TC 40D PTO Generator - Disappointing

[AndyMA]

I tried to do some load calculations, but obviously do not have any idea of your heat load. I would say that I believe you overloaded the generator (not the PTO hp). The combination of those loads and their cycling on and off with peak start loads requies much more generator than you have. A/C loads tend to cycle on and off. The resistive heat loads are pretty much continuous and I believe place too much of a bias on the generator to let it handle all the cycled loads. I think you were probably running beyond the breaker capacity (at least during peak loading). The breaker which is a heat operated device will take longer to trip (ie handle an overload) at lower temps as some of its heat is dissipiated into the atmosphere. I would hook up all the loads again and put the current meter on the load. You may be suprised. I had a 5500 watt generator for years and their was no way I could run even close to half your load. BTW, what is the rated capacity fo your generator vers the peak load? Also did you have the load evenly spread between the 2 120 v legs?

Andy

 

[Soundguy]

Perhaps an older brush type design with very poor regulation and filtering would throw bad wave forms. Most of the brushless designs i see.. even the ones with passive ( capactivie ) regulation put out some pretty pure sign untill you mash them against the wall... even then.. at least the few I've tested.. stay withi spec tolerance.

Soundguy

I did say "many", not "all". I am not referring to frequency or voltage - on most generators, those are easy to control. We routinely scope people's generators and often see things that look more like square waves with all kinds of shoulders and humps - not even close to a sine wave (I should take a picture of one some time). That type of wave can cause havoc with some devices - some compressors seem to be vulnerable, for example. It was because we saw things like this that and the resulting damage that we decided to sell high quality generators for our customers. I do not know of anyone who has had any problems with a high quality generator that was operating correctly and many people get away with the lower quality generators but not all.

I am just warning people to look closely at what they are buying since most people just look at the frequency and voltage specifications which all but the worst generators can meet.

Ken

 

[Soundguy]

Most of my deisels have opaque elements.. so I just get in the habit of servicing them when i do oil changes. However.. the last time i did service my yanmar.. it's filter 'looked' fine.. looked clean. however I discovered the element was saturated with water, and had fine particulates embedded in the element. None of this was visible to the eye. Fuel flowed from that line 2x to 3x better after the new paper filter was installed.

Not saying yours is that way... just saying that after a close call, and a 'stranded' session.. I don't scrimp on a 13$ fuel filter every year.

Soundguy

Thanks for the warning Ken, but the quality of the sign wave from my generator is top notch. In years past, I've used/borrowed three other generators and mine is better than all three. THD, when moderately to heavily loaded is still in the 5% range and the waveform is still almost a perfect sine, although when loaded up as when I experienced problems, it merely had a lower RMS value and reduced frequency. Looks like I need to do the testing. Maybe this weekend.

Soundguy, I'm not one to operate in the "don't touch it unless it's broke" mode when it comes to filter changes, especially if I can't see inside to the element. That said, I do keep and eye on it and have had other tractor filters get dirty in the past, so I thought I knew what to look for. Once, a year or two ago, there was a couple of parafin globs settled in the bottom of the bowl, but they eventually disolved and went away. There is absolutely NO evidence of any dirt, sediment buildup, coating, etc on the filter, so I figure it is clean. The bowl and filter look brand new! If there was some slime, particles or crud of some sort, I'd be much more suspicious. I'll be changing it anyway, but when you can see something so clearly, and it looks so very clean, I just always thought it was. Maybe I've learned one more thing here thanks to TBN!

 

[Soundguy]

One thing.. a small 3600 rpm gas genny or even 1800 rpm job.. the engine was less rotational mass to spin up.. so it's gov may correct faster. A diesel may have much more mass to spin up.. though.. on the other hand.. if there is more rotational mass.. then loads shouldn't hit it as hard either..

I think the ideal situation is to have about 25-30% more genny than you need.. and 2x the minimum pto hp needed for 'trouble free' operation.

