Winged One wrote:
FWIW, I contacted PI regarding using my EF3000ISEB several years ago.
Neither indicated any issue with using my generator, and in fact they both encouraged me to use the EMS device with my generator.
Joel_T wrote:
I'm surprised they made no mention of needing a pure sine output. I'd still like to know how to figure out whether a genny's putting out pure or modified.
Progressive does in fact say their EMS units must be used with a "true" sine wave signal, the exact words used in their Yamaha EF2000iS disclaimer, with no mention of "modified" sine wave. However, in his email response to myself the Progressive CSR said -
"Concerning the use of a generator with an inverter, our EMS are designed to be used in the RV environment using a commercial power source. The hazard to our device when using an aftermarket generator, is that some provide a modified sine output, which can cause damage. Others provide a pure sine wave at all times, and others will switch to a modified sine wave under heavy loads. The portion of our units than can be damaged is the surge protect and is not bypassed using the bypass switch. Since there are many brands of generators on the market and numerous models I can not offer specific guidance on which one to select."These are his words, not mine ... my suspicion however is that the CSR didn't really mean "modified" sine wave in it's truest sense but rather a sine wave that under some generator load and speed conditions can degrade to such an extent that the waveform exhibits sharp edges consistent with a modified waveform, which by definition is stepped and which is known to cause damage to their EMS units. Probably what he should have said is "non-sinusoidal" or "non-true sine wave", the words Progressive uses in it's Yamaha EF2000iS disclaimer.
Clearly some are confused by the differences between generators, be they inverter or synchronous, and battery powered inverters. Fossil fueled generators exist for the purpose of generating a waveform output that emulates power generated by conventional utilities and therefore by definition are "pure" sine wave, or more correctly "sine wave" since a sine wave in itself is "pure". My pet peeve - referring to a sine wave as "pure" sine wave is redundant, just as is referring to a water heater as a "hot" water heater - of course a water heater is a "hot" water heater, saying it doesn't make it any more so! :S Progressive has designed their EMS units to be used with a "pure" or "true" sine waveform, nothing else, and has made that clear -
"... our EMS are designed to be used in the RV environment using a commercial power source."Battery powered inverters are an entirely different kettle of fish, as they can be designed to output
any type of waveform desired, be it square wave, modified sine wave, true sine wave, or anything between. These days there are probably far more modified sine wave inverters in use simply because they're relatively inexpensive to produce yet the waveform produced is "good enough" for powering many devices, especially resistive loads. There are however some devices that don't run well on anything less than true sine wave, induction motors being an example which will run less efficiently, hotter, and often noisier than they should ... ergo, the reason I chose a (true) sine wave inverter myself as my primary use for it is to power 120 vac fans in the camper.
Bottom line - concern over whether a
generator produces a "pure" or "true" sine wave isn't the issue, it's whether it can maintain that sine wave output under all operating conditions, which Progressive claims the Yamaha EF2000iS cannot. It however is the
only generator model so identified by Progressive so unless there's other proof out there somewhere I would have to assume that generators such as my Honda EU2000i or the class leading EU3000iS or even other similar Yamaha models do consistently produce a true sine wave output regardless of what speed they may happen to be running or load they may be supporting.
