# How do I calculate the number of power modules required on a CE switch

Description
How do I calculate the number of power modules required on a CE switch?
Solution
Calculate the total power consumption of all working modules on the switch and divide this value with the maximum power that a power module can provide. Add 1 to the integer part of the calculation result. The sum N is minimum number of power modules required for the switch. In real-world applications, more than N power modules are configured to implement power redundancy. The power modules can work in N+1 or N+N backup mode.

For example, a CE12808 chassis uses 2700 W AC power modules and is configured with two 48*10GE interface cards, five CE-SFU08A cards, and two MPUs.

With this configuration, the maximum power consumption of the chassis is 2455 W. 2455 W divided by 2700 W is smaller than 1, so the integer part is 0. That is, a minimum of one power module is required (0 + 1 = 1). Considering power redundancy, the number of power modules used on the chassis is:

In N+1 backup mode: N + 1 = 1 + 1 = 2

In N+N backup mode: N + N = 1 + 1 = 2

For details, visit http://support.huawei.com/onlinetoolsweb/network_configtool/index.jsp?lang=en&audience=enterprise