Each power supply module max capacity is 2000 watt. With 4 power supply modules together, the total capacity can go up to 8000 watt.
In regular condition, all 4 share the same loading. If any module is down, the rest 3 will take over. If system power consumption is less than 4000 watt and any 2 power modules are down, the rest 2 power modules will take over and keep system in operation. If system power consumption is less than 2000 watt, then it can have up to 3 power modules down and still keep in operation.