Power Supply Efficency for 9600 series PSUs

[stephengrace20]

Hello, 

I have been looking into the Cisco 9600 series data sheet and install guide and I have some questions!

In the Installation Guide, Table 4 under the Product Overview will give the power output in combined mode for the PSUs. Above it will explain the formula of how the output wattages were calculated, with the share ratio being 97%. However, the 110VAC row for the C9600-PWR-2KWAC seems to uses the ~94% as the share ratio, which coincidentally is the value of the power supply efficiency given in the data sheet. All other rows use the 97% share ratio.

Was it intentional to use 94% as the share ratio for that one row, or is it supposed to be 97%? 

In the Installation Guide, Tables 15 through 17 under the Technical Specifications gives the AC Input and DC Output in Watts for each component in the switch. Above the tables is a note that informs the customer that "the percentage difference between the two values (AC and DC values) is the efficiency of the power supply." When doing the math for each component, the efficiency comes out to be 89.9 to 90%. This does not coordinate with the 94% power efficiency value (for an AC PSU) that is given on the data sheet.

What is the power supply efficiency supposed to be for the PSUs (AC), 90% or 94%? 

[Ramblin Tech]

Take the PSU efficiency rating given in the data sheet with a grain of salt, as it is subtly caveated with a "typical" disclaimer and you do not know the conditions under which it was measured/calculated.  Data sheets are written to promote sales, not dissuade them.

For purposes of calculating the input power lost to heat generation (and subsequent demand on your cooling system) use your 90% number instead of 94%.