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| Number | Title | Issue Date |
| 7852064 | Meter device and method of testing a cut neutral conductor A meter device for checking the measurements of an electrical meter, such as that used by electrical utilities is provided. The meter device has a base with electrical phase conductors arranged to couple with a meter socket. A housing is attached to the base. Electr... | 12/14/2010 |
| 7286953 | Device testing automation utility and method Various apparatuses, methods, computer programs, and other systems are disclosed for facilitating testing of a module. In embodiment, a method is provided that comprises the steps of creating a plurality of tasks in a computer system, each of the tasks comprising a ... | 10/23/2007 |
| 7112946 | Transformer with selectable input to output phase angle relationship A three-input induction transformer in which the phase relationship of the power output relative to the power input is selectable/adjustable after the transformer is placed in operation in the field. The transformer includes a primary set of windings and a three-pol... | 09/26/2006 |
| 6456097 | Fault current detection method A method for measuring the impedance of electrical distribution equipment includes: applying a voltage at a first selected frequency to electrical distribution equipment, waiting a delay time for transient effects to settle, measuring current through the ... | 09/24/2002 |
| 6147616 | Automatic power interruption and re-supply relay for an electric power line The present invention provides a digital automatic power interruption and re-supply relay for performing detection and comparing operation to inform a state of an accident with voice and numerals and automatically operating a connected relay to interrupt ... | 11/14/2000 |
| 5796259 | Methods and apparatus for detection of fault direction Apparatus and methods for detecting the direction of a fault in relation to a switch connected between a source and a load are shown to include a voltage sampler for generating samples of the voltage during first and second power cycles. A current sampler... | 08/18/1998 |
| 5714889 | Method and device for indicating the direction of rotation of a three-phase system A method and measuring device are provided for measuring the direction of rotation of a three-phase system. The measurement is carried out by measuring sensors. A coupling circuit is connected to each measuring sensor and transforms the voltage produced i... | 02/03/1998 |
| 5652505 | Power consumption measurement device for a multiphase alternating current system Disclosed is a watt/watthour meter which is capable of automatically correcting incorrect connections between the apparatus and a multiphase AC system. Each power line of the multiphase system is connected to the watt/watthour meter by means of a voltage ... | 07/29/1997 |
| 5420503 | Phase sequence indicator 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 i... | 05/30/1995 |
| 5390067 | Phase selection for ground fault 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 negati... | 02/14/1995 |
| 5314353 | Test lead adapter An adapter is provided for adapting a voltage or phase rotation indicator for use with multiphase electrical power. The adapter allows the phase rotation indicator to be used in situations where it might not otherwise be used, such as when the power condu... | 05/24/1994 |
| 5298853 | Electrical apparatus for detecting relationships in three phase AC networks An electrical apparatus for visually indicating phase sequence, phase asymmetry and presence of three phases of an AC network comprising two transistors connected by their emitters to a first voltage terminal of the three phase network, the bases of the t... | 03/29/1994 |
| 5184063 | Three phase reversal detection system A polyphase reversal detection and correction system which operates over a wide range of line frequencies and produces an automatic phase correction for maintaining proper phase sequence to a rotating device. The system includes a circuit arrangement for ... | 02/02/1993 |
| 5039936 | Voltage rotation indicator mounting apparatus 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... | 08/13/1991 |
| 4879509 | Zero-phase-sequence voltage sensing apparatus This invention relates to a voltage sensor for sensing a voltage on an electrically charged object such as a distribution line or the like, the sensor being disposed with an insulation space to the object. The voltage sensor includes an amplifier circuit ... | 11/07/1989 |
| 4804922 | Voltage sensor This invention relates to a voltage sensor for sensing a voltage on an electrically charged object such as a distribution line or the like, the sensor being disposed with an insulation space to the object. The voltage sensor includes an amplifier circuit ... | 02/14/1989 |
| 4723189 | Negative sequence detector for a continuous wave frequency transducer A negative sequence occurring in a polyphase power system control including a continuous wave frequency transducer causes a second harmonic to be generated which for a 60 Hz system comprises a 120 Hz signal. In a preferred embodiment of the invention, the... | 02/02/1988 |
| 4607309 | Apparatus for detecting arcing faults on low-voltage spot networks A protective relay for detecting power arcing faults on a three-phase electrical power spot network. A phase-to-phase power arc on a spot network produces harmonics on the phase-to-phase voltages, and the phase currents; a phase-to-ground arc produces har... | 08/19/1986 |
| 4447843 | Negative sequence network having a frequency compensated filter Disclosed is a phase sequence network. The network is compensated for frequency variations in the signal applied to the sequence network so as to develop a desired sequence component output that is accurate over a limited but adequate range of frequencies... | 05/08/1984 |
| 4366521 | Sequence filters for determining the symmetrical components of multiphase AC power systems Negative sequence filters employing one to three operational amplifiers and a single reactive element generate the negative sequence voltage of a three phase AC power system by generating two line-to-line voltages, phase shifting one of them to bring them... | 12/28/1982 |
| 4342062 | Sequence network circuits for protective relaying applications Sequence network circuits are provided for use in three-phase protective relaying applications. In one embodiment, the circuit includes input circuit means for receiving input signals, one of which comprises a reference input signal, and signal processing... | 07/27/1982 |
| 4231074 | Zero sequence current source for transformer having a nonwound tertiary A three-phase electrical transformer utilizes a conductor independent of the transformer windings for sensing zero sequence current upon the occurrence of a ground fault. A current transformer coupled with the independent conductor provides polarization t... | 10/28/1980 |
| 4156186 | Method and apparatus for determining negative sequence current in a multi-phase dynamoelectric machine A method and apparatus are disclosed for accurately determining negative sequence current in a three-phase turbine-driven generator, the currents indicative of power oscillations and of torques harmful to turbine buckets. A signal conditioner and phase-sh... | 05/22/1979 |
| 4150412 | Filter excitation circuitry The circuitry for generating filter excitation signals from a multi-phase alternating current input is provided with the following circuitry for each phase of the multi-phase alternating current input. A current transformer connected to a respective phase... | 04/17/1979 |
| 4146913 | Symmetrical component sequence filter A symmetrical component sequence filter which provides a signal responsive to a predetermined sequence quantity of an electrical power system, while using only one phase shift other than 180 degrees. A single reactive element provides the phase shift. A s... | 03/27/1979 |
| 4039937 | Acoustic test apparatus for electrical networks including multi-phase power systems A local power source, such as a battery, is connected to a tone generator oscillator circuit which includes an audio reproducer. The tone generator includes a voltage sensing element such as a dark-resistance photoconductor, a resistor, or a Zener diode, ... | 08/02/1977 |
