In this example of a motor drive application, isolation between the high-voltage and low-voltage parts of the system must be checked against the requirements of the IEC61800-5-1 standard for electrical power drive systems. Isolation must be designed to withstand the rated impulse voltage, temporary overvoltage, and the working voltage. In addition, the physical distance between exposed metal parts on the high- and low-voltage side must meet the minimum creepage and clearance requirements.

Table B.1 of the IEC60664-1 standard defines the impulse voltage for a 690-V, 3-phase, unearthed system (such as an IT system, OVC III) as 8000 V. This value matches the V_IOSM (8000 V_PK) rating of the AMC1411.

Table B.1 of the IEC60664-1 standard also defines the system voltage of a 690-V, 3-phase IT system as 1000 V. According to table 7 of the IEC61800-5-1 standard, the temporary overvoltage for a system voltage of 1000 V is 3110 V_PK, which is lower than the V_IOTM (10500 V) of the AMC1411.

The working voltage in this example is 1200 V_DC and is also lower than V_IOWM (2260 V_DC) of the AMC1411.

The minimum clearance for a 8000-V impulse voltage according the IEC61800-5-1, table 9, is 14 mm for reinforced isolation. The AMC1411 provides a minimum clearance of 14.7 mm and meets the requirement.

Finally, the minimum creepage distance for a working voltage of 1200 V_DC, insulating material group I, pollution degree 2, reinforced isolation is 2 × 6.04 mm = 12.08 mm according to IEC61800-5-1 table 10. 6.04 mm is the interpolated value between the 1000 V_RMS and 1250 V_RMS and is doubled for reinforced isolation. The AMC1411 provides a minimum creepage of 15.7 mm and provides significant margin against the minimum requirement.