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How does a Marine generator maintenance?

2014-09-06 16:44      Click:

Q: how does a Marine generator maintenance?

A: Marine 50 hz or 60 hz ac generator for three phase synchronous generator.According to the engine, steam turbine generator and can be divided into the gas generator diesel generator Three.On some large ship and some ships, the use of steam turbine generator or gas turbine generator.Ships are usually with medium-speed diesel generators.And the ship with low speed shaft generator and mostly medium capacity.

1. The general maintenance
To guarantee the normal work of the generator, should not have water in its neighborhood and accumulation of oil and dirt, there can be no corrosive gas, so as not to damage the generator winding insulation.
At the same time of moistureproof and dustproof, pay attention to not affect the normal ventilation and cooling of the generator.Often should clean the dust dirt inside the vent way, keep unimpeded.The temperature of the cooling air shall not be too low, so as to avoid condensation water drops on winding and other conductive device.
To stop running for short-term generators, collector ring can not bind up protection, but between the brush and slip ring gasket with insulating board, paraffin paper or tar paper, so as not to brush on the surface of the collector ring - formation of spots.
Generator of machined surface, if the oil, paint falls off and corrosion, should be timely cleaning, and coated with anticorrosive paint.
2. Disassembling matters needing attention
Generator disassembling method and the asynchronous motor is roughly same, but, because of the large generator weight should be paid attention to when disassembling don't touch.Remove the end cover, be careful not to touch the wound out the surface of the stator coil at base;When you take out the rotor pad with cardboard between the stator, rotor, in case of damage when used in wire bundle rotor core and winding, wire shall not run into rotor shaft neck, feng fan, collector and changed hands lead.Tie wire must be pad with wood or rubber;
3. The drying of generator 
The newly installed good synchronous generator, before running, generally should be dry.If insulation resistance meet the requirements, you can not drying, but running start within 24 h of load should not exceed 50% of the rated capacity.
People who are running generator parking overhaul or discontinuation in excess of the prescribed time limit, insulation resistance is lower than the specified value, must be dry.Such as surface is be affected with damp be affected with damp, dry loading method can be used to dry.
Drying method are many, are available on the ship for the following methods:
Hot air method: (1) the host to produce dry clean the waste heat of the wind into the generator for drying, rotor winding.In order to prevent the shaft deformation, should cycle to rotor turned 180 degrees.When dry, should control winding surface temperature.With a thermometer, winding surface shall not exceed 85 ℃, the inlet air temperature shall not exceed 90 degrees.
(2) the short circuit current dry method: put the generator output terminal through the ammeter nipple, adjusting the rotor excitation current, the stator each phase current is 50-70% of the rated current.Generator can not run under the rated speed, but should maintain a constant speed, so as to avoid temperature instability.
Short contact, had better choose in the stator lead wire end can also be the transformer sub, dry with transformer.
This method can dry the stator winding and sold the at the same time.
(3) the dry loading method: Marine generator be affected with damp be affected with damp, if only for surface drying drying can be used with load.Dry, the generator can take 50% rated current first load operation.Then press 65%, 85%, 85%, increases to the rated current value.Each level load operation 24 h.In the process of drying the winding insulation resistance measurement shall be periodically.
The matters needing attention when dry;
Should be done in clean air heating dry, dry with compressed air to power generators had swept clean before.
If wet winding is serious, the need to use first method of hot air drying, the drying time, to bring load is dry, so as to avoid insulation breakdown.
Dry, should put on some more thermometer, distribution in each part of the generator, in order to control the temperature of each part, to prevent local overheating.
Heating should be slow, in order to avoid the coil internal moisture evaporation and insulation damage occurred abruptly.If the drying temperature can not meet the requirements of the temperature, can be in slightly under the low temperature drying, just time should be extended appropriately.
Generator early drying, the evaporation out, with a winding fever make insulation resistance drops, and then gradually rising, rising more and more slow, finally stability to a certain value.At constant temperature, keep unchanged over 3 h insulation resistance, dry end work.
No matter what method, after drying, when the coil cooling to 60 ℃, the stator winding and turnover winding resistance at 500 v megohmmeter measurement, should be not less than 0.5 M.
4. Maintenance of generator bearing
In the ring lubrication of the sliding bearing, bearing the amount of oil should be certain, oil generally not run time.Oil under prescribed liquid level, oil bearing should not be left, in order to avoid splashing onto the winding.
Adopt ball or roller bearing of the motor, when running about 2000 h, namely the need to change a grease.Bearing used in dust and damp environment, should be replaced according to often lubricating oil.
Before start long-term outage generators: if equipped with rolling bearings, must first check the lubrication state, if the original is dirty or grease has hardened metamorphism, must first to bearing is rinsed clean, then clean with gasoline.Finally complete clean grease.Fill in the quantity for two-thirds of the bearing chamber space, do not fill in too much.
5. Maintenance of collector ring and brush
The surface of the collector ring should be kept smooth and cylindrical.If the surface is green and the burning marks, 00, fine grinding emery cloth.When grinding, should put cloth in diameter corresponds to the slip ring arc on the shingle.Can also be used in the operation of grinding.
If serious burns or collector ring surface deformation, should be light car, light truck into the factory in the ship repair.
In order to make the collector ring wear uniform, must be replaced within a year the polarity, one or two times.
Brush is easy to damage the parts, often should check.
A. take A closer look at the generator inside, can not have sundry, prevent fall into screw, tools, such as cloth foreign body.
B. with about two atmospheres dry compressed air or tiger skin remove dust generator of each part.In order to avoid damage to the coil, can not use metal blowpipe.
C. check the lubrication condition of generator bearing.Quantity and quality of lubricating oil and grease must comply with the provisions of the maintenance requirements.
D. monitor the connection of the generator and its prime mover are in good condition.At the same time check whether the axis of the two machines in a straight line.
E. check whether the rotor is flexible, at the same time, check the bearing quality.
F.Clean the collector ring.
G. Check the brush device;Brush a 14.7 to 19.6 kPa pressure.
H. measuring insulation resistance, measured with 500v megohmmeter shall not be less than 0.5 M euro.

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