The 6000W ACV and 4200W ACV power supplies feature combined Mode Power Resiliency as an extension of the traditional combined mode power-supply behavior. Each power supply contains two smaller power supplies (called subunits). In Combined Mode Power Resiliency the system relies only on power from three out of four power-supply subunits. When using 200 VAC, this feature helps ensure that maximum power is available while the switch is protected against a single input power failure or subunit component failure.