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Original question:

MSP430AFE253: Simple single-phase energy meter

MSP430AFE253: Power measurement voltage spikes

Cristian Dinca
Prodigy 135 points
Part Number: MSP430AFE253

Hi! I'm coming back to this issue with new updates.

I have reviewed the schematics and create a new PCB, I will attach the schematics here.

The problem remains the same, it seems that the clamping diodes are worsen the situation, the voltage spikes have higher values when the diodes are present.

(VP - VN) SIGNAL

I will try to place some Zener diodes, but I guess they will not be fast enough to catch the spike.

It seems that the problem have no resolution, at least not in this configuration. The size of PCB is 75mmx50mm and I think moving the relays way apart from the actual PCB will reduce also de voltage spikes influence.

  • 0
    TI__Mastermind 49692 points

    Hi,

    Cristian Dinca said:
    The problem remains the same, it seems that the clamping diodes are worsen the situation, the voltage spikes have higher values when the diodes are present.

    I'm sorry to hear that. I'd recommend adding back the varistor (S20K275) between Line and Neutral. For RV1 and RV2 shown here, those should be placed as close to the relays on the output side as possible. Also, can you try changing them from S10K275 to S20K275? For the clamping diodes D14 and D15, these are normally used on the current channel differential inputs, not voltage inputs. However, I don't know why adding them makes the voltage spike worse. Perhaps, it's because there's only one pair on the positive input and not another pair on the negative input.

    Regards,

    James

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