Single phase

[Treemon]

Thought id bagged a bargain Ryetec circular saw bench off ebay - only its single phase and needs 6kva not the 3kva supplied by my generator. Does anyone know if a step up transformer could work it ?

[eggsarascal]

I think you can get an inverter from 3kva to 6kva, but i may be wrong, i had an inverter a few years ago to take a single phase up to three phase.

Edited August 8, 2011 by eggsarascal
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[ash1]

Thought id bagged a bargain Ryetec circular saw bench off ebay - only its single phase and needs 6kva not the 3kva supplied by my generator. Does anyone know if a step up transformer could work it ?

 

I'm not an electrician but I think kva is the output, nothing to do with the phase. In other words you need a higher output generator, 3Kva is not man enough!

[Justme]

Sorry but no you cant.

 

You can convert a 3kva 240v (so 12.5 amps) to 110 v at 27 amps. Or 27amps at 110 to 12.5amps at 240v. Both have the same total power / energy.

 

You cant increase the output power above the input power.

 

Or you could get free power.

[eggsarascal]

Sorry but no you cant.

 

You can convert a 3kva 240v (so 12.5 amps) to 110 v at 27 amps. Or 27amps at 110 to 12.5amps at 240v. Both have the same total power / energy.

 

You cant increase the output power above the input power.

 

Or you could get free power.

 

How do those inveters work then-the ones you plug into a fag lighter in a car and get 240volts out of them?

[gensetsteve]

How do those inveters work then-the ones you plug into a fag lighter in a car and get 240volts out of them?

 

240v ac with very low watts. Or if you get one that has lots of watts it will kill your alternator and battery.

[caledonian bob]

Use a phase converter ?

[Treewolf]

How do those inveters work then-the ones you plug into a fag lighter in a car and get 240volts out of them?

 

Roughly speaking the power in to the device = the power out from the device plus losses (heat etc) in the device.

 

Power (Watts) = Volts x Amps

 

So if the output is (say) 240 Volts and 2 Amps = approx 500 Watts, then the input current on 12 V would be approx 500/12 = 42 Amps, and that doesn't allow for losses. That'll make your cigarette lighter wiring glow!

 

[before anyone jumps in and tell me it is not quite this simple, I know!]

 

A 6kVA tool will draw approx 25 Amps from a single-phase mains supply, and the only place you'll find a supply like this is in industrial premises. The only things you can do realistically are a) sell the tool, b) remotor the tool (if possible), or c) or buy a much bigger generator. Most generators above 3kVA are three-phase rather than single phase, so you may find it difficult to find something suitable. The only good thing is that larger generators second-hand are generally better value for money since there is less demand for them. Running a 6kVA single phase tool from a three phase supply won't be easy either due to the need to balance the load across the three phases.

 

If the saw has an external motor you might be able to replace the motor either with a smaller single-phasae one, or a three-phase one. Otherwise I think you may be better off selling the saw.

 

A step-up transformer will not do anything to help you since it cannot gain power from anywhere; it can only increase the voltage at the expense of the current (plus inevitably it will be a 'lossy' device, ie it will waste power as heat).

[Ridd]

I think I know where there may be a portable 3 phase genny for sale, not sure of the KVA but I can ask the man in question if you like?

[Treemon]

Thatnks for all your ideas decided to put a 5.5hp engine on it off a rotavator as it has a pulley drive gear box