generator overload

[zorgglub]

Good evening ,
please let me tell you a story about two gensets of 3 generators each:
the first one is powered by 4045HF150 John Deere engines , with Stamford UC224D alternators. rated to 110 KVA standby.we can call it George.
the second one , powered by John Deere 4045HF150 and fitted with Stamford UC224D alternators , is rated to 140 KVA standby.lets call him Lennie.
george is installed in a small hospital , with almost no load, and is quite happy.
Lennie is supplying power to a much more busy hospital , and is acting weird: when load reach 50% , the engine start to lose frequency and shutdown ,the load sharing system start another engine and Georges gets crazy , with a loop of under frequency on the 3 engines of the genset and final shutdown of the entire genset.oups.
Okay , lets check the programming of PLC , cooling system , fuel system , injection pumps , wiring ad so on. all is good. damned !
lets look at the specs of the engines and alternators.
well it occurs that , according to the manufacturer , the UC224D alternator has a rating of ...63 KVA.
an intresting thing is that Lennie has a name plate on each alternators , apparently homemade , who stipulate that the prime power is 142 KVA...
the John Deere database (

https://jdpsproductdata.deere.com/jdpspdsweb/web/GetProductInfo)

is very good , i found that George and Lennie engines have the same specifications and were manufactured at the same date , in the same factory.
do you guys have already seen such a thing ? relabeling an alternator to a higher power ?

Best regards

Jean Michel

 

[waross]

One set closely sized for a known load. The set that was supplied was rated at 240 Volts. 208 Volts was needed. The set was 13% undersized. We had to reduce the load.
An agreement called for a 100 KVA set, installed. A 60 KVA set was delivered and the supplier disappeared without installing the set.
A set was ordered rated at 100 KVA single phase. A set was delivered that was rated at 100 KVA three phase. The set would only develop 67 KVA when connected for single phase (2/3). In this instance the supplier did refund some money.
A large extended family ordered 7 sets for standby for their homes. Someone estimated the load at 15 KVA. All were undersized. I eventually replaced all 7 with sets ranging from 30 KVA to 50 KVA.
Your case is a new one, but it would fit this list very well.
A possible solution: Program the load control panel with the actual rating of the gen sets. Things will probably be more sane if the panel calls in the second set based on loading rather than frequency.
I sympathize with your situation. Even if the supplier agrees;
"Just bring it back and we will replace it with the correct set."
When you are stuck with ocean freight and handling both ways, it is sometimes cheaper to "suck it up" and make do with what you have.
Fraud charges may be in order.


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

 

[wayne440]

I claim no expertise, but in my experience that engine in good condition is good for about 100KW of load @ 1800RPM.

 

[waross]

John Deere says it is good for about 80 KW.
That is a little overpowered for an alternator rated at 63 KVA.

https://www.deere.ca/en_CA/products...tier_1_powertech/4045_series/4045HF150_B.page

When the engine is set up with the generator end it may be "Dead-racked" at less than full possible power.
If you are in an area where the diesel fuel is heavyer than what the set was tested with, you may well get 100 kW from that engine.

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

 

[zorgglub]

after some investigations , it could be possible that the alternator might be a UCI274 , either C ou D (based on size of the housing) cause Stamford do not have the serial number matching with one of their model.
we are going on the safe side , and according to the specs sheets from engine and least powerfull alternator (UCI274C), program the DSE 8610 control module with a max output power of 90 Kw /112 KVA and a max current of 310 amps at 208v, for an input engine power of 100 KW.

i hope the genset will behave better , giving us some time to find a sustainable solutio.
thanks Waross and Wayne440 !

 

[FreddyNurk]

If you contact Stamford then often based on serial number they're able to provide you with the 'as sold' rating of the equipment. Often set nameplate is lower than what the generic datasheet tells you as it takes into account different (usually higher, in my experience) ambient temperatures and so on.

The other thing to check is to see what the shaft output power of the engine is. In my experience with load control panels (I've never worked on the Deep Sea stuff though) they will flag an overload when going over the nameplate setpoint, but loss of speed on the unit is not normally due to the controller attempting to back the engine off in overload conditions. A lack of VA if you like (with an appropriately sized prime mover), will probably cause the alternator to release magic smoke, but a lack of prime mover (W) would cause the underspeed or load shed event, rather than an underrated alternator.

 

[waross]

You may want to check the engine specs on the link that I have provided.
At one time big green used heavy fuel, about 105 heavier than their competitors. They were able to publish KWHr per Gallon figures and maximum power figures about 10% higher than their competitors for an equivalent engine.
If you get caught on this, you may be able to blend in 50 weight motor oil with the fuel to get a little extra out of the engine.


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

 

[Tmoose]

Is this a new installation, or a new problem?

 

[zorgglub]

Hello Gentlemen,
After many discutions with the nice guys from John Deere Factory and Stamford UK , it appears that the 110 KVA and 140 KVA generators have the same engine (4045HF150 with 16ME injection pump) and that the alternators are the same (UCI274D).
so basically we can expect a standby power of 120KVA , 110KVA prime , and continuse of 77KVA.

"Hello Jean,

Yes the UCI274D, wdg 311, 480V, 60Hz alternator when connected with 105 kWm engine will give 120 kVA at 0.8 p.f. with an efficiency of alternator = 91.9%.
If there are any questions please contact me. "

As the national producer supply at best 6 hours of power to the hospitals (arghh!)we are going to reprogram the DSE panels to input the real capacity of the generators so that the load and amps are correctly calculated.
we have found a company here who can do the job , they have a home made load bank (brine dummy load)that seem rather primitive , but as a low tech enthousiast i can't wait to see it at work !
- now a tricky question for you guys:
the breakers fitted on the alternators (inside the canopy) are rated 400 Amps. the cables to the ATS panels are 4/0 or 100mm², one per phase.from what i saw in various tables , it seems a little under sized.
What will you suggest for the size calculation ? base on the breaker capacity or on the nominal value of current +20% ?

best regards

Jean Michel