Hi to all, there is my concern if some can help me please.
I use a 1200VA along with two 190Ah batteries to operate a 220V 0.5Kw immerged water pump.
When i plug it to the pump, the red light goes on, the pump doesn't operate while the clamp ammeter shows 700 watts (i do not reach the 1000W).
When i use a honda 2000W gasoline generator, the pump works good at 500W.
Why does it get stuck at 700W with the inverter and works good with the generator ?
Many thanks.
the 500W pump sounds like its the nominal rating. The AC motor will likely require a signficantly higher power to start up.
From what you're describing, the honda is capable of providing that start up power, and after the motor starts to turn, the power draw goes back down to the nominal 500W.
The inverter looks like its not capable of providing the start up power to the pump, and so the motor doesn't turn. The motor is however still drawing power as the AC is still going through it (which is why the clamp meter is giving you a reading... the 700W (VA?) is likely limited by the resistance & inductance of the motor, not by the inverter).
If you want to use an inverter the easiest way is to use a larger VA unit (looks like a >2kVA unit would work given your experience with the genset). Other engineers might be able to chime in on whether there's something that can be done to reduce the inrush current requirement.
edit: after thinking a bit more, I should add that both the genset and the inverter likely have undeclared design margins, and that the pump conditions may well be variable relative to your test with the 2kVA honda. The pump specs should give you (or get from the mfg) the start up requirements; size the inverter according to that.
Hello Kai,
Thank you for the answer. Another thing i forgot to mention is that i made the wires longer with some connexions. Do you think this may prevent the inverter from making the pump work ? is the inverter more sensitive to long wire/many connexions than the honda gas generator ?
I want to explore all possible ways before buying another inverter.
Thanks.
you'll have to measure things (at least voltage) at start up / normal use for anyone to give a good answer.
longer wires can in some cases help overcome starting current, as they work as a resistor. but depending on the type of pump, and if it has to start with back pressure present or not, this might either help or make things worse.
Their may be another alternative. There are devices to reduce the surge current when starting AC motors. They consist of capacitors and electronics to prevent surge current from overloading devices like inverters and generators. In the US a company called MicroAir makes them, I am sure their are other manufacturers. The URL for MicroAir is:
https://www.microair.net/collections/easystart-soft-starters
Pat
