AC Applications - using a DC Contactor

Gigavac does not test, qualify, or rate any of our Power Product contactors for AC usage.  Application suitability must be verified by the customer.  To determine suitability, Gigavac recommends calculating the worst-case peak current and max voltage that the contactor may be required to open, and the total number of cycles required.  Then, compare the results to the DC switching cycle graph on the corresponding datasheet and derate the number of life cycles by 50% (half).  Note, the above described derating only pertains to switching under load.  In contrast, both the continuous current capability (thermal withstand), and the isolation performance of the contactor will remain the same regardless of whether the contactor is carrying AC or DC.  It is important to understand that the  50% de-rating is an approximation and should be used as a general guideline only. If an application requires greater than 1,000 cycles there is no way to apply a linear approximation to the life cycle curve.  For example, if AC load breaking is infrequent (only during a fault condition) that usage may be acceptable, but the same contactor may not survive repeated/numerous load break events.  In summary, each application is different and must be evaluated on an individual basis.