390 results about "Corona discharge" patented technology

The invention discloses a power transmission channel risk early warning evaluation method and system, and relates to the technical field of power transmission channel abnormal condition early warning, and the method comprises the steps: analyzing the current waveform distortion degree caused by a nonlinear load in a power transmission line through monitoring the voltage harmonic distortion rate, and evaluating the influence of harmonic waves on the insulation aging and heating loss of the line and equipment; the real-time gradient of the temperature of the wire is analyzed, abnormal heating conditions of different sections of the wire are judged, and the abnormal rising degree of the temperature of the wire and potential thermal damage accumulation caused by overload and poor contact factors are evaluated; by monitoring and analyzing multi-dimensional indexes such as the voltage harmonic distortion rate, the lead temperature real-time gradient, the sag dynamic deviation rate and the corona discharge intensity, the defect of a traditional monitoring means in the aspect of abnormal heating risk assessment is overcome.

The invention discloses a high-precision defect detection system for a track inspection robot, which relates to the technical field of track inspection and comprises a multi-mode visual acquisition module, a time sequence synchronization module, a data fusion processing module and a defect identification output module, by adopting a multi-modal visual fusion detection technology, various modal visual technologies of visible light vision, infrared vision and ultraviolet vision are combined, fusion processing is carried out on all modal image data, visual defects such as cracks and abrasion on the surface of a track can be clearly recognized through visible light vision, and the visual performance of the track is improved. The infrared vision can detect temperature abnormity of a track component to find out potential poor contact and other problems, the ultraviolet vision can be used for detecting corona discharge and other phenomena, track information is comprehensively obtained, the accuracy and reliability of defect recognition are effectively improved, defects which are difficult to find in a single mode can be detected, and the detection efficiency is improved. And powerful support is provided for safe operation and maintenance of the track.

The invention provides a flexible temperature-sensitive device based on electrostatic automatic pattern filling, a temperature-sensitive device body comprises a temperature-sensitive material, a flexible substrate material and a packaging layer, the temperature-sensitive material is a temperature-sensitive particulate matter cluster, and temperature-sensitive material powder does not need to be prepared into slurry or ink. An electric field loaded by corona discharge can be deposited on the flexible substrate, the conductive electrode is automatically identified and avoided, and only the non-conductive substrate area is filled. According to the method, the use of an adhesive is avoided, the sensitivity of the flexible temperature-sensitive device is improved, the cost is low, the process is simple, the preparation time of the device is saved, the production efficiency is improved, meanwhile, heat accumulation between the temperature-sensitive device and the skin can be avoided, the measurement error is reduced, and the real and reliable temperature measurement is ensured; the temperature-sensitive device is not sensitive to stress and strain, decoupling of various external signal stimulation is achieved, and the accuracy of measured data of the temperature-sensitive device is improved.

The invention relates to the technical field of electrical equipment defect monitoring, in particular to a high-voltage equipment defect positioning system and method based on multi-modal image fusion, and the system comprises an ultraviolet triggering module, a modal synchronization module, a space positioning module, a structure recognition module and a fusion diagnosis module. According to the method, automatic calibration of a suspected defect area can be realized by performing quantitative threshold judgment on a corona discharge signal in an ultraviolet image, the consistency of three-mode data in space and time dimensions is ensured, and the accuracy of the defect area is improved by comparing three types of coordinates of a lead hot spot, boundary geometry and a spot center in the image and performing registration offset correction. The image feature alignment precision is improved, the insulator chain light spot distribution path is extracted, the continuous distribution length is calculated and corresponds to the pollution level standard, automatic identification of the pollution level is achieved, a multi-modal image fusion feature block is constructed, and a risk sorting label is given. And the defect positioning accuracy and the comprehensive evaluation capability on the defect property and the influence degree are effectively improved.

The invention discloses a direct-current corona discharge mode recognition method and system based on YOLOv8 and a CNN model, and relates to the technical field of power equipment monitoring. The invention aims to solve the technical problem that the corona discharge phenomenon of high-voltage direct-current electrical equipment is difficult to monitor in real time and accurately classify. According to the scheme, the method comprises the following steps: firstly, shooting a corona discharge visible light image by using a digital single lens reflex camera, and carrying out manual labeling and data enhancement processing; then detecting and positioning a corona discharge source by using a YOLOv8 model; inputting the positioned corona discharge area image into a deep convolutional neural network (CNN) for classification of discharge modes; finally, the output results of the CNN models are fused through integrated learning, and the classification accuracy is improved. According to the method, real-time monitoring and accurate classification of the corona discharge phenomenon of the high-voltage direct-current electrical equipment can be realized, a powerful guarantee is provided for safe operation of power equipment, the operation and maintenance efficiency is remarkably improved, and the equipment fault risk caused by corona discharge is reduced.

