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Galvanic isolation between high voltage side and low voltage side in HV - sensor

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Newbie level 3
Feb 13, 2013
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Hello everyone,

I have a high voltage measurement sensor which has one high voltage measurement input (+450V & Gnd reference), operational supply voltage input (+12V & Gnd) and a CAN-bus as communication bus. The sensor measures every second the high voltage input and sends the value to the CAN-bus. As mentioned, the sensor is also powered with +12 VDC supply as operation supply. However the problem is that in the sensor I don´t have any galvanic isolation between the HV-measurement ground reference and low voltage supply ground reference. So the ground is same for both measurement and operational supply. In future there will be a 800V isolation between high voltage side and low voltage side but that kind of sensor is not available yet.

Because I can´t get the new version of the sensor soon, I have to make the isolation by myself. Could someone say if my idea is right and safe in the schematic that I´ve attached to this post? I´ve never been thinking this kind of design of isolations before.

The idea simply:

Instead of having the isolation in the circuit board, can I have it between the sensor and the vehicle. (The sensor is supplied by the low voltage system (+12V) in the vehicle and the CAN bus is also in the vehicle where the sensor is sending the data.)

Here is the schematic: View attachment Isolation_schematic.pdf

Thank you for all kind of help!

With kind regards,


Hi chuckey,

I decided to use DC/DC converter as galvanical isolation for supply voltage of the sensor. However I have the CAN-bus as communication bus and now I need a way to make the isolation also for the bus with optocouplers. The problem is that I don´t know if it´s possible to install the optocoupler just in the middle of the bus between the sensor and the vehicle. I try to find solutions for this now.

Thank you still for your information!


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