# How to calculate the power requirements of a fan motor? [closed]

I bought a fan from the USA to use in Europe. The fan's specifications states the following:

Requires a grounded electrical supply line of 120 volts AC, 60 Hz, 15 amp circuit.

Here we use a 220V, 50-60Hz supply. I've managed to find a step down transformer at a local electrical store that is a 220V-110V transformer for home use. They have a two models — 50VA and 100VA.

Which one would I need to power my fan? Is the 50VA, sufficient?

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VA is the apparent power. So, assuming there is no reactive power, your power requirement is $V*I=120*15=1800 W$ or $VA$. Now, when you double your voltage, your power requirement will not change, but the current needed will change. A 100VA transformer will give you $\dfrac{100 VA}{220 V}=0.45 A$. You need 8.2A at least without calculating the losses. That fan will not spin very fast. What you need is a 1.8kVA step-down transformer. – abdullah kahraman Jun 19 '12 at 8:05
By the way, what kind of fan is that?! – abdullah kahraman Jun 19 '12 at 8:08
Hi Abdullah, Here's the spec sheet.: fanimation.com/support/download_pdf.html?media_id=3478 – Mridang Agarwalla Jun 19 '12 at 8:32
Supporting consumer electronics is off topic for our site. – Kortuk Jun 19 '12 at 11:11

## closed as off topic by Kortuk♦Jun 19 '12 at 11:11

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Impossible to say. The spec mentions a 15 A circuit, but that's probably startup current; a 120 V/15 A fan would consume 1800 W, and would probably need a fan itself. The 15 A circuit refers to the fuses. Lower rated fuses might trip when switching the fan on.

If the fan has a 15 A startup current the 50 VA transformer, that's about 0.4 A won't probably be sufficient.

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Ouch. it was real big mistake ordering the fan and an even bigger one to accidentally not choosing the 220V option. Steven, would you happen to know if are there are home transformers available for this power rating? Maybe the ones that I've been looking at have been designed for smaller devices like electrical shavers. Thank you. – Mridang Agarwalla Jun 19 '12 at 8:34
@Mridang - No, shavers need far less power. I saw you link to the datasheet, and it appears to be a regular size fan. I would suggest you go to a local shop where they sell these things and try to find out what their typical power is. – stevenvh Jun 19 '12 at 8:38
Hi Steven, I'll try to find out some more information. What is the variable that I'm looking for here? We know the voltage and the amperage. Do we need to find out the Wattage or something else? Thanks. – Mridang Agarwalla Jun 19 '12 at 9:26
@Mridang - Voltage $\times$ Amperage gives you VA, which is an indication for power, which is given in watt. (In resistive loads they are the same.) For a home fan like the one we're talking about the package will probably mention the power (watt), not current or VA. – stevenvh Jun 19 '12 at 9:34