What are the main tasks involved in the maintenance of electrostatic precipitators?

Main items for minor repairs of electrostatic precipitators: a. Handling broken pole wires. b. Check and adjust individual pole pitches. c. Check the dust accumulation on the collecting electrode and the discharge electrode; if any abnormalities are found, analyze the reasons and take appropriate measures. d. Check the tightness of each shaft and hammer in the rapping system; broken or damaged safety pins should be replaced promptly. e. Inspect the reduction gearbox and eliminate leaks promptly. f. Check the temperature control system and replace any damaged thermometers. g. Check for air leaks at the smoke box, housing, ash hopper, and manholes; weld or replace gaskets as necessary. h. Inspect for leaks in the valves of various pipelines. i. Remove dust accumulated on the insulating porcelain poles of the discharge electrodes, bushings, vibrating porcelain shafts, cable terminal boxes, etc., wipe them clean, and replace any damaged porcelain components.

Mechanical component maintenance 1. Dust removal from the main body (1) Preparatory work before dust removal from the main body: The electric field must be allowed to cool naturally for a certain period of time before the access doors of the electric field can be opened to accelerate the cooling process (for large electrostatic precipitators, the natural cooling time for the electric field is generally not less than 8 hours). Work can be carried out inside the electric field only when the internal temperature drops below 50 degrees. It is necessary to strictly prevent sudden exposure to cold air, as this can cause sudden temperature changes that lead to deformation of metal components such as the housing, pole wires, and polar plates. At least two workers must enter the electric field, with at least one person remaining outside to supervise. (2) Inspection before dust removal: 1) Initially observe the degree of dust accumulation on the anode plates and cathode wires, analyze the causes of the dust accumulation, and keep technical records. 2) Initially observe the air flow distribution plate and make technical records. 3) Plate bending and displacement, deformation of the cathode frame, detachment or loosening of the pole wires, etc., as well as macroscopic inspection. (3) Dust removal methods and precautions 1) Remove the dust accumulated inside the electric field, including on the anode, cathode, shaking devices, trough plates, ash hoppers, inlet and outlet end caps as well as guide plates, air flow distribution plates, and the inner walls of the orifice plate housing. 2) When cleaning the dust, it should be done from top to bottom, in the order from the inlet to the outlet; personnel and tools used for cleaning must not fall into the ash hopper. 3) When the ash hopper is clogged with dust, it is generally not allowed to discharge the dust through the manhole in the hopper. When cleaning the ash accumulation in the ash hopper, the ash flushing water should be turned on to activate the ash discharge valve, so that the accumulated ash can be discharged through normal channels. If the ash inside the ash hopper becomes compacted, it must be removed by manual knocking or other methods. 2. Inspection procedures and quality standards for the anode plate array (1) Inspection of anode plate integrity 1) Check for bending or deformation of the anode plates using visual inspection or the wire-tugging method. After measurement, the planarity error of the anode plate shall be ≯5 mm, the diagonal deviation of the plate array shall be ≯10 mm, and the deviation shall be ≯L/1000 with a maximum value not exceeding 100 mm. 2) Check for rust and electrochemical erosion on the plates, identify the causes, and eliminate them. Porous plates, as well as those whose damage depth and area are so large that they cause the plates to bend and make it impossible to maintain the pole pitch, should be replaced. 3) Check whether the fixing screws of the straps connecting the anode plate arrays are loose, and whether there is any welding failure; ensure that the plate arrays are properly assembled, with no straps coming loose or the small steel pipes becoming unseated due to welding issues. Any such problems must be addressed. When the plate array is constructed using welded small steel tubes, DC welding machines should be used for patch welding to minimize the impact on the flatness of the plate array. The lateral movement gap between the plates in the plate array is about 8 mm, allowing for slight movement. 4) Check whether the clamping plates of the anode plate array and the impact rod have come loose, suffered weld cracks, or become deformed; carry out repair welding and adjustment if necessary. The impact rod should be confined within the extreme limits of the anode, with a certain amount of movement allowance. (2) Measurement of the same-pole distance of the anode plates: 1) The same-pole distance is measured for each electric field, using the relatively flat surface of the anode plate in the middle as a reference. The distance can be measured at the entry and exit points of each row of plates, at three points along the upper, middle, and lower parts of the plate; additional measurement points can be added where the plate height is significant or where deformation is evident. Measurements should be taken at the same location during each major overhaul, and the measured and adjusted data should be recorded in the equipment register. 2) The allowable deviation for the same pole pitch is: ±17 mm when the plate height is ≤ 7 meters, and ±20 mm when the plate height is > 7 meters. The same-pole distance measurement table must be recorded accurately, and the data must not be falsified. (3) Overall adjustment of the anode plate 1) Adjustment for equal pole distance: When the bending deformation is significant, a wooden hammer or rubber mallet can be used to strike the area where the bending is most severe; thereafter, the force should be gradually reduced as the strikes are moved toward both ends in order to make the adjustment. 2) When the plates are severely misaligned or sunken, the pole distance exceeds the specified value and cannot be corrected on-site, requiring plate replacement, preparations for removing the roof cover should be made ahead of the major repair, along with the preparation of a detailed maintenance plan. 3) Each newly installed anode plate should be tested in accordance with the manufacturer’s specifications; the flatness and diagonal deviations of the plate array after assembly must meet the manufacturer’s requirements. Care should be taken to maintain the original arrangement when lifting them. Other relevant precautions for replacing the plate array: 3. Inspection procedures and quality standards for the cathode frame and cathode wires (1) Inspection of the cathode suspension device 1) The inspection of the cathode suspension device mainly involves checking whether there is any mechanical damage or insulation failure in the support insulators and insulating sleeves. The method is: wipe the supporting insulator and the surface of the insulating sleeve with a clean, dry soft cloth. Inspect the insulated surface for mechanical damage, insulation breakdown, and signs of discharge, and replace any cracked support insulators or insulating sleeves. Check whether the crossbeams of the load-bearing support insulators (or insulating sleeves) are deformed; appropriate fixing measures should be taken if necessary. Carefully transfer the support points to temporary supports, ensuring that the load is distributed evenly among the four support points to avoid damaging the components of the other three. Precautions: After replacing the insulating sleeve, make sure to seal the area around its bottom with asbestos rope to prevent air leakage. Test item: A dielectric strength test should be conducted before replacing the insulating components. Test standard for newly replaced high-voltage insulation components: AC withstanding voltage at 1.5 times the rated field voltage, with no breakdown required after 1 minute. 