I have experienced failures of RS-485 links due to magnetic induction from ~52V battery power lines running very close in parallel. Standard shielding around the RS-485 cables did not solve the problem but a clearance distance of 1 inch did. The fault probably occurred when a high current such 90A was interrupted by the opening of a relay or a breaker. I have the following questions about such cases:
- Standards: Is there any accepted guideline regarding clearance distances in this particular scenario? The recommendations I have seen are based on house wiring cases where there is a chance of shorting the data and power lines running through walls. Moreover, section 1.16 "Electrical Clearance" of IPC-A-620B (2012) leaves clearance spacing between cables up to design and only gives guidelines based on voltage. And while the IEC 61000-4-x tests appear to be very applicable here, they would apparently focus on protection at the transceiver level.
- Calculations and simulations: What is the recommended approach for calculating the induced voltage or power in such cases? Which tools are prevalent in the industry for computer simulations of such scenarios? Are such calculations followed by experimental testing?
- Behavior of DC current at trip: This is a more general question. For simulating scenarios like the one described, I will probably need to assume a maximum di/dt value. How fast and in what manner does a DC current terminate when its path is broken with an MCCB or a latching relay? Is it dependent on the source and load? Can waveforms from other cases be applied for this case or will I have to gather empirical data for my own system?