A TinyMaix-based switch cabinet partial discharge detection and identification algorithm comprises the following steps: designing four typical insulation defect models, and respectively simulating corona discharge, suspension discharge, surface discharge and internal discharge; 200 samples are collected for each insulation defect, a sample set of 800 samples is formed in total, and a phase-resolved partial discharge (PRPD) graph is constructed according to a phase value in combination with a power frequency synchronization signal; the method comprises the following steps: dividing a power frequency sine wave into 360 phase windows, calculating a discharge frequency and a discharge amplitude average value in each phase window, constructing pulse counting distribution # imgabs0 # and average pulse amplitude distribution # imgabs1 #, extracting a probability pwin, a mean value mu and a variance sigma, and further calculating 19 statistical characteristics such as skewness Sk; a mean square error is selected as a loss function in each iteration of model solution, model parameters are updated according to the gradient of the loss function, and model convergence is accelerated; and inputting a partial discharge signal to be detected into the trained model, and outputting a classification result of the signal by the model to realize identification and classification of the partial discharge signal.

The invention discloses a lightning stroke attachment point calculation method of a complex surface flat plate structure, and aims to overcome the defects of an existing lightning stroke attachment point numerical calculation method, and on the basis that finite element software is utilized to construct a typical needle plate model based on an electric field model method, an electrode is moved downwards to simulate the thunder and lightning development process under first guidance. A pilot / corona onset criterion is established based on short-gap discharge and material corona discharge theories, a numerical simulation algorithm is provided for evaluating the lightning protection design of a complex surface flat plate structure, the determination accuracy of the attachment points of the flat plate structure with similar surface material conductivity, complex surface microstructure and no salient points is improved, the attachment point simulation algorithm is optimized, and the method is suitable for application and popularization. And tedious and high-cost test links are effectively avoided.

The invention relates to the technical field of high-voltage electrical equipment, and particularly discloses a high-insulating-property thermoplastic sleeve and a method for preparing the same based on a co-extrusion process, the surface of a nonlinear layer is wrapped with an insulating material, so that the corona discharge phenomenon is avoided; and meanwhile, the same thermoplastic material is adopted as the insulating layer (including the first thermoplastic layer and the second thermoplastic layer) material and the base material of the nonlinear layer, so that no obvious interface exists between the insulating layer and the nonlinear layer, charge accumulation is avoided, insulation failure is avoided, the insulation and voltage resistance of the sleeve is improved, and the operation reliability is improved.

The invention belongs to the technical field of detection, relates to a free radical detection method, particularly provides a water free radical cation detection method, and aims to realize water free radical cation detection which is efficient, rapid, free of sample pretreatment and convenient to analyze. According to the invention, an LTQ-XL linear ion trap mass spectrometer is used as a detection tool, and a dielectric barrier corona discharge method is adopted to provide a water free radical cation detection method. The method comprises the following steps of: filling argon (Ar) between two discharge electrodes as a working gas, applying a certain voltage to two electrodes of a dielectric barrier discharge ionization source (DBDI), detecting water free radical cations to obtain a corresponding mass spectrum to represent the water free radical cations, and optimizing a target signal to obtain corresponding mass spectrum data. The method can be used for efficiently and quickly detecting the water free radical cations without sample pretreatment and the like, is convenient to analyze and apply, and has remarkable innovativeness and wide application prospects.

The invention discloses a high-power corona preionization excimer laser, which is characterized in that a laser discharge cavity is arranged in a shell, a main discharge electrode is arranged in the laser discharge cavity, and the main discharge electrode comprises a main discharge cathode and a main discharge anode; corona rods capable of conducting discharge preionization on working gas are arranged in the laser discharge cavity and located on one side of the main discharge cathode at intervals, each corona rod comprises a preionization electrode and a ceramic insulator, gaps are formed between the peripheral face of each ceramic insulator and the outer side wall of the main discharge cathode and the inner side wall of the insulation cavity, and the preionization electrodes and the main discharge anode are grounded. The main discharge cathode is connected with a negative high-voltage pulse, and when the excimer laser works, the driving voltage pulse of the corona rod is the same as the driving voltage pulse of the main discharge electrode. Corona discharge preionization is carried out through the corona rod, the main discharge electrode cannot be corroded, discharge dust cannot be generated, and it is ensured that the main discharge electrode carries out uniform glow discharge to generate high-quality laser.

