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Hello. I hooked up a kill a watt meter to my sump pump today and read the following watt > 910 Amps> 10.5. The reason for all this is to figure out the surge current of the pump so i can purchase the right inverter. The numbers dont make sence since we are at 10.5 amps which is 120v x 10.5 amps = 1260w I read a surge current for a pump can be 6 to 7 times its wattage The kill a watt meter is telling me another story. My question is that can i use the xantrex prowatt pure sinewave 2000w for this with out any problems. Thanks
Why not use a DC pump? Not sure how high you are pumping the water but maybe a bilge pump would work? I have one of the small ones that pumps 500 gal per hour (granted at low lift) and only draws about 20 watts. I think it can lift 5-10 feet but the GPH drops and the power goes up. These things are dirt cheap (way cheaper than an inverter, etc.) Just throwing out an option.
My situation is unique i pumping 15feet up . I beleive its a 1/2 horspower home depo submersable pump. It works for me the only issue i have is that the float get stuck some times.
Basically, a Kill-A-Watt won't read the surge; it happens too fast for the meter to sample. There are some (very expensive) latching Ammeters that can do it. Pumps are tricky. They don't have a fixed rate of draw. Put resistance against the motor (as in trying to lift a column of water) and the current draw goes up. Most sump pumps (pedestal type?) are about 1/4 HP. That would be 186.5 Watts if you try to calculate it from one electrical HP. See how far off the numbers are? You've already seen nearly 1 kW draw! Rather than guess or buy an expensive meter or a much too large inverter, I like Peter_V's answer: the DC sump pump. If you want this for emergency power back-up, a pump like this one is cheaper than an inverter which could run a standard unit.
Like the other post I made about the lag of current flow vs the ac voltage waveform: Power = voltage x current x cosine (current phase angle) Inductive motors are not resistive loads where current follows voltage exactly (cosine of zero is 1.0). With motors, the lagging phase angle is around a 0.6 power factor... 1/0.6 = 1.67 Or, your inverter will need to output 1.67x more current to account for the inductive qualities of an induction motor. -Bill
This is a complex issue and I cannot type much from my phone right now... Centrifugal pumps use less power as flow is reduced/restricted and positive displacement pumps (like piston pumps use more). A VFD (variable frequency drive) may also be an option for you. -Bill
15' is a bit tall for a boat bilge pump, so you really need a sump pump. The sticking float is a problem. that can either burn out the motor, or flood your basement, depending how it sticks. Niether is good. What is your normal water input, 5 gallons a day? 1 GPM ? How much do you need to move ? maybe a smaller pump, with longer run times, is better than a large pump cycleing on - off - on all the time Amazon.com has a pretty good listing and varity, but first, the amount and frequency of pumping needs to be known. We'll try to get you to a workable solution
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