Does the output voltage of a transformer, affect the power drawn by the load?

Thread Starter

babaliaris

Joined Nov 19, 2019
160
I'm just wondering to know what will happen. By the way, I'm currently enrolled in a Lab where we play with overvoltages (100kV-500kV), but the professor does not let us touch or power anything unless he says it's okay.

We make our circuits in a caged room called the Farraday's cage and we leave that room before we power the circuit (watching from outside).
 

crutschow

Joined Mar 14, 2008
34,282
Now if we short the load, what will happen in the Lines? Will they become the load and blow up or something?
Well, if a circuit breaker doesn't open, then the weakest link in the chain will blow. likely in spectacular fashion.

Fuses and circuit breakers are what protects the electrical chain form overload.
There is no other method used to limit current.
 

Wendy

Joined Mar 24, 2008
23,415
Think in terms of watts, the wattage out is the wattage in on the transformer. W=V x I
if the transformer is 12 volts out and 120 volts in and you pull one amp on the 12 Volt side, that will be 12 watts. So 12 Watts on 120 Volt side would be 0.1 amps.
 

Thread Starter

babaliaris

Joined Nov 19, 2019
160
Think in terms of watts, the wattage out is the wattage in on the transformer. W=V x I
if the transformer is 12 volts out and 120 volts in and you pull one amp on the 12 Volt side, that will be 12 watts. So 12 Watts on 120 Volt side would be 0.1 amps.
This is a really good explanation!

One thing that is still confusing me is what happens between the 2 transformers (in the Line Impedance). If we forget about the rest of the circuit and only focus on the transmission lines, then Sline= V_high_voltage^2 / Zline (in terms of magnitude).

So it seems to me that the higher the voltage, the higher the Sline.
 

MrChips

Joined Oct 2, 2009
30,710
I'm just wondering to know what will happen. By the way, I'm currently enrolled in a Lab where we play with overvoltages (100kV-500kV), but the professor does not let us touch or power anything unless he says it's okay.

We make our circuits in a caged room called the Farraday's cage and we leave that room before we power the circuit (watching from outside).
Well, there is a good reason why you have to watch from outside if you value your life.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
Now if we short the load, what will happen in the Lines? Will they become the load and blow up or something?
Yes the distribution line becomes the load and will display the effect of the excess current at any higher resistance junction point.
Doesn't matter if it is a AC power line, or a Automotive battery, the same effect occurs if you short the power terminals. :oops:
 

Thread Starter

babaliaris

Joined Nov 19, 2019
160
If I short my wall plug with a wire will the wire draw a big current, so the current inside the wall conductors will also increase, triggering the circuit breaker of my house?

Will I see a spark boom as well in the plug and why?

(Don't worry I won't try it, just wondering)
 

WBahn

Joined Mar 31, 2012
29,978
This is a really good explanation!

One thing that is still confusing me is what happens between the 2 transformers (in the Line Impedance). If we forget about the rest of the circuit and only focus on the transmission lines, then Sline= V_high_voltage^2 / Zline (in terms of magnitude).

So it seems to me that the higher the voltage, the higher the Sline.
You seem to be abusing Ohm's Law. Remember, Ohm's Law relates an impedance to the current through THAT impedance and the voltage across THAT impedance. V_high_voltage is NOT the voltage that appears ACROSS the line impedance. The voltage that appears across the line impedance is relatively small. The voltage across the transmission line would be given by the current in the line multiplied by the line impedance, so the higher the transmission voltage (the voltage between the lines, not across one of the lines) the lower this current and the smaller the voltage drop across the line, and hence the less the power dissipated in the line.
 
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