The test items of the normal state hairpin transfer winding are mainly to measure the DC resistance insulation resistance and AC withstand voltage of the rotor winding. In the ground fault state, since the rotor is already in the crucible, a more accurate positioning inspection test is required. This paper introduces the test method for diagnosing faults in combination with fault cases. The common fault of the generator rotor is a point ground fault, which means that a certain point or part of the winding loop loses the insulation performance, that is, the insulation resistance between the conductive part of the winding and the rotating shaft reaches zero value or maintains low resistance contact. In normal operation, the generator rotor winding has a certain insulation resistance and distributed capacitance between the ground, and its insulation resistance is greater than 1 when the river is grounded and then the mountain forms a current loop. There is no direct impact on the operation of the generator. However, if a second grounding point occurs in the excitation circuit, a point-to-earth fault will be formed, which seriously jeopardizes the safety of the generator. In the domestic generator protection, the rotor point grounding signal is installed, and the rotor point grounding protection acts on the trip. After the generator rotor is grounded, the load should be transferred as much as possible, and the shutdown should be scheduled for maintenance.
1 Accident example In December 2000, during the trial operation of a steam turbine generator set of a power plant, the rotor winding insulation was gradually reduced and eventually developed into a point grounding fault. The unit is a brushless excitation system, and the return circuit is unaware from the disconnection point. Before the machine is started for the first time, the rotor voltage is 50 or so. The insulation monitoring meter on the control panel is about 20 for the positive pole and about 20 for the anode. The phenomenon is that the rotor loop is insulated. normal status.
Due to the progress of the project, no progress check is made, that is, the grid is loaded. At this time, the rotor point grounding protection is set to 1 and no action is signaled; and the rotor insulation resistance test value is 1% of the static river dynamic. 1 The factory test time is July 1999. Since the factory time has been very long, the initial judgment is that the winding is damp. During the shutdown period, the winding is subjected to through-flow baking by DC current method. After the baking is cooled, the static insulation resistance increases, while the dynamic insulation resistance decreases to 0.6. 1 The generator operation specification is still required. Less than 0.5 corpse is again connected to the grid with load. 24 1! After that, the insulation of the rotor is checked from the insulation monitoring device. The negative pole is the positive pole. The rotor is about 90% of the rotor voltage, and the rotor point is grounded to protect the alarm. Then the shutdown is checked. 2, 2 rotor winding ground fault treatment process and test method 2.1 Winding The main phenomenon in the initial stage of baking rotor winding failure is that the insulation of the rotor winding is reduced. Since the static insulation resistance is better than the dynamic insulation resistance, the principle of the simple and complicated is considered, and the cause is likely to be the moisture of the winding or the environmental uncleanness. Take measures to clean the external cooling of the air-cooling chamber of the hair dryer and the rotor winding, and use the DC current to bake the rotor winding. The baking method is to use DC welding machine as DC power supply. The current applied is about 80% of the rated current of the rotor. After baking 24, the insulation resistance of the rotor is still not improved obviously. The static insulation resistance is changed from 3 to 4 dynamic insulation. The resistance is determined by the positioning test of the 0.6MQiSo.7MHYu2.2 slot. 2.2.1 AC withstand voltage test at the rotor point grounding protection action; in the static strip to the rotor winding sister, AC withstand voltage test, the voltage rises to the position will be grounded click At home, the bulb is used in the test under dynamic conditions, and the bulb is bright between the positive pole and the ground, indicating that the grounding point has broken down.
2.2.2 Transfer location positioning test Since the unit adopts the brushless excitation system, the rotor measurement and protection circuit are first removed, and the insulation of the part of the circuit is checked. 1 The connection between the rotor circuit and the exciter circuit is often dismantled on the shaft. Check the insulation of the exciter circuit is normal, and the insulation resistance of the rotor circuit is determined according to the on-site tea piece. This method is relatively simple. The position of the grounding point of the rotor winding and the value of the grounding resistance can be determined. Measuring wiring
Apply a DC voltage to the rotor slip ring, measure the voltage between the positive and negative slip rings and the negative ring to ground voltage and calculate the grounding resistance at the initial stage of the fault. The voltage between the positive and negative poles of the rotor is 90, and the value of 1 is about 20 is about 60. From this formula, it is judged that the grounding has not yet occurred. But after the time of the operation. It becomes 90.6 very small. At this point, the rotor point grounding protection action report has become a direct grounding. According to this data, it can be preliminarily determined that the rotor is nearly damaged by the hungry grounding point. And not turning around the crotch. Other test methods include flow resistance comparison method DC high current method and the like. I will not repeat them here.
2.3 Treatment after ground fault location Since the rotor has been grounded at the point. Must be managed to eliminate. After many discussions, the method of demolition and development of the rotor of the motor was finally carried out for inspection. According to the preliminary test, the grounding point is determined at the retaining ring.
