Does power rating mean the same thing as Power dissipation?

Thread Starter

worldHello

Joined Oct 15, 2014
23
I know power rating means the power an element can handle.
For example, if a 2-ohm resistor has power rating of 1W, then a current of 1A yields V=2 V, and P = 2*1=2 W. 2 W > 1W, so the resistor will be damaged and overheated.

Does power dissipation mean the same thing?
I personally think so, but would like to have more confirmation.

Thanks!
 

crutschow

Joined Mar 14, 2008
25,632
Yes, the power rating is the power the device can dissipate, typically at 25C ambient temperature. Normally, for good reliability, you don't want to operate the device at much above about 50% of its rating.
 

Thread Starter

worldHello

Joined Oct 15, 2014
23
Yes, the power rating is the power the device can dissipate, typically at 25C ambient temperature. Normally, for good reliability, you don't want to operate the device at much above about 50% of its rating.
Thank you. If a device's power dissipation is "internally limited", what does it mean?

I understand it means it dissipates very minor power, but I guess it should have some kind of power rating that tells you how much power it can handle, right?
 

bertus

Joined Apr 5, 2008
20,869
Hello,

Most voltage regulators have a thermal protection.
The regulator will limit or even shutdown when the device gets to hot.

Bertus
 

GopherT

Joined Nov 23, 2012
8,012
Yes, the power rating is the power the device can dissipate, typically at 25C ambient temperature. Normally, for good reliability, you don't want to operate the device at much above about 50% of its rating.
They are the same unless you are buying a ShopVac! "...may not be indicative..."

Horsepower Rating
Peak horsepower is the maximum output horsepower of a motor determined from a laboratory dynamometer test. Since peak horsepower is outside the normal operating range of a vacuum cleaner, it may not be indicative of actual air power differences when comparing two cleaners.
https://www.shopvac.com/specifications/quiet_series.asp
 

studiot

Joined Nov 9, 2007
4,998
Does power dissipation mean the same thing?
No it doesn't, quite.

The power dissipation is the actual power dissipated.
So in your resistor example if the current was only 0.5 amps then the power dissipation in your 2ohm resistor would be only 0.5 watts
But its power rating would still be 1 watt.

The power rating is the maximum power the device can safely dissipate in normal working at a given temperature.

You should always note the given temperature because a device may require cooling measures to achieve this.
There are formulae for derating (reducing the rated power) for operation at higher temperatures.
 
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