The paper from Texas Instruments explains the key parameters for both the protection device and the transceiver in order to design an isolated CAN system with correct bus protection.
To read the paper, click here.
How to design isolated CAN systems with correct bus protection
One common reason for transceiver damage is due to insufficient bus protection. External ESD protection is either not designed in at all, or the protection device is chosen in a way that does not pair well with the transceiver. It is imperative for the protection device to be chosen to interface well with the transceiver.