2) Check whether the nuts at the top of the suspension rods of the main frame are loose; determine whether the overall position of the main frame relative to other fixed components has changed, and make appropriate adjustments as necessary. Check the levelness and verticality of the main frame, and keep records for easy comparison and analysis. Check that the concentricity of the dust cover and the suspension rod is within the allowable range; otherwise, adjust the position of the dust cover accordingly. The concentricity deviation between the dust cover and the suspension rod is less than 5 mm. (2) Maintenance of the cathode frame: 1) Check that the overall planarity tolerance of the cathode frame meets the requirements, and carry out adjustments if necessary. The overall diagonal tolerance is 20 mm; the entire large frame structure is robust, with no cracks, welding failures, or deformation. 2) Inspect the large frame for local deformation, welding defects, cracks, etc., and carry out adjustments and reinforcement. 3) Check whether the ladder retaining tubes on the main frame are loose or have welding defects, and take reinforcement measures. (3) Maintenance of the cathode small frame 1) Check the connection between the upper and lower small frames, as well as the fixation of the small frames to the frame. When distortions, deformations, welding failures, or severe wear are detected, correction, replacement, or weld repair is carried out. Quality standards: Each small frame is free from distortion or loosening, is properly fixed to the large frame, and the upper and lower frames are well connected. 2) Check the flatness of the small frame and correct it if it exceeds the specified limits. Quality standard: The flatness tolerance for a single frame is 20 mm, while the flatness tolerance when two frames are combined is 18 mm. (4) Cathode wire maintenance 1) Thoroughly inspect the fixation of the cathode wire to determine whether it is loose, detached, or broken, and identify the cause of the issue for correction. For wires that have come loose due to nut detachment, try to reinstall the nuts and tighten them as specified; also, perform stop-welding on the bolts. The length of the bolts used must be appropriate, and the welding points must be free of burrs to prevent abnormal discharge. When the disconnected wire is in a location out of reach, it can be welded using electric welding as long as this does not affect the small frame structure (such as causing a decrease in strength or deformation) and the distance between the opposite poles is maintained. The burrs on the weld spots must be smoothed; if welding is not possible, that pole wire should be removed. The remaining part of the broken wire should be removed. Identify the cause of the wire breakage (such as mechanical damage, electrocorrosion, or rust) and take appropriate measures. To check for loose pole wires, one can first shake each row of small frames to listen for any knocking sounds and observe the degree of movement, which can help in identifying such issues initially. In cases where the pole wires have become loose due to loose nuts, it is necessary to tighten the bolts first and then weld them in place. For situations where this approach is difficult, spot welding can be used to secure the movable parts, thereby preventing the nuts from coming loose and the pole wires from becoming loose again. Quality standards: The cathode wires must not be loose, broken, or detached; the distance between the electrodes in the electric field must be maintained at the appropriate level, and the cathode wires must have good discharge performance. 2) If the wires secured with wedge pins become loose, they should be tightened to the specified tension according to the manufacturer’s guidelines before the wedge pins are reinstalled. Damaged wedge pins should be replaced, and those that are deformed should be repaired to ensure proper tightening. 3) Check the performance status of various types of cathode wires and keep records of them, as data for a comprehensive analysis of the equipment’s operating conditions and performance. 4) Replace the cathode wire: Use a cathode wire of the same model and specification. Before replacement, check whether the cathode wire is in good condition; if it is bent, correct it so that it meets the requirements specified by the manufacturer. For the pole line connected by bolts, one end should be fixed while the other end should be adjustable. Make sure that the bolt retention welding is reliable, with at least two spot welds; the length of the bolts used must meet the requirements, and the welds should be free of burrs, with no sharp corners protruding. Replace the helical thread that tends to come loose due to insufficient tension; when replacing it, be careful not to stretch it too much, as this could render the helical thread unusable. When adjusting and replacing small frames that have significant deformation or many issues with their pole wires in conjunction with the anode plates, it is necessary to use special brackets to keep the frame in a vertical position during the replacement of those pole wires, thereby preventing deformation. When the newly hoisted small frame is reinstalled, make sure its relative position to the cathode shaking shaft remains unchanged. (5) Detection and adjustment of the pole distance difference 1) The detection of the pole distance difference should be carried out after the major framework has been repaired, and the pole distance of the anode plate rows has been adjusted to the normal range. For those polar distances achieved after adjustment, an adjustment mark is made, and the data before and after adjustment are recorded in the equipment file. Standard: Data records must be clear, measurements must be taken carefully and accurately, and data must not be falsified. 2) Placement of measurement points: For the convenience of work, measurement points are generally placed on the first pole line on the inlet and outlet sides of each electric field. 