Orion Star Robot - Common faults and solutions of robot motors

One. The generator is overheating

1: The generator does not operate according to the specified technical conditions, such as the stator voltage is too high, and the iron loss increases; If the load current is too large, the copper loss of the stator winding increases;

The frequency is too low, which slows down the speed of the cooling fan and affects the heat dissipation of the generator; If the power factor is too low, the excitation current of the rotor will increase, causing the rotor to heat up. The indication of the monitoring instrument should be checked to see if it is normal. If it is abnormal, necessary adjustment and treatment should be carried out to make the generator run 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 cricket phase current imbalance, and the three-phase current imbalance will produce a negative sequence magnetic field, thereby increasing the loss and causing the heating of components such as magnetic pole windings and ferrules. The three-phase load should be adjusted so that the current of each phase is balanced as much as possible.

3: The air duct is blocked by dust and poor ventilation, which makes it difficult for the generator to dissipate heat. The dust and grease in the air duct should be removed, and the air duct should be unobstructed.

4: The inlet air temperature is too high or the inlet water temperature is too high, and the cooler is blocked. The inlet air or water temperature should be lowered to remove the blockage in the cooler. Until the fault is resolved, the generator load should be limited to reduce the generator temperature.

5: Bearing grease too much or too little, should be greased according to the regulations, usually 1/2 - 1/3 of the bearing chamber (low speed to take the upper limit, high speed to take the lower limit), and not more than 70% of the bearing chamber is appropriate.

6: Bearing wear. If the wear is not serious, the bearing will be overheated locally; If the wear is severe, it may cause friction between the stator and the rotor, causing the stator and rotor to overheat. The bearing should be checked for noise, and if friction between the stator and rotor is found, the machine should be stopped immediately for maintenance or replacement of the bearing.

7: The insulation of the stator core is damaged, causing a short circuit between the chips, resulting in an increase in the local eddy current loss of the core and heating, and in serious cases, the stator winding will be damaged. The machine should be stopped immediately for maintenance.

8: The parallel wire of the stator winding is broken, which increases the current of the other wires and heats up. The machine should be stopped immediately for maintenance.

Two. The neutral line of the generator has an abnormal voltage to the ground

1: Under normal circumstances, due to the influence of higher harmonics or manufacturing process and other reasons, the air gap under each magnetic pole is uneven, the magnetic potential is unequal and the very low voltage occurs, if the voltage is in one to a few volts, there will be no danger, do not need to deal with it.

2: The generator winding has a short circuit or poor insulation to the ground, resulting in the deterioration of the performance of electrical equipment and generator, which is easy to heat up, and should be repaired in time to avoid the expansion of the accident.

3: There is no voltage on the ground on the neutral line at no load, and the voltage occurs when there is a load, which is caused by the three-phase unbalance, and the three-phase load should be adjusted to make it basically balanced.

Three. The generator current is too high

1: The load is too large, and the load should be lightened.

2: If the transmission line has a phase-to-phase short circuit or grounding fault, the line should be repaired, and it can be restored to normal after troubleshooting.

Four. The voltage at the generator end is too high

1: The grid voltage of the generator parallel to the grid is too high, and the voltage of the generator in parallel should be reduced.

2: The failure of the excitation device causes overexcitation, and the excitation device should be overhauled in time.

Five. Insufficient power

Due to the insufficient compensation of the voltage source of the excitation device, the excitation current required for the armature reaction cannot be provided, so that the voltage at the generator end is lower than the grid voltage, and the rated reactive power cannot be sent, 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 end and gradually increase the magnetic potential of the excitation device.

2: Change the phase of the magnetic flux potential of the exciter voltage and the voltage of the generator terminal, so that the total synthetic magnetic flux potential increases, and the resistance of thousands of ohms and 10W can be connected in parallel at both ends of each phase winding of the reactor.

3: Reduce the resistance of the rheostat to increase the excitation current of the generator.

Six. Stator winding insulation breakdown, short circuit

1: The stator winding is damp. For generators that have been out of service for a long time or have been overhauled for a long time, the insulation resistance should be measured before they are put into operation, and those who are unqualified are not allowed to be put into operation. The damp generator should be dried.

