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/.
Published by Department of EEE, ADBU:
tinyurl.com/eee-adbu