3) Create a custom measurement table based on the layout of the measurement points; the record should include the following information ； Electric field name, number of channels, measurement point number, cathode wire number, person in charge of measurement, measurement time, and measurement data. Try to keep the measurement positions unchanged during each major overhaul, and pay attention to matching them with those from the installation phase and the previous major overhaul, so as to facilitate comparative analysis. Quality standard: The deviation of the pole pitch is ±8 mm when the plate length is ≤17 m. When the plate length is ›7m, ±10mm. All pole separations shall meet the above standard requirements. 4) In an electric field where adjustments for equal pole distances, frame sizes, and pole lines are carried out in accordance with standard requirements, it is theoretically possible to ensure that the polar distances remain within the standard range. However, in practice, due to factors such as heavy workload, tight deadlines, inadequate testing and maintenance methods, and equipment aging, it may not be possible to keep all aspects related to equal pole distances, frame sizes, and pole lines within the normal range. In such cases, partial adjustments must be made to ensure that all measurement points for polar distances are within the standard limits. Other areas between the anode and cathode must be inspected visually by experienced personnel and checked using special T-shaped go/no-go gauges. For individual barb wires, the orientation of the barbs and the distance between their two tips can be adjusted accordingly, but such adjustments should be made carefully, with the proportion not exceeding 2% of the total number; otherwise, changes in the discharge center will result in a loss of the optimal configuration with the electrodes, affecting the discharge performance of the wire. 4. Maintenance of the anode rapping device: (1) In conjunction with the inspection for dust accumulation on the anode plates, identify the fields and anode plate rows where the rapping is insufficient, and carry out targeted inspections and repairs. (2) Check the deviation of the striking anvil’s knocking center under operating conditions, as well as the wear condition of the striking anvil. Check whether the impact anvil and the ram head are loose, detached, or cracked, whether the bolts are loose or detached, and whether there is any welding failure; make adjustments and take reinforcement measures as necessary. Position adjustment should be carried out when the anode plate array is loosened, and components should be repaired or replaced. When the hammer and anvil engage with each other, adjustments or replacements should be carried out depending on the degree of engagement, to prevent the shaking shaft from getting stuck. Quality standard: In operation, the contact point between the hammer and anvil in the rapping system should be aligned vertically and horizontally (with a deviation of 12 mm each), without any tilting; moreover, the length L of the contact line between the hammer and anvil should be greater than 1/5 of the total length when they are in full contact. The damaged hammer and anvil were replaced. The hammer and the swinging arm rotate smoothly, and they can drop automatically once they pass the critical point. The clearance between the bushing of the hammer shaft and its outer sleeve is 0.5 mm. (3) Check whether the bearing housing (support) is deformed or weld-separated, and whether the positioning bearing has shifted; restore it to its original position. Inspect friction components such as bushings, cast-iron parts of dust bearings, support plates of fork bearings, and small rollers of idler bearing types, and replace them if necessary. Quality standard: Bearings in dusty environments whose wear thickness between the shafts exceeds 1/3 of the original outer diameter should be replaced. Bearings or related components in dusty environments that cannot be used until the next major maintenance cycle must be replaced. (4) Rapping shaft: Rotate or activate the rapping system to check whether any of the shafts are bent, skewed, or causing shaft vibration or jamming due to exceeding specified limits; make adjustments if such issues are found. When the shaft sinks but the bearing wear, coaxiality tolerance, and shaft deflection are all within acceptable limits, this can be compensated for by thickening the bearing base shims. The bearing seats on the same drive shaft must be leveled and centered; the height of the drive shaft’s centerline must correspond to that of the vibration striking position, and adjustments must be made if these specifications are not met. Quality standard: The coaxiality tolerance between adjacent bearing seats is 5 mm; for an overall shaft length of 4 mm, the number of shims used should not exceed 6. (5) Inspection of the vibration exciter connection area: 1) Check whether the universal joint flanges, connection bolts, and spring washers are present in full quantity, and whether there is any looseness, loss, or breakage; replace or supplement those that are missing. Those that are loose should be tightened, and anti-loosening welds should be applied. Quality standard: The flanges are well connected, with no bolts missing. 2) Inspect and replace the universal joints that have cracks or local breaks. Quality standard: The joint must have no mechanical damage. 3) Check passively. 4) Replace the vibration protection pins for old and damaged ones; make sure the specifications meet the requirements specified by the manufacturer, and be careful not to mix up the pins for the anode and cathode. Quality standard: The safety pin is undamaged. 5) Replace the felt pad of the insulation tank. Quality standard: No air leakage at the areas where vibration is applied to penetrate the wall. (6) Inspection and maintenance of the vibration reducer: 1) Visually check whether the reducer is leaking oil, whether the frame is intact without cracks, and whether the oil level indicator can show the oil level clearly. Quality standards: The reducer is in good condition, and the oil level indicator is clear. 2) Start the motor to check whether there are any abnormal noises or vibrations in the reducer, and whether the temperature rise is normal. Quality standards: Check for wear on components such as the pin gear sleeves inside the gearbox; change the oil in gearboxes that show no abnormalities, and seal any areas where oil is leaking. Quality standard: The pin tooth sleeve should be smooth, free from rust and irregularities. 4) Perform disassembly and repair on reducers that exhibit abnormal noises, vibrations, and temperature increases, as well as those that have been in operation for longer than the time specified by the manufacturer. (7) Conduct a trial run after the completion of maintenance on the shaking device: 1) Reset the shaking hammer head; 2) Manually rotate the device to check its rotation and the positioning of the shaking points. The machine is not overloaded, the fuse (pin) is not broken, and there is no shaft jamming; the sound and temperature rise of the reducer are normal. 5. Maintenance of the cathode rapping device: (1) Based on the degree of dust accumulation on the cathode wires, identify the fields and cathode wires where the rapping is insufficient, and conduct focused inspections and repairs. (2) Check the deviation of the striking anvil and hammer head’s striking center under operating conditions, as well as the wear, detachment, and fragmentation of the striking anvil and hammer head; the details are the same as those for anode striking. Quality standards: Refer to the anode rapping standards; the center deviation, contact line length, and wear condition are determined based on the size ratio between the anode rapping hammer and the anvil. (3) The inspection of the bearings and shaking shafts in the dust is the same as that for the anode shaking. (4) Inspection of the rapping connection components is the same as that for the anode rapping. (5) The maintenance of the vibration reducer is carried out in the same way as that of the anode vibrator; the sprockets and chains are removed for cleaning, and their wear condition is checked. Those that are severely worn are replaced. After installation, lubricant should be applied, and attention should be paid to the tension of the chains. Quality standards: The chain and sprockets should be free from rust, without slippage or seizing. (6) Maintenance of the cathode rapping chamber and the porcelain shaft 1) Clean the dust from the cathode rapping chamber, remove the dust accumulated on the polytetrafluoroethylene plates, check the degree of oil contamination on these plates as well as the sealing condition of the rapping chamber, eliminate any oil contamination, and improve the sealing. Quality standards: The shaking chamber is free of dust accumulation, the insulating dust shield shows no signs of discharge, and the shaft penetration areas are properly sealed. 2) Use a soft cloth to clean off the dust accumulated on the porcelain shaft, and check for any cracks or signs of discharge; replace the shaft if such issues are found. A voltage resistance test should be conducted before replacement. Quality standard: The porcelain rotating shaft must be free from any mechanical damage or insulation failure. Before replacement, it should withstand an AC voltage test at 1.5 times the rated field voltage for 1 minute without any flashover occurring. 6. Inspection of the ash hopper: (1) Check for corrosion on the inner wall of the ash hopper, as well as any leaks at the flange joints, cracks in the welds, and pores. Enhance inspections in light of dust leakage and corrosion that occur during equipment operation; carry out welding repairs to seal leaks as necessary. The scars resulting from such welding repairs must be removed using a grinder to prevent dust from accumulating there. Quality standard: The inner wall of the ash hopper must have no leakage points, nor any spots where ash is likely to accumulate. (2) Check whether the arc-shaped plate at the ash hopper corner is intact and whether it has become detached from the side wall; after welding repairs, it must be smooth and free of scars to prevent dust accumulation. Quality standard: The four corners of the ash hopper are smooth and free from deformation. Inspection and maintenance of the slide valve: replace the sealing packing at the slide valve and the ash hopper flange to eliminate dust leaks at the joint surfaces. Inspect the operating mechanism of the plug valve to check whether it rotates smoothly and operates flexibly, for any signs of jamming, and carry out adjustments as well as rust removal, lubrication, and maintenance. 7. Shell and peripheral equipment, inlet and outlet end caps, and trough plates – maintenance: (1) Inspect the corrosion on the inner wall of the shell; weld repairs should be made at any areas where there is leakage of water or air. If necessary, use the kerosene penetration method to locate the points of leakage. Check for dust accumulation on the inner wall; if there is any depression or deformation on the inner wall, identify the cause and make corrections to keep it straight and prevent the formation of eddies. Quality standard: The inner wall of the shell is free from leaks and corrosion, and is straight. (2) Check the sealing condition of each manhole (ash hopper manhole, electric field maintenance manhole, cathode pulsing chamber manhole, insulator chamber manhole); replace the sealing packing if necessary, correct any deformed manholes, and replace any damaged bolts. The “High Voltage – Danger” signs on the manhole covers should be complete and clear. Quality standards: The manhole door must be leak-free, and safety signs must be complete. (3) Check the insulation of the electrostatic precipitator casing. Quality standard: The recommended thickness of the insulation material is 100–200 mm. The insulation layer should be compacted and have a uniform thickness. It meets local insulation requirements, has complete coverage, solid metal guards, and is capable of withstanding the strongest local winds. (4) Inspect and record the wear and corrosion conditions of the inner walls of the inlet and outlet end caps as well as the supporting components; if necessary, adjust or add guide vanes in the inlet flue, and install wear-resistant linings in areas with severe wear. Repair the areas where water seeps in or air leaks out by welding, and replace the support components that are severely worn. Quality standard: The inlet and outlet end caps must be free from deformation, leakage, and excessive wear. (5) Check whether the flange joints between the inlet and outlet end caps and the flue are in good condition; repair and reinforce any dented areas on the inner walls. A test is conducted on the uniformity of air flow distribution, and the angle of the guide plates as well as the openings in the air flow distribution plates are adjusted based on the test results until the requirements are met. Quality standard: Replace the entire unit if the wear area exceeds 30%. (8) The inspection and maintenance of the distribution plate rapping shall be carried out in reference to anode rapping. (9) Inspect the wear and deformation of the channel plates, and carry out corresponding patch welding, correction, or replacement. (10) Check the wear condition of the guide plates, and replace or weld them as necessary. (11) Check whether the grid (square perforated plate) at the outlet head is blocked, remove the dust accumulated in the holes, and weld repairs to the worn areas. (12) Repair and apply rust prevention maintenance to stairs, platforms, railings, and rain shelters. 