Importance of isolation in motor phase circuit

[TRS300]

Hi all. I'm doing a motorcycle EV conversion and I have a question about isolation between the MC 12v frame and components being fully isolated from the EV batteries and phase drive circuits. I have a Kelly KLS96601-8080NPS controller that has optical isolation so I figured this was normal design. The Kelly Controller is Huge and I was looking at other controllers. I'm finding that most of the controllers I'm reviewing don't seem to have isolation? Is Isolated systems common or not common? I understand the safety advantage of an isolated controller but I'm starting to question if it's a strong requirement? So I'm asking others here how they feel about needing isolation and if their custom builds have it or not. Thank you.

 

[harrisonpatm]

My two cents? I don't know that much about the requirements and precautions re isolation when it comes to motorcycle frames. But I do know that automotive/motorcycle frames are grounded for 12v systems, and 12v is basically zero shock risk. When it comes to EV voltage, I don't feel comfortable using the frame as a grounding/negative point. Therefore, for all my motorcycle conversions, I made new wiring harnesses from scratch, that don't use the frame as a ground. That way I don't have to worry about isolation.

 

[TRS300]

My two cents? I don't know that much about the requirements and precautions re isolation when it comes to motorcycle frames. But I do know that automotive/motorcycle frames are grounded for 12v systems, and 12v is basically zero shock risk. When it comes to EV voltage, I don't feel comfortable using the frame as a grounding/negative point. Therefore, for all my motorcycle conversions, I made new wiring harnesses from scratch, that don't use the frame as a ground. That way I don't have to worry about isolation.

Agree about the shock hazard. I probably threw the question off the focus when I mentioned the frame ground... Let me rephrase. When I say isolated it means that there would be no connection between the ground of the high voltage EV battery and any ground of the frame or the 12v wiring system. If you put a meter on both grounds it would be an open circuit.

 

[slaphappygamer]

Seems like the only advantage would be to keep high voltage flowing through the low voltage circuit, if the high voltage shorts against a common ground. This would protect the low voltage components. Maybe there are other reasons too. Noise?

I have a 48-12v converter with an isolated ground. Probably want to keep the potential 12v off a common ground as well.

 

[j bjork]

When you have an isolated system you need to get in contact with both positive and negative to get electrified. When you have common ground you are probably already in contact with the ground and only need to get in contact with the positive. (You seem to understand this, it is more for other readers)
I have made the same obsarvations, and vas surpriced as I thought that it wouldn't even be legal in a system over 60v