wrote:

How about ..... for a full wave rectified sine wave

PEAK = 1.4 * RMS ( SQRT(2) )

MEAN = 0.9

The avo will have this latter factor built into its scaling, Suppose we have, a full wave rectifier feeding a resistive load. If the rectifier output is 10 amps.(mean) DC

An AVO in series with the output should read 10 amps on the DC scale. An AVO measuring the AC input should read 11.1 amps rms I believe within measurement accuracy this would be the case.

Now feed the same resistor via half wave rectification. Both meter readings will halve. (the meter is an averaging one and is seeing the same current for half the duty cycle)

But what are the new Actual currents?. Mean DC current is actually halved, so the DC reading is correct However the true RMS current has reduced by SQRT(2) , only down to 7.9 amps rms. So the good old well trusted AVO is under-reading.

could be ILLUMINATING

. . . . . Briefly.

Ian

*> . . . . . Avo's do not show true RMS on the AC*How about ..... for a full wave rectified sine wave

PEAK = 1.4 * RMS ( SQRT(2) )

MEAN = 0.9

*** RMS ( 2 ***SQRT(2)/PI )The avo will have this latter factor built into its scaling, Suppose we have, a full wave rectifier feeding a resistive load. If the rectifier output is 10 amps.(mean) DC

An AVO in series with the output should read 10 amps on the DC scale. An AVO measuring the AC input should read 11.1 amps rms I believe within measurement accuracy this would be the case.

Now feed the same resistor via half wave rectification. Both meter readings will halve. (the meter is an averaging one and is seeing the same current for half the duty cycle)

But what are the new Actual currents?. Mean DC current is actually halved, so the DC reading is correct However the true RMS current has reduced by SQRT(2) , only down to 7.9 amps rms. So the good old well trusted AVO is under-reading.

could be ILLUMINATING

. . . . . Briefly.

Ian