FEDEVEL
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rief , 08-11-2023, 03:22 PM

I have a problem when sensing high voltage DC, it is quite risky but what I know is just using common voltage devider, the last time I use it, it blow up the connector, I know it is a problem with my connector soldering, but I think it will be better if I have another safety voltage sensor, is anyone have any recommendations the easiest IC or any reference to make isolated voltage sensor for high voltage DC?

QDrives , 08-11-2023, 07:53 PM

How high voltage?
Does the voltage have the same reference or do you need galvanic isolation?
A new idea: https://www.youtube.com/watch?v=12bO3xOtVqc

rief , 08-11-2023, 10:30 PM

It's for EV Car about above 100VDC

rief , 08-11-2023, 10:37 PM

Actually I don't have any ide is it should be in the same reference or need a isolation, I just need to sensing the battery voltage in the ev car for data monitor, but I will looking for that later, thankyou for the reference btw

QDrives , 08-12-2023, 03:27 PM

For anything below 1kV I still would use a voltage divider.
But do keep the maximum operating voltage of the resistor in mind. This would often require multiple resistors. And naturally, considering your connector reference, the clearance and spacing requirements.

Robert Feranec , 08-17-2023, 05:34 AM

I would add, not only maximum operating voltage of resistor, but also maximum current through the resistor and pin distance to meet isolation requirements. Maybe there is also something else but I dont normally design this kind of higher voltage boards

QDrives , 08-17-2023, 08:01 PM

Maximum current and 800V? Maximum power yes, as 1mA and 800V is already 0.8 W(att). You'll be lucky if a 1206 can handle that.
However, I did assume that power rating of resistors was known, but I can be mistaken.
Do also note that often with TH resistors, the temperature rise at the rated power can be something like 250°C !!!

rief , 08-23-2023, 04:36 PM

I have try to make seperated voltage sensing module using common voltage devider, the last one i make the voltage devider in the same board with the data monitoring controller and it blow up the connector when I make poor soldering.

This one have a better connector spacing cause I use more proper terminal blocks for the connector, and I place it quite far from the main board, I hope it didn't blow up again 😅

rief , 08-23-2023, 04:41 PM

Yes I also usually calculate the power dissipation for each resistor in the maximum power and use a resistor size with higher power dissipation like 1.5 or 2 times than the calculation result

rief , 08-23-2023, 04:42 PM

Btw thank you @Robert Feranec and @QDrives for the answer