PDA

View Full Version : Will you get charged for KVAs?


hobbes88
11-14-2007, 05:14 PM
Hi,

I was wondering what would happen if you installed a 1,200 watt transformer and only used say two of the 300 Watt sections? So two of the toroids are not connected on the secondary side. On the primary side essentially these will be basically an inductive load.

If my electrical engineering serves me correctly, it will be drawing amps but in effect use very little power, because in an inductive load the current vector is orthogonal (90 out of phase) with the voltage vector.

Will the house hold meter of a client / homeowner therefore "over charge" the home owner? Note Amperes are flowing, but few Watts of energy are being consumed.

warmest regards, Mike. :hammerhead:

Pro-Scapes
11-14-2007, 05:36 PM
Lets see.. how can I put this. It will only consume enough power to power the load if this makes sence. Im sure someone will have a better way to explain it.

a 1200w transformer loaded to 600 w will still only draw about 5 amps on the primary. If you shut the other commons off since they are not in use there should be no draw for that half of the transformer. Without load there is no draw. I really doubt there is much of any draw for the unused 600w of the transformer. You should always be checking your primary amerage draw on every system.

600w draw x 5 hours per night would be 3kwh if i am not mistaken. In my area that would cost about 33 cents to run per night assuming a 5 hour run time.

I think you are way over thinking this with your vectors and such.

Am I wrong ?

JoeyD
11-14-2007, 06:07 PM
You only consume what you have loaded on the Unit. a tf good for 10 amps but only has 4 on the primary will only draw the 4 amps not the 10 it is capapble of drawing at full load.

EOL
11-14-2007, 09:11 PM
Hi,

I was wondering what would happen if you installed a 1,200 watt transformer and only used say two of the 300 Watt sections? So two of the toroids are not connected on the secondary side. On the primary side essentially these will be basically an inductive load.

If my electrical engineering serves me correctly, it will be drawing amps but in effect use very little power, because in an inductive load the current vector is orthogonal (90 out of phase) with the voltage vector.

Will the house hold meter of a client / homeowner therefore "over charge" the home owner? Note Amperes are flowing, but few Watts of energy are being consumed.

warmest regards, Mike. :hammerhead:

Don't sweat it!!!!

ChampionLS
11-15-2007, 06:26 PM
Whether or not you have a load on the secondary, it will still consume a small amount of electricity. The more load on the secondary, the more load occurs on the primary, thus increasing your electric bill. Think how many of those little class 2 plug-in AC adapters we have in our homes. Desk lamps, chargers, small electronic gadgets. It all adds up. Think about this.. It it's plugged in and it's warm to the touch, it' drawing something.