8. Maintenance of the reduction gear: The maintenance of cycloidal pinwheel reducers is covered under the maintenance of the ash storage area. III. Maintenance of electrical components (I) Maintenance of the rectifying and stepping-up transformer 1. Inspection and treatment of the rectifying transformer’s exterior: Wipe away dust and oil from the transformer’s casing using a soft cloth; check whether the paint on the casing has peeled off, whether there is any gypsum that has fallen off, and whether the casing is corroded. Also, address any oil leaks caused by heat. Quality standards: The ceramic pieces must be free from damage or signs of discharge, with a clean surface free from contamination. The oil level in the oil pillow is normal, the enclosure is well-sealed, and there is no oil leakage. The respirator is in good condition, and the desiccant shows no signs of moisture absorption (the discolored area does not exceed 3/8). The surface paint has not peeled off, and the casing is free of rust. 2. Inspection and handling of the core of the rectifier transformer: This applies to transformers that have been transported over long distances, those whose manufacturing date is more than half a year old, as well as those that exhibit abnormal conditions such as oil leakage, severe heating during operation, exposure to high current surges, etc., within 8 hours. The timing range starts from when the tank body is lifted or drained, and ends when the tank body is lowered into the fuel tank or fueling begins. The lifting eye on the body of the hoist cannot be used to lift the entire transformer. For high-voltage leads connected by wires, the oil level should be lowered below the connection point when disconnecting the wires. During the lifting process, there must be a dedicated person to give instructions and supervise; the device’s body must not come into contact with the casing or any other hard objects. Once lifting is complete, the device’s body should be stabilized. During the core inspection, remove all the input and output leads at the rectifier transformer junction box and label them, so that they can be reconnected as before once the inspection is complete. (1) Magnetic circuit inspection and treatment: Check whether all the fastening components in the magnetic circuit are loose (especially when abnormal noises occur during operation), and be careful not to damage the insulated parts when tightening them. Check whether the core heats up severely due to eddy currents caused by a short circuit, and look for signs of overheating such as peeling or discoloration of the insulating paint on its surface (especially in cases of abnormal overheating or excessive hydrocarbon levels during operation). If such issues are detected, take measures to restore the insulation strength; in severe cases, the component should be sent back to the factory or the manufacturer for repair. Quality standards: The core should not be overheated, the surface paint should not change color, all fastening components should be secure, the bolts connecting the core elements should provide good insulation from ground, with an insulation value of over 5 MΩ (measured using a 1000V megohmmeter); there should be no two-point grounding of the core, and one-point grounding should be proper (as measured with a multimeter). (2) Inspection and treatment of the oil circuit: After lifting the transformer body, visually inspect the color of the oil in the tank to check whether the oil circuit is unobstructed. Identify the source of any other objects that have fallen into the tank. Any cracks causing oil leakage during operation must be welded up; for this purpose, gas welding should be used, the transformer oil must be drained, and the inner walls cleaned thoroughly. After welding, the exterior of the transformer should be coated with anti-rust paint. Quality standards: The oil circuit is unobstructed, the oil color is clear without any impurities, and there is no rust corrosion or oil leakage on the inner walls of the fuel tank. There is no signs of aging in any of the sealing rubber gaskets. (3) Circuit inspection and treatment: Check the fixation of each coil as well as the insulation condition of the coils; secure and tie any loose parts, and identify the causes of severe heating in those areas in order to enhance the local insulation. Replace the burned high- and low-voltage coils (or send them back to the manufacturer for repair). Check the surfaces of all high-voltage insulation components for any signs of discharge (especially if this occurred during operation); these components should be removed from the equipment, and a direct current voltage should be applied according to the rated voltage indicated on their nameplates, or an insulation test can be carried out using a 250V megohmmeter. It should be noted that a 2500V megohmmeter often cannot detect soft breakdown faults in silicon stacks. To check for faults in the high-voltage and low-voltage coils, a turns ratio test is commonly used. This involves removing the silicon stack on the high-voltage side and disconnecting the connections between the various high-voltage windings. A voltage of 10–30 V is usually applied to the low-voltage side, allowing the actual turns ratios of each set of high-voltage and low-voltage windings to be measured. These values are then compared with the turns ratios calculated based on the parameters indicated on the nameplate. If there is any deviation from the expected values (a significant difference between the actual and calculated ratios), it indicates a fault ； When the input voltage changes, the turns ratio also changes); this allows one to determine whether it is a high-voltage pack or a low-voltage pack, as well as which group of high-voltage packs has a problem. When replacing the high-voltage and low-voltage windings, it is important to retain the relevant label parameters on the faulty winding (such as the date of manufacture, model specification, wire diameter, and number of turns). For the high-voltage winding, it is also necessary to indicate the location where it is to be installed, so that the manufacturer can supply the appropriate replacement parts. When replacing the high-voltage winding, its position must not be changed, as the installation location and technical parameters of the reinforced high-voltage winding differ from those of other windings. This also applies when replacing the high-voltage silicon stack, since the reinforced winding usually comes with a corresponding reinforced bridge. Quality standards: There should be no melting, poor soldering, or desoldering of the internal solder wires, and no damage or breaks in any of the leads. There are no signs of breakdown in the silicon rectifier elements or voltage equalizing capacitors. The high-voltage sampling resistor and its connection points show no signs of deformation, cracking, wire breaks, looseness, discharge, or overheating. The high and low voltage coils show no signs of insulation damage such as cracks, discoloration, or brittleness in the insulation layer. The coil is securely fixed with no signs of looseness. The high-voltage insulating plates and high-voltage ceramic components show no signs of creepage, cracking, or breakdown. The high and low voltage shields are well grounded. There is no misalignment, poor contact, or arcing between the insert blade and the blade holder. 1. The DC resistance of the primary and secondary coils shall be consistent with the values indicated on the coils; if the deviation exceeds 2% of the factory-set value, the cause must be identified. The data from the first measurement shall be recorded as the original data. After repair, it should be tested in accordance with **professional standards. After on-site repair, the following tests shall be conducted and must meet **professional standards or the manufacturer’s relevant requirements: no-load current test of the transformer, temperature rise test under rated load, and open-circuit test of the transformer’s high-voltage circuit. 