36 results about "GTEM cell" patented technology

The invention discloses a calibration system and a calibration method of a partial discharge ultrahigh frequency detection device in the technical field of online detection of the partial discharge of power transformers and gas insulation combination switch devices. The calibration system comprises a standard antenna, a standard pulse source, a detection and control computer and a partial discharge ultrahigh frequency detection device to be detected, wherein the standard pulse source, the detection and control computer and the partial discharge ultrahigh frequency detection device to be detected are connected sequentially. The partial discharge ultrahigh frequency detection device to be detected comprises a sensor for collecting voltage signals. The calibration system further comprises a coaxial cavity, the coaxial cavity is composed of an outer cylinder, an inner cylinder, two outer cones and two inner cones which are coaxial, and a detection window is arranged in the middle of the outer cylinder. The invention also provides the calibration method with the calibration system. The calibration system utilizes the matched coaxial cavity to replace a small GTEM (Giagahertz Transverse Electromagnetic Cell) for the calibration of the partial discharge ultrahigh frequency detection device, and is simple in structure and easy to implement.

The invention relates to a shielding effect testing method of an electromagnetic radiation resistance shielding clothes, which is characterized in that a GTEM small chamber is used for replacing a half electric wave dark chamber or a wide testing field to teat, the method uses a smaller-space gigahertz transverse electromagnetic wave small chamber (the GTEM small chamber) to replace the electric wave dark chamber, and needed instrument devices are cheaper than the original instrument devices. Compared with the traditional method, the shielding effect testing method has lower cost of a testing device of a whole system, which is one fifth to one tenth of the cost of the traditional method.

The invention relates to the technical field of partial discharge detection and in particular provides an ultrahigh frequency partial discharge detection system calibration method. Devices used by the method include a pulse signal source, a GTEM cell, a single-pole standard probe, a high speed digital oscilloscope and a measurement and control computer. The method calibrates an ultrahigh frequency partial discharge detection system by detecting the frequency domain equivalent height of a detected ultrahigh frequency sensor, the sensitivity of the ultrahigh frequency partial discharge detection system and the dynamic range of the ultrahigh frequency partial discharge detection system; detection results are expressed as a unified dimension, and the physical nature of detected objects is reflected; the method takes into full consideration the installing structure of the ultrahigh frequency sensor for detection thereof and fully reflects the engineering practice detection capability thereof; when being used for detection of the ultrahigh frequency partial discharge detection system, the method has the advantages of high shield effectiveness, stable testing results and less influence from external environment disturbance.

The invention provides a radiation EMI testing method based on a GTEM cell. According to the method, the horizontal radiation field intensity and the vertical radiation field intensity of a standard tested object with a frequency point of f0 in a radio wave dark room are firstly calculated, then, the horizontal polarization equivalent radiation field intensity and the vertical polarization equivalent radiation field intensity of a total power algorithm and a Lee algorithm of the standard tested object in a wide field are calculated respectively, a phase compensation and calibration factor corresponding to the frequency point of f0 is calculated according to a formula, the phase compensation and calibration factor and the horizontal polarization equivalent radiation field intensity and the vertical polarization equivalent radiation field intensity of a total power algorithm and a Lee algorithm of any tested equipment are plugged into the formula, and then, the testing result of any tested equipment in the wide field can be obtained. According to the testing method, on the basis of the total power algorithm, the Lee algorithm is used for phase compensation, so that the problem of lower accuracy of a testing result due to the fact that the phase factor is not considered when the total power algorithm is used alone and errors are caused by approximate hypothesis when the Lee algorithm is used alone is solved.

The invention discloses a GIS partial discharge UHF sensor equivalent height sweeping frequency reference calibration method. Firstly a calibration platform composed of a GTEM cell, a sweeping frequency signal source, a high-speed digital oscilloscope, a single-pole standard probe, a sensor to be tested, a measurement and control computer, calibration software and various cable accessories is established; continuous sine wave voltage signals of fixed amplitude are injected in the GTEM cell via the sweeping frequency signal source, the output ports of the single-pole standard probe and the sensor to be tested are respectively connected with the measurement port of the oscilloscope, and the voltage signals coupled by the single-pole standard probe and the sensor to be tested are acquired in real time via calibration software; and the frequency domain equivalent height curve of the sensor to be tested is calculated according to a sweeping frequency reference method. The method has clear principle and can effectively measure the equivalent height curve of a GIS partial discharge UHF sensor; degree of integration is high and operation is simple and convenient; and measurement precision is high, intermediate error generated by performing FFT transform on time domain pulse signals can be eliminated, and scientific evaluation of coupling performance of the GIS partial discharge UHF sensor can be realized.