An ozone generating cell includes a corona discharge chamber with a curved side wall. The cell includes a high-voltage electrode, a ground electrode, and a dielectric material positioned between the high-voltage electrode and the ground electrode. The cell includes a gas channel formed between the dielectric material and the ground electrode. The channel has a first end in fluid communication with a gas opening in the dielectric material, which is in fluid communication with a gas port. The channel has a second end in fluid communication with another gas port. The channel further includes multiple concentric segments between the first and second ends of the channel.

The invention discloses a power transmission line corona discharge risk analysis method, device and equipment, and relates to the field of power transmission line safety analysis, and the key points of the technical scheme are as follows: establishing a dielectric model for representing the polarization characteristics of different types of bird nests on a power transmission tower, and calculating the power transmission line corona discharge risk based on the weighted sum of the dielectric model; obtaining a first mathematical model used for describing bird nest polarization characteristics, and introducing an environment correction factor of the power transmission line to correct the first mathematical model to obtain a second mathematical model; determining the polarization intensity of different types of bird nests on the power transmission line according to a second mathematical model; correcting the initial corona field intensity of the power transmission line containing the bird nest according to the electric field distortion rate and the polarization intensity to obtain the corrected initial corona field intensity; and constructing a corona discharge probability model according to the corrected initial corona field intensity, the electric field distortion rate and the polarization intensity, and analyzing the corona discharge risk of the power transmission line based on the corona discharge probability model.

The invention relates to a ring main unit intelligent detection and fault early warning method and system. The method comprises the following steps: deploying an ultrahigh frequency sensor, an infrared thermal imager, an ultraviolet sensor and a high-frequency current transformer, and synchronously acquiring multi-modal data such as partial discharge, temperature distribution, corona discharge and grounding current of the ring main unit; carrying out feature extraction on the collected data, wherein the feature extraction comprises a time-frequency statistical feature and a temperature-load correlation feature of the partial discharge signal; the Dempster-Shafer evidence theory is utilized to carry out fusion calculation on the multi-source feature evidence, and confidence coefficients for insulation degradation, poor contact, arc faults and other fault types are obtained; arc fault prediction is carried out in combination with a long-short-term memory network model; and finally executing a grading early warning strategy according to the fault confidence. The problems of low detection reliability and fault early warning lag of a single sensor are solved, early accurate diagnosis and predictive maintenance of the insulation fault of the ring main unit are realized, and the operation safety and reliability of power equipment are remarkably improved.

The invention provides a porcelain insulator quality evaluation system based on multi-physics field coupling analysis, and relates to the technical field of rod-column porcelain insulator data processing.The porcelain insulator quality evaluation system adopts an electricity-heat-force multi-physics field joint simulation model to comprehensively reflect the heat accumulation and stress deformation effect caused by electric field concentration; an electric field concentration coefficient, a temperature rise trend coefficient and a stress gradient coefficient at a sharp point can be accurately captured, and degradation path prediction in a real operation environment is formed; according to the technology, the thread coupling abnormal index F alpha i of the ith rod-type column porcelain insulator is constructed, whether the thread structure has the risk of partial discharge, flashover or breakdown or not can be dynamically evaluated, and by introducing equivalent dielectric layer simulation of various environmental media, the simulation of the influence of various pollutants, attachments and climates on electric field concentration in reality is promoted; quantitative evaluation of the corona discharge risk of the sharp point is realized, and the reliability of the structural design of the insulator is promoted and improved.

The invention provides a GIS equipment partial discharge type classification method based on partial discharge time domain signals, and belongs to the field of partial discharge detection and classification. The problem that the method for judging the partial discharge type through the partial discharge mode spectrogram fails due to the fact that an externally applied voltage signal cannot be obtained in the field detection process is solved. The method comprises the following steps: respectively acquiring time-domain data sets of partial discharge light of a sample in the occurrence process of three partial discharge phenomena of corona discharge, surface discharge and suspension discharge through an experimental platform, and preprocessing the time-domain data sets; adopting a dual-threshold peak searching method to perform dual-threshold peak searching on data in the time domain data sets of the three types of preprocessed partial discharge light to obtain corresponding partial discharge peak data sets, and processing the partial discharge peak data sets into corresponding partial discharge light signal amplitude difference spectrograms; partial discharge type classification is realized through the partial discharge optical signal amplitude difference spectrogram; the method is applied to partial discharge detection of the GIS equipment.

