Conclusion

In order to determine if additional precautions are needed to prevent electrical hazards at the system level, it is important to fully understand the failure modes of isolators used in high-voltage systems under both normal and fault conditions. Isolators, by definition, “fail short” when voltages across the isolation barrier exceed rated limits (failure mode 1). This failure mode can be avoided by choosing isolators that meet, preferably with margin, the specifications set forth by the relevant end equipment electrical safety standards. Because TI reinforced isolators offer the highest isolation performance available in the market today, they provide the highest margin against this type of failure mode. When the safety-limiting current or power limits of the isolators are violated (failure mode 2), the isolator’s isolation barrier can potentially be compromised. For TI reinforced isolators that use series-capacitor isolation, the damage in this mode is limited to one capacitor. That leaves the other capacitor intact, causing these isolators to “fail open,” preserving basic isolation.”