electrical schedule

ghermel08 · #1 Jul 23, 2009, 02:16 AM

What is the formula for the electrical load for single phase electrical layout for the formal architectural plan.?..

Can you give me the exact formula?..thanks...

gopalakrishnan · Jul 23, 2009, 04:14 AM

vI cos(phy)

ghermel08 · Jul 23, 2009, 04:36 AM

can you explain further your formul vI cos(phy)/...thanks

tkrussell · Jul 23, 2009, 05:15 AM

I am an electrician, and I am not sure what one formula there is to help you, let alone the formula that was provided.

vI cos should get your power factor, not sure how that will be helpful.

Perhaps if you start by reviewing Article 220 of the NFPA 70 National Electric Code may help:

http://www.askmehelpdesk.com/electri...ne-270277.html

KeepItSimpleStupid · Jul 23, 2009, 07:19 AM

Actually cos(phy) or cos(theta) is the power factor. It has a maximum value of 1.

Power = voltage * Current * cos(theta) where voltage and current waveforms are periodic with different amplitudes. Theta is the phase angle between these two voltages. Inductive loads, such as motors, cause this phase angle to change and in commercial situations, the power company charges more for your electricity when the PF is not nearly 1. There are ways to power factor correct with capacitors.

I don't think the info is relevant, except to clear up the post.

Power = V * I for resistive loads; cos(0) = 1

Power = V * I * cos(theta) for loads where v(t) and i(t) have the same shape and only their rms value is different.

A high power factor requires transformers to be oversized for the loads and that's why the utility gets upset.