3. Dielectric strength test of rectifier transformer oil: A dielectric strength test must be conducted on the transformer oil during each major overhaul. When taking samples, the oil drain hole of the transformer is opened; a small amount of oil is used to clean a dry and clean oil sample container, after which chromatographic analysis is performed on the oil sample. The methods and criteria for evaluation are in accordance with the relevant standards for electrical high-voltage tests. When the dielectric strength of transformer oil is not up to standard, oil filtration should be carried out. If the breakdown voltage remains below the specified value after treatment, it should be replaced. Quality standards: For newly installed or treated oil, the required withstand voltage is ≥400 KV/2.5 mm; after one overhaul cycle, the voltage can be reduced to at least 35 KV/2.5 mm for operation. (II) Maintenance of the high-voltage circuit in electrostatic precipitators 1. Maintenance of damping resistors: Clean the damping resistors, conduct an visual inspection, measure their resistance values, and check the condition of the electrical connections. These resistors should be replaced if there are bubbles or cracks on them, if the wire diameter of mesh-type damping resistors or wound ceramic tube resistors has decreased significantly due to electrical erosion, or if the insulating rods show cracks or carbonization. Quality standards: Visual inspection of the damping resistor shows no breaks, cracks, or bubbling; the surface of the insulating components has no signs of burning or arcing, and there is no melting or poor contact at the connection points with the disc. The resistance value matches the designed value. 2. Inspection and treatment of the rectifier transformer and field grounding: Check whether the grounding of the rectifier transformer’s enclosure is reliable (grounding via pulleys is not sufficient; a dedicated grounding circuit is required, using either braided bare copper wire with a cross-sectional area of at least 25 square millimeters or 3*30 galvanized flat iron). It should be checked that the working ground of the rectifier transformer (i.e., the grounding at the “+” terminal) is connected to the ground grid separately; this grounding point must not be shared with the working grounds of other electrical circuits or the grounds of other equipment. The grounding wire should have a cross-sectional area of at least 16 square millimeters, and it must be properly grounded. The working ground at the positive pole of the rectifier transformer must be absolutely reliable, with the grounding resistance of both the rectifier transformer and the electrical circuits being less than 1Ω; the resistance of the connection to the ground grid should preferably be no more than 0.1Ω. 3. Maintenance of high-voltage isolating switches: (1) Visual inspection and mechanism adjustment. Wipe the porcelain bottle with a soft cloth, replace any cracked ones; if there are signs of discharge, identify the cause and conduct a dielectric strength test if necessary. Check the contact condition of the static and moving contacts; if the pressure is insufficient, adjust or replace the spring clamps of the static contacts. After the maintenance is complete, apply an appropriate amount of electrical compound grease to the moving and static contacts. When rust causes inflexibility, rust removal should be carried out. The high-voltage isolating switch installed at the top has a soft-operating mechanism whose wire may experience operational difficulties due to rust; in severe cases, it should be replaced or an alternative type of operating mechanism used. Clean the transmission parts of the operating mechanism, apply new lubricant, tighten any loose components, and replace those parts that are severely worn and have affected the smooth and reliable operation of the switch. Quality standards: Visual inspection shows that there are no cracks or signs of discharge on the supporting porcelain insulators; the limit switches corresponding to the isolating switch are in the correct position, the contacts make reliable contact, the locking mechanism functions properly, and the locking function of the mechanism operates reliably. (2) Insulation testing: Under normal circumstances, only a megohmmeter is used for insulation checks, and a full-voltage withstand test is not performed. If necessary, it can be carried out in combination with cable testing (with T/R arranged at a low level) or an open-circuit test of the rectifier transformer (with T/R arranged at a high level). The high-voltage insulators to be installed must undergo a voltage resistance test. The other high-voltage insulation components in the electric field are also tested in accordance with this standard. Quality standard: The insulation resistance measured with a 1000MΩ megohmmeter should be ≥10MΩ; the test voltage is 1.5 times the rated voltage, and no flashover should occur after 1 minute of testing. 4. High-voltage cable maintenance (1) Visual inspection and treatment. Check whether the cable insulation is damaged and take appropriate remedial actions. Check the cable terminals for oil leakage, glue seepage, overheating, and signs of discharge; in conjunction with preventive tests, reprocess any defective cable terminals. The manufacturing process for cable terminations follows or refers to the construction process for 35KV power cables. Check whether the several grounding points of the cable (the grounding of the armor strip, as well as the protection and shielding at the cable ends) are in good condition, and whether there are any broken connections; take appropriate action if necessary. Quality standard: The cable terminal shall have no oil or glue leakage, overheating, or discharge. The cable terminal is properly protected and grounded, the enclosure or shielding layer is well grounded, and the cable insulation is intact. (2) Preventive testing: Under normal circumstances, a routine preventive test is conducted on the cable every two major maintenance cycles. When abnormalities such as overheating, oil leakage, or sealant leakage occur in cables and terminal fittings, enhanced monitoring and preventive testing should be carried out. Cables that have suffered breakdowns or failed preventive tests during maintenance should be repaired by reprocessing the cable terminals or replacing the cables, with an effort to avoid having intermediate joints; if any are necessary, there should not be more than one. Quality standards: The standards for preventive testing shall be followed in accordance with the relevant regulations when alternating current is used. Test standards for high-voltage DC cables dedicated to electrostatic precipitators: The DC test voltage is 4 times the rated voltage, with a test duration of 10 minutes. Implement measures. (III) Maintenance of high-pressure control systems and safety devices. 