KVAR RATING CALCULATOR,CAPACITOR BANK SIZE CALCULATION

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  Determination of Required Capacitor Rating by measurement 3 Methods are used. 1. Measurement with current and power factor 2.Measurement with recording of Active and Reactive power. 3.Measurement by Reading Meters . 1 . Measurement with Current and power factor The active power P is calculate from the measured voltage V ,apparent current Is and Power Factor P=√3*Voltage*apparent Current*cosψ *10^-3 If the desired power factor cosψ has been specified, the capacitor power rating can be calculate from the following formula: Qc = P. (tan ψactual - tanψ desired) Let's See the Example Measured Apparent Current Is : 248 Amps Power Factor cos ψ1 = 0.86 Desired Cos ψ2 = 0.92 Voltage V :397 V p=√3 * 397 * 248 * 0.86 * 103 P = 146.6 KW Qc= P. (tanψ actual - tanψ desired) = 146.6(0.59 - 0.42) = 24.9 KVAR
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Estimation of Uncertainty in Hardness Measurement & Maximum Permissible Error of Brinell Hardness Testing Machine As Per ISO 6506-2 & ASTM E10-15

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Source of Uncertainty of Hardness Measurement

  1. Certified Value of CRM
  2. Determine the User Machine Repeatability
  3. Assessment according EN ISO 6506
  4. Uncertainty from the Measured Material.
  5. Resolution of the Indentation diameter measuring device.                     

1. Certified Value of CRM 




    Xcrm = 222 HBW 10/3000

   Ucrm    = 土 1.4 HBW  (2σ Uncertainty)



2 . Determine the User Machine Repeatability
 

    H₁ = 221
    H₂ = 220
    H₃ = 220
    H₄ = 221
    H₅ = 220

    Mean = 220  HBW

                     b )  Repeatability of Hardness Measurement
                    H₅ = 220
                    H₁ = 221
                         = -1 HBW

                (C) Standard Deviation
    
                    
                                    =0.55 HBW

 3. Assessment according EN ISO 6506

        a) The error ( E) of the testing machine

                    
                                       = 222 - 220
                                                   =2 HBW
Permissible Error = ((222*3)/100)

 

                                =6.66 HBW

 

                                (Note: This permissible Error is based on the ISO 6506-2)

    Accuracy or Maximum Permissible Error of Brinell Hardness                             Testing Machine (ISO 6506-2)

 Brinell Hardness Testing Machine Accuracy or Permissible Error



 Maximum Permissible Error or Accuracy  of Brinell Hardness        Testing Machine (ASTM E10-15)






4.Uncertainty from the Measured Material

 



    x₁ = 224
    x₂ = 223
    x₃ = 224
    x₄ = 224
    x₅ = 223

                                Mean Value  = 224 HBW


   Estimate the uncertainty of the mean value, x , following               mathematical model has been used  

Combined Uncertainty = 



         (a) Permissible Error (E1𝝈)    = (E₂𝝈 /2)

                               =(6.66 HBW/2)
    
                            = 3.33 HBW

            (b) Uncertainty of Resolution of the Indentation diameter measuring device.     
                
                

ẟms = 0.01 (Resolution of the indentation  diameter measuring device)
                        HBW= 224 
                        d = 4.04 mm
                        D = 10 mm
                        Ums =0.3347

            (c) Uncertainty of Certified Reference block 

            The uncertainty ucrm is a 2-Sigma uncertainty,





Ucrm    = 土 1.4 HBW  (2σ Uncertainty)

Ucrm (1σ) = Ucrm (2σ) / 2
=1.4/2
       =0.7 HBW

          (d)   The uncertainty of H (mean value of users machine on CRM)


t = 1.15

sH = 0.55 HBW

                                           n = 5 (Five number of test is performed)

Uncertainty of Mean value  = (1.15*0.55)/√5)

                                =0.2828

        (e) The uncertainty of x (measurements on a material)



t = 1.15
sX = 0.547723 HBW
Uncertainty of Measurement of Material = (1.15*0.547723)/√5
       
                                             =0.2777


Combined Uncertainty = √3.33²+0.7²+0.2828²+0.277²+.3347²

=√11.8476

=3.4420

                        Expanded Uncertainty 
=2*3.4257

                                           =Significant figure rounding the Expanded Uncertainty
in to two digits

= 土 7 HBW


Reported Result 

 


The above reported expanded uncertainties are based on standard

 uncertainties by a coverage factor k =2. Proving a level of

 confidence of approximately 95% . The uncertainty evaluation was

 carried out in accordance with UNCERT recommendations.







                      

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