An unmanned aerial vehicle (UAV) 1002 to inspect and monitor electrical power transmission lines including measurement of S- parameters of a magnetic field to determine the permittivity of a medium, e

The invention discloses a cable partial discharge on-line detection method based on a non-calibration pulse current method, which belongs to the field of power equipment partial discharge detection, and comprises the following steps of: designing four typical insulation defect models by combining actual operation and detection conditions of a cable, and respectively simulating corona discharge, suspension discharge, surface discharge and internal discharge; building an experimental platform, coupling partial discharge pulses by using a bushing sensor, and providing a phase synchronization signal; through the designed matching impedance circuit, the capacitance value of the bushing sensor can be measured. According to the function relationship established between the capacitance value and the discharge conversion coefficient, the partial discharge amplitude is rapidly estimated; a partial discharge pulse signal is collected by a pulse current method partial discharge sampling system, and a phase resolution partial discharge (PRPD) graph is constructed according to a phase value in combination with a power frequency synchronization signal.

The invention discloses a fault diagnosis method based on characteristic product concentration percentage and ratio dual threshold values, comprising the following steps: step 1, carrying out environment-friendly gas local overheating, spark discharge and corona discharge experiments, and detecting decomposition products; 2, screening characteristic decomposition products, and calculating the concentration percentage and the concentration ratio of the characteristic decomposition products; and step 3, constructing a fault diagnosis criterion based on double thresholds of the concentration percentage and the concentration ratio of the characteristic decomposition product, and diagnosing the fault. The problems that in the prior art, environment-friendly gas insulation medium decomposition products are very many in variety and similar in structure, and misjudgment is likely to be caused in fault diagnosis are solved, local overheating, spark discharge and corona discharge of environment-friendly gas insulation power equipment can be effectively diagnosed, misjudgment among various types of faults is avoided, and the fault diagnosis accuracy is improved. And the accuracy of fault diagnosis is improved.

An electrophotographic roller comprising a substrate having a conductive outer surface and a resin layer on a side of the outer surface of the substrate, in which the volume resistivity of the outer surface of the electrophotographic roller is 1.0×106 Ω·cm or higher, when a corona discharger having a grid part is relatively moved along the axial direction of the electrophotographic roller to charge the electrophotographic roller, and the potentials of the outer surface after 0.06 seconds from passage of the grid part are measured, a maximum value of the potentials is lower than 20.0 V, the ionization potential of the outer surface of the electrophotographic roller is 5.0 to 5.6 eV, and an elastic modulus E1 in a region from the outer surface of the electrophotographic roller to a depth of 0.1 μm is 200 MPa or higher.

The utility model discloses a device for corona discharge phenomenon teaching demonstration and volt-ampere characteristic measurement, which comprises an experiment box body, an experiment table is arranged on the experiment box body, a transparent cover and an electrode spacing adjusting mechanism are arranged on the experiment table, and the transparent cover can be selectively opened or buckled on the experiment table. An electrode bracket is arranged on the electrode distance adjusting mechanism, and an electrode is mounted on the electrode bracket; a power supply, a voltmeter and an ammeter are arranged in the experiment box body; an output electrode of the power supply is connected with an electrode on the electrode bracket through a wire; an ampere meter is arranged between the output electrode of the power supply and the electrode on the electrode support, and the ampere meter can be selectively connected to or disconnected from a circuit; the voltmeter is connected in parallel between the two output electrodes of the power supply. The device for corona discharge phenomenon teaching demonstration and volt-ampere characteristic measurement disclosed by the utility model has the advantages of simple experimental device, convenient operation, easy adjustment of experimental parameters, easy observation of experimental phenomena and the like.

The invention provides a spark discharge device and a spark discharge accurate control method, and relates to the technical field of spark discharge. The device comprises a pair of spark electrodes, a rotary switch, a capacitor and a power supply, wherein a gap exists between working ends of the spark electrodes; the spark electrode, the rotary switch and the capacitor are connected in series to form a discharging loop, and the capacitor and the power supply are connected in series to form a charging loop; the rotary switch comprises a rotatable rotor and a toothed bar connected with the rotor; a contact is arranged in the discharge loop, and when the contact is in contact with the toothed bar, the discharge loop is conducted. According to the invention, the discharge loop is rapidly switched on and switched off through the rotary switch, various parameters of spark discharge can be accurately and stably controlled, so that the spark discharge is not influenced by the environment, such as spark breakdown voltage, discharge frequency and the like, and the spark discharge can be prevented from being converted into corona, glow or arc discharge, for example, the spark discharge can be normally generated under low air pressure.

