Transformer power consumption
 

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

TIA, Colin

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

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).

--

Reply address is spamtrapped. Remove theobvious for valid e-mail address

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?

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


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

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

15w for a hot switcher more like =A35 a time.

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


NT

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

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.

--
Tony Williams.

Paul King wrote:
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?
Should I switch off the plug sockets that the transformers are
plugged into when the devices plugged into the transformers are not
being used?

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).

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.)

wrote in message
oups.com...
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?


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


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

Snip

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



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!

Tony Williams wrote:
In article ,
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? Should I switch off the plug sockets that the
transformers are plugged into when the devices plugged into the
transformers are not being used?

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.

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.

Mike wrote:

wrote in message
oups.com...
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?


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


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

Don't say that.
You'll upset all the AGA users./

On 26 Jan 2005 05:42:43 -0800, wrote:

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

upto you. 3w for a wallwart will cost you about £1 a year each in
lcccy while on standby.

Hi,

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

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

1Wy = ~67p.

cheers,
Pete.

On Wed, 26 Jan 2005 18:46:35 +0000, Pete C wrote:

( (3w * 24h * 365d) / 1000) * 7.68p =3D =A32ish (using London prices)

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.

--
Cheers
Dave. pam is missing e-mail

In article ,
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?

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.

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

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.

--
*If at first you don't succeed, then skydiving definitely isn't for you *

Dave Plowman London SW
To e-mail, change noise into sound.

"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 message , Cuprager
writes

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


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!

So it's you that's responsible for global warming ...

--
geoff

In article , Owain owain41276
@stirlingcity.coo.uk writes
"Colin" wrote
| 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.

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.
--
fred

Cuprager writes

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


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?

If they are too hot to touch then I always look for a lower temp
alternative.