2: The winding itself is defective or the maintenance process is improper, resulting in winding insulation breakdown or mechanical damage. The insulating material should be selected according to the specified insulation grade, and the embedded winding and dipping paint drying should be carried out in strict accordance with the process requirements.

3: The winding is overheated. Overheating of the insulation will reduce the insulation performance, and sometimes the insulation breakdown will be caused very quickly at high temperatures. Daily inspections should be strengthened to prevent overheating of all parts of the generator and damage to the winding insulation.

4: Insulation aging. Generally, the generator has been running for more than 15-20 years, and its winding insulation is aging, the electrical performance changes, and even the insulation breakdown. It is necessary to do a good job in the maintenance and preventive test of the generator, if the insulation is found to be unqualified, the defective winding insulation or replacement winding should be replaced in time to prolong the service life of the generator.

5: Metal foreign bodies enter the inside of the generator, do not leave metal objects, parts or tools into the stator chamber after overhauling the generator; Tighten the lashing wire of the rotor and tighten the end parts so that they do not loosen due to centrifugal force.

6: Excessive voltage breakdown:

(1) The line suffers from lightning strikes, and the lightning protection is not perfect. Lightning protection facilities should be improved.

(2) Misoperation, such as raising the generator voltage too high when there is no load. The generator should be boosted in strict accordance with the operating procedures to prevent misoperation.

(3) The internal overvoltage of the generator, including the operating overvoltage, arc grounding overvoltage and resonant overvoltage, etc., should strengthen the preventive test of winding insulation, and find and eliminate the defects in the stator winding insulation in time.

7: Stator core relaxation:

Due to improper manufacturing and assembly, the core was not tightened properly. If the entire core is loose, for small generators, two iron plates smaller than the inner diameter of the end of the stator winding can be used to tighten the core by wearing a stud bolt. After the original shape is restored, the original clamping bolts of the iron core are tightened. If the iron core is partially relaxed, you can first apply silicon steel sheet paint between the relaxation sheets, and then inject hard insulating materials into the relaxation parts.

Seven. Short circuit between iron chips

1: The core lamination is relaxed, and the core vibrates when the generator is running and damages the insulation; If the insulation of the iron chip is damaged in some places or the core is partially overheated, the insulation will be aged, and the method in the original plan will be treated.

2: There are burrs on the edge of the iron chip or mechanical damage during maintenance. A fine file should be used to remove the burr, trim the damage, clean the surface, and apply a layer of silicon steel paint.

3: If there is a solder or copper short-circuit core, the metal welding solder joint should be scraped or chiseled off, and the surface should be treated.

4: The arc short circuit of the winding may also cause a short circuit of the iron core, and the burned part should be removed with a chisel and the surface should be treated.

Eight. The generator loses its remanence and cannot generate electricity when it starts

1: The remanence is often lost after shutdown, because the material used for the exciter's magnetic pole is close to mild steel, and the remanence is less. When there is no current in the excitation winding after the shutdown, the magnetic field disappears, and a battery should be prepared to magnetize before generating electricity.

2: The magnetic pole of the generator loses magnetism, and a DC current larger than the rated current (for a short time) should be introduced into the winding for magnetization, that is, sufficient remanence can be recovered.

Nine. The temperature of the excitation reactor of the automatic excitation device is too high

1: The reactor coil is partially short-circuited, and the reactor should be overhauled.

2: The air gap of the magnetic circuit of the reactor is too large, and the air gap of the magnetic circuit should be adjusted.

Ten. After the generator starts, the voltage does not rise

1: The excitation circuit is disconnected, so that the voltage cannot rise. Check whether the excitation circuit is broken and whether the contact is good.

2: Remanence disappears, if there is no instruction in the voltmeter of the exciter indicating that the remanence disappears, the exciter should be magnetized.

3: The polarity of the magnetic field coil of the exciter is reversed, and its positive and negative connecting wires should be reversed.

4: When doing some tests in the generator maintenance, the magnetic field coil is mistakenly passed through the reverse direct current, resulting in the disappearance or reverse of the remanence, and the magnetization should be re-magnetized.

Orion Star Robot - Common faults and solutions of robot motors

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