Transformer power consumption

Strictly speaking, they aren't transformers - they're switched mode power supply AC/DC adapter units (a box with electronics *AND* a transformer). As such they will draw a (minimal) current from the mains even when the main appliance in switched off/disconnected from the plug-in "transformer", because the electronics inside is still running. Of course that current demand increases when the appliance is switched on (obviously).

yes, but not much. The hotter it is, the more its eating.

upto you. 3w for a wallwart will cost you about =A31 a year each in lcccy while on standby.

Anything that gets positively hot is best switched off for safety.

NT

Little wallwart-type chargers often have shunt regulators, so can consume as much power off-load as on-load. Feel their temperature off-load. If they are warm they are dissipating power.

Many of these lower power devices are transformers, not SMPS. For a few of the transformers, the load actually goes up when unused, due to absolute minimisation of cost of production. (not usually the case)

(the core is on the borderline of overloading due to being too small for the voltage, and is brought back to normal when used.)

Anything that gets "positively hot" when not in use needs to be binned.

Snip

I have some computer kit thats plugged in 24/7... an adsl router, wireless base station etc etc. The plug transformers on these give off a fair amount of heat. Do you think they should be switched off when not in use? Just that its so handy having them on and ready to use all of the time!

In all those I've opened (10-20?) this is not the case. The transformer is simply so small that it can barely handle the mains voltage unloaded without melting. As load is drawn, the transformer comes out of saturation, and may cool down.

You'll upset all the AGA users./

Hi,

I'd have thought it's a bit more,

( (3w * 24h * 365d) / 1000) * 7.68p = £2ish (using London prices)

cheers, Pete.

Your paying to much for your power... Wander off to one of the websites that list the alternative suppliers and what you would pay them based on your consumption.

Wall warts? Any such device will draw *some* power when plugged in, but with a well designed one - with no load - it will be tiny.

The appliance it's feeding might make the difference, since some when 'switched off' may draw nearly the same current as when switched on. I had an STB like this.

However, what you have to take into consideration is that any energy used by these devices when 'off' will be transposed into heat, so at this time of the year not be totally wasted - if you have thermostat controlled gas central heating. You will merely pay the extra cost of electricity over gas. If you are using full price electrical heating it will cost you near as dammit nothing.

"Colin" wrote | I have several transformers plugged in around the house (laptop, | battery chargers, musical keyboard, etc.) I was wondering whether | they drew power when the device plugged into them was switched off?

A little.

| Should I switch off the plug sockets that the transformers are plugged | into when the devices plugged into the transformers are not being used?

If you believe the government television campaign on at the moment showing a mobile phone charger starting to smoulder - yes.

Owain

In article , Owain writes

An appalling piece of scaremongering I thought, makes a nonsense of the BS (EN I s'pose) that they are all meant to be approved to, but if it's a transformer one the electrolytic caps will last longer if they are switched off when off load. From experience they are rarely margined up by much and when off load they will charge to peak plus the off load regulation which for a crappy little one will be 10% plus, reducing their life.