47 results about "Impedance plane" patented technology

An NDI system includes an ultrasonic transducer and an electronic device having an indicator, such as a light source. The electronic device energizes the transducer, receives sinusoidal signals from the transducer, determines impedance-plane coordinates corresponding to quadrature-phase separated components of the sinusoidal signals, and automatically activates the indicator if impedance-plane coordinates exceed a preset threshold. The system may be used in methods of inspecting layered structures such as composite aircraft components and repair patches applied to such structures.

The invention relates to a quick distinguishing method for zero-sequence directional elements of an alternating-current and direct-current serial-parallel power grid. The quick distinguishing method includes computing sampling values of zero-sequence voltage and zero-sequence current according to sampling values of three-phase voltage and three-phase current at a protection mounting position; establishing a time-domain differential equation based on instantaneous sampling values of the zero-sequence voltage and the zero-sequence current; computing weights of zero-sequence resistance and zero-sequence inductance by the aid of the time-domain differential equation and a least square method; converting the weight of zero-sequence resistance and the zero-sequence inductance of a system to frequency domain, and computing power-frequency zero-sequence impedance; and judging whether forward or reverse grounding faults occur or not by means of judging whether an area of an impedance plane with the zero-sequence impedance is in a positive-direction action area or a negative-direction action area. The method is not affected by low-frequency weights, fractional harmonic waves or the fact that positive-sequence impedance is unequal to negative-sequence impedance after the alternating-current and direct-current serial-parallel power grid fails, reliability of computation results is guaranteed, action performances of the zero-sequence directional elements are far superior to those of various power-frequency directional elements based on full-period Fourier algorithm and semi-period Fourier algorithm, and the quick distinguishing method has an extremely important application value.

The invention discloses a design method for improving the limit sensitivity of eddy current detection by changing the resonance frequency. The frequency generated by the resonance circuit is used to replace the quartz crystal oscillator in the eddy current detection instrument. The eddy current detection coil is used as the inductance part of the resonance circuit. Through this method design The eddy current detection instrument can obtain the impedance signal diagram of the resonant eddy current detection including amplitude, phase and frequency information. In addition to the working characteristics of the first generation resonant eddy current instrument, it also has the advantages of the second generation impedance plane analysis eddy current instrument. The superposition of mechanisms further improves the limit sensitivity of eddy current detection.

The invention provides a multi-lateral current magnitude voltage magnitude based transformer relay protecting method, which has the advantages of convenience, reliability, sensitivity and the like. The method comprises the following steps that: 1) a relay protection device acquires sampling values of three-phase voltage and current on each side of the transformer, and calculates out the current magnitude and the voltage magnitude on each side of each phase of winding; 2) the relay protection device calculates the branch impedance of each phase of the winding according to the current magnitudeand the voltage magnitude; and 3) a +R axis area is set on an impedance plane as an action area, and failure inside the transformer is determined when the branch impedance drops in the region more than the set time.

An eddy current object testing system includes an EC probe and an acquisition channel which is configured to receive an EC signal from the EC probe and to generate a visual output, namely an impedance plane representation, of the output. A display is coupled to the acquisition channel to display the visual output. The at least one probe is provided with a test loop substantially surrounding it and has a series switch which can be selectively closed or opened to thereby cause the image plane to assume a state that is indicative of a fault, if any, in the EC probe.

The invention discloses a device and a method for non-contact magnetic induction impedance plane projection imaging. An alternating current magnetic field is generated in an excitation coil by introducing alternating sinusoidal current, a measured object with certain conductivity is arranged in the alternating current magnetic field, the inside of the measured object generates same-frequency alternating eddy current due to electromagnetic induction, measuring coils which are arranged into a plane in a matrix way are used for respectively detecting magnetic filed signals caused by the alternating current eddy current, according to the relationship of the measuring signals and the impedance distribution of the measured object, the impedance distribution condition of the part of the measured object corresponding to each measuring coil is respectively calculated, and all calculating results form an impedance plane projection image according to the positions of the measuring coils.