Diesel Engine Driven Generator Operation without Cooling Fan 2

[FARHANRAZA]

Dear All Members,
We have been operating a Diesel Engine Driven Generator of following specs:
Generator:
Make: UNELEC France.
Rating:1900 KVA, 1520 KW, 174 Amps, 6.3KV
Diesel Engine:
Type / Model:240-V16-GS-PE-1977
MFG'R: SACM

Recently during startup of Generator after oil change, its cooling fan got damaged. I have following queries:

1. The weight of fan is about 170 kg. Is this fan used for cooling of Generator only or is it used as fly wheel as well.
2. We are going to get this fan casted from local market. In the mean while, is it safe to run the generator in case of emergency requirement by application of external air with an arrangement of hose pipes and external industrial grade fans. Insulation class of Generator stator and rotor windings is B.
3. How can we re-design the fan to make it light weight and less prone to damage, while providing the same cooling air to Generator.

 

[LionelHutz]

Yes, that's what I posted??? An axial fan with a big hub and little stubby blades. I would be quite wary of another cast replacement fan unless the casting company has the proper experience and engineering to ensure the new casting will survive without failing like that fan did.

 

[MikeHalloran]

Clearly, the axial fan's 'buckets' were cast individually, and bolted to a large central rimmed disk, which appears to have been fabricated from plate and bar, joined by welding, and split for radial assembly.

On the disk, I don't see the draft, fillets and radii that I would expect to see in a single large casting, or two large cast halves of a fan cast with integral buckets.

I can't find an indication of a drive key on the shaft, but the photos do not provide complete coverage. Where the fracture surface intersects the central bore, the near side detail looks a bit like the remains of a keyway.

... which is where it should fracture in a bad sync event.
... and not in a startup, ever.

... but a bad sync event that was bad enough to fracture that fan wheel just against its own inertia, could cause a lot of other damage.

HAVE YOU INSPECTED THE ENGINE CRANK AND INTERNALS?



Mike Halloran
Pembroke Pines, FL, USA

 

[waross]

FARHANRAZA (Electrical)
(OP)
21 Dec 16 03:35
An old crack has been found in the fan, which has dust ingress. This shows fan was damaged due to starting jerk which old crack couldn't bear. Fortunately no one was hurt in this incident.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[FARHANRAZA]

Today we have successfully test run the generator without cooling fan and with above arrangements:

Max Power: 1.46 MW
Max winding temp: 70 deg celcius
Max Driven end bearing temp: 56 deg celcius
Max Non Driven end bearing temp: 45 deg celcius
Max vibration on generator bearing = 5 mm/sec

 

[itsmoked]

That's nearly full load!

That was with the two fans and no ducting?

Did you confirm the temperatures actually stabilized and reached steady-state?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[FARHANRAZA]

Yes, the test was performed without fans ducting. Actually as rightly pointed out by everyone fans without ducting were of no use. I switched off the fan after sometime, and it made nearly no impact on the temperatures.

Test was performed for about 2 hrs, and yes temperatures were stabilized. Air spargers helped alot and fans like this were of no use.

Thanks all for your continued support. We hope to get fan casted & balanced in 2 weeks time and after that it will be installed back.

 

[itsmoked]

I am very surprised FARHANRAZA by the results you report.

Thank you for keeping us informed. Thanks for the informative pictures too. We all learn that way. Good luck with the new cast fan! We'd like to see it when it shows up.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MikeHalloran]

Well, I'll be dipped in ... er, used food.

Mike Halloran
Pembroke Pines, FL, USA

 

[waross]

Don't feel bad MikeH
I missed that post myself the first couple of times through.
Can I buy you one in the Pub?


Bill
--------------------
"Why not the best?"
Jimmy Carter