The invention relates to the technical field of ultraviolet imaging detection, in particular to a solar blind ultraviolet imaging light spot analysis method and system. The method comprises the following steps: based on different gains of a solar blind imager, pre-establishing ANFI S evaluation models corresponding to the different gains for evaluating the discharge intensity based on a light spot image; s1, acquiring a light spot image of the surface of the electrical equipment; s2, performing feature extraction on the light spot image, and determining an emission radiation area s and an observation distance d of the light spot image; and S3, based on the gain corresponding to the solar blind imager, inputting the emission radiation area s and the observation distance d into the ANFI S evaluation model of the corresponding gain, so as to evaluate the predicted discharge amount q on the surface of the electrical equipment. The system comprises a solar-blind imager used for collecting light spot images so as to carry out solar-blind ultraviolet imaging light spot analysis. According to the method, factors such as the discharge radiation area, the discharge capacity, the observation distance and the imager gain are comprehensively considered, the ANFI S algorithm is applied, an accurate estimation model is constructed, and accurate estimation of the corona discharge capacity is achieved.

The invention provides an active lightning triggering device and method for a fan blade. The device comprises two copper rods with tip heads, a protection circuit, a boost lightning circuit and a metal shielding net. The two copper rods are arranged in parallel at the blade tip of the fan blade, one copper rod is directly grounded, and the other copper rod is connected with the boost lightning circuit through the protection circuit; the boost lightning guide circuit comprises a charging capacitor, an inductor, a high-frequency switch and a diode and is used for sensing positive high voltage and dynamically adjusting resonance characteristics so as to enhance voltage difference between thundercloud and a copper rod and trigger uplink and downlink leader to form a discharge channel; the metal shielding net wraps the blade tip and is connected with the grounding device to ensure that lightning current is preferentially discharged through the copper rod, and the blade tip structure is prevented from being damaged. According to the method, environmental meteorology and blade attitudes are monitored in real time, a boosted circuit is started in combination with threshold judgment, and control parameters are optimized by using a remote monitoring platform, so that intelligent lightning protection management is realized. According to the device, by actively exciting corona discharge and accurately guiding a lightning path, the lightning protection efficiency of the blade is remarkably improved, the damage risk of a non-lightning-receiving area is reduced, meanwhile, a maintenance decision is supported through datamation operation and maintenance, and the device is suitable for wind generating set protection in a thunderstorm area.

The invention relates to a rotary jet plasma excitation device and method, and the device comprises a carrier which is provided with a jet hole in the surface; the dielectric barrier discharge assembly is arranged on the surface of the carrier, is coaxial with the jet hole and comprises an insulating dielectric layer, a plurality of high-voltage electrodes and a plurality of low-voltage electrodes, the low-voltage electrodes and the high-voltage electrodes are annularly arranged on the inner side and the outer side of the insulating dielectric layer at intervals, and the single high-voltage electrode and the single low-voltage electrode correspondingly form an independent dielectric barrier discharge unit; the corona discharge assembly is arranged outside the dielectric barrier discharge assembly in a sleeving mode and used for outputting normal main jet flow into the jet flow hole, the corona discharge assembly comprises at least one pair of discharge electrodes, and the at least one pair of discharge electrodes are provided with discharge structures; and the power supply and control assembly comprises a power supply module and an intelligent control module. The rotary jet plasma excitation device can form composite rotary jet, effectively disrupts coherence of a turbulent coherent structure, and realizes efficient flow control.

The invention discloses a power system equipment operation risk intelligent identification and early warning system. The system comprises an environmental parameter acquisition module, a passive ultraviolet fluorescence detection module, an active ultraviolet laser excitation module, a background fluorescence analysis and dynamic threshold calculation module, an abnormal signal confirmation module, an intelligent determination module and a closed loop verification and alarm module. Environment characteristic indexes are calculated by monitoring temperature, humidity and air pressure in real time; collecting and analyzing a natural ultraviolet fluorescence signal, actively emitting ultraviolet laser to excite environmental fluorescence response, and adaptively calculating a dynamic anomaly judgment threshold value; abnormal signals are accurately confirmed by utilizing multi-dimensional feature combination and feature space analysis, and corona discharge and line discharge are distinguished through intelligent judgment; and finally, carrying out automatic secondary verification positioning on the visible light image, and automatically generating a discharge early warning signal. The system has the characteristics of high sensitivity, strong interference resistance and high intelligent degree, and the discharge detection reliability is effectively improved.

