Inductance and Capacitance

Thread Starter

tony8404

Joined Jun 11, 2008
98
Sorry everyone i decided to rewrite this.

I really have a question about transformers... Why does, High Voltage - Low Current and Low Voltage - High Current?

What i was just reading it shows a picture of two transformers, it has the smaller transformer with low voltage-high current and the big transformer High voltage-low current labelled in the picture but in the text does not explain why that is... I know alittle bit about transformers but not following this right now.. I still have some reading but this is bothering me lol thanks
 
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wr8y

Joined Sep 16, 2008
232
I am of the firm belief that you cannot understand inductance and capacitance WITHOUT an understanding of reactance and impedance.

My suggestion (after 28 years in component-level RF troubleshooting, a CETsr, an Extra Amateur license and an ASEET) is to not be afraid to move on now.

You can always come back to basics if needed - electronics isn't quite like Math where you have GOT to get things down about 100% before moving on.

Be encouraged! (And do NOT forget to look EVERYWHERE for the explanation of the same topic. I read ARRL, RSGB and Bill Orr books when studying - as well as my college textbooks when trying to learn something. Sometimes, someone will explain something that will "click" in your mind when you have read someone else's input that didn't make sense before.)
 

Thread Starter

tony8404

Joined Jun 11, 2008
98
Sorry everyone i decided to rewrite this.

I really have a question about transformers... Why does, High Voltage - Low Current and Low Voltage - High Current?

What i was just reading it shows a picture of two transformers, it has the smaller transformer with low voltage-high current and the big transformer High voltage-low current labelled in the picture but in the text does not explain why that is... I know alittle bit about transformers but not following this right now.. I still have some reading but this is bothering me lol thanks
 

Thread Starter

tony8404

Joined Jun 11, 2008
98
lol, I know about step up and step down but i am confused i thought high current = high voltage and low current = low voltage. I thought i read that current is proportional to voltage
 

bertus

Joined Apr 5, 2008
22,270
Hello,

Here is a page with transformer theory.
http://sayedsaad.com/fundmental/index_transformer.htm

The link comes from this page on transformers from the EDUCYPEDIA.
http://educypedia.karadimov.info/electronics/electricitytransformers.htm

There are links for other components too.

Passive semiconductors technology: Batteries Diodes Photovoltaic systems Switches Buzzers Diode types Quartz crystals Thermoelectric Capacitors General overview Relays Transformers Capacitor types Heat Sinks Resistors Transformers-RF Coils Photo diode Resistors-Nonlinear Transformer types
Greetings,
Bertus
 
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ron_o

Joined Mar 1, 2009
6
tony8404,
The answer to your question has nothing at all to do with inductance or reactance (Unless I misunderstood you, why did you title your post that way?) The answer is in the relation between Current and Voltage. The only formula you need to look at is:

P = E X I

The relationship between Voltage and Amperage changes in regards to certain static elements in an electric circuit. For Ohm's Law (I=E/R) when resistance stays the same (and in almost every circuit it does stay basically the same) Voltage and Current are directly proportional. Just stick in the numbers and you'll see that is correct. However, in regards to a transformer, power will stay the same (resistance changes in a transformer), and thus Voltage and Current will become indirectly proporional. The voltage/current relationship is relative to Power or Resitance.

Transformer ---> Power in = Power out (less efficiency)

When you increase the voltage and power stays the same, then your current *must* decrease in size and vice-versa. This is the fundamental quality that makes A/C so attractive to the entire world. Reducing amperage means a smaller wire (for the same amount of work) and also less voltage drop.

Just remember to always, always follow what the formula tells you when something doesn't make sense. Plug in the formula and you'll soon realize what happens in an electrical circuit.

There may seem like there are some contradictions to this but there isn't. Another imporant formula in this regard is

Power = the square of Voltage / Resistance
( http://www.allaboutcircuits.com/vol_1/chpt_5/5.html ).

The less the voltage in a given circuit when resitance stays the same (as it almost always does) the less the power. This answers the question as to what happens when you hook up 120 volts to a 240 volt utilization equipment. Your Power will actually be cut proportional to the square of the Voltage. In real world terms that means it won't be as efficient if it works at all. (I only mentioned this because there are many electricians who confuse the Voltage and Current relationship with regards to transformers and regular circuits.)

BTW, my name's Ron. This is my first post. Hehe, I just had to register and answer this one. :)
 
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