1. Inspection and maintenance of the rectifier transformer protection devices and safety facilities: Remove the thermometer for calibration by the thermal engineering team; send the gas relay to the relay protection team for calibration, and inspect the oil level gauge on-site. Rectifier transformers installed at high positions need to be inspected to ensure that the alarm and tripping devices for oil temperature and gas, as well as the rain protection measures for the output circuits, are in good condition. It is also necessary to check the fixing of the low-voltage incoming cables and the condition of the rubber gaskets used to protect those cables from wear. A fresh water discharge flow test is conducted from the oil collection tray to the sewage outlet (tank). Quality standards: The oil level and oil temperature gauges of the rectifier transformer, as well as the gas relay, are in good condition, provide clear readings, and have clean surfaces. The gas relay and temperature indicator must be calibrated properly, and the alarm and tripping circuits must function correctly. When installed at a higher position, reliable measures must be in place to prevent accidental tripping or alarms caused by wind, rain, and snow, as well as to protect the cable insulation from wear. 2. Inspection of the high-voltage measurement circuit: The high-voltage sampling resistor is tested using a 2500V megohmmeter to determine whether there is any damage in the series components; attention must be paid to the polarity when conducting this test (measure in reverse). The secondary current sampling resistor and the secondary voltage measurement resistor are measured using a multimeter, with the external circuit disconnected during the measurement. The data from the first measurement is recorded as raw data in the device file. Quality standard: The shielding wires of the secondary voltage and current sampling circuits are intact, with one end properly grounded. The high-voltage sampling resistor, the secondary voltage measurement resistor, and the secondary current sampling resistor shall be consistent with the values specified in the manufacturer’s original design. If the deviation exceeds 10%, the cause must be identified, the components shall be replaced or reconfigured, and the readings shall be recalculated. The characteristics of the voltage-sensitive component connected in parallel with the secondary voltage measurement circuit are normal. 3. Reactor maintenance (1) Visual inspection and treatment. Check whether the connections of the reactor are overheating. Check for any poor contacts, ensure that the porcelain insulators are in good condition, and verify that there is no oil leakage from the oil-immersed reactors. Inspect whether the reactors are securely fixed; if necessary, disassemble them for repair. Quality standards: The porcelain bushing should be intact, without cracks or damage; the enclosure should show no oil leakage; the connections should be in good contact, with no signs of overheating. (2) Performance testing. Measure the DC resistance value of the coil using a bridge (especially when there is abnormal heating during operation), and measure the insulation of the coil with respect to ground using a 1000V megohmmeter. This inspection is carried out simultaneously with the inspection of the rectifier transformer’s core; for the inspection methods and precautions, refer to the relevant details outlined in the inspection procedure for the rectifier transformer’s core. Quality standards: All coils are secure and not loose, and all tightening bolts are tight. The coils, core, and core-penetrating bolts maintain good insulation from ground. The coil insulation shows no signs of aging, and the core has no insulation damage or overheating issues. The core is properly grounded at one point. The oil tank is clean, free of debris, and the oil is clear with no impurities. 4. Maintenance of high-voltage control cabinet (1) Visual inspection and treatment. Clean the dust from the high-voltage control cabinet; before cleaning, remove the voltage automatic regulator. Check that all components in the main circuit (main contactor, fast fuse, thyristor, air switch, etc.) are in good condition in terms of appearance, and verify that the primary and secondary wiring is intact. Quality standards: There is no dust accumulation inside the control cabinet, and the panel surface is free from rust. The control cabinet is properly and reliably grounded, with both primary and secondary grounding in good condition, without any signs of looseness or overheating. (2) Inspection and processing of the performance of main components and devices. Check whether the cooling fan of the thyristor component is stuck or not rotating smoothly; replace the faulty fan. Inspect and remove dust accumulated on the heat sinks, check the contact between the component and the heat sinks, and use a clean, soft cloth to remove any dirt or dust from the surface of the thyristor component. Pay special attention to the connection of the trigger terminals. The performance of thyristor components can be simply assessed using a pointer multimeter; if available, a thyristor characteristic tester can also be used. Quality standards: The thyristor cooling fan must function properly, and the heat sinks must not be clogged with dust. Use a multimeter to measure the resistance between the various terminals of the thyristor; the normal value according to empirical data is generally for the control terminal and the cathode. Tens to a dozen ohms ； The control electrode to the anode, and the cathode to the anode, both exhibit resistances of several hundred kiloohms. (3) Check the opening and closing status of the air switch, and open the panel to inspect the contact condition and any heating issues. Examine the thermal elements as well; address any abraded contacts or overheating joints. Adjust the overload protection settings or conduct a testing procedure (the thermal element should react at 1.5 times the rated primary current of the rectifier transformer, within 1.5–2 minutes; overload protection should activate at 6–10 times the rated current). Remove the arc extinguishing cover from the main contactor, check for overheating or abraded contacts and make necessary repairs. Inspect the operating mechanism of the contactor, adjust or replace relevant components, remove oil and dust from the areas where the core comes together, and replace any faulty silent energy-saving compensators. Quality standards: The air switches and AC contactors operate properly; the contacts show no signs of overheating, sticking, poor contact, or abnormal noises. The protection functions are intact. All switches and buttons operate flexibly and reliably. (4) Meter calibration. Remove the primary and secondary voltage and current meters for professional calibration at the instrumentation shop; when removing them, make proper markings on the wiring and meters respectively, and short-circuit the primary current measurement circuit. Due to the special nature of the power supply device for electrostatic dust removal in the sampling circuit, when calibrating the secondary voltage and current meters, it is not sufficient to focus only on the meter gauges; the interaction with the sampling circuit must also be taken into account. This calibration is usually carried out during the no-load voltage rise test of the electric field after major repairs are completed. Using specialized measuring devices (such as high-voltage electrostatic meters or dedicated high-voltage measurement rods with resistive voltage division), and by comparing with the reference table, the measured values should be around the normal operating range. After the wiring is completed, the adjustable parts should be secured with red paint; each meter should be properly marked. The fixing plates for the secondary voltage and current meters in different electric fields (which contain calibration potentiometers) generally cannot be interchanged. ] Quality standards: The gauge indicates correctly, exhibits good linearity, with errors within the allowable range; there is no sticking in the gauge, and it can reach the mechanical zero position. 