Synchronous generator fault diagnosis and troubleshooting method - Database & Sql Blog Articles

SMD aluminum Electrolytic capacitor

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

1. Generator overheating (1) The generator does not operate according to the specified technical conditions. If the stator voltage is too high, the iron loss increases; the load current is too large, the stator winding copper loss increases; the frequency is too low, so the cooling fan speed changes. Slow, affecting the heat dissipation of the generator; the power factor is too low, causing the rotor excitation current to increase, causing the rotor to heat up. The indication of the monitoring instrument should be checked for properness. If it is not normal, the necessary adjustments and treatments must be carried out to operate the generator in accordance with the specified technical conditions.
(2) The three-phase load current of the generator is unbalanced, and the overloaded one-phase winding will overheat; if the difference of the three-phase current exceeds 10% of the rated current, it is a serious 蛄 phase current imbalance, and the three-phase current imbalance will be generated. The negative sequence magnetic field increases the loss and causes the components such as the pole winding and the ferrule to generate heat. The three-phase load should be adjusted to keep the phase currents as balanced as possible.
(3) The air duct is blocked by dust and the ventilation is poor, which makes the generator difficult to dissipate heat. The dust and grease should be removed from the air duct and the air passage should be unobstructed.
(4) If the inlet air temperature is too high or the inlet water temperature is too high, the cooler is blocked. The inlet or inlet temperature should be lowered to remove blockages from the cooler. The generator load should be limited to reduce the generator temperature before the fault is eliminated.
(5) If the bearing is too rich or too little, the grease should be added according to the regulations, usually 1/2~1/3 of the bearing chamber (the upper limit of the low speed, the lower limit of the high speed), and not more than 70% of the bearing chamber is suitable.
(6) Bearing wear. If the wear is not serious, the bearing is partially overheated; if the wear is severe, the stator and the rotor may be rubbed, causing the stator and the rotor to avoid overheating. The bearing should be inspected for noise. If the stator and rotor are found to be rubbed, stop immediately to repair or replace the bearing.
(7) The insulation of the stator core is damaged, causing short circuit between the sheets, causing the eddy current loss of the core to increase and heat, and the stator winding may be damaged in severe cases. It should be shut down immediately for maintenance.
(8) The parallel wires of the stator winding are broken, so that the current of other wires increases and heats up. It should be shut down immediately for maintenance.
2. The generator neutral line has abnormal voltage to the ground (1) Under normal conditions, due to the influence of high harmonics or manufacturing process, the air gap under each magnetic pole is uneven and the magnetic potential is unequal. If the voltage is one to several volts, there is no danger and it is not necessary to deal with it.
(2) The generator winding has short circuit or poor insulation to the ground, which leads to deterioration of electrical equipment and generator performance, and is prone to heat. It should be repaired in time to avoid accidents.
(3) Neutral line has no voltage to ground when no load, and voltage occurs when there is load. It is caused by three-phase unbalance, and the three-phase load should be adjusted to make it basically balanced.
3, the generator current is too large (1) the load is too large, should reduce the load.
(2) If the transmission line is short-circuited or grounded, the line should be repaired and restored to normal after the fault is removed.
4. The voltage at the generator terminal is too high (1) The voltage of the generator grid parallel to the grid is too high, and the voltage of the parallel generator should be reduced.
(2) Over-excitation caused by the failure of the excitation device, the excitation device should be repaired in time.
5. Insufficient power Due to insufficient compensation of the excitation excitation of the voltage source of the excitation device, the excitation current required for the armature reaction cannot be provided, so that the generator terminal voltage is lower than the grid voltage and the rated reactive power cannot be delivered. The following measures should be taken:
(1) A three-phase voltage regulator is connected between the generator and the excitation reactor to increase the voltage at the generator terminal, so that the magnetic potential of the excitation device is gradually increased.
(2) Change the phase of the magnetomotive force of the excitation device and the voltage of the generator terminal to increase the total magnetomotive force. Several thousand ohms and 10W resistors can be connected in parallel at each end of the reactor.
(3) Reduce the resistance of the varistor and increase the excitation current of the generator.
6. Stator winding insulation breakdown and short circuit (1) The stator winding is damp. For generators that have been deactivated for a long time or have been repaired for a long time, the insulation resistance should be measured before putting into operation. Those who fail are not allowed to put into operation. The damp generator should be dried.
(2) The winding itself is defective or the maintenance process is improper, resulting in insulation breakdown or mechanical damage of the winding. The insulation material should be selected according to the specified insulation grade, and the embedded winding and the dipping paint should be strictly in accordance with the process requirements.
(3) The winding is overheated. When the insulation is overheated, the insulation performance is lowered, and sometimes the insulation breakdown is quickly caused at a high temperature. Daily inspections should be strengthened to prevent overheating of various parts of the generator and damage the winding insulation.
(4) Insulation aging. Generally, the generator runs for 15 to 20 years, and its winding insulation is aging, electrical properties change, and even insulation breakdown. To do the maintenance and preventive test of the generator, if the insulation is found to be unqualified, replace the defective winding insulation or replace the winding in time to prolong the service life of the generator.
