Dell Force10 S25N-S50N Installing S50N and S50V Systems - Page 29

5 Installing Backup Power This chapter covers the following topics: • Backup Power Components • The Power Connections on the Switch on page 30 • Installing the Backup DC Power Supply for the S50V on page 30 • Inserting Tandem S50V PSUs into a Rack on page 31 • Connecting the S50V DC-to-DC Cable on page 32 • Installing the Backup DC Power Supply for the S50N on page 34 • DC Components on page 34 • Installing the External Power Shelf (optional) on page 35 • Inserting an S50N PSU into the EPS on page 36 The S50V and S50N switches have both AC and DC power connections (S50N-DC has two DC terminal blocks, no AC). You can connect either one or both. When both are connected, the AC input is slightly preferred over the DC (about 60% / 40%). When you connect the Dell Force10 470W DC Power Supply Unit (PSU) to the Current Sharing terminal of the S50V, the AC and DC are in additive mode, totalling 940W. NOTE: Neither internal nor external S-Series power supplies are field serviceable. If an internal power supply fails, the switch must be replaced. WARNING: To prevent electrical shock, make sure the switch is grounded properly. If you do not ground your equipment correctly, excessive emissions can result. Use a qualified electrician to ensure that the power cables meet your local electrical requirements. See other relevant cautions in Information Symbols and Warnings on page 5. Backup Power Components The optional Redundant Power Supply Unit (PSU) for the S50V supplies 470W DC, supporting both the switch itself and the PoE feature. The PSU kit includes: • The AC/DC rectifier (catalog number S50-01-PSU-V) • DC-to-DC cable to connect the PSU to the switch • AC cable to connect the PSU to the AC power source • PSU mounting hardware: extended rack ears, twinning plate, screws, cage nuts, and four rubber feet that you can attach to the PSU if you want to set it on a table Installing Backup Power | 29