Operation And Maintenance of Marathon MX Series Generator

What do you know about Marathon MX Series three phase AC synchronous brushless generator? In the previous article, we have talked about the general information and installation of the generator. In this post, you will learn the inspection, operation and maintenance of Marathon MX Series 3 phase alternator.

V. Inspection and operation

1. Inspection:

a. Though the generator, AVR and auxiliary devices are solid and well insulated, if the generator was stored for longtime, it might be moistened or failed and should be inspected carefully before operation.

b. Measure the insulating resistance of windings against the ground by megohm-meter, if the value is less than 2 MΩ in cold condition, the generator should be dried.

Caution: At measuring, the electronicelements and capacitor should be short circuit, and the AVR should be disconnected to avoid damage.

c. Make sure all connecting joints are tight and connected well.

d. Be sure the frame is properly grounded, and ground wire should be same as the size of lead wires.

e. Be familiar with the related data of nameplate before operation.

f. Slowly turn rotor of two bearing generator to assure there is no bumping, scraping and abnormal cacophony.

2. Voltage adjustment:

The generator output voltage is adjusted in routine test, and in common with the rated voltage. If desired voltage is different, making adjustment see the DVR voltage regulator manual.

3. DVR voltage regulator:

The wiring principle diagram and various settings are shown in the DVR manual.

4. Operation:

After inspection and adjustment have been made, and no trouble is found, the generator can run normally and generate the electricity. In order to keep generator running well, please remember following notices:

a. The generator output must be disconnected from the load, then start the prime mover.

b. Check the speed and adjustment to the rated PRM. The voltage of generator will get to normal value.

Then, close the main circuit breaker to the load. The Gen-set speed may be changed under load, and the

frequency may be lower than normal frequency. Check and adjust the speed as necessary.

c. Before shut down the Gen-set, remove load and turn off the main circuit breaker.

d, Three phase generator should be operated at balanced load. More attention should be paid to the load and the balance of current to prevent the generator running load on the single phase or serious unbalancing condition, or the AVR and generator may be damaged.

VI. Miantenance Overhaul

1. Maintenance:

a. Routine overhaul should be done frequently. Usually, maintenance period depends on the operation environment.

b. Generator should be installed in the dry, clean, ventilating place to prevent the direct contact of wind driven dirt, rain, snow and sunlight.

c. Take note of the ventilation and heating of generator at times, and the current and voltage don’t exceed the rating data.

d. Check all living parts to see whether the interface is tight, and screw & nut are right, so as to assure the grounding and electric function.

e. Pay attention to the vibration and the noise when the generator is operating and deal with the abnormal conditions.

f. If necessary, insulation resistance should be measured by 500V Megohm-meter.

g.The generator should not be operated at the place where full of water vapor, dust and flammabfe gas.

h.The bearing in the bearing house should be re-lubricated once annually or per 3000~5000 hours running, If the environment is bad, the times of re-lubrication should be more often. The grease added into the bearing house should be compatible with SRI-2, or grease will degenerate and the bearing may be damaged.

2. Major overhaul — Usually, can be done with engine:

a. Measure insulating resistance with 500V megohm meter. If the reading is less than 2 MΩ, the generator should be dried. (Must disconnect AVR with generator during measuring).

b. Clean the interior of generator by blowing and take care of the all junctions. lf inner contaminate is serious, clean with cleaner or soivents (petrofeum drstillates), then water cleaning and varnish treatment.

c. Inspect all living parts and make sure joint nut is tight and contact well.

d. Inspect all insulation and wirings to see whether there are any problems such as damage, falloff, cautery, etc. lf necessary, do some rebinding, varnish and baking to the generator.

e. Replace the grease in the bearing house, and clean the surface of two shield bearing or replace the bearing.

3. Overhaul attention:

a. Take care of the disassembled parts and avoid bumping each other or missing.

b. Should lightly place main parts such as rotor, stator, bracket, etc to prevent damage.

c. In order to reassemble easily, should make the mark for the disconnected wiring and avoid wrong connecting.

d. Disassembled bearing and bearing cap should be covered by clean paper to prevent dirt or replace the dirty grease,

e. After double-bearing generator is reassembled, should rotate the rotor slowly, ensure there is not abnormal sound and halt.

f. The bracket screws should be driven crosswise. Don’t drive the screws one by one.

g. Please use Cheveron SRI or equivalent anti-friction, high quality grease (temperature range of -30℃~175℃). The l/3~1/2 of bearing house filled with grease is enough. Please remember the reservoir can't be too full.