Does an alternator obey Ohm's law?

[torbor]

Do alternators obey Ohm’s law? The alternator output voltage is proportional to the rotor excitation current. When reducing rotor excitation, the output voltage drops and the load resistance stays constant. Can why still use ohm law to determine the output current.

Example alternator 480 v / 4 ohm current output is 120 a if why now reduce rotor excitation output voltage drops tu 220 v / 4 ohm output current is 55 a can why calculete like this.

Another example is car alternator have 900 w of pawer tu give that pawer with 13.7 v output current is 65 a and load resistance is 0.21077 this all calculation are based on ohm low.

Can why calculate like this of course every equipment must support rated current

also i understand principle of impedance can why calculate a show i above examples

if why can apply ohm's law tu alternator haw why can determinant output current

i am really confused about this because i am always thought that resistance determine the current same people say they alternator does not follow ohm law ok but haw then calculate current output and load itself

 

[NascentOxygen]

Example alternator 480 v / 4 ohm current output is 120 a if why now reduce rotor excitation output voltage drops tu 220 v / 4 ohm output current is 55 a can why calculete like this.

Hi Torbor.

The excitation current is a DC current you supply to the alternator to create the electromagnets, and these magnets are spun (on a rotor) inside a set of stationary coils (the stator). The alternating output voltage from the stationary coils will be greater if the electromagnets are supplied with higher current or if they are spun faster.

 

[anorlunda]

You must analyze a generator or a motor as part of a closed circuit including the load. Considered alone, with no load, the current is always zero.

One tool you can depend on is conservation of energy. Power produced by a generator must always match power consumed by the load if RPM stays the same. Charge is also conserved, so generator current and load current must also match.

That should help you see why behavior of the generator and behavior of the load must both be considered.

So, if the load on the alternator is a resistance R, then load V=iR must match the generator V and I, if RPM remains constant. If the alternator supplies a load that is not constant resistance, then things will be different.

 

[jim hardy]

Do alternators obey Ohm’s law? The alternator output voltage is proportional to the rotor excitation current. When reducing rotor excitation, the output voltage drops and the load resistance stays constant. Can why still use ohm law to determine the output current.

Example alternator 480 v / 4 ohm current output is 120 a if why now reduce rotor excitation output voltage drops tu 220 v / 4 ohm output current is 55 a can why calculete like this.

Because Ohm's Law says Current is Volts divided by ohms.
You have defined the values of volts and ohms. That's why you can calculate like this.

i am really confused about this because i am always thought that resistance determine the current same people say they alternator does not follow ohm law ok but haw then calculate current output and load itself

Did you look at the responses to your very similar thread yesterday ? It's at https://www.physicsforums.com/threads/how-do-i-calculate-the-output-current-of-an-alternator.924471/