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110v site transformer
locoboy - 12/3/09 at 01:43 PM

Guys i have bought a 110 site chop saw on ebay and it needs a transformer to power it.

Does anyone have one spare for sale?

Also there seems to be quite a range of load ratings about for these things, anyone know how i find out which one is best suited to running the saw?

Im seeing things like 3.3Kva, 5Kva........means nowt to me but i dont want to damage either the saw or the transformer so i need to get the right one.
The saw has a 1600W motor if it makes any difference.


dhutch - 12/3/09 at 02:00 PM

kVA is kilo volt amps.

For a purely resitive load (light bulb) this is directly the same as kW (kilo watts) P=VI if you remember anythin from physics lessons.

However for capacitive or inductive loads (inc motors, microwaves, etc) they arent quite the same.

I dont know what the powerfactor (diffence between kVA and kW) for the saw would be.
- I would be happy running a 1.6kW saw of a 2.5kVA transformer, although no doubt someone who actaully knows whats standard practice will be able to advise better.

Also, obvisouly, a local source is advisable as the postage will be huge on what is basicaly a block of iron and copper.


Daniel


matt_claydon - 12/3/09 at 02:01 PM

For DC Volts*Amps = Watts so kVA would be the same as kW. However, for AC the relationship is not so simple and depends on the type of load. Generally you include a 'power factor' so

Watts = VA * Power Factor

The power factor depends on the type of load - for a resistive load like lights or a heater it would be near enough to 1, but for an inductive load like a motor it can be a lot lower. 0.6 is generally used as a good average for motors etc.

In you case therefore you need a transformer with a rating of at least 1600/0.6 = 2700 VA or 2.7kVA.

That is the theory, I don't know what general practice is in reality though.

[Edited on 12/3/09 by matt_claydon]


BenB - 12/3/09 at 02:33 PM

quote:
Originally posted by matt_claydon


That is the theory, I don't know what general practice is in reality though.

[Edited on 12/3/09 by matt_claydon]


If the transformer blows up or melts you need a bigger one?


adam1985 - 12/3/09 at 04:47 PM

ive got the small one from machine mart and its fine for everything a use ie drills saws core drills lamps i think the only time it would have problems is if i used alot of tools at the same time with it but its got a reset button anyway so you would know when its at its limit