Motor starting current; genset capacity

starting, 9 amp

manufacturer recommends

of a generator

surge capacity

reqm'ts of the

genset work, for

a 20 amp circuit

breaker rating and

the breaker will take the surge.... the generator capacity is the generator capacity and if you ask more if it, you wont much... a short blip.. thats it... the drive motor is maxed...it has no surge capacity.

If you want ot close off the pump discharge or suction (yes discharge if is a single stage single impeller pump, most comon except for wells) the pump will start with much less amperage draw and free wheel. So even with the small generator it might get rolling..and come up to speed, then you can open the valve.

Phil Scott

Not enough information to really answer the question. Motors can draw 6 times FLA on start 9X6 =54 amps. Not knowing what kind of pump or head on the pump there is no way guide you.

the 2.5kw might start the motor, with out an load for a while. Your pushing it really hard.

The 20 amp is all that is needed for the motor as the starting current is only a few cycles. Most generators will try to carry the load. Sometimes they run into a brick wall and then the genset shorts out and your left with an noise maker. Look into an softstart for your application. Might be cheaper than an larger genset than you need. Especially when you consider the fuel and maintenance.

Oversizing the wire when on the genset will help a little. Voltage drop is very important when starting an load. I.E. run #10 gauge stranded to the motor instead of the #12.

Gensets have an finite amount of power. The utility is almost and infinite amount.

The pump is rated for 5 gpm at 400' head. It's set at a depth of 210' and the elevation difference b/t the well-head and the house is 0'.

My simple mind wants it to be true that 1/2 the head equals 1/2 the load equals 1/2 the starting current.

depth of 210' and

0'.

Thats a multi stage high pressure pump.. you will need the full locked rotor KW gen set to start that baby...if its a gasoline fired gen set the gas available these days may not work to produce the max rated HP... also as the gen set ages it will not produce max rated KW.

For example my brothers camping generator and lawn mower quit running well or at all.. he drained the gas and filled with motorcycle race gas and they ran perfectly. the gas people are screwing with us these days.

Go with a propane or natural gas fuelled gen set if you want stable stand by capability go one size larger...Genrac might make one that small.

Phil Scott

.

starting, 9 amp

manufacturer

reqm't of a generator

at surge

reqm'ts of the

genset work, for

why a 20 amp

breaker rating

surge-draw.

knowing what kind

while. Your

starting current is

run into a

noise maker.

cheaper than an

the fuel and

Voltage drop is

stranded to the

almost and infinite

10/8/2004

1/2 the load

thats because you havent considered two other things... inertia, accelerating the rotor and head of water up to speed at start...and inrush current resulting from a stalled rotor under such a load. so locked rotor will remain high (starting current)... half the head will reduce the *duration of the starting current...but not the peak locked rotor amperage significantly, and yer generator set *dies at its peak surge load rating... and you do not want to buy a gen set that has to run at 100% load regardless... you want it to run easy so it lasts longer.. ... 60 to 70% of full load as a rule. not

100%

Manufactures tend to be optimistic on thier ratings as well.

Phil Scott

depth of 210' and

is 0'.

starting, 9 amp

manufacturer

reqm't of a

that at surge

reqm'ts of the

genset work, for

why a 20 amp

breaker rating

surge-draw.

knowing what kind

while. Your

starting current is

they run into a

noise maker.

cheaper than an

the fuel and

little. Voltage drop

stranded to the

almost and

>> Version: 6.0.775 / Virus Database: 522 - Release Date:

10/8/2004

Well, I was planning on converting my gas generator to propane, but I'm not sure that this solves anything. The rated capacity of the genset is twice the nominal current reqm't of the pump but only half of the starting current.

propane, but I'm not

genset is twice

starting

I dont think it will work but its a half hour job to try it.

message

is

a

not

ages

quit

with

people

want

might

that

current

2.5Kw

and

the

they

an

consider

little.

gauge

>> > Version: 6.0.775 / Virus Database: 522 - Release Date:

You need a soft start controller such as:

Bill Kaszeta Photovoltaic Resources Int'l Tempe Arizona USA snipped-for-privacy@pvri-removethis.biz

snipped

snipped again

Sorry dude with that much of an head your talking seconds of locked rotor current on the motor. Your genny will never handle it, if it does it will not for very long. With that much head the soft start will have to be pushed out a lot farther in time than I would want for my pump. Before looking into the softstart better check with the manufacture of the pump to see how the pump will handle the situation. As a wild assed thought have you considered an 2 speed motor? Start on low, get the water moving then move to high. Again check with the pump manufacture about doing this before doing it.

Bottom line you need an bigger gen set. Unless you really into creating an monster that no one but you will be able to handle. What about the SO when your not around and this needs to work?????

| Go with a propane or natural gas fuelled gen set if you want | stable stand by capability go one size larger...Genrac might | make one that small.

Smallest Generac on NG or LP is 7 kW. But I think he needs at least that big, anyway. Next size up is 10 kW commercial model and 12 kW home model. Kohler models start at 10 kW.

A neighbor has a 5.5 kW gasoline generator, and his big screen TV won't run on it at all. But on utility power, that TV blinks half the lights almost to zero for a very brief instant to get the TV on. I think he needs a bigger genset. I'm trying to talk him into a 25 kW NG model. Then he can have some hot pizza while watching TV in the big blizzard (if his dish doesn't ice up).