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Water pump start up current on inverter - advise please!


Noobie
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So I am thinking of connecting my JoJo tanks pressure pump on to my inverter so that in the event of a power failure I won't have to go outside and turn the bypass valve on. I know, its me being lazy  ;)

The pump is a 230V 850watt DAB pump, it pulls 3,8 amps running current. My concern is that the pumps start up current will trip the inverter output supply.

 

The research I have done says that the startup current on a motor is between 3 and 5 times the running current (between 11,4amps and 19amps)

The inverters surge power is 6000VA - 4800watts (3k 24v plus Mecer) @ 230 volts, this would equate to 20amps.

 

So if I have done my calculations correctly the inverter will be able to supply enough current to start the motor without tripping out - 20amps max inverter surge output vs. 19amps motor startup current.

 

This would be great if my pressure pump was the only thing connected to my inverter, but unfortunately this is not the case. If I am pulling a base load of 5 amps from the inverter and then the pump starts up this will push the current draw over the 20amp surge limit tripping out then inverter.

 

I have done a bit of reading and think I may have a solution? A soft starter relay from RS components connected to the pressure pumps 

supply.

 

Heres the link: http://za.rs-online.com/web/p/soft-starts/3305358/

 

Has anyone out there done something similar and had success or am I on the wrong path here? :huh:

 

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Noobie, I have that exact same pump (DAB Jetcom, 0.85kw motor, 3.8 amp indicated on the motor), and my 1600VA Victron starts it without a hitch. The red overload LED flashes for half a second but that's it. This particular inverter can handle momentary peak power of 3kva. It's going to depend on how much other things are also on the inverter, but I haven't had a problem yet.

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My power failed at 5AM this morning (because I forgot to buy prepaid :-P), so this morning my irrigation system fired up the DAB Jetcom pump off the inverter... which is no biggie, except I had a couple of fans, DSTV PVR and a laptop or two, and a fridge running at the same time. So while I was in the garage punching in the newly bought code, the freezer decided to turn on. So ye olde Victron made this loud groaning Bzzznnnt noise, flashed the overload LED twice... and continued on its way, fans blowing as if it might take off. It's only a 1600VA unit...

 

So really, I don't see why there'd be an issue starting this pump even without a soft starter.

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  • 4 years later...

I know this is an old post, but want to check on feedback if the Soft Starer from RS-Online worked for the pumps. I also have the same issue with the PUMPS startup amps which Im trying to reduce as it overloads the inverter. Anyone else have experience with this setup will be greatly appreciated

 

 

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I wound up having to replace my pump shortly after and have never bothered connecting it to the inverter.

I got a DAB easy box mini

I do have a bypass valve on the municipal supply so during load shedding I can use this valve to supply the house with water straight from council (bypassing the pressure pump and tank)

I have only ever had load shedding and a Joburg water outage once. What I wound up doing was running an extension cord from an inverter socket and plugging the pump into this and it worked 100%.

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Thanks for the feedback!  Yeah I actually have the same setup though with a Borehole integrated into the water system.  Looking at the specifications of the DAB E.SYS  it doesnt go above the rated KW and only reaches its peak on demand.  Ill have to just check the water flow as I have irrigation also with my 1.5kw pump (2.5 startup). This is useful, so maybe this is my better option on the long run!

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