The invention provides an ultrahigh-frequency sensor evaluation method by utilizing a GTEM cell. The method comprises the following steps that 1) a test area of an ultrahigh-frequency sensor in the GTEM cell is determined; 2) a signal output curve of a signal generator is set; 3) the ultrahigh-frequency sensor is placed in the test area, the signal generator is controlled to carry out output according to a signal output curve, and the voltage peak of an output signal of the ultrahigh-frequency sensor in each frequency point of the signal output curve is recorded; and 4) the equivalent height of each frequency point is calculated according to the field intensity of the test area and the voltage peak. Compared with the prior art, the method of the invention can test the equivalent height of the ultrahigh frequency sensor effectively, and the average equivalent height in a preset frequency range is calculated and serves as an index for evaluating the sensor performance.

Provided is a gigahertz transverse electromagnetic (GTEM) cell for measuring an insertion loss and an insertion loss measurement method using the GTEM cell. The GTEM cell may include an output port configured to measure an insertion loss of a test object occurring when an electromagnetic field having specific intensity is applied to the test object, and may measure the insertion loss of the test object from the GTEM cell based on a change in the intensity of the electromagnetic field measured using the output port.

The invention discloses a partial discharge ultra-high frequency (UHF) sensor performance evaluation method based on time domain parameters. Performance of a UHF sensor is represented through the time domain parameters, a time domain analysis impulse response function is obtained through Hilbert transformation on the basis of GTEM cell impulse measuring system measured data, and three time domain parameters of an envelope peak value, an envelope width and oscillating time are extracted. The ill-conditioned problem caused in the process of time domain parameter obtaining through frequency domain deconvolution is solved by means of the Guillaume-Nahman technology, and the situation that a system impulse response is drowned in high frequency burrs is avoided. Compared with an existing evaluation system, behavior characteristics of the UHF sensor can be described more accurately when an impulse signal is received, and a technical support is provided for effective comparison and analysis of partial discharge UHF detection signal time domain waveforms.

The invention discloses a GTEM cell radiation EMI (electro-magnetic interference) test method based on the radiation source characteristic. The method comprises the following steps of: 1) according to the near field wave impedance theory, judging the radiation source type of equipment to be tested, i.e. judging whether the radiation source is based on common-mode radiation or differential-mode radiation; 2) if the radiation source type of equipment to be tested is based on the common-mode radiation characteristic, processing a GTEM result with an extreme difference-averaging method; and if the radiation source type of tested equipment is based on the differential-mode radiation characteristic, processing the GTEM result with a variance method. By aiming at a test experiment used for the radiation emission for a GTEM cell, the GTEM cell radiation EMI test method based on the radiation source characteristic has the characteristic that the test result accuracy obtained when the GTEM cell is used for the radiation EMI test can be greatly improved, and an effective reference is provided for the GTEM-based radiation EMI measurement.

The invention relates to an amplitude and phase calibration device for an optical fiber type electromagnetic field probe. The device comprises a vector network analyzer used for measuring amplitude and phase values in the calibration device, a power amplifier used for carrying out microwave power amplification, an adjustable attenuation/phase shifter used for changing the amplitude and phase values in the calibration device, a bi-directional coupler used for coupling the input power of a GTEM cell and the reflective power of the GTEM cell, a first power meter, a second power meter, the GTEM cell used for forming a stable and uniform electromagnetic field, a probe used for sensing amplitude and phase changes of the electromagnetic field of the position where the probe is, and a demodulatingdevice used for separating electromagnetic wave information carried in optical carrier waves to obtain amplitude and phase information of an electromagnetic wave signal. The invention further discloses an amplitude and phase calibration method for the optical fiber type electromagnetic field probe. The device is closed in structure, low in transmission loss, difficult to subject to external interference, large in amplitude calibration range, easier to construct and suitable for field rapid calibration of the optical fiber type electromagnetic field probe.

The invention discloses an automatic calibrating system for an ultrahigh-frequency partial discharge tester and a method thereof. The system comprises a calibrating signal generator, an UHF partial discharge sensor and a calibrated ultrahigh-frequency partial discharge tester. The ultrahigh-frequency partial discharge tester is connected with the UHF partial discharge sensor. The high-frequency signal output end of the calibrating signal generator is connected with a signal input coaxial joint of a GTEM small chamber. The UHF partial sensor is placed at the central part of the GTEM small chamber. The middle part of the GTEM small chamber is provided with a field strength probe. The field strength probe is connected with an oscilloscope which is arranged outside the GTEM small chamber. Theoutput signal of the oscilloscope is connected with a controller. The controller is connected with the calibrating signal generator. The automatic calibrating system performs real-time hardware part controlling, data acquisition and displaying processing on the ultrahigh-frequency partial discharge tester. The system has advantages of high reliability, real-time measurement and effective calibrating efficiency improvement. A feasible method is supplied for automatic calibration of the ultrahigh-frequency partial discharge tester. The automatic calibrating system further has advantages of highcalibration precision and simple control method.

