Help with choice of generator

[scarecrow]

I have 6.5hp generator which I think is around 3.5 kva and it won't drive a welder if I remember correctly the minimum was around 5 kva I can try the grinder and compressor on it tomorrow for you to see if it will run them

 

[the snooper]

it will run the grinder but i doubt it will run a 2hp compressor they need roughly tripple the running current at start up be careful not to damage your genny

 

[greenflag99]

thanks guys for all your help looks like i am going to have to spend tripple the cash on a genny that will power what i need to hire one for a week is £200 so might as well buy one

 

[the snooper]

i have a 5 kva diesel i will try it tommorow welding steel of the same guage as a car and post the results tommorow night

 

[brightspark]

a 4 kva generator will start and run a 3 hp motor

 

[the snooper]

not a chance as you would require tripple to start the motor

 

[brightspark]

not a chance as you would require tripple to start the motor

no look up macfarlan generators on google it gives the calculations for start up load

 

[greenflag99]

have found a 5.5 kvh petrol genny for under 300 quid so thats not bad if it will work look forward to the results snooper thanks mate

 

[the snooper]

i have 2, 5kva diesel generators and neither will run my compressor after i had rebuilt one of them it failed to excite but everything checked out wouldnt even run a grinder so i stuck my compressor on it it did excite it and the genny just threw a wobbler as did my other one when i tried that aswell so i know from experience

 

[brightspark]

macfarlane generators website calculations for loading if anyone wants the corect information

 

[greenflag99]

macfarlane generators website says for a 2 hp motor (compressor) i need 8.0kva

 

[brightspark]

starting sequence 1 direct on line 240 v for 3hp= 4kva 2hp is 3kva

 

[greenflag99]

opps tried it again on that site and it now shows 4kvh for a 2hp that would work the compressor but would it still work the clarke welder?

 

[Justme]

I run a 2hp on a 6kva (4800watts) no problem.
(diesel large engined genny from a big brand stable)
Even whilst running other loads

I also run the same compressor on a 3kva inverter (quality one not a cheepy ebay job) again with no problems, again with other loads.

I also run my 210amp mig welder but not at full amps (not had the need for full amps yet so dont know how far I can take it yet) but up to 120amps ish.

 

[brightspark]

QUOTE=greenflag99;184024]opps tried it again on that site and it now shows 4kvh for a 2hp that would work the compressor but would it still work the clarke welder?[/QUOTE]try again 3hp 4kw
sequence 1 . 3hp dol start single phase =4kw. i dont know about the welder

 

[the snooper]

just found this web site http://www.sawdustmaking.com/ELECTRIC%20MOTORS/electricmotors.html which says

Capacitor Start

This motor has a capacitor in series with a starting winding and provides more than double the starting torque with one third less starting current than the split phase motor. Because of this improved starting ability, the capacitor start motor is used for loads which are hard to start. It has good efficiency and requires starting currents of approximately five times full load current. The capacitor and starting windings are disconnected from the circuit by an automatic switch when the motor reaches about 75% of its rated full load speed.

Uses

Common uses include: compressors, pumps, machine tools, air conditioners, conveyors, blowers, fans and other hard to start applications.

me and brightspark seem to have differing opinions as to what size genny will start your compressor i suggest you contact a company that sells gennys and ask for their advice as i think it will be a capacitor start motor.
however either me or brightspark could be wrong or both and i would hate you to waste your cash if i am wrong so take some advice from a specialist before buying

 

[brightspark]

just found this web site http://www.sawdustmaking.com/ELECTRIC%20MOTORS/electricmotors.html which says

Capacitor Start

This motor has a capacitor in series with a starting winding and provides more than double the starting torque with one third less starting current than the split phase motor. Because of this improved starting ability, the capacitor start motor is used for loads which are hard to start. It has good efficiency and requires starting currents of approximately five times full load current. The capacitor and starting windings are disconnected from the circuit by an automatic switch when the motor reaches about 75% of its rated full load speed.

Uses

Common uses include: compressors, pumps, machine tools, air conditioners, conveyors, blowers, fans and other hard to start applications.

me and brightspark seem to have differing opinions as to what size genny will start your compressor i suggest you contact a company that sells gennys and ask for their advice as i think it will be a capacitor start motor.
however either me or brightspark could be wrong or both and i would hate you to waste your cash if i am wrong so take some advice from a specialist before buying

i would agree with that it is a minefield with a lot of variables

 

[greenflag99]

have just phoned machine mart who say that i would need at least 8kva to power the mig welder and 4.5kva for the compressor with a 2hp motor