Calculate Transformer Regulation & Losses (As per Transformer Name Plate)

Calculate Transformer Regulation and Losses for following Transformer Name Plate Details

  • KVA rating of Transformer(P)=16000VA
  • Primary voltage(Vp)=11000V
  • Secondary voltage(Vs)=433V
  • No load losses(W0)=72Watt
  • No load current(I0)=0.59Amp
  • Full load losses(W)=394Watt
  • Impedance voltage(Vi)=480Volt
  • LV resistance(Rs) =219.16 miliΩ
  • HV resistance(Rp) =215.33 Ω
  • Amb temperature(c)=30 Deg C
  • Total Connected Load on Transformer(Pl)=10000VA

Calculation:

  • % Loading of Transformer=Pl/P
  • % Loading of Transformer=10000/16000 = 63%

I2R Calculation:

  • HV Full load current (Ip) =P/Vpx1.732
  • HV Full load current (Ip) =16000/11000×1.732=0.84 Amp
  • LV Full load current (Is)=P/Vsx1.732
  • LV Full load current (Is)==16000/433×1.732=21.33 Amp
  • HV Side I2R losses= IpxIpxRp
  • HV Side I2R losses= 0.84×0.84×215.33=227.8 Watt—–(A)
  • LV Side I2R losses= IsxIsxRs
  • LV Side I2R losses==21.33×21.33×219.16=149.63 Watt—(B)
  • Total I² R losses @ Amb temp(Ir)=A+B
  • Total I² R losses @ Amb temp(Ir)=227.8+149.63=377.43 Watt
  • Total Stray losses @ Amb temp (Ws) =Full Load Losses-I2R Losses
  • Total Stray losses @ Amb temp (Ws) =394-377.43=16.57 Watt
  • I² R losses @75° c temp =Irx310/235xc =149.63×310/235×30 =441.52Watt
  • Stray loses @ 75° c temp  =(Wsx(235+c))/310
  • Stray loses @ 75° c temp  =(16.57x(235+30))/310=14.16 Watt
  • Total Full load losses at @75° c=441.52+14.16=455.69 Watt
  • Total Impedance at ambient temp (Ax)=Vix1.732/Ip
  • Total Impedance at ambient temp(Ax)=480×1.732/0.84=989.94Ω
  • Total Resistance at amb temp (Ar)=Ir/IpxIp
  • Total Resistance at amb temp (Ar)=377.43/0.84×0.84=535.15Ω
  • Total Reactance (X)=√AxxAx+ArxAr
  • Total Reactance (X)=√989.98×989.94+535.15×535.15=832.82Ω
  • Resistance at@ 75° c (R)= (310xAr)/(235+c)=310×535.15/235+30 = 626.03Ω
  • Impedance at 75° c (X1)=√2X+2R=√2×626.03+2×832.82 = 1041.88Ω
  • Percentage Impedance = (X1x0.5774xIpx100)/Vp
  • Percentage Impedance = (1041.88×0.5774×0.84×100)/11000=4.59%
  • Percentage Resistance (R%)  =(Rx0.5774xIpx100)/Vp
  • Percentage Resistance(R%) =(626.03×0.5774×0.84×100)/11000=2.76%
  • Percentage Reactance(X%) = (Xx0.5774xIpx100)/Vp
  • Percentage Reactance(X%) = (832.82 x0.5774×0.84×100)/11000=3.67%

Regulation

  • Regulation at Unity P.F =2.76
  • Regulation at Unity at 0.8 P.F =((R% x cosØ)+(X% x SinØ))+(0.005x((R% x SinØ)+(X% x CosØ)))
  • Regulation at Unity at 0.8 P.F =((2.76 x 0.8)+(3.67 x 0.6))+(0.005x((2.76 x0.6)+(3.67 x 0.8)))=4.43

Results

  • Total I² R losses @ Amb. temp(Ir)= 377.43Watt
  • Total Stray losses @ Amb. temp (Ws) =16.57 Watt
  • Regulation at Unity P.F =2.76
  • Regulation at Unity at 0.8 P.F =4.43

 

 



View more at https://electricalnotes.wordpress.com/2020/06/22/calculate-transformer-regulation-losses-as-per-transformer-name-plate/.
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