Transformer vs inductor

[mbrooke]

Is this being done with a VFD? I ask because I see 70.9Hz in post #19.

 

[gar]

170121-1110 EST

mbrooke:

I have no idea what the scope did to get that frequency measurement. All my tests have been with 60 Hz line power. If you look at the time base it is 2 mS per major division. By count the zero crossings are very close to 8.33 mS per half wave.

In the first plot of post #19 the scope's so called Measurement data is from channel 2 and that is the current channel. The current is very noisy near its zero-crossings. Thus, my guess is that frequency is measured from zero-crossings and probably only from a limited time frame that may be just what is shown on the screen. My experience with this Rigol scope is that it is quite good for the price.

In the second plot of post #19 the current waveform is much cleaner, and the frequency measurement reads 60.026 Hz.

I will turn Measurements off.

.

 

[mbrooke]

170121-1110 EST

mbrooke:

I have no idea what the scope did to get that frequency measurement. All my tests have been with 60 Hz line power. If you look at the time base it is 2 mS per major division. By count the zero crossings are very close to 8.33 mS per half wave.

In the first plot of post #19 the scope's so called Measurement data is from channel 2 and that is the current channel. The current is very noisy near its zero-crossings. Thus, my guess is that frequency is measured from zero-crossings and probably only from a limited time frame that may be just what is shown on the screen. My experience with this Rigol scope is that it is quite good for the price.

In the second plot of post #19 the current waveform is much cleaner, and the frequency measurement reads 60.026 Hz.

I will turn Measurements off.

.

Keep it on, it makes everything way more interesting. But that would be a good theory and my best guess. Thank you for taking the time to test this out, it makes this thread worth gold :happyyes: