How to configure a UPS and the calculation formula for UPS configuration.
A computer room has 4 PCs, 1 server, and 1 network switch that need 2 hours of power protection. The calculation is as follows:
1) Total load calculation
4 PCs 250W x 4 = 1000W
1 server 700W x 1 = 700W
One network switch: 100W x 1 = 100W
Total: 1800W
2) UPS capacity calculation
Online UPS systems typically have a power factor of 0.8. 1800W ÷ 0.8 = 2250VA. Considering redundancy in UPS capacity, it is generally set at 20% to 30% (because the optimal operating condition for a UPS is 70% to 80% load).
Therefore, the recommended UPS capacity is 2250VA x 13 = 2925VA, which leads to the conclusion that a 3000VA UPS should be selected. 3) Calculation of battery capacity.
The power factor of the American Santak 3000VA STK C3KS UPS is 0.8 (this can be found in the datasheet), so the actual power of 3000VA is 3000VA × 0.8 = 2400W. The DC voltage of the battery in the American Santak 3000VA STK C3KS UPS is 96V (this can be found in the datasheet). According to W = U × I , I = W ÷ U = 2400 – 96 = 25A, which calculates to a current of 25A. A 25AH battery is needed for a 1-hour delay. To extend the time by 2 hours, a 50AH battery is required. Commonly used batteries on the market include Shenyang Panasonic, with common capacities of 24AH-12V , 38AH-12V, 65AH-12V , and 100AH-12V . Based on the above calculations, a set of 65AH-12V Shenyang Panasonic batteries can provide a 2-hour delay. Since the standard battery voltage for UPS is 12V, while the battery voltage for C3KS UPS is 96V, 8 batteries are required (96V:12V=8).
Therefore, it can be calculated that using a 3000VA UPS from the American Santak brand, equipped with eight 65AH-12V Shenyang Panasonic batteries, plus a battery cabinet, can provide 2 hours of power protection for the protected equipment.