Well, not all wattage is converted directly into heat.

1 watt is the conversion or transfer of 1 joule per second.

Then you have to consider things like active, apparent and reactive power.

 

@ericgibbs thx a lot. yea i understood. for the cameras i'm going to purchase a 12V 10A power supply.

i put that power adapter image as an example since the rated input current is way higher than the theoretical input current. for instance even for a 100v input, it should be 12W / 100V = 0.12A. which is 1/5th of the rated input current (0.6A). may be it's due to that inrush current as member "panic mode" has described.

@panic mode thank you so much. valuable info. didn't know about that.

@ElectricSpidey thx a lot.

 

Here Ihave a radical suggestion: Why not ACTUALLY MEASURE the current drawn by one camera??
Record the current at the moment that power is applied, and then the current after that, and then the current drawn while operating the different motorized adjustments on one camera.
The measurements will allow choices made based on reality, totally avoiding all guesses and assumpions.
Consider that the current draw given on the label may not be an exact value.
It might not even reflect that model of camera operation at all. At least, that has been my experience.

 

Record the current at the moment that power is applied, and then the current after that, and then the current drawn while operating the different motorized adjustments on one camera.

The TS didn't say his cameras are motorized with X Y Z axes.

Many of my cameras have X, Y, Z motors what draw power. I only move one camera at a time, so the total power is much lower than the numbers seem to say.

The question at large is what size power supply should he use. That's been answered.

12V 10A switching power supplies are common, cheap and efficient.

 

not all wattage is converted directly into heat.

So is indirectly, things such as going through an electronic device or motor before being converted into heat?
Of course one (perhaps only) way it would not be converted into heat if it is radiated away into space as an EM wave.

 

@MisterBill2 thank you very much. yea the camera power adapter question has been answered. power adapter question with that photo is just a side question i had when looking at the power adapters in general.


by the way i googled and it gave me the same answers as the members suggested above.



thx a lot for your continuous help. i learned some important facts about power adapters.

 

Of course one (perhaps only) way it would not be converted into heat if it is radiated away into space as an EM wave.

The other more common way is to perform any mechanical work.

 

The other more common way is to perform any mechanical work.

True.
But that eventually also gets converted to heat in the end from friction.

I think all the energy generated in the universe will either end up as radiation or heat.

 

True.
But that eventually also gets converted to heat in the end from friction.

I think all the energy generated in the universe will either end up as radiation or heat.

True, but that's just a statement of the laws of thermodynamics.

Consider a crane lifting materials for skyscraper. It could remain in that state for centuries.

 

Consider a crane lifting materials for skyscraper. It could remain in that state for centuries.

True, that's transferring energy into gravitational storage, similar to stretching a spring or compressing air into a chamber.
But eventually it will be all be turned into heat.

 

The intrinsic flaw with converting useful energy into heat is that it tends to spread , which reduces the usefulness. It is the differenence in energy levels that allows useful work to be done.

 

The intrinsic flaw with converting useful energy into heat is that it tends to spread

I wasn't talking about deliberately turning energy into heat, I was just stating that most of the useful work it does eventually ends up as heat.

 

Power adapter rated output is 12V 3A. but each camera has a sticker which says "Input Rating 12V 0.8A". so when all the 8 cameras are working and drawing their max current, isn't it going to be 0.8A x 8 = 6.4A ?

My guess is that the PS (Power Adapter as you refer to it) is intended to run a single camera. Does the instructions tell you to use one PS for all 8 cameras? Or do you have 7 more PS's, one for each camera?

As others have said, you can't run all 8 cameras from that PS. The most you can run from a single supply, assuming the numbers are letigimate is 3. That's a total of 2.4A; something a 3A supply can handle fairly well.

 

hi,
The TS's thread was created for the following query.
i'm trying to calculate the total current at the extension cord (assuming all 5 devices are drawing their max current). thank you.

Please keep on topic.
Moderation

 

All 5 devices are putting out various voltages and amperages. The total is 7.4A. But that is not an accurate reflection of the amount of current being used. We don't know the efficiency of each device. However, I would venture a guess and say that the shared amperage among all five devices will be far beneath the amperage rating of the extension cord or even the outlet the extension cord is plugged into.

 

@ThePanMan thank you so much. all 8 cams are same type simple cams which are not motorized. they have red color LEDs illuminate only at night. factory power supply is an 8 way 12V 3A power supply. something like we see in this picture.



as the members suggested for more safety i ordered a new power supply rated 10A.

 

To get any information that is much better than a "good guess" you will certainly need to actually measure the current draw of one of the cameras. I suggested that back in post #23, and it is still a very useful action. Published current requirements are always based on more than actual measured values.

 

something like we see in this picture.

Can you take a picture of what you actually have? "Something LIKE" can mean anything. Or nothing.