AVK Alternator Problem

Sounds like a bearing or an electrical short....My advice is to remove it and have it tested....otherwise just replace it...or rebuild it...I would replace the regulator too....

sound is coming like continuous short circuit inside alternator

You can have them tested at a local parts dealer...If that's an option

It could be from bearing , fan blade or internal continuous short circuit. If it is the short circuit , you should have experiencing uneven or low load sharing by now. Stop it and inspect as soon as possible

what is alternating rating and engine specification (number of cylinder) mentioned it.

Rolls-Royce B35:40 V 20AG, Alternator 10600 KVA

Does this occur only under parallel load share config or in standalone as well?

Filter?

Noise ("hum") for generator during in parallel may cause by :

- Core looseness problems

- Shifting of magnetic centerline problems

- Unbalance air gap problems

- Power reverse problems

- Rotor winding problems

- Excitation problems

When problems source is coming from winding or excitation, check the following items, but not limited to :

1. Do inspection the rotating diodes, measure the Rf and Rrev, compare the result with the diodes data (normally AvK used Semicron Diodes)

2. Do Insulation resistance on the exciter and rotor winding

3. Do Copper winding resistance on the exciter and rotor winding

4. Do Surge comparison Test on the rotor winding, if the surge comparison instrument is not available do Voltage drop on the rotor winding, compare the winding impedance from pole to pole (use 120 Vac) connected to the JK cable on the Rotor, and check each pole, it should have balance "Z" (impedance) at each pole. measure the voltage and current, calculate Z = Vac/Iac.

The voltage adjacent fault pole will be slight lower than the voltage other healthy poles, its caused the flux on the healthy pole will flowing to the fault pole

Voltage drop on the fault winding will be +/- [(m-1)/m] x healthy winding voltage, where "m" is number of poles

5. Repeat test step on item 4 with rotate the pole position, example, when pole no.1 at 1^st test is located at the top position, rotate to the side and bottom position, it useful to analyzed that the rotor may short only when the rotor winding is short due to mechanical force, During rotor at stand still may "no short circuit" was occurred on the winding, because winding rotor stand still have a micro distance, so no mechanical contact between copper winding, but when rotor spin, all copper will forced out and it will contact to each other.

Goodluck

Siswanto

www.sispowergeneration.blogspot.com

I have found one broken laminated sheet inside the alternator, also location have been identified,

So it was a "core looseness problem" per #8?

Is it fixed yet?

No remedy is taken yet, my suspicion is sound is coming for high voltage discharge from stator winding to stator core. what is the remedy

Partial Discharge phenomena's occurred on the winding higher than 4kV and PD is never resulting "hum" in the stator , PD activities in the frequency ranging 40 kHz to 100 MHz, its only would be detected by measurement or visual when PD has occurring on the surface and endwinding.

Partial Discharge can cause by:

1. Void in the insulation

2. Poor contact on the semiconductive coating to ground (core)

3. Stress grading coating damged on the end winding ( normally stress grading applied for machine 11 kV or above).

Following figures stator winding breakdown on Electric Motor 13.2 kV due to PD activities, for your references:

Stator winding 13.2kV was Breakdown

Semiconductive on the wall insulation seen totally damaged, inspected after winding completely removed from the slot.

White powder and electric discharge tracking on the endwinding areas is indicate PD activities

Sample PD measurement, on the Turbo Generator 145 MW, 15kV

For your generator, If looseness is suspected, degree of looseness can be evaluated by carefully inserting a knife blade between punchings at several locations. If a 10-mil (1 mil = 0.0254 mm) blade penetrates more than round a quarter of an inch (6mm), the core may be not sufficiently tight.

See illustration below:

GoodLuck

Siswanto

wwww.sispowergeneration.blogspot.com

Lot of thanks Mr. Siswanto