The embodiment of the invention provides an electric precipitator polar line surface defect identification method and system, and belongs to the technical field of electric precipitation. The method comprises the following steps: acquiring an original digital color image of the polar line in a corona discharge state; generating a grayscale image based on the original digital color image, and constructing a binary image for representing a brightness area according to a preset threshold; performing median filtering and mean filtering in sequence based on the binary image to construct a de-noised binary image, and performing Canny edge detection on the de-noised binary image to generate a halo edge image of a burr tip point; and based on the halo edge image, corona discharge positions and brightness information of two sharp points of each barb are extracted, and a polar line surface defect identification result is output according to a preset normal distribution mode. According to the scheme, the corona discharge characteristics can be stably extracted in complex imaging environments such as high dust and weak light, so that the polar line surface defects can be reliably identified.

The application provides a preparation method of a device based on electrostatic field induced microparticle patterning directional assembly, comprising the following steps: preparing a pre-patterning electrode and printing or depositing the pre-patterning electrode on a substrate to obtain a pre-patterning substrate; uniformly laying microparticles on a lower substrate and placing the pre-patterning substrate between the lower substrate and an upper substrate; forming a controllable electric field between the upper substrate and the lower substrate through corona discharge, and driving the microparticles to deposit on non-conductive areas of the pre-patterning substrate by electric field force to form a patterning conductive channel corresponding to the electrode; and packaging the substrate on which the patterning directional assembly is completed. The application realizes template-free, contact-free and solvent-free patterning directional assembly of microparticles, and has the advantages of simple process, low cost, high efficiency and strong universality. The application can be used to prepare multiple devices such as photoelectric detectors, pressure sensors and flexible electronics, and has important industrial application value.

The invention discloses a plasma-based transformer substation noise reduction system and method, and belongs to the field of transformer substations. The system comprises a high-voltage power supply device, a corona discharge device, a noise acquisition device and a control module, the high-voltage power supply device is connected with the corona discharge device; the control module is respectively connected with the noise acquisition device and the high-voltage power supply device; the corona discharge device comprises a high-voltage electrode and a low-voltage electrode; the noise acquisition device comprises a reference microphone and an error microphone; the control module comprises a signal acquisition unit and a signal conversion unit. The signal conversion unit comprises an A / D conversion circuit, a DSP processor and a D / A conversion circuit. The plasma active noise reduction technology is adopted, low-frequency noise generated by the transformer substation can be effectively controlled, and meanwhile the noise reduction device is simple in structure, small in size and convenient to install. Through the active noise reduction logic of noise collection-signal processing-inverse sound wave generation, the problem that the low-frequency noise of the transformer substation is difficult to control is solved in a targeted mode, and noise reduction is more direct and efficient.

An image forming apparatus (1) includes an apparatus main body (3) and a drum unit (31). The apparatus main body (3) has an opening (27) and a drum unit storage part (21) communicating with the opening (27). The drum unit (31) is detachably attached to the drum unit storage part (21) through the opening (27). The drum unit (31) includes photosensitive drum (41), a corona discharging device (43) and a drum cover (47). The corona discharging device (43) corona-charges the photosensitive drum (41). The drum cover (47) is turnable in a protective posture for covering the photosensitive drum (41) and an exposure posture for exposing the photosensitive drum (41). When the drum unit (31) is attached to the drum unit storage part (21), the drum cover (47) is turned from the protective posture into the expose posture to block a flow path communicating a space around the corona charging device (43) with an outside of the apparatus main body (3).

This application relates to the field of lightning rod lightning protection monitoring technology, specifically to a corona field delayed lightning rod and its operation monitoring method. The method includes: collecting corona current and electric field intensity at each moment within each monitoring cycle during the operation of the lightning rod; calculating the first evaluation value and electric field anomaly degree for each time period in each monitoring cycle to obtain the first interference degree for each time period in each monitoring cycle; determining the second evaluation value and cycle anomaly degree for each time period in each monitoring cycle to obtain the second interference degree for each time period in each monitoring cycle; determining the interference coefficient for each monitoring cycle; and evaluating the data distortion status monitored during the operation of the lightning rod. This application, by evaluating the monitored data distortion status, reduces the possibility of misjudgment or omission of lightning strike risk by the lightning rod, and improves the accuracy of assessing the strength of corona discharge generated by the corona field delayed lightning rod under the action of the electric field and the activity of thunderclouds.