(5) The inside of the generator enters the metal foreign matter. After repairing the generator, do not leave the metal objects, parts or tools in the stator ;; tie the tying line of the rotor and fasten the end parts so as not to occur due to centrifugal force. And loose.
(6) Excessive voltage breakdown: 1) The line is struck by lightning and the lightning protection is imperfect. Lightning protection facilities should be improved. 2) Misoperation, such as when the load is too high, the generator voltage is too high. The generator should be boosted in strict accordance with the operating procedures to prevent misuse. 3) The internal overvoltage of the generator, including the operating overvoltage, arc grounding overvoltage and resonant overvoltage, etc., should strengthen the winding insulation preventive test, and timely find and eliminate the defects in the stator winding insulation.
7. The stator core is loose and the core is not fastened due to improper manufacturing and assembly. If the entire core is slack, for small generators, two iron plates smaller than the inner diameter of the stator winding end can be used, and the studs can be put on and tightened. After the original shape is restored, the original clamping bolt of the iron core is tightened. If the local core is slack, first apply a silicon steel sheet paint between the slack sheets, and then insert a hard insulating material into the slack.
8. Short circuit between iron chips (1) The iron core lamination is slack. When the generator is running, the iron core vibrates and damages the insulation; if the insulation of the iron chip is damaged or the iron core is partially overheated, the insulation is aging, according to the original plan The method in the process.
(2) There is a burr on the edge of the iron chip or mechanical damage during maintenance. Use a fine boring tool to remove the burrs, trim the damage, clean the surface, and then apply a layer of silicon steel paint.
(3) If there is solder or copper short-circuited iron core, the metal welding joint should be scraped or chiseled to handle the surface.
(4) The arc short circuit occurs in the winding, which may also cause the core to be short-circuited. The burned part should be removed with a chisel and the surface should be treated.
9, the generator loses residual magnetism, can not generate electricity when starting (1) often loses residual magnetism after shutdown, because the material used in the magnetic pole of the exciter is close to soft steel, less remanence. When the field winding has no current after the shutdown, the magnetic field disappears. A battery should be provided to magnetize before power generation.
(2) The magnetic pole of the generator loses its magnetic force, and a DC current (short time) larger than the rated current should be applied to the winding for magnetization, that is, sufficient residual magnetism can be recovered.
10. Excitation reactor temperature of the automatic excitation device is too high (1) The reactor coil is partially short-circuited, and the reactor should be repaired.
(2) If the air gap of the magnetic circuit of the reactor is too large, the magnetic gap of the magnetic circuit should be adjusted.
11. After the generator is started, the voltage does not rise. (1) The excitation circuit is disconnected, so that the voltage does not rise. Check the excitation circuit for broken wires and good contact.
(2) The residual magnet disappears. If the exciter voltmeter has no instructions to indicate that the residual magnet has disappeared, the exciter should be magnetized.
(3) The polarity of the field coil of the exciter is reversed, and its positive and negative connecting lines should be reversed.
(4) When performing some tests in the generator overhaul, the magnetic field coil is mistakenly connected to the reverse direct current, causing the residual magnet to disappear or reverse, and the magnetization should be re-energized.
12. The generator's oscillation is out of step. Under normal conditions, the power generated by the generator is balanced with the load power. When a short-circuit fault occurs in the system or the generator is heavily loaded, the power of the generator is not balanced with the load of the user. In order to adjust the load to balance, a process is required due to rotor inertia and governor delay, during which the stable operation of the generator will be destroyed, causing the generator to oscillate. If the story is serious, it can even cause the generator to lose synchronization with the system. When the generator oscillation is out of step, the duty officer should create the conditions for restoring synchronization by increasing the excitation current; it can also be appropriate#p#page title#e#
Adjust the load on the machine to help restore synchronization.
13. Generator vibration (1) The rotor is not round or the balance is not adjusted properly. The quality of the rotor should be strictly manufactured and installed or the balance of the rotor should be re-adjusted.
(2) When the shaft is bent, the shaft can be corrected by a grinding method, a heating method, or a hammer method.
(3) If the coupling is not connected correctly, the clamping force of the bolt should be re-engaged with the high-speed coupling. If necessary, the end face of the coupling should be reworked.
(4) Structural component resonance, which can be changed by changing the support method of the structural component.
(5) The field winding is short-circuited between the layers, and the field winding should be inspected and insulated.
(6) If the oil supply or oil pressure is insufficient, the nozzle diameter should be increased to increase the oil pressure; increase the oil supply port to reduce the gap.
(7) If the oil supply is too large or the oil pressure is too high, the nozzle diameter is reduced, the oil pressure is reduced, the area pressure is increased, and the gap is increased.
(8) When the stator core assembly is loose, the iron core should be reloaded.
(9) The bearing seal is too tight, so that the shaft is partially overheated and bent. The bearing seal should be inspected and adjusted so that it has a proper fit clearance to the shaft.
(10) The generator ventilation system is asymmetrical. Attention should be paid to the structural arrangement and size selection of the wind deflector and the rotor support wind deflector at both ends of the stator core, so that the wind path system is symmetrical, and the rigidity of the cover plate and the wind deflector is tight. Solid and reliable.