US 11,971,452 B2
Device and method for nondestructively detecting transient characteristic of conductive screw of turbo-generator rotor
Yuewu Zhang, Hangzhou (CN); Jianxi Liu, Hangzhou (CN); Yanxing Bao, Hangzhou (CN); Weihua Zha, Hangzhou (CN); Qianyi Zhang, Hangzhou (CN); Dongbing Liu, Hangzhou (CN); Weixing Yang, Hangzhou (CN); Xu Han, Hangzhou (CN); Miaoye Li, Hangzhou (CN); Zirui Wang, Hangzhou (CN); Junliang Liu, Hangzhou (CN); Jie Luo, Hangzhou (CN); Weitao Shen, Hangzhou (CN); Yu Fu, Hangzhou (CN); and Han Gao, Hangzhou (CN)
Assigned to HANGZHOU HENUOVA TECHNOLOGY CO., LTD., Hangzhou (CN)
Appl. No. 17/922,599
Filed by HANGZHOU HENUOVA TECHNOLOGY CO., LTD., Hangzhou (CN)
PCT Filed Apr. 25, 2021, PCT No. PCT/CN2021/089474
§ 371(c)(1), (2) Date Oct. 31, 2022,
PCT Pub. No. WO2021/227837, PCT Pub. Date Nov. 18, 2021.
Claims priority of application No. 202010410028.8 (CN), filed on May 15, 2020.
Prior Publication US 2023/0168303 A1, Jun. 1, 2023
Int. Cl. G01R 31/34 (2020.01)
CPC G01R 31/343 (2013.01) 2 Claims
OG exemplary drawing
 
1. A method for nondestructively detecting a transient characteristic of a conductive screw of a turbo-generator rotor, wherein the method is implemented base on a device for detecting the transient characteristic of the conductive screw of the turbo-generator rotor, wherein the device for detecting the transient characteristic of the conductive screw of the turbo-generator rotor comprises a personal computer (PC), an extremely-steep pulse generator, an ultra-high-frequency double-isolation transformer, and a pulse emitting and coupling module, which are connected in sequence: wherein the pulse emitting and coupling module is connected to a load; a synchronous pulse receiving non-inductive divider circuit synchronously receives a characteristic waveform from the load, and the synchronous pulse receiving non-inductive divider circuit is connected to an ultra-high-speed analog/digital (A/D) module through a nonlinear saturation amplifying circuit that amplifies a signal; the PC receives a signal from the ultra-high-speed A/D module:
the load comprises a positive and negative excitation lead loop that is in a 180° symmetrical and instantaneous short-circuit state and a rotor shaft: the extremely-steep pulse generator is a nanosecond high-voltage steep pulse generator, and the synchronous pulse receiving non-inductive divider circuit is a resistor divider circuit; from a positive or negative excitation lead to the conductive screw and to a main winding of a rotor, a transient rotating electric field pulse of a same parameter has different spatial damping correlations for media of different structures and materials; time-shared tests are performed separately, and characteristic waveforms of two positive or negative transient pulses are compared; inconsistencies in phase and amplitude occur when a dielectric constant of a part of a conductive screw is changed; and through the comparative analysis of the waveforms, a defect location and severity of the conductive screw are determined;
the specific detection method comprises the following steps:
(1) controlling, by the PC, the extremely-steep pulse generator to generate a pulse;
(2) applying a pulse by the ultra-high-frequency double-isolation transformer with a pass-band of 10 MHz or more as a secondary superposition source;
(3) coupling, by the pulse emitting and coupling module, a pulse after secondary superimposition to the load;
(4) receiving, by the synchronous pulse receiving non-inductive divider circuit, a feedback pulse from the load synchronously;
(5) amplifying, by the nonlinear saturation amplifying circuit, a voltage signal in step (4), and connecting the ultra-high-speed A/D module;
(6) receiving, by the PC, a signal from the ultra-high-speed A/D module to form a waveform; and
(7) subjecting the waveform formed in step (6) to time-shared recording and synchronous comparison;
wherein an amplitude of a characteristic waveform of the load decays rapidly after multiple oscillatory waves; and
the nonlinear saturation amplifying circuit amplifies and converts a superimposed wave front of a transient wave with a slope in step (4) into an ultra-high-frequency extremely-narrow pulse oscillatory wave that is allowed to be displayed horizontally.