Need help with 21kw genset

[GameRV]

Working on the GameRV (GameRV.com) and having an issue with generator. This is an Isuzu / Norpro diesel genset (model 4LE1) with analog controller. Problem began with PMA alternator not putting out 14 volts so we decided to replace the 20 amp pma (replacement quoted at least $500) with a standard / traditional automotive alternator rated at 60 amps for $125. When I fire up one system and ac's on low cool, system is stable. Fire up all 16 tv's and xbox 360's along with max cool on all 4 ac's, after a while (30 minutes or so) generator dies. It is acting like it can't handle the load, but at 21kw there should be plenty of power available for the tv and xbox's (2amps draw each for a max total of 32 amps) and 4 ac's. Tomorrow I will test with fluke multimeter to determine if battery draining faster than can be replenished by alternator. Did I mess up by replacing PMA with regular alternator? What am I doing wrong so generator won't stay on?

Thanks in advance for any and all help,
Mike

[REdiculous]

4 AC units all coming on at once could be creating a huge surge which could stall the engine if it can't ramp up fast enough. Just a guess.

[GameRV]

Well, I can fire up the gen with all 4 ac's on high so I don't think that's it, it just won't stay on.

[DanG]

Generator windings usually are 240VAC split into two 120VAC circuits - to get the name plate power you need to balance the two 120VAC sides or draw only off the 240VAC.

ALS0: Unless the game/flatscreen power supplies are 'power factor correcting'  their loads are much greater than their nameplate - ie: 2500 watts of sixteen x-box games would appear as 3200 or 4000 watt draw.

[GameRV]

Gamerbus in Virginia has 3 ac's with 2 6.5kw gens and XBUS in Oregon has one 16kw gen with 3 ac's. My 21kw with 4 ac's should be ok. Yes they also have 16 tv's and 16 XBOX 360's. Like I said, Gen can start with 4 ac's on high and all systems up, just not long enough. No breakers ever get thrown. Gen should only stop if water temp too high, only temp looks like 180-185 so that's ok, and can shut down if oil pressure is too low and oil pressure gets as low as 40 psi. And circuit panel is evenly balanced so 2 ac's on each leg.

[bob g]

when was the last time you changed both primary and secondary fuel filters?

or checked the air cleaner and piping for birdsnests?

my bet is the fuel filter(s) are not able to support the load, probably need to change them?

also check all the soft fuel lines for kinks or degradation, any sediment in elbows also will restrict flow.

get a fuel pressure gage and connect it to the injection pump to check for primary pressure
it should be in the neighborhood of 30psi minimum at full rated speed and load. also put a vacuum gage on the suction side of the transfer pump and check restriction to the pump, it should be less than 5 inches vacuum under full rated load. if it is higher you have filters and or lines/fittings that are in need of service.

bob g

[GameRV]

when was the last time you changed both primary and secondary fuel filters?

or checked the air cleaner and piping for birdsnests?

my bet is the fuel filter(s) are not able to support the load, probably need to change them?

also check all the soft fuel lines for kinks or degradation, any sediment in elbows also will restrict flow.

get a fuel pressure gage and connect it to the injection pump to check for primary pressure
it should be in the neighborhood of 30psi minimum at full rated speed and load. also put a vacuum gage on the suction side of the transfer pump and check restriction to the pump, it should be less than 5 inches vacuum under full rated load. if it is higher you have filters and or lines/fittings that are in need of service.

bob g

New fuel filter (only one to my knowledge)
New air filter.
Will check those things.

Thanks!

[bob g]

look very carefully for another fuel filter or stainer before the transfer pump, it might be in the pump housing as a little round/tubular screen.

check to make sure you have good fuel flow to the transfer pump if it has one, which it should.

i have seen everything from cellophane, leaves, rust, sand and even a bird feather clog a fuel elbow from the tank to the pump on just about every diesel in common use today at one time or another causing the problem you describe.

also check the fuel cap for a vent, or the tank for a vent, there must be a vent somewhere to keep from drawing a vacuum in the fuel tank which will eventually starve the engine for fuel after it has run a while.  you might try running the unit under load with the cap loose to see if that might be the culprit, if it runs longer than the usual half hour i would be looking for a clogged vent.  things like paint can clog the vent as can a bug, grease, dirt, tar or any number of other gooey things.

good luck
bob  g

[Hilltopgrange]

Check for a strainer inside the banjo bolt on the bottom of the lift pump. Follow the lift pipe from the tank to the lift pump and remove the (17mm or 11/16 AF)  banjo bolt completely and check inside it, watch you don't drop the copper washers, the plastic strainer should screw out, just clean it and refit it. This was a very common fault on Isuzu engines a few years back when I worked for a Hyster dealership The strainer has a very fine gauze and blocks real easy, I cant mind the models but it was a very common fault so is worth a look.

Russell

[GameRV]

I will check with my mechanic tonight on those items recommended. We had concern about the psi on the fuel lift (10 psi when keyed over). We never tested the psi under load though I don't think. I called Norpro about the psi on the lift and they stated 10 psi was expected. I will attach a pic of the lift.

[bob g]

is that a little electric pulse type lift pump i see just above the fuel filter?

by above i mean between the red baldwin fuel filter and the injection pumps?

because of the kind of injection pumps i would expect 10psi to be plenty, however
it needs to keep a steady 10psi or so at full rated load, so i would sure check that pump
to see if it can deliver the requisite pressure at full load, most especially over time.

if you can get a pressure gage in there, check the pressure and see if it stays up to ~10psi
when the engine is under load and particularly when the engine starts to stumble and die after the half hour run time.

if the lift pump is an electric pulse pump, make sure the wire leading to it is adequately sized and not getting hot when the engine starts to stumble, you might want a volt gage on there to see if the voltage drops off to below 12volts when the engine starts to die.

check the ground connections and wire also if it has one, bad grounds can limit power to the pump which in turn limit the pumps ability to maintain the required fuel flow and pressure to the injection pumps.

hope that helps, hard to diagnose from a distance, but that is some of the things i would be checking.

diesel diagnostics is my main source of income in my trade.

btw, electric pulse lift pumps are notorious for failing or becoming intermittent, especially under load.

because i can't tell for sure on my little screen (netbook), i am making an assumption
about the lift pump being electric, so if this is not the case please disregard.

bob g

[GameRV]

You are correct, electric lift.

[GameRV]

So, last night the mechanic changed a connection involving the exciter wire and the volts increased on the batteries. We had 4 ac's on max cool and all 16 units up and running. It stayed on for almost sn hour with no trouble. Only died when I tried to make it die at that point by turning on some of the 240v electric heaters. At that point I am convinced that I had reached the max amp draw of 92 amps. With all units running and 4 ac's, the draw was between 50-60 amps. Btw, the fluorescent lights, when on, draw about 10 amps. So either I was reaching max load or at that load, fuel hungry. Will play with it again today, family in town.
I'll update.
One other weird thing. There is a large fan u may be able to just make out in the far left of the photo. Prior to new alternator and batteries, u could start the gen while that fan was running. Now, the fan draws so much volts, I can't start the gen unless I disconnect the fan first. I think the gen won't attemp to start unless it gas like 12 volts and fan puts it around 9.

Thanks to all, very helpful and informative.
Mike

[bob g]

if your generator is rated with a powerfactor of 1.0, you may not be able to actually supply the full rated amperage to your motor loads if their power factor is much below unity.

its not uncommon to have induction motor loads down in the .75 pf range, which will limit
the 92amp generator rating to something under 70amps with all the air conditioner units running at the same time.

now if the generator is  rated at .8 power factor it would handle the loads far better.

it might be you are overloading the generator with your loads?

bob g

[GameRV]

How do I determine power factor?

[bob g]

if it were me i would order up a GE digital kwatt/hr meter from ebay
it is one of the residential style meter heads, and plugs into a standard base
which is cheap as dirt at any box store.

the meter head can be set to read out power factor of the system loads as they are running
in real time, along with voltage, amperage, and about 300plus other parameters.

very accurate, and the most inexpensive method i know of for a getting the info you might like to have.

bob g

ps. you could also read the data plates on the each of the airconditioners, they usually list amps, volts, powerfactor and a few other things on that plate. that would give you a pretty good idea what you are dealing with.  modern energy star rated units generally have a fairly high power factor, however it is cheaper to skimp on capacitors and sell in a more competitive market.

[bob g]

here is the meter i use

http://cgi.ebay.com/GE-744X000001-WATTHOUR-ELECTRICITY-KV-METER-NIB-/220751621290?pt=LH_DefaultDomain_0&hash=item3365d26caa

bob g

[DanG]

wow - quite the spread of technology on the GE lines.. .

http://www.gepower.com/prod_serv/products/metering/en/utility_revenue_meters/kv_electricity.htm

[bob g]

i bought one about 2 years ago, new in the box off an ebay seller that had jillions of them

i then set about googling the darn thing to find out how to use the thing to do what i wanted, and found that they are capable of accurately measuring over 300 parameters. literally everything one can imagine it can measure, store and display.

the front screen can display about 6 parameters that you can easily toggle through, and another dozen or so you can toggle through with a magnet over an internal read switch,

the really cool  thing is you can press an internal switch and put it in calibration mode
and measure right down to watt/hrs with very good resolution. this is incredibly useful in doing BSFC testing of generator sets at various loads.

that internal switch requires taking the globe off to access which is a problem, but being "lexan" (plastic) i simply drilled a small hole through the front to access it with a short piece of wire (drill bit) which allows me to reset the meter head into calibration mode.

i found there is a company in north carolina iirc that can program the head to read out exactly what you want to monitor,  again the limit is about 6 parameters on the front screen and another dozen or so with a magnet over the reed switch. 

there are also option cards available that either open or close a set of contacts if any programmed parameter is out of spec, things like over/under voltage, over/under frequency etc.

the front screen also has a neat little led direction arrow that tells you whether your system is taking power from the grid or putting power back to the grid, a nice addition to
a very cool meter head.

i bought a combination meterbox/breaker panel, it is good for 100amps split phase
and has iirc 6 breaker (squareD Q series), i paid 34 bucks for the box at home depot.

this thing enabled me to quit using clamp on amp meters, along with separate voltmeters and all the other instrumentation, because this puppy does it all, and much more accurate and safer as well.

other things i use it for is measuring power factor, harmonic distortion, amps, volts, watts, watt/hrs, instantaneous or peak watts and amps, cummulative kwatt/hrs, and watt/hrs, and a plethora of other interesting stuff.

bob g

[GameRV]

I am having an epiphany this morning. Gamerbus in Virgina has two 6.5kw generators and is getting 55 amps each. This threw me for a loop. I was wondering why at 13kw he was getting 110 amps and my 21kw was only getting 92 amps..... The math didn't add up. Until now. I assume we are both running single phase power and not 3 phase. I also bet he is running 120 volts (confirmed). That's what gives him 110 total amps. I am currently running single phase, 240 volts (I bet) for a max output of .........wait for it........87 amps. This explains why I am shutting down! This would be why the spike in compressor shuts me down. Too close for max load, let alone continuous load. Now, why am I running 240? My guess is because of these 5 electrical heaters that I think run on 240. Reason I say that is because they require a breaker twice the size of everything else in the panel. I think the gen is putting out 240 and it's broken into two 120 legs. If I could just go 120 from gen and lose those damn heaters (FYI my Duotherm's have heaters) I could get my max output to 187 amps and relieve worries of maxing out gen. What do you think? Panel is 3 wires, red, black and white. Red and black are at 120 while the white is like 4. I also believe you can make out in the picture a yellow electrical connection that I have never messed with. I can maybe recall my mechanic telling me it was a connection for a large electrical device (240?). I can't guess what a bookmobile was doing with a 240 connection at the generator.

[GameRV]

How do i determine if my Generator us wired/putting out 120 or 240?

[dnix71]

How do i determine if my Generator us wired/putting out 120 or 240?

Take a volt meter to the outlet where the heaters are plugged in.  If they are 240v heaters and they work correctly, it must be 240v.

I don't know what your panel looks like, but if the heaters are hardwired to a panel, then you could pull the panel cover and carefully check from there.

240v output usually allows more power out. With all that eqiupment up and running you need to derate that genset a lot. The PF has to stink with a bunch of a/c's running.

If you have a regular outlet inside available unplug an a/c and plug a Kill-A-Watt meter into the outlet and the a/c into it.

http://www.radioshack.com/product/index.jsp?productId=3025185 $60 and in stock. There should be a Radio Shack somewhere near you.

http://en.wikipedia.org/wiki/AC_power#Real.2C_reactive.2C_and_apparent_power  You might need double the power you think you do because of the a/c's

[GameRV]

Ok, here's the latest. Buddy from work is an electrician and is convinced the gen is wired for 240. That's 2 legs of 120 and a common (red, black and white (may have been originally yellow) wires. He likes the wiring and panel and recommends leaving it as is. Now for interesting part. With all 16 tv's and 16 xbox's up and running, the amp draw from one leg is 11 amps while the other leg is 12 amps (very well load balanced). Those would be the red and black wires. The common then has an amp draw of .3 and he was ok with that. He said he wouldn't want to see that common ever above .5. When I turn on one of the ac's, the amp draw on the leg associated with it goes up about 10-11 amps as expected. However, the common jumps from .3 up to 16.8 or more. He states that is indicative of a serious wiring problem at the ac. Turn on an additional ac and that common amp draw drops to like 6 amps. He is an electrician but not an ac guy and not comfortable re-wiring the ac unit/units. I will gave the guy who installed one of my ac's come out and show him what I described above. So, are we on the right track or is high amp draw on common no worry?

[RP]

Can you try running that AC alone to see what you get on each leg and common?  It sounds like either the compressor is running off of 120VAC (one hot and common) or maybe one or more blower motors are.

[bob g]

how old are the airconditioners?

my bet is they have low power factors, and that is what is up with the currents

bob g

[GameRV]

Bus is 1997. Now I am thinking it is 120/240 split phase. I guess that means I am in indeed putting out 240 and ax amps is 87.5. I want to rewire to put out 120 and this raise max amps available to 175. Only drawback is no 240 service available but I have no need for 240. Split phase would explain why when one ac is on, common spikes and I bet draw is the same to balance the load. This did happen and was confusing when I fired up second ac and number on common dropped. Reason being, it was closer to being balanced. I just want to make sure I am not giving up anything by going from 240 to 120. I see nothing but positives in getting those amps available ramped up.

[GameRV]

Now how do I rewire the gen head from 240 to 120?

[bob g]

there should be a plate on the generator head itself that clearly shows how to interconnect
for 120 or 240/120 operation.

check for the plate, however i am not convinced that this change is going to do anything for your problem. it will however probably cause other problems with needed increase in wire size from the generator to the breaker panel.

generally going down in voltage doesn't improve anything, but generally causes other issues that will only aggravate your existing problems

ymmv
bob g

[GameRV]

Bob,
Please help me understand. Assume I need 100 amps. At 240 I cannot get there and be stuck at 87.5 and 87.5 isn't enough for my needs. Going to 120 gets my amps available up to 175. Please help me understand why getting more amps is a bad thing.

[bob g]

at 240 you got 87.5amps or 21kva

at 120 you get 175amps or 21kva

so what is the advantage?

i really think with all the various loads you are servicing the power factor is not good
as it could or needs to be.

things like older puter power supplies, motor loads all can have varying degree's of poor power factor,

poor power factor reduces the ability of the generator to provide useful power to the loads
and it also reduces the systems wiring ability to deliver useful power to the loads.

i really don't see how going to a lower voltage is going to help you get what you need done,

this is what i would suggest, get someone that really knows AC power and have him look
at the systems power factor and make recommendations on what needs to be done so that your generator can cover the loads.

also find the data plate on the generator and find out what the power factor rating is of the generator itself. if it is rated at 1.0 or unity it will have a hell of a time delivering full rated power into a load that is less than unity power factor, in actuality it cannot deliver full rated power into a load with a power factor of less than unity (1.0)

it may well be that the technician can determine which loads are presenting the lowest power factors and they you can either decide to replace those loads with something that has a higher power factor, or... have power factor capacitors added to that load, or... buy a larger capacity generator that has enough head space to cover the poor power factor loads.

it may well be you have one of more airconditioner units that have poor power factor that can be corrected with relatively cheap capacitors and get the power factor up enough that the overall system can operate without issues.

5 or 10 amps reduction here or there might make enough difference to get you going.

bob g

[GameRV]

Bob,
Just got off the phone with Norpro to order a manual. I guess it is worse than I thought. He said it is a 3 phase gen head and not single phase like I thought. That being said, max amp draw is now dropped down to 63 amps at 240. I thought this genset could go single phase or 3 phase. I guess I was wrong and it is 3 phase. That being said, rewiring to 120 will get my max amp draw to 126. He said I could wire it something he called "series delta" 120 and the max amp draw would be 140.

Thoughts?

[GameRV]

Still confused. Attached photo of genset clearly states phase 1.

[joestue]

that's a single phase generator. 4 poles, 2 coils.
parallel the coils for 187 amps at 120 or 90 at 240/120.

btw, you cannot directly substitute the power factor number read by a watt meter delivering power to an 'electronic' load for "powerfactor" when refering to the lagging load of an airconditioner, because the current isn't a sine wave. It is however, in phase.

Ok, here's the latest. Buddy from work is an electrician and is convinced the gen is wired for 240. That's 2 legs of 120 and a common (red, black and white (may have been originally yellow) wires. He likes the wiring and panel and recommends leaving it as is. Now for interesting part. With all 16 tv's and 16 xbox's up and running, the amp draw from one leg is 11 amps while the other leg is 12 amps (very well load balanced). Those would be the red and black wires. The common then has an amp draw of .3 and he was ok with that. He said he wouldn't want to see that common ever above .5. When I turn on one of the ac's, the amp draw on the leg associated with it goes up about 10-11 amps as expected. However, the common jumps from .3 up to 16.8 or more.

this doesn't concern me at all.
Remember, the neutral in this case is only a few feet long... the current flowing through the windings is equal and only equal to the current flowing through the "hot" legs.
yeah, its less than optimal but if you're running extension cords to power all the 120vac loads, then you're not saving any copper on the neutral anyway so this extra current isn't costing you anything.