UPS power supply has always been an important power guarantee measure for computer room equipment, has been accepted by many computer room IT users, while preventing power interruption, it can also play a role in current stabilization, frequency stabilization, filtering and other functions. If it is a low-power UPS, configure the conventional discharge time of about 1-2 hours, you may already have a habitual choice of battery number and capacity. But if it is a high-power UPS, or requires a very accurate discharge time requirement, how to calculate it at this time? As a professional company in the UPS power supply industry, Suzhou Feirui Power Supply Co., Ltd. summarized the calculation methods of two UPS power backup batteries and shared them with you, as follows:
1. Constant current mode calculation:
According to the principle of conservation of energy, it is calculated according to the following formula:
C＝（PL×T）/（Vbat×η×K）
Among them: C–battery capacity, (Ah)PL–UPS output power (W); T–Battery backup time (h);
Vbat–battery pack voltage (Vdc)η–UPS battery inverter efficiency (0.90-0.95, selected according to the model).
K – battery discharge efficiency (coefficient).
K is selected according to the following table:
According to the calculation results, determine the number of Ah of the battery, and select the appropriate configuration according to different brands of batteries.
For example: Emerson’s new generation of rack-mounted high-performance low-capacity UPS-ITA series 6KVA, battery pack voltage 192Vdc (16 12V power supplies in series), UPS battery inverter efficiency 0.94, according to full load 4.8KW, backup 2 hours calculation
C=4800*2/(192*0.94*0.7)=76Ah (estimate) Select 12V85Ah battery 16 cells, such as C&D 12-76 LBT.
Second, the constant power calculation formula:
W = PL÷(N*6*η)（watts/cell）
Among them, PL is the active power (KW) of the rated output of UPS; N is the number of batteries at 12V; Vf is the rated voltage of the battery pack, η is the inverter efficiency.
That is, first calculate the power required by the single battery, and then find the battery model that can meet the requirements through the constant power discharge meter provided by the battery manufacturer.
The termination discharge voltage is determined according to 1.75V/cell. Usually the power meter given by the battery manufacturer is the power of the single 2V/Cell, defined as watts/cell. The power meter given by some manufacturers is watts/block, which needs to be multiplied by the factor of 6.
For example: Emerson’s new generation of rack high-performance low-capacity UPS-ITA series 20KVA, the number of battery cells is 32 (30-40 even number of cells are adjustable), the UPS battery inverter efficiency is 0.95, according to the full load of 20kVA * 0.9=18KW, backup 2 hours calculation.
W/cell = PL/(N×6×η)=18000/（32*6*0.95）=98.68 watts/cell
The discharge power meter of C&D’s MPS series 12-76 is shown in the figure: the 2-hour discharge power is 51.5w/cell at 1.75Vdc, select 98.68/51.5=1.92 groups, and take 2 groups of 32 12V76Ah C&D MPS series batteries, a total of 64 cells.
The above are the 2 methods of UPS power backup battery configuration summarized by Suzhou Feirui Power Supply Co., Ltd., hoping to help you UPS power backup battery selection. If you still have questions about configuration, welcome to Suzhou Feirui Power Co., Ltd.
Suzhou Feirui Power Co., Ltd. long-term cooperation UPS power supply brands include Vidi, Schneider, Delta, Crestec, INVT, Baoxing and other international and domestic first-line well-known brand manufacturers, in the long-term project cooperation and implementation, our company has also accumulated a group of project design, project delivery, after-sales maintenance professionals, if you have the needs of UPS power supply in the room, please contact Suzhou Feirui Power Supply Co., Ltd.
Article source: https://www.ups-eps.net
