AZSMOKER wrote:
Hi everyone,
I have been chipping away at this thread, but I have a questions that someone here might be able to answer. I have an electric chainsaw and tried using it today on my two champions on parallel. The chainsaw caused the two gens to overload. It's a WORX 16-Inch, 3.5 HP, 14.5 Amp Chain Saw. I'm confused, the outlet on the parallel is 30 amp, not sure why the chainsaw is causing the gens to overload?
TIA,
Ryan
The outlet on the parallel unit is
rated for 30 amps but does not supply 30 amps. The maximum amperage available will be 26.4 (13.2 amps x 2 units) under the best of conditions - or about 3,200 watts. This is a rating for a resistive load like incandescent lights or an electric heater - not an inductive load like an AC motor. A 3.5 H.P. electric motor computes to 2,611 watts (746 x 3.5). This conversion is based on WORK, not efficiency. Since the efficiency of electric motors will vary the wattage is often higher than the H.P. rating providing you are not looking at some advertiser's synthetic peak H.P, figure like you find on vacuum cleaners. The 14.5 amp rating does not agree with the H.P. rating on your saw (14.5 amps = 1740 watts. 1740/746 = 2-1/3 H.P.) "If" it is really drawing 14.5 amps, when we factor in efficiency the true H.P. will drop below the 2 H.P. figure.
OK - using straight up figures you should have something like 600 excess watts if we believe 3.5 H.P., or 1,460 excess watts if we believe 14.5 amps. But, here is the catch 22 - it is called LRC or locked rotor current. It will take considerably more current to get a motor moving from a standstill than to keep it moving. This is especially true in something like a chain saw that has gear reduction friction and the chain/bar drag making a higher starting load than a totally unloaded motor starting up. LRC normally is only a second or so in time. Randall mentioned in-rush current which is similar to LRC - but even higher than LRC for a shorter period of time.
The CPE inverter units have a very short period of time that they can handle either LRC or in-rush current - typically no more than 400 ms. even on the units having the latest software and stator (but the newest software and stator from SuperGenProducts is a
big improvement over the original).
Still, I would "think" two parallel CPE2000i units would power your electric chainsaw - including LRC and/or in-rush currents.
At this point it would be interesting to further analyze the saw with a meter able to capture in-rush current and time as well as peak or LRC current for comparison. Knowing you most likely do not own one of these meters you can only guess or suppose what item is at fault (saw or generator(s)? Unfortunately, a commonly used and inexpensive Kill-A-Watt meter has a 15 amp internal fuse and could be damaged if used to measure higher currents when parallel (OK for a single unit).
You might try some other electrical tools to see if you get the same results. I suggest trying sanders, circular saws, grinders, electric drills, etc. paying attention to their amperage and wattage ratings. You might also try intermittently "bumping" the power trigger on the saw to coax the saw to begin moving while making the bump interval short enough to keep the generator(s) from overloading until the saw comes up to speed. Another consideration for parallel units is if one overloads the second unit will immediately overload as well. Thus, if one of the two inverters is not providing its full power both will appear weak when parallel. You might want to try some of the lower power rated tools on each unit individually to see if one generator overloads more quickly or frequently. At least this will give you some benchmark to work from.
