How To Repair Output On Generator

Dec. nineteen, 2022

Fault diagnosis and troubleshooting method

Generator overheating

(i) The generator does not operate in accordance with the specified technical atmospheric condition, such as too high stator voltage, iron loss increases; if the load current is also large, the copper loss of the stator winding increases; if the frequency is besides low, the cooling fan speed becomes wearisome, affecting the heat dissipation of generator; the power factor is too low, so that the rotor excitation current increases, resulting in the rotor heating. Bank check whether the indication of monitoring instrument is normal. If information technology is aberrant, necessary adjustment and handling must exist carried out to operate the generator in accordance with the specified technical conditions.

(2) The 3-phase load current of the generator is unbalanced, and the overloaded one-phase winding will overheat; if the difference of three-phase current exceeds 10% of the rated current, it is a serious phase current imbalance, and the three-phase current imbalance will generate negative sequence magnetic field, which volition increase the loss and cause heating of components of magnetic pole winding and hoop. The iii-phase load should be adjusted to keep the phase current as balanced as possible.

(iii) The air duct is blocked by grit accumulation, and the ventilation is poor, which results in the difficulty of generator heat dissipation. Dust and oil dirt should be removed from the air duct.

(4) If the inlet air temperature is besides high or the inlet water temperature is besides high, the cooler volition be blocked. The inlet or inlet temperature should be lowered to remove blockages in the libation. Generator load should be limited to reduce the generator temperature before failure is eliminated.

(v) Grease should be added to the begetting according to the regulations, usually 1/2~1/3 of the bearing sleeping room (the upper limit of the low speed, the lower limit of the high speed), and not more than 70% of the begetting room is suitable.

(6) Bearing wear. If the habiliment 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 overheat. The bearing should be inspected for noise. If friction betwixt stator and rotor is found, generator should be stopped immediately to repair or replace the bearing.

(7) The insulation of the stator core is damaged, which causes curt excursion between the sheets, resulting in local eddy current loss and heating, and the stator winding will be damaged if it is serious. Car should be shut downwardly immediately for maintenance.

(8) The parallel wires of the stator windings are broken, causing the current of other wires to increase and estrus up. The machine should exist stopped immediately for repair.

ii. The generator neutral line has aberrant voltage to the ground.

(i) Under normal circumstances, due to the influence of high harmonics or manufacturing process, the air gap nether each magnetic pole is uneven and the magnetic potential is unequal, and the voltage is low. If the voltage is in the range of one to several volts, there volition be no danger, do not have to deal with.

(2) The generator winding has short circuit or poor insulation to the ground, which leads to the deterioration of electrical equipment and generator performance, like shooting fish in a barrel to heat. It should be repaired in fourth dimension to avoid accidents.

(3) Neutral line has no voltage to ground at no load, and voltage occurs when there is load. It is caused by three-phase unbalance, and the three-phase load should be adapted to make it basically balanced.

3. Generator current is too big.

(one) If the load is also big, the load should be reduced.

(2) If the manual line has curt circuit or grounding fault, the line should exist overhauled and restored to normal later troubleshooting.

4. The generator last voltage is as well high.

(1) If the grid voltage of generator parallel to the power grid is also loftier,  and the voltage of parallel generator should be reduced.

(two) If the error of excitation device causes overexcitation, the excitation device should exist repaired in time.

5. Insufficient power

Since the voltage source chemical compound excitation bounty of the excitation device is insufficient, the excitation current required for the armature reaction cannot exist provided, so that the generator concluding voltage is lower than the grid voltage and the rated reactive ability cannot exist delivered. The following measures should be taken:

(1) A three-stage voltage regulator is continued between the generator and the excitation reactor to increase the last voltage of the generator, so that the magnetic potential of the excitation device is gradually increased.

(two) Change the stage between the voltage magnetic-flux potential of the excitation device and the last voltage of the generator to increase the total magnetomotive force. Several thousand ohms and 10W resistors tin exist continued in parallel at  both ends of each phase winding of the reactor.

(3) The resistance of the varistor is reduced to increment the excitation electric current of the generator.

6. Stator winding insulation breakdown, curt circuit

(1) The stator winding is damped. For generators that take been stopped for a long time or overhauled for a long time, the insulation resistance should be measured earlier putting into operation. Those who are non qualified are not allowed to put into functioning. The damp generator should be dried.

(ii) The winding itself is lacking or improperly repaired, resulting in winding insulation breakdown or mechanical damage. The insulation fabric should be selected co-ordinate to the specified insulation course, the embedded winding and the dipping paint should be strictly carried out in accordance with the technical requirements.

(three) The winding is overheated. Insulation overheating will reduce insulation operation, and sometimes the insulation breakdown is apace acquired at a high temperature. Daily inspection should be strengthened to forbid the generator parts  from overheating and dissentious the winding insulation.

(4) Insulation aging. Mostly, generator runs for xv ~ 20 years, winding insulation aging occurs, electrical performance changes, and even make insulation breakup. If the insulation is found to exist unqualified, replace the defective winding insulation in fourth dimension to prolong the service life of the generator.

(5) Metal strange matter enters the within of the generator. Afterward repairing the generator, do non leave the metal objects, parts or tools in the stator; necktie the binding wire of the rotor and fasten the stop parts and so every bit non to exist loosened by centrifugal force.

7. The stator cadre is loose.

The core is not attached due to improper manufacturing and associates. If the whole core is loose, for small generators, two iron plates smaller than the inner bore of the stator winding end tin be used to tighten the iron core past putting on double head bolts. Subsequently the original shape is restored, the original clamping bolt of the fe cadre is tightened. If the local iron cadre is relaxed, silicon steel sail paint tin be applied between the slack sheets, and so insert a hard insulating material into the slack parts.

8. Short excursion betwixt iron chips

ane) The iron cadre lamination is slack. When the generator is running, the atomic number 26 core vibrates to impairment the insulation; if the insulation of the fe chip is damaged or the core is partially overheated, it will crusade insulation aging.

(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, repair the damage, clean the surface, and then apply a layer of silicon steel paint.

(3) If there is solder or copper particles brusque iron core, the metal welding articulation should be scraped or cut off to deal with the surface.

(4) The arc short excursion occurs in the winding, which may also cause the short circuit of the atomic number 26 core. The burned part should be removed with a chisel and the surface should be treated.

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

(1) Remanence is oft lost later shutdown, because the cloth used in the magnetic pole of the exciter is close to the soft steel, and the remanence is less. The magnetic field disappears when there is no current in the excitation winding after shutdown. A battery should be provided to magnetize earlier generating electricity.

(2) The magnetic pole of the generator loses its magnetism, and a DC current (in a short time) larger than the rated current should be applied to the winding for magnetization, that is, sufficient remanence tin can be restored.

10. Excitation reactor temperature of automatic excitation device is too high.

(ane) The reactor coil is partially short-circuited, and the reactor should be repaired.

(two) If the air gap of the magnetic excursion of the reactor is too large, the air gap of the magnetic circuit should be adjusted.

11. When the generator starts, the voltage will not ascension.

1) The excitation circuit is asunder, preventing the voltage from rising. Bank check whether the excitation loop is broken and the contact is good.

(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.

(iii) The polarity of the field coil of the exciter is reversed, and its positive and negative connecting lines should exist swapped.

(4) When performing some tests in the generator overhaul, the magnetic field whorl is mistakenly connected to the reverse direct current, causing the residual magnet to disappear or reverse, and the magnetic field should be remagnetized.

How To Repair Output On Generator,

Source: https://www.dieselgeneratortech.com/generators/troubleshooting-for-generator-no-electricity-output.html

Posted by: brunoloicher.blogspot.com

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