EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: fant on December 29, 2020, 11:48:20 am
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Good morning;
I have this instrument ( a multifunction energy meter that analyze the mains for power, energy, power factor and harmonics ) that suddenly has begun to show on the ampere function a malfunction: during measurement of the current with the current clamps, the current indication begin to indicate the current from 5A and higher.
At 4,9 A and lower the indication is always 0,0 A.
Opened and following the current path, the signal (sinewave of the current value ) is existing with the correct amplitude, both above o below 5 A, up to the CPU analog input ( pin 95, named P10_0/AN0 of the RENESAS M30624FGFAP CPU; also the reference voltage of 4,485 V on pin 98 named VREF is correct ).
Any idea or schematic ?
Thank you in advance