Country Living
Country Living, Country Skills
Country People - A Country Living Resource and Community
Message Board
Country Topics
Trading Post
Memory Lane
Country Skills
Country Cooking

The Kitchen

Photo Gallery
Vintage Photos
Special Collections

Country Humor
Country Sounds
Coloring Book
Interactive Story

Farm Tractors
Tractor Parts
Tractor Manuals

Classic Trucks
Antique Tractors
Modern Tractors
Site Map
Links Page
Contact Us

Country Discussion Topics
To add your comments to this topic, click on one of the 'Reply' links below.

Transformer Question??
[Return to Topics]

Wyo    Posted 02-05-2005 at 15:49:50       [Reply]  [No Email]
I have a "step-up" transformer, 120 V to 240 V, to run my well pump. The pump draws 10 Amps and is a 1-1/2 HP. My question is what is the load on my transformer? The 120 V is L1 to the pump and the input to the transformer. L2 is the output from the transformer and the second leg of the pump. My transformer has 15 amp overloads and they have not tripped so does each leg draw 10 amps or does L1 do double duty and draw 20 amps since it is the input to the transformer and the output from the power source? This probably sounds convuluted but any stab at a reply will be appreciated.

Larry 8N75381    Posted 02-05-2005 at 17:35:43       [Reply]  [No Email]

The easiest way to think about electricity is to think as if it were water flowing in pipes.

So if L1 is hooked to one wire on your pump and L2 is hooked to the other, just like water running thru a pump, the same amount going in MUST come out the other side.

Now a step-up transformer will work just like Illinios said. So the use the water anaology again, we need to think of a transformer as a water pump hooked to a water (hydraulic) motor. BUT in this case the pressure of the pump is twice that of the motor. So the motor has to be geared up, by two in your case, meaning that the motor has to turn twice as fast as the pump. That would require that the water in the motor flow twice as fast. That is the 20 amps of 110V to get 10 amps of 220V.

Now if the pump and motor were connected to a "cross" (a fitting with four connections) it would look like a transformer with a common terminal for the two windings. BUT the flow rate in each pipe loop is only determined by the things in that loop since water that might try to go in to the other loop would be stopped because there is no way for it to get back. It cannot go in and out the same "hole", just does not work.


Illinois    Posted 02-05-2005 at 16:33:52       [Reply]  [No Email]
Wyo, the current draw of the motor being 10 amps at 240 volts is 2400 watts. The power out cannot be more than the power in, so, power in must be 2400 watts. Actually, it will be a little more because of losses.

So, assuming 100% efficiency, there would have to be 2400 watts input to the transformer. At 120 volts, that would be 2400/120=20 amps.

That is 20 amps input to the primary, 10 amps out of the secondary. 2400 watts input, 2400 watts output.

[Return to Topics]

[Home] [Search]

Copyright © 1999-2013
All Rights Reserved
A Country Living Resource and Community