Abstract: A power supply apparatus includes an uninterruptible power supply (UPS) having an input configured to be coupled to a first power source and an output configured to be coupled to a load and a first static switch configured to provide a switchable bypass path from the first power source to the load. The apparatus further includes a second static switch controllable to provide a switchable path between the load and a second power source, and a controller circuit configured to cooperatively control the first and second static switches to transfer the load to the second power source. The controller circuit may be operative to transition the load from a first state wherein the load receives power from the first power source via the first static switch to a second state wherein the load receives power from the second power source while isolated from the first power source.