Using multiple system power supplies for redundancy

Multiple system power supplies are used to provide redundant power to redundant controllers and can be used to provide redundant power to simplex controllers. Multiple system power supplies can also be used to provide additional power to the I/O only.

Providing redundant power to redundant controllers and the I/O subsystem

A redundant controller consists of a pair of S-series controllers installed on separate Power / Controller Carriers. Each controller in the redundant pair is powered from a separate System Power Supply (24 VDC) installed to the left of the controller on the Power / Controller Carrier. In addition to providing redundant power to the controllers, the power supplies also power the I/O.

Refer to the preceding image:

• Power supply one on Power / Controller Carrier one is providing power to the primary controller and to the I/O.
• Power supply two on Power / Controller Carrier two is providing power to the secondary controller and to the I/O.
• Power supplies one and two provide redundant 12 VDC power to the LocalBus for the I/O subsystem.

Providing additional power to the I/O only

Ensure that the LocalBus power demand does not exceed the capacity of the system power supplies if one power supply fails. You can install an additional Power / Controller Carrier and power supply to the left of existing Power / Controller Carriers to power the I/O only. In the following example, power supply 3 is providing power to the I/O only; not to the controllers.

Providing redundant power to a simplex controller

To provide redundant power to a simplex controller, install a second Power / Controller Carrier and second System Power Supply (24 VDC) to the left of the Power / Controller Carrier holding the simplex controller and its power supply. The secondary power supply installs in the right slot of the second Power / Controller Carrier and powers the controller and the I/O as shown in the following image.