5. Inspection and adjustment of the voltage automatic regulator (1) Visual inspection and handling. Check whether the guides of the drawer-type adjuster are loose or deformed, and whether the wires on the external connectors are loose, have poor contact, or are soldered poorly. Use a soft brush to remove dust from all parts of the adjuster, and wipe them with a clean, soft cloth dipped in anhydrous ethanol. Inspect all connection components, plug interfaces, and components on the connectors for any signs of looseness, poor soldering, broken copper sheets, corroded pins, or loose fastening nuts. If adjustable components are replaced, seal them with red paint after adjustment. (2) On the simulation debugging bench, with no load in the electric field, it is verified that protections such as current limit, primary overcurrent, secondary overcurrent (open circuit), and low voltage delay meet the manufacturer’s requirements. By repeatedly observing the one-time voltage value, it is checked whether the thyristor conduction angle indication roughly reflects the thyristor’s conduction condition. When an electric field is applied to the flue gas and a flashover occurs in the field, it is checked whether the flashover sensitivity is appropriate. 6. Inspection and testing of safety interlock devices (1) Inspection and testing of the safety interlock for manhole covers. Clean the safety interlock panel, check the internal wiring connections, verify that the labels on the keys are complete and correct, ensure that the safety lock (car switch) operates smoothly and reliably, check that the contacts make solid connections, and verify that the locks on the access panels are in place and function properly. Finally, in accordance with the safety interlock design requirements for manhole doors, interlock tests were conducted on the start and stop controls of the high-voltage control cabinet (these tests can be carried out before the no-load voltage rise test in the electric field; at this time, only the main contactor should be closed while the high-voltage control cabinet should not output power, to prevent the rectifier transformer from experiencing frequent shocks). Quality standards: The wiring on the safety interlock panel is in good condition; there is no loosening or welding failure. The safety interlock function matches the design specifications, all indicator labels are intact, the locking and unlocking mechanisms operate smoothly, and the contacts function reliably. (2) Inspect and test the locking circuit of the high-voltage isolator; check whether the limit switches correspond to the \"on\" and \"off\" positions of the high-voltage isolator, and measure the contact condition of the contact point transition on the high-voltage control cabinet. Finally, operate the isolating switch directly to carry out interlock tests for starting and stopping the high-voltage control cabinet (this can be done before the no-load voltage rise test in the electric field; at this time, only the main contactor should be closed, and the electric field must be in a state ready for voltage application, so that no overvoltage occurs on the high-voltage side after the high-voltage isolating switch is opened). Quality standards: The limit switch corresponds to the position of the high-voltage isolating switch; the contacts make good contact, the switching is flexible and reliable, and the locking circuit functions properly. (IV) Maintenance of the low-voltage electrical system 1. Maintenance of the power distribution section (1) Perform maintenance work on 380V distribution equipment, such as low-voltage busbars, circuit breakers, switches, as well as distribution panels, power cabinets, and lighting cabinets, by shutting off power first. (2) Check whether the cutters and switches on each distribution panel, power box, and lighting box operate smoothly, whether the blade positions are correct and the tightness is appropriate, whether the fuse bases are loose or damaged, and whether the fuse elements are intact. Also, verify that all electrical connections (cable terminals, power terminal strips, busbar connections, cutter terminals, switch terminals, fuse terminals, etc.) have good contact, and check for any issues such as overheating of cable terminals, insulation damage, melting of tin-plated or aluminum wires, discoloration due to overheating of copper or aluminum conductors, or annealing of spring washers. (3) Check that the markings on each power circuit are complete and accurate, and that the fuse specifications match the indicated capacity. (4) Use a 500V megohmmeter to check the insulation quality of each power circuit. Quality standard: The surfaces of all busbars, power cabinets, and distribution panels must be clean, with no contamination or damage to the insulating components. The interiors of each power box and distribution panel are clean; the circuit breakers and switches operate smoothly and reliably, and there is no overheating at any electrical connections. The circuit markings are clear, and the actual specification of the fuses matches the indicated value, being greater than 1 MΩ.

I have studied it. Is there any national standard regarding the maintenance of silicon rectifier transformers?

1. Handle the broken polar line. 2. Check the dust accumulation on the collecting electrode and the discharge electrode; if any abnormalities are found, analyze the reasons and take appropriate measures. 3. Check the tightness of each shaft and hammer in the rapping system; broken or damaged safety pins should be replaced promptly. 4. Check the vibration drive gearbox and eliminate leaks promptly. 5. Check the temperature control system and replace any damaged thermometers. 6. Check for air leaks at the smoke box, housing, ash hopper, and manholes; weld or replace gaskets if necessary. 7. Inspect for leaks in the valves of various pipelines. 8. Remove dust accumulated on the insulating porcelain posts of the discharge electrode, bushings, vibrating porcelain shafts, cable terminal boxes, etc., wipe them clean, and replace any damaged porcelain components.

Very good, a comprehensive introduction; I’ve saved it and studied it. Support for the third floor

It’s too detailed, too precise. Is there any information on bag filter dust removal?