The invention provides a multi-parameter ultra-high frequency sensor performance comprehensive evaluation method. The method comprises steps: a GTEM cell is adopted to carry out equivalent height test and sensitivity test on a to-be-tested ultra-high frequency sensor; a network analyzer is adopted to carry out standing-wave ratio test on the to-be-tested ultra-high frequency sensor; and a GIS (Gas Insulated Switchgear) is adopted as a test model to carry out fault model signal-to-noise ratio test on the to-be-tested ultra-high frequency sensor. Compared with the prior art, the multi-parameter ultra-high frequency sensor performance comprehensive evaluation method provided by the invention comprehensively evaluates the performance of the ultra-high frequency sensor from four aspects of the equivalent height, the standing-wave ratio, the sensitivity and the fault model signal-to-noise ratio.

The invention discloses a test system for electronic device false triggering under strong electromagnetic radiation by applying optical fiber communication, which comprises a radio frequency signal generator, a power amplifier, a GTEM cell, an electric-optical signal converter, a field strength tester, an optical fiber, an optical-electric signal converter and an oscilloscope, wherein the radio frequency signal generator generates radio frequency electric signals; the power amplifier amplifies the radio frequency signals; the GTEM cell uses the amplified radio frequency signals to excite a uniform high-frequency strong electric field around a core board; the electric-optical signal converter is used for converting false triggering electric signals generated by a tested electronic device due to radiation interference to optical signals not disturbed by the radiation interference; the optical signals are transmitted to the optical-electric converter outside the cell through the optical fiber and are converted to electric signals; and finally, the false triggering electric signals are displayed by the oscilloscope. Complete transmission of the electric signals with no interference in the strong electromagnetic radiation environment can be realized, and the system has the advantages of shielding outer interference and isolating pollution on the outside by the self electromagnetic field.

The invention provides a GTEM cell suitable for detection of a partial discharge UHF sensor. The GTEM cell of a rectangular pyramid shape comprises a top pole plate, a conductive pole plate and a bottom pole plate, the top pole plate and the bottom pole plate arranged in two conical surfaces not adjacent to each other in the GTEM cell, and the conductive pole plate is fixed between the other two conical surfaces; the top pole plate is connected to the conductive pole plate via fastening lines; the top pole plate is provided with a circular hole, and a circular disk is mounted on the circular hole; and the circular disc is used to accommodate the detected partial discharge UHF sensor and a reference antenna. Compared with the prior art, test results for different partial discharge UHF sensor detected by the GTEM cell are within a reasonable range, and the test results are repeatable.

The invention discloses a method for testing the sensitivity and read-write distance of an ultra-high frequency radio frequency identification (UHF RFID) label by using a giaga-hertz transverse electromagnetic (GTEM) cell, which comprises the following steps of: putting a label to be tested in the specific direction of a specific area in a GTEM cell; arranging a UHF RFID test system (which has the functions of a UHF RFID reader and label signal analysis) at the port of the GTEM cell to test the minimum transmitted power of the system when the label can reflect a signal; and calculating electromagnetic field intensity at the periphery of the label by using a relevant formula of the GTEM cell to obtain the sensitivity (the minimum electromagnetic field intensity) indicating that the label can reflect the signal, and then calculating the read-write distance of the UHF RFID label in a free space through the formula provided by the invention. The sensitivity and the read-write distance of the label are calculated by the formula provided by the method, so the method is easy to operate and has low cost and the sensitivity and the read-write distance are accurately measured.

The invention relates to an ultrahigh frequency partial discharge sensor performance test tool and device based on a GTEM cell, the tool comprises a fixing ring, a flange plate, a clamping assembly and an angle adjusting assembly, the flange plate is installed in the inner ring of the fixing ring and can rotate in the circumferential direction of the inner ring of the fixing ring; the multiple clamping assemblies are evenly distributed on the edge of the flange plate in the circumferential direction of the flange plate, the radial distance of the clamping assemblies is adjustable, when a sensor is installed, the multiple clamping assemblies make contact with the side face of the sensor and clamp the sensor, and the angle adjusting assembly is arranged on the flange plate and the fixing ring. The angle adjusting assembly is used for adjusting the rotation angle of the flange plate relative to the fixing ring and fixing the position of the flange plate. Compared with the prior art, the position and the angle of the sensor can be accurately adjusted, and the problem that an existing testing method is poor in result consistency is solved.