Soundguy

Ksimolo has hit it on the head, the generator I purchased was due to the fact that it was a very high quality one with less than 2% THD. It was rated for TVs, and computers. The only reason I bought it was that it was marked down to the same price as the "regular" generators. I guess they couldn't move it at such a higher price, with the same 10,000watt less expensive twin sitting next to it. Jinman is right on the money also about your governor's sensitivity. I don't think that our tractor governors are as sensitive, and throttle correcting as quickly as the one's coupled to the stand alone generators.....this would result in wider swings in the voltage. If you had another source for winter heat, such as a wood or coal stove to heat, then I think that to just use the PTO generator for appliances, lights, even the TV would be OK, due to the fact that there would never be a big load placed on the tractor governor. I noticed that even with my 10K unit. It just hummms along with out even breathing hard. Run an extension cord over to the neighbors to power up there "walk in" side by side refridgerator, and then you can tell a load is being placed on it by the slight rpm drop, and the throttle is being pulled open b the governor. Still very glad I've got it, and "Jenny" has gotten me through a few extended time whn the main power was off.

 

[Soundguy]

Good point.. motor start loads can be 2x rated power.. and even 3x if an older or particularly ineficient unit..

Soundguy

I tried to do some load calculations, but obviously do not have any idea of your heat load. I would say that I believe you overloaded the generator (not the PTO hp). The combination of those loads and their cycling on and off with peak start loads requies much more generator than you have. A/C loads tend to cycle on and off. The resistive heat loads are pretty much continuous and I believe place too much of a bias on the generator to let it handle all the cycled loads. I think you were probably running beyond the breaker capacity (at least during peak loading). The breaker which is a heat operated device will take longer to trip (ie handle an overload) at lower temps as some of its heat is dissipiated into the atmosphere. I would hook up all the loads again and put the current meter on the load. You may be suprised. I had a 5500 watt generator for years and their was no way I could run even close to half your load. BTW, what is the rated capacity fo your generator vers the peak load? Also did you have the load evenly spread between the 2 120 v legs?

Andy

 

[IH3444]

CorrectO Soundguy, they say to add up all the wattage you are going to use, then buy a gernerator with twice that capacity. You should only tax the jenny 50% of what it's output is. This allows startup motor surges to be absorbed.

 

[djradz]

Andy, thanks for attempting to analyze this, but as you say, you really don't have enough information, nor do I at this point. I hear what you are saying about overloading the generator, but I'm somewhat doubtful because I would have thought the first indication was a voltage drop or collapse of the waveform, not a drop in generator frequency.

I do remember one other thing that occured, and that was what I have to call a scraping or vibrating sound coming from the generator when the microwave was used along with everything else. Makes me wonder if the generator was "chattering" which I've heard is an indication of very poorly balanced load between the two 120v legs. Not that this should have slowed the frequency, but maybe again, indicating I had if heavily loaded, and not very balanced. More testing needed!!!

 

[Soundguy]

Freq drop will be based on rpm drop.. I.e. if your genny is dropping freq.. then the pto rpm is dropping.

PTO rpm will drop as the load goes up, if the governor is not compensating fast enough.. or cannot compensate.

I think this is all pointing back to a tractor issue.. not a generator issue.

Not many other ways to mess with the freq on that fixed pole genny that pretty much solely relies on input rpm to determine output freq.

Soundguy

 

[SteveInMD]

Could it be that the governor is just not designed to be precise enough for this application?

 

[Soundguy]

Hmm.. I doubt it.. but then.. i don't own a TC series machine.

My 1975 ford 5000 and my 2002 NH 7610s keep my 12.5kw pto gen rock solid. If I listen real close, i can hear the 5000's engine power up when I throw a big motor start load on her... The 8n will laod up.. but handles the load ok. The 7610s.. never even blinks..not a hair of change in engine sound or rpm.. notheing.. no smoke puf.. nada... course.. she don't blink pulling a 15' mower into a swath of 2-3' tall weeds either.. so i think the 12kw pto gen aint much of a load to her..

Soundguy

Soundguy