Disassemble the exciter side guard ring. A trace of the grounding point of the carbonized material of the burning medium is found at the retaining ring 13. The insulating lining is also burned through. Carefully inspect the rotor windings. No obvious grounding point was found. After the insulation lining was removed, the rotor insulation was normal. Handle the winding burr to clean the rotor surface. Replace the insulation lining and re-install the rotor to start again. Cut back to normal. It can be determined that the fault is caused by the accumulation of dust between the rotor winding and the insulating lining and the insufficient safety distance.
3 It is recommended that the generator rotor ground fault is mainly caused by poor production quality or unclean operating environment, so the manufacturer should carefully eliminate the rotor coil burrs and clean the rotor surface. Ensure the quality of manufacturing; the operating unit should pay attention to the cleanliness of the operating environment. The operating personnel should pay attention to monitoring the rotor insulation monitor when the generator is running. If the abnormality is found, the maintenance department should be notified in time to find out the cause and eliminate the hidden danger.
1 return to the factory disintegration inspection and the shape of the broken head of the cabinet 3 fully explained.
The disconnection of the potential connection is not due to the pulling force. According to the characteristics of the copper braid, the potential connection break should be finer under the action of the tensile force. This shows that the potential connection is affected by the effect of the lateral lateral force. 1.3 The on-site inspection of the pressure line is not tightened during the transportation process, so that the high-pressure outlet is subjected to the front and rear or left and right swinging force during transportation. Repeatedly. The swaying force is also applied to the connection of the erecting line potential through the notch of the phenolic skeleton of the end ring to connect the end ring with the high voltage lead. Since the phenolic skeleton slot is not treated with a lead angle, the notch is like a saw blade. The potential is connected to the left, and the effect of the rocking force 5 is repeatedly sawn and thrown away. Finally, fatigue and sweating.
4 Conclusions and Suggestions The root cause of the damage of the two-phase reactor is caused by the collision of the railway transportation; further, the internal potential is disconnected due to the disconnection of the secondary potential. The original flash is caused by on-site installation. 1 foot car transportation caused.
Damage due to the 60 two-phase reactor. Luohe Station has been in operation since its inception. The coincidence of the Tianlian 5001 line was not put into operation. The safe operation of the 500 grid has been greatly affected, and the economical damage to the factory for repair and replacement of coils and cores has also caused great economic losses. therefore. It is recommended that the factory should strengthen the internal bamboo. Ensure that the quality assurance system is implemented; the secondary damage of the phase reactor occurs on the potential line. Explain that the design is still incomplete. The stomach should increase the length of the clamp connection so that even the high voltage lead is subjected to tensile force. Also + will break the clamp line; the end ring insulation skeleton outlet slot should be treated with a lead angle. In order to reduce the potential connection, the sawing is done here; the tightening of the high-voltage lead root has been increased; the on-site installation of bamboo is strengthened. Make sure to install a good brother. Give full play to the guidance of the factory for high-parallel reactors and do not perform important tests such as partial discharge at the site. The secondary damage of the 0-phase reactor is exactly what can not be found in the routine test. The on-line measuring device for insulating oil and the partial discharge measurement with electricity are effective for internal discharge. The 500 1 live or online partial discharge measurement should be strengthened and improved. The southern power grid in Hebei should be Choose one spare reactor as early as possible. In view of the original product has many years of operating performance. And it can make it better with Baobei Lianzhou Luhe Reactor. Priority should be given to the original product.
In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine by use of a post processor, and then loaded into the CNC machines for production. Since any particular component might require the use of a number of different tools – drills, saws, etc. – modern machines often combine multiple tools into a single "cell". In other installations, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design
Computer Numeric Control (CNC) is the automation of machine tools that are operated by precisely programmed commands encoded on a storage medium (computer command module, usually located on the device, see picture right-->) as opposed to controlled manually by hand wheels or levers, or mechanically automated by cams alone. Most NC today is computer (or computerized) numerical control (CNC), in which computers play an integral part of the control.
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CNC Machining is the metals to make use of CNC machine tool processing, is refers to the use of nc Machining tools for processing.Index of the CNC control machine tool controlled by nc programming language, usually in the form of G code.Nc machining G code what language told CNC machine tool The cartesian coordinates, and controls the tool feed rate and spindle speed, as well as the tool changer, coolant, etc.Nc machining relative manual processing has great advantages, such as CNC machining to produce parts very precise and repeatability.Nc machining process can produce manual can't complete with complex shape parts.Nc machining technology has been widely adopted, most of the machining with CNC processing ability, the typical machining workshop, the most common way of nc machining with CNC milling, CNC and CNC EDM wire cutting, EDM wire cutting cut).For nc milling tool is called numerical control milling machine or numerical control machining center.To carry on the lathe of numerical control turning processing is called numerical control lathe work center.Can manual programming nc machining G code, but usually machining using CAM (computer-aided manufacturing) software automatically read CAD (computer-aided design) files and generate G code program, control of CNC machine tool.Leading technology of numerical control machine tool brands have Hass, DMG (Deckel Maho Gildemeister), Mazak, Mori Seiki, Fadal and Wasino.
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