alvinc
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Re: 3000W Chinese Gensets Info.
presp wrote: Consider http://www.tinytach.com/tinytach/gasoline.php (hours & rpm) $36.95 The only concern I would have about the tinytach is that it has a NON-replaceable battery that good for 5+ years. Otherwise it combines an hour meter and tach. The tach would be useful for checking frequency. Either 1800 or 3600 rpm should be 60 hz.428Views0likes0CommentsRe: 3000W Chinese Gensets Info.
sjptak wrote: Can anyone tell me how to wire in an hourmeter? Quick answer: Buy one rated for AC, mount it, hook it up to the AC with it's own fuse before the circuit breaker. The AC drives a little motor in the hour meter that counts the time. Generator off, the motor doesn't turn. Hour meters at Grainger.com413Views0likes0CommentsRe: 3000W Chinese Gensets Info.
Wyatt-S wrote: I did this mod yesterday. The voltage never dropped below 112 at full load (28 amps) but the breaker will trip if I pull a sustained load above the 28 amps. This is with the RV connected to the normal 120V outlet. The current output of the generator as originally wired on 120V will be limited to the capability or limits of the circuit breaker on each leg of the 240V circuit. That is if one circuit breaker might trip at 17 amps, the other might not trip until 19 amps over several seconds. For a 240V circuit, it will be limited to 17 amps (the smaller of the two 120V breakers) at 240V. After changing the wiring to parallel the windings, the maximum current that you will be able to obtain is not the sum of the two breakers. One winding will provide more current than the other winding. If this happens to be the winding with the 17 amp breaker limit, the other winding is likely providing only 11 amps of the load. Continuing with Wyatt-S's example above. This has a lot to do with how similar the windings are with respect to impedance. In this case, I would argue that, you want two breakers, one to protect each winding of the generator. If you had only a single breaker and one winding had an open, the other winding would try to carry the full 30 amps and I believe you would be in a smoke and fire situation. Circuit breakers (or fuses) are used to protect the wiring from over current situations. It's not clear to me that a single winding in the generator can support 30 amps. Willing to be wrong.....tell me why.537Views0likes0CommentsRe: 3000W Chinese Gensets Info.
The rated capacity of any electrical generator will be de-rated as the temperature of the windings rises. This applies to alternators in hot engine bays, generators whether in open or enclosed, and hydro-electrict power house generators. Typical cold amp ratings are at 25C (77F). Finding de-rating information about alternators is hard because no-one seems to want to talk about it. The de-rating could be as high 20%, or higher, when the temperature reaches 100C (212F). There is also a loss with increase of altitude by both the engine and the alternator windings. Thinner air means less efficient engine and less efficient winding cooling. Industrial generators actually specify this info....typical: 3% per 18F above 77F, and 1.3% per 328 ft over 656 ft. Example: a 3500 Watt generator running in the shade with outside temp of 113F at 1610 ft would be derated by 6 x 3.9 = 23% or only 2695 watts. Onan rates the Marquis Gold deratings at 3.5% for each 1000 ft above 5000 ft, and no derating for temperature below 120F. Pretty conservative. Knowing the desire for good numbers, I bet the cheaper generators are rated generously. http://www.onan.com/pdf/rv/a-1425.pdf Imagine the difference of taking an open frame generator and adding insulation, or a box, around it. For the most dependability, buy a generator that is designed to be in enclosure. OT comment: A friend of mine moved to Denver, from Calif, and had to upgrade the CPU cooling on his computer (he's a gamer and runs his stuff hard).423Views0likes0Comments
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