Voltage Transformers

WasterEx

Hey electrician folks, I have a quick question.

I'm going to be buying a step-up voltage transformer to use for some of the electrical items I have in Canada once I have them shipped over. The voltage there is 110v but the transformer brings it up to 240v. My question is; Some transformers you can buy have a specified wattage (100W, 200W, 750W, etc.) What does that even mean? What would you recommend?
Cheers.

cast_iron

It depends on the appliance. A hair dryer, for example might be over 2000w. A transformer that is rated for 2000w will be expensive - certainly alot more than the price of a new hair dryer over here.

The higher the wattage, the more expensive the transformer you require. You will need to check the wattage of each item and evaluate whether or not it is worth it. What are the items?

WasterEx

cast_iron wrote: »

It depends on the appliance. A hair dryer, for example might be over 2000w. A transformer that is rated for 2000w will be expensive - certainly alot more than the price of a new hair dryer over here.

The higher the wattage, the more expensive the transformer you require. You will need to check the wattage of each item and evaluate whether or not it is worth it. What are the items?

Excellent mate! I've figured it out now

Cheers

ted1

Do they use 50hz or 60hz in Canada?

DublinDilbert

Any device with a switch mode power supply will typically auto range, so will run off the 110V fine. So your iphone charger, laptop, most desktop PCs etc will all be fine. For larger electrical loads, eg hair dryers, as said above you'd be better replacing them.

What I do when I travel to canada, I bring an adapter plug to convert back to the BS plug and a plug board. This means I can charge my laptop, phone and a few other bits and pieces.

2011

Agree with the previous posters.

Just to point out a few things:

1) Transformers are normally rated in VA (volta amps) or kVA (1000 volt amps) not watts (W).


2) If the VA value of the transformer is greater than the power requirement (in watts) this is not a problem, whereas if the VA value is less than the power requirement of your device the transformer is not large enough to meet your load requirements. In other words, too large a transformer is not a problem, too small is.

Without getting too technical, kVA and kW are "first cousins".

cast_iron

2011 wrote: »

1) Transformers are normally rated in VA (volta amps) or kVA (1000 volt amps) not watts (W).

I agree with all you say, but just on this, most of the traffos aimed at the domestic market are advertised in watts.

I suppose a good rule of thumb is to buy a traffo rated to at least 10% over the rating of the appliance. Again, it all depends on the type of appliance.

2011

cast_iron wrote: »

most of the traffos aimed at the domestic market are advertised in watts.

This is why I sated:
"Transformers are normally rated in VA (volta amps) or kVA (1000 volt amps) not watts (W)."

I would think (I am open to correction) that that is the case if the transformer (or switch mode power supply) is supplied with a specific item such as a laptop. In a case such as that the manufacture knows the size and power factor of the load, so it is possible to state the power output of that device when connected to the known load.


In this case however I would think that the OP has nonspecific appliances to be connected to a step up transformer, perhaps several even several devices to one transformer.

Bruthal

It would be like a yellow site transformer used in reverse.

Bruthal

2011 wrote: »

This is why I sated:
"Transformers are normally rated in VA (volta amps) or kVA (1000 volt amps) not watts (W)."

I would think (I am open to correction) that that is the case if the transformer (or switch mode power supply) is supplied with a specific item such as a laptop. In a case such as that the manufacture knows the size and power factor of the load, so it is possible to state the power output of that device when connected to the known load.

A transformer can only really be rated in VA or kva, if supplying an AC load. A 100 va one could supply a 100 watt bulb, but not likely a fully loaded 100 watt motor.

An AC adaptor could more accurately be given a watts rating when supplying a DC load probably.

cast_iron

Well I suppose it might be a hard sell for a company to advertise in VA to the average Joe that's not too up on the technicalities of it all.

Most likely, the OP will be after something like this:
http://www.maplin.co.uk/productsearch.aspx?navigationCommand=Ntk:si_1%7cmain+transformers%7c1%7c,Ro:0,N:4294956694&criteria=main+transformers

He will do well to find, let alone understand a VA rating on the box.

Bruthal

Yea it will be simply a case of them selling a 2kva transformer as 2000 watts, or if they include a bit of a factor, something like a 2350va transformer could be sold as 2000 watts.