Chapter11 - Various types of tariffs

Exa 11.1 - page 290

In [4]:
from __future__ import division
import numpy as np
#Given Data :
E=438000 #in kWh(Energy consumed per year)
pf=0.8 #unitless
cosfi=pf #unitless
LoadFactor=40 #in %
#tarrif=Rs. 75/year/kw of max demand plus 3 paise per unit per reactive KVA
h=8760 #no. of years in a year
AvgLoad=E/h #kw
MaxLoad=AvgLoad/(LoadFactor/100) #in kw
MaxLoad_KVA=MaxLoad/pf #in KVA
tanfi=np.tan(np.arccos(cosfi)) #unitless
ReactiveKVAR=h*tanfi*AvgLoad #in KVA
AnnualBill=75*MaxLoad+(3/100)*E+(1.5/100)*ReactiveKVAR #in Rs.
CostPerUnit=AnnualBill/E #in Rs.
CostPerUnit=CostPerUnit*100 #in Paisa
print "Cost per unit = %0.3f Paisa" %CostPerUnit

Cost per unit = 6.265 Paisa

Exa 11.2 - page 291

In [8]:
from __future__ import division
import numpy as np
#Given Data :
#tarrif=Rs. 275/year/KVA of max demand plus 35 paise per unit
C1=275 #in Rs.year/KVA
C2=35 #in paisa/unit
LoadFactor=30 #in %/year
LoadFactor=30/100 #in fraction
#Let MaxDemand = x KW
#Case (i) PF=1
cosfi=1 #unitless
AnnualBillBYx=C1/cosfi+(C2/100)*LoadFactor*24*365 #in Rs.(Here 24*365 is for No. of hours in a year)
AnnualBill=AnnualBillBYx*100/(LoadFactor*24*365) #in paisa/unit
print "Cost per unit(at unity power factor) = %0.2f paisa" %AnnualBill
#Case (i) PF=0.8
cosfi=0.8 #unitless
AnnualBillBYx=C1/cosfi+(C2/100)*LoadFactor*24*365 #in Rs.(Here 24*365 is for No. of hours in a year)
AnnualBill=AnnualBillBYx*100/(LoadFactor*24*365) #in paisa/unit
print "Cost per unit(at 0.8 power factor) = %0.2f paisa" %AnnualBill

Cost per unit(at unity power factor) = 45.46 paisa
Cost per unit(at 0.8 power factor) = 48.08 paisa

Exa 11.3 - page 292

In [11]:
from __future__ import division
import numpy as np
#Given Data :
FixedLoad=200 #in kW
PF=0.8 #unitless
cosfi=PF #unitless
h=10 #in hours/day
d=300 #in days
Time=h*d #in hours
Energy=FixedLoad*Time #in kwh/year
# (i) tarrif=Rs. 100/KVA/Annum plