You can replace internal power supplies as needed while the switch is operating ("hot swapping").
All installed power supplies must have the same airflow direction (front-to-back or back-to-front) and must also match the airflow direction of the fan modules.
To replace one or both AC internal power supplies in a VSP 7400 Series switch, follow the steps in Installing a 750 W Internal AC Power Supply.
To replace one or both DC internal power supplies in a VSP 7400 Series switch, follow the steps in Installing a 750 W Internal DC Power Supply.