box is connected to a second electrical outlet in the building. The second electrical outlet has an unknown phase which may be different from the reference phase. The receiver box receives each data packet and senses each phase zero-cross-over of the unknown phase. The receiver box uses the time between each reception of a data packet and each detection of an unknown phase zero-cross-over to determine the phase angle of the unknown phase relative to the reference phase.

Abstract: An integral electronic meter system diagnostics package including a microprocessor, storage memory, logic for automatically and periodically performing a pre-select series of system diagnostic tests, and recording any results which exceed predefined programmable thresholds, and display means for displaying error and/or diagnostic messages identifying selected diagnostic data and/or errors discovered in the meter tests during a predefined period.

Abstract: A phase sequence indicator with two measuring contacts for contacting with connections of the object to be measured has a grouring contact touchable by the user, an evaluation circuit connected to the measuring contacts and the grounding contact, and an indicating device controlled by the evaluation circuit for indicating the direction of the rotary field. The evaluation circuit has a voltage-testing circuit for detecting the value of the voltage occurring between the measuring contacts, and the indicating device comprises additional indicating elements for indicating the value of the voltage.

Abstract: A method and a device for phase selection for single-pole tripping of high-impedance ground faults in direct grounded power networks. Starting from the ratio of the negative-sequence voltage to the zero-sequence current (U2/I0) and the ratio of the negative-sequence voltage to the positive-sequence voltage (U2/U1), two criteria with different conditions are formed, each of which indicating a faulted phase, and if both criteria indicate the same phase as faulted, single-pole tripping can take place.

Abstract: A real time three-phase analyzer stores digitized values of the signals of the three-phase circuits in memory so that they may be addressed according to circuit and sample number. Positive, negative and zero phase sequences are developed without the need for trigonometric calculation by combining samples offset in memory by a number of samples approximating 120.degree.. That number of samples may be determined for an arbitrary frequency of the three-phase system by identifying zero-crossing points of one such signal and assuming the number of samples equates to 360.degree. of phase of that circuit. The phase sequence of the three circuits necessary for the calculation of the positive, negative and zero phase sequences may be determined by comparing the relative position of positive going zero-crossings for each of the three circuits.

Abstract: A voltage rotation indicator for testing the phase sequence of live multi-phase electrical power is mounted within a housing. The housing is provided with structure for removably mounting the indicator on a meter box or can during voltage rotation testing. Contact plungers extend from the housing and contact meter jaw test points in the meter box during testing. Field personnel are thus not required to insert their hands into the meter box to attach test clips to the live circuit.