# I need help with another formula:)

Discussion in 'Homework Help' started by ESPguitar, Aug 26, 2005.

1. ### ESPguitar Thread Starter Member

May 15, 2005
16
0
Hi again

If i have 3 elements, each rated at 200W, 500W and 800W, how do i calculate the total power for these three elements?

Thanks,

Robin

2. ### ESPguitar Thread Starter Member

May 15, 2005
16
0
I forgot to ask if it is the same formulas for power as for resistors?

Since heating elements is resistors..

Thanks,

Robin

3. ### string New Member

Aug 26, 2005
1
0
hey man,if all the elements are resistors ,then u can add all the powers.

But if there is any presence of reactive elements then u need to find the resultant of resistive and reactive powers to get the total power,

suppose total resistive power=P

and total reactive power=Q

then the resultant power is reprsented by P+jQ

its magnitude is √ (P square+Q square)

4. ### ESPguitar Thread Starter Member

May 15, 2005
16
0
Ok, thanks string

But what about the total power if i just get this information:

Three heating elements is connected in paralell, the voltage is 230V and the elements have this ratings:

P1=200W
P2=500W
P3=800W

Is the total power of this 1500W? Or do i have to calculate how much resistance each elemt have and work from there?

Thanks guys

Robin

5. ### pebe AAC Fanatic!

Oct 11, 2004
628
3
As the devices are specifically heating elements, reactance will be negligable. So just add the individual powers. Your assumption of 1500W is correct.