10 faults of robot motor and its treatment methods

1. Generator overheating

1. The generator does not operate in accordance with the specified technical conditions. For example, if the stator voltage is too high, the iron loss will increase; If the load current is too large, the copper loss of stator winding will increase.

If the frequency is too low, the cooling fan speed will slow down and the heat dissipation of generator will be affected. The power factor is too low, which increases the rotor excitation current and causes rotor heating. Check whether the indicator of monitoring instrument 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 overload one-phase winding will overheat; If the difference of three-phase current is more than 10% of the rated current, it is considered as serious mantis phase current imbalance. The three-phase current imbalance will generate negative sequence magnetic field, thus increasing losses and causing heating of magnetic pole winding, collar and other parts. The three-phase load should be adjusted to keep the balance of each phase current as far as possible.

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

4: if the air inlet temperature is too high or the water inlet temperature is too high, the cooler will be blocked. Should reduce the air or water inlet temperature to clear the plug in the cooler. The generator load should be limited to reduce the generator temperature before the fault is removed.

5: if the bearing is lubricated too much or too little, grease should be lubricated according to the regulations, usually 1/2~1/3 of the bearing chamber (upper limit for low speed, lower limit for high speed), and it is advisable not to exceed 70% of the bearing chamber.

6: bearing wear. If the wear is not serious, the bearing local overheating; If wear is serious, may cause stator and rotor friction, causing stator and rotor avoid overheating. Check the bearing for noise free. If stator and rotor friction is found, stop the machine immediately for maintenance or replacement of the bearing.

7. Insulation damage of stator core will cause short-circuit between pieces, and local eddy current loss of the core will increase and heat up, which will seriously damage stator winding. Stop the machine immediately for maintenance.

8. Breaking of parallel conductors of stator winding causes the current of other conductors to increase and become hot. Stop the machine immediately for maintenance.

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

1. Under normal circumstances, a very low voltage occurs due to uneven air gap and unequal magnetic potential under various magnetic poles due to the influence of higher harmonics or manufacturing process, etc. If the voltage is in one to several volts, there will be no danger, so it does not need to be handled.

2. Short-circuit of generator windings or defective insulation to the ground will lead to the deterioration of electrical equipment and generator performance and easy to generate heat. Timely maintenance should be carried out to avoid the expansion of accidents.

3: when there is no voltage between neutral line and ground, and when there is load, the voltage appears, which is caused by the unbalance of three phases. The three phases load should be adjusted to make it basically balanced.

The generator current is too high

1: the load is too large, should reduce the load.

2. In case of inter-phase short circuit or ground fault of the transmission line, the line shall be overhauled and restored to normal after troubleshooting.

4. Generator terminal voltage is too high

1: if the grid voltage of the parallel generators is too high, the voltage of the parallel generators should be reduced.

2: overexcitation caused by failure of excitation device should be timely repaired.

5. Underpower

Due to the insufficient voltage source compound excitation compensation of the excitation device, the excitation current required by 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 shall be taken:

1. Connect a three-phase voltage regulator between the generator and the excitation reactor to increase the generator terminal voltage and gradually increase the magnetic potential of the excitation device.

2: change the phase between the excitation device voltage flux potential and the generator terminal voltage, increase the synthetic total flux potential, and parallel thousands of ohms and 10W resistance at both ends of each phase winding of the reactor.

3: reduce the resistance value of the rheostat and increase the excitation current of the generator.

6. Stator winding insulation breakdown and short circuit

1. Stator winding is damp. Insulation resistance should be measured before the generator is put into operation for a long period of time, which is out of service or has been overhauled for a long time. Unqualified generator is not allowed to be put into operation. Damp generator should be dried.

2: winding itself defects or improper maintenance process, resulting in winding insulation breakdown or mechanical damage. Insulation materials should be selected according to the specified insulation grade, embedded winding and dip drying should be carried out in strict accordance with the technical requirements.

3: winding overheating. Insulation overheating will reduce the insulation performance, sometimes in high temperature will quickly cause insulation breakdown. Should strengthen the routine inspection, prevent the generator parts overheating and damage to the winding insulation.

4: insulation aging. General generator operation more than 15~20 years, its winding insulation aging, electrical performance changes, even make insulation breakdown. To do a good job in the overhaul of the generator and preventive test, if found unqualified insulation, should be promptly replaced with defective winding insulation or replacement winding, in order to extend the service life of the generator.

5. Metal foreign objects enter the generator. Do not leave metal objects, parts or tools in the stator chamber after the generator is repaired; Tighten the binding line of the rotor and tighten the end parts so as not to loosen due to centrifugal force.

6: over voltage breakdown:

1, the line was struck by lightning, and lightning protection is not perfect. Lightning protection facilities should be improved.

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

(3) the generator internal overvoltage, including operating overvoltage, arc grounding overvoltage and resonant overvoltage, should strengthen the winding insulation preventive test, timely detection and elimination of stator winding insulation defects.

7: stator core relaxation:

The iron core was not fastened properly due to improper manufacturing and assembly. If the whole core is loose, for small generators, two iron plates smaller than the inner diameter of the end of stator winding can be used to tighten the core. To restore the original shape, and then the core of the original clamping bolt tightening. If the partial core relaxes, you can brush the silicon steel sheet paint between the relaxation sheets, and then insert the hard insulation material in the relaxation part.

7. Short circuit between iron chips

1. Loose lamination of the iron core, which causes vibration and damages the insulation when the generator is running; Iron chip individual place insulation is damaged or iron core is local overheat, make insulation aging, undertake processing according to the method in original plan bar.

2: iron chip edge burr or mechanical damage during maintenance. Use a fine file to remove burrs, repair the damage, clean the surface, and apply a layer of silicon steel paint.

3: there are solder or copper grain short welding core, should scrape or chisel off the metal welding spot, treated the surface.

4: arc short circuit of winding may also cause short circuit of iron core. The burnt part should be cleaned with chisel and the surface should be treated well.

8. The generator loses remanence and cannot generate electricity when starting

1. Remanence is often lost after shutdown, because the material used for magnetic pole of exciter is close to mild steel, and remanence is less. When there is no current in the field winding after stopping the machine, the magnetic field will disappear.

2: the magnetic pole of the generator lost magnetism, should be in the winding than the rated current large dc current (time is very short) for magnetization, that is, can restore enough remanence.

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

1: the reactor coil local short circuit, the reactor should be repaired.

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

After the generator starts, the voltage cannot rise

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

2: the remanence disappears. If there is no instruction on the exciter voltmeter, the remanence disappears, the exciter should be magnetized.

3: the magnetic field coil of the exciter is connected with the opposite polarity. The positive and negative connection wires should be exchanged.

4: during some tests in the overhaul of the generator, the magnetic field coil is mistakenly passed to the reverse direct current, resulting in the disappearance or reverse of the residual magnetic field, which should be recharged.

Source: guangke intelligent reprint source