We have this Ingersoll Rand Lightsource light tower that we use solely as a generator. Uses a Kubota D905 engine and is supposed to be able to put out 6KW. Issue is at the 110V outlet. Things don't run so well plugged into the outlet. For example a grinder spins really slow or a heat gun doesn't get that hot or spin the fan as fast as if it was plugged into the wall. This light tower has no lights on it only running it for the 110V and 220V outlets. My thought is that I could put a volt meter in the 110V outlet and increase the RPM on the engine until I see 110V. The reason I haven't done that is because I had heard the outlets may have a capacitor attached to them that could go bad? I knew the lights had capacitors and I believe those are still on the machine but I didn't know the outlets use a capacitor as well. Is this correct and should I start by checking the capacitor (and where is it located)?
Light towers will be a cap regulated alternator; Should be a cover on top of the gen end that will have the cap. Will need to check the uF rating on the cap versus the actual reading with a meter.
As always thanks for the help. I can do that. Will look around on the generator end for the capacitor. I know where the light tower parts are located but haven't dug into the generator end yet.
The thing needs to run at 1800 RPM nominal or maybe 1900 max. If it is not running at the correct speed do not do anything else until it is. Then measure voltage at the source both unloaded and loaded. And again at the equipment in case it is just a wiring problem or something.
I don't have any reason to believe the RPM has been touched from where it was set. It has 6000 hours but I don't know that anyone has touched the RPM. I will take a look at the capacitor first. If that checks out we're gonna adjust RPM until I get 110V
I believe the cap is 22.5uF. Can I replace that just as a matter of course since its been running for 6000+ hours since 1999? Can I match up the exterior size of the current one to find a replacement or does it have to be that exact part number from Ingersoll/Doosan?
You need to check engine RPM first. This is the same setup many truck APU's utilize for making 120VAC. Low engine RPM = low output VAC. Usually the capacitors in this type system don't degrade in value but rather blow the end out, or open internally which eliminates output till it's replaced.
Good to know. I definitely have output so I guess it could be RPM. I have no way of testing RPM other than raising it until I get 110V at the outlet.
Some multimeters have a frequency setting/selection on them. Easy to measure and if you are close to 60cps/hz, you are very close to 1800rpm.
I was gonna ask if a Hz reading would help - I should be able to test Hz and go from there to adjust up to it.
If you have a Fluke meter, Hz is the way to go. If you have an off-brand, they are usually totally useless for Hz. Buy a Fluke if your meter gives strange readings. 62-63 Hz unloaded is usually best so it lugs its way into 60 Hz. It has to always run 60-63 Hz no ifs ands or buts. If voltage is still low then fix the electrical problem, don't change engine speed (which is directly locked to Hz reading).
I will check for Hz tomorrow and if we're at 1800RPM 60Hz I'll report back. Curious what the next thing to look at would be if the RPM/Hz is correct?
Take out the capacitor(s) and check, most good voltmeters have a capacitor check function.
Ok so here is what we have. The hertz comes in right at 61. The voltage was around 70 or 80. So low voltage but correct Hz. Time to pull the capacitor. I haven't removed a capacitor to test before. Do I first short out the poles with an insulated screwdriver? Then pull it and test resistance or capacitance? My meter can test for capacitance but I haven't done that before so any detailed instructions would be appreciated.
Here is a video on testing caps: There are other ways to test them using a charging voltage through a resistor and measuring how long it takes to reach 63.2% of the charging voltage. The capacitance should be marked on the capacitor. You don't need a Fluke meter. Any quality multimeter should work.
Thanks! I am going to try to pull that capacitor tomorrow and test. Would it be a good guess to say the capacitor is bad even before I test?
I would test it first. Do you have the manual for the unit?
I found the manual online once. In the troubleshooting section it didn't give any help when the issue was low voltage - just wanted you to see dealer.
it will have a voltage regulator and most likely a pair of slip rings and brushes which could also be the problem.
Gotcha thank you. So I guess now we're gonna see if the capacitor is the problem or part of the problem. Sure would be easiest if it was something as simple as a capacitor replacement!
If it has a capacitor, it does not have a voltage regulator. Capacitors are cheap but usually if one goes, it is lights out completely. We shall see I guess.
Tested the capacitor across the terminals after discharging it with a screwdriver. I am seeing 42.4uF. Its a rock steady 42.4uf. According to the label I need to be at 70 uF (please confirm I am reading that correctly). So I think its time to try a new capacitor. Can any 2 wire 70 uF cap be used and is this a "motor start capacitor"? It fits with velcro from the factory so I can fit just about anything. If anyone could let me know what I am looking for in a replacement I'll probably hop on eBay right away to locate a new replacement (or is there a better site?). Link below for pic: https://ibb.co/QY0sbDQ
Not a black plastic motor start capacitor. Maybe a metal can motor RUN capacitor with 70 uF/microfarads, or two in SERIES of 140 each will work also, if you can't find one with close to that voltage rating. 140 would be rare I guess, you could do series parallel, but just get the 70 with the highest volt rating you can find. edit: Italfarad 70040 is what that is supposed to say for the model, they are available, but I'd try what I had that's close, then get the genuine if you feel like it. The farad rating is what matters, the voltage rating is a measure of how long it will last, roughly.
Thanks. Best I can find in my search is this. Says up to 440V: https://www.amazon.com/Capacitor-Co...or&qid=1643308735&sprefix=70+uf,aps,59&sr=8-3
Thanks I ordered the one from Amazon for delivery tomorrow. Hate that its chinese but need to get this going. If this gets it going will probably pickup a quality one or original at some point. Hopefully this cheapo works for a little while at least. Says 5 years in an air conditioner so might be good.
Just wanted to thank all of you for getting this generator back to 110/220V! Put the new capacitor in there and we got 121V at the outlet! Plugged in a little space heater and the coil glowed bright red! Hopefully the little stick welder enjoys the 220V side just as much. Once more - thanks all for the assistance I couldn't have done this repair without you.
I've probably replaced five caps on truck APU's over the past calendar year for either no output power, or only one very low output. Yours' fell right in line with my experiences but do remember to keep a check on your frequency and try not to run overloaded. For some reason when these little sets are run with just a bit too much on them, that cap fails on short order. Probably in truck usage a combination of HVAC, microwave oven, refrigerator, and hot plate, or coffee maker running at the same time. Poor little generator set only knows output as much as it can as they don't use a voltage regulator.....
Thanks. Good tips! I will follow that. We don't have much need for it. Really the hardest draw on it would be a welder every so few weeks and even that is such a short term use. I will check out the frequency on the outlet from time to time but honestly its pretty easy to tell the cap is going and the frequency is off running just about anything lol. The grinder used to spin so crappy at 70V lol - worked but slow. This machine was new to me so at first I thought it was just so weak haha