Power Generation: Product Operation and Maintenance

[Star12]

Hi Experts,

Our CAT 3412 Generator ran overspeed, but the overspeed protection didn't shut it down. This incident made the push rods damaged.

Can this happen?

We think the main problem is in the protection.

Thanks,

regards,

Star

[mikel]

In an overspeed condition valves can "float", possibly causing contat between the valve head and the piston crown. Also the push rods, lifters and cam surfaces can be damaged from impact from the results of this "float".

Overspeed protections should be checked on a regular basis, newer electronic overspeeds have the ability to be tested or verified at speeds less than the actual trip point, so there is really no good excuse to test them regularly.  Mechanical overspeeds. like the Synchro-Start switch, require more work to get properly set and tested, and most end users these days would be better served by retrofitting a newer style protection.

Mike L.

[mikel]

Another point, an overspeed protection responds to an abnormal condition, so the root cause of your overspeed isn't the protection, the protection failed to prevent engine damage after to root cause failure. On a 3412, this is likley a governor problem, but other factors can contribute depending on application and operating environment.

Mike L.

[Star12]

Mr. Mike,

what kind of  abnormal condition?  

overspeed protection should respond when overspeed happen, right?

When overspeed occurred, the protection won't work.

Is overspeed protection out of order? Or should I change the protection to new one?

Thanks, I appreciate it

[mikel]

You have two problems,

First, something caused the unit to overspeed, this is the root cause and needs to be identified and fixed. The governor not properly controling engine speed is the most likely "abnormal condition", but you have provided no details of you equipment, site conditions and application, so from here it's a guess.

Second, you overspeed protection didn't work. What kind of protection is currently installed?  How often is it tested? Have you identified why it failed to operate?

Mike L.

[see-deif]

Good points, Mikel.

Star12, you did not say if this is a newer, electronic ECU or an older, mechanical linkage system. Please give us more details.

One might guess that perhaps the speed feedback to the governor failed, causing it to go to maximum. But we are only guessing without more information. ECU/electronic engines have speed feedback loss detection and should have shut it down if the feedback failed.

Mikel is spot-on with you having 2 problems: governor / speed control system failure AND a protection system failure. Both should be fixed before returning this machine to operation.

good luck

Steve

[Star12]

Mr. Mike and Mr. Steve

we have contacted our dealer in our country and made some inspection to the generators.

there's no problem with the governor. it's worked properly.

they explained everythings about the generator.

but, they said our CAT 3412 is a failure product.

i just can't believe the conclusion.

we just bought it 7 months ago.

thank for the attention.

you're so kind. 

[see-deif]

Star12

I am not a CAT employee, but I have never heard of a CAT3412 being a "failure product."

Sure, every manufacturer has minor issues, but generally CAT makes some of the best engines in the world.

Maybe someone in CAT corporate can help. Hello? Anyone in Peoria interested in helping? Or where ever the 3412 is made?

I agree with you, I can't believe that is the conclusion. It sounds like he would rather sell you a new one instead of supporting an existing machine.

Keep pushing on that rope and don't give up!!

Regards

Steve

[mikel]

3412 has been out of production for a while, so if you've only had it 7 months you likely bought a used or surplus product.

The 3412 has a long and well earned history of robust and reliable operation in many applications, any dealer who calls this a "failure product" has his head firmly up his rear end.

Diesel engines don't overspeed unless something is wrong, that is why governors are installed.  You could have a governor problem, an internal fuel injection pump problem, or an external issue, such as a combustible mixture like natural gas or hydrocarbon vapors being pulled in with the intake air.

How about some details, like serial number, where you are at, what the engine is doing (application), and what kind of facility it's installed in.

Mike L.