Page 1 of 1

Diesel Generator low frequency on high load.

Posted: Thu Jun 16, 2016 11:23 pm
by sabih
Dear sir,
I have diesel generator of 630KW capacity installed onboard. We have recently conducted its 3000hrs routine in which we have carried out following work:
1- Removal and cleaning of all heads.
2- All cylinders and pistons were de-carbonized.
3- Gauging of valve guides.
4- Valve grinding and lapping.
5- Injector testing.
6- Testing of cylinder heads.
7- Overhauling of fuel pumps.
It is pertinent to mention that we did not touch its governor. and alternator side. But upon trial, we are facing a problem that after 350KW load, its frequency starts decreasing. We have then also cleaned its turbocharger and its accessories but the problem persists.

Plz help me with your knowledge that what could be the reason of frequency decrease.

Re: Diesel Generator low frequency on high load.

Posted: Fri Jun 17, 2016 6:05 am
by JK
Have you done any compression readings on the engine. If it worked before the overall, there is something up with the engine. Obviously.
Did you use OEM parts? Bootlegged injectors are the kiss of death

Re: Diesel Generator low frequency on high load.

Posted: Fri Jun 17, 2016 5:52 pm
by Revolver
Steadily decreasing to the under frequency trip, and manually bringing freq up before the trip has it continue to drop steadily, yeah. And gov wasn't touched...
Hrmm.

Like jk said, oem parts? And injector tests were spot on...

All potential air was properly bled from fuel pump over haul?
No stickey parts in the fuel pumps, keep a good eye on the fuel rack. A mix of oil + diesel is usually good to get them loosey goosey, make sure there's no sticking going on.

Re: Diesel Generator low frequency on high load.

Posted: Sat Jun 18, 2016 6:19 am
by The Dieselduck
Do you have enough fuel to the machine? check the stack, if not blowing a bit of black under that kind of load, maybe she's starving for fuel. I would check the simple things should be checked first - filters, fuel valves position, fuel pressure, etc.

Re: Diesel Generator low frequency on high load.

Posted: Sat Jun 18, 2016 11:53 am
by Merlyn
Dragging in air thro' a union let go for stripping?
Is it CR or older straight mechanical job?

Re: Diesel Generator low frequency on high load.

Posted: Mon Jun 20, 2016 10:43 pm
by sabih
JK wrote:Have you done any compression readings on the engine. If it worked before the overall, there is something up with the engine. Obviously.
Did you use OEM parts? Bootlegged injectors are the kiss of death


All parts are original as per OEM and technical manual but the the problem persists.

Re: Diesel Generator low frequency on high load.

Posted: Fri Jun 24, 2016 3:59 am
by Merlyn
How goes the genset RPM?

Re: Diesel Generator low frequency on high load.

Posted: Fri Jun 24, 2016 5:32 am
by D Winsor
I understand the governor wasn't touched but was the linkage to the fuel rack disconnected from the governor?
If so you should check to make sure it was placed back in the correct position on the governor spline shaft or linkage connection points. If the linkage is in the wrong position or the wrong length the governor and or fuel rack will reach it's maximum travel or load limit setting before maximum load is reached on the engine causing the engine to slow down at high loads. I've seen this many times on overhauled engines with mechanical actuators and governors such as the Woodward UG8 or similar type Governors

Re: Diesel Generator low frequency on high load.

Posted: Fri Jun 24, 2016 7:52 am
by Merlyn
Wonder how the new fangled Rolls Royce Remote control boys would handle this from their control room thousands of miles away?
You know, the people that are going to make us all redundant ?
It's bad enough trying to sort a remote problem out without even being on the scene.
How are they going to whip the linkages off and physically bar it up against the stop remotely?
How are they going to adjust the max rpm stop?
But is it common rail or straight mechanical?
What engine can it be and what model?

Re: Diesel Generator low frequency on high load.

Posted: Thu Jun 30, 2016 6:06 am
by Merlyn
Genset seized up then?
Or is it a " so that's all it was then jobby ? "
Shhhhhhhh.
Must have been trapped air on that bend I told you about said the voice.
H.E. Jobby?

Re: Diesel Generator low frequency on high load.

Posted: Tue Jul 19, 2016 9:49 am
by Merlyn
Ah well, looks like the genset has gone the same way as pushrods Pete ( Frank Perkins article re the bent pushrods since turbo change? )
Now we will never know the outcome.
I reckon a Shhhhh jobby.
Don't say anything but ...........