Kalkulasi " Sizing" Baterai

Diketahui :

Capacity of the UPS                           : 15 kVA

Load (Autonomy)                               : 15 kVA

Cos Phi                                                : 0.85

Autonomy                                          : 180 Minutes (at 100% load) 

Nominal DC Voltage                          :  220 V

Float DC Voltage                                :  243  V 

Minimum DC Voltage                        : 194.40  V

Float voltage per cell                           : 2.25  V 

Inverter Efficiency                              : 88.00 %        

Life Time Battery                                : 25 years

CALCULATION OF SIZING THE BATTERY

Number of cells

                                  

                           

    

                      Float DC Voltage               

         N    =  -----------------------------     

                      Float Voltage per cell          

         N      =  243 / 2.25 = 108 cell

Power Input to Inverter

            
                         

                          Load x Cos Phi                

Pinv    =  -----------------------

               Inverter Efficiency           

                           

          Pinv     = 12750/ 0.880 = 14488.64  W

Minimum allowable voltage per cell

                                Minimum DC Voltage       

Vmin    =    ----------------------------------- 
                 Total amount of cells                      

             Vmin = 194.4/ 108 = 1.80 Vpc

Discharge current maximum at 100% load.

                                         Pinv *1       

Idisc    =   -----------------------------------
                 Minimum DC Voltage                   

                 Idisc = 14488,64/ 194.4 = 74.53 A

Considering Ageing factor (1.25) and Design Margin (1.15):

            Idisc    =   Idisc x Ageing Factor x Design Margin     =   107.14     A

According to Datasheet from GNB-Exide Absolyte GP  (attached), that for discharged constant c  =   107.14    A with back up time 180 (One Hundred and Eighty) minutes, end voltage 1.8 Vpc, the battery type to be used is 6-90G11 (432 AH/8 Hrs). No. of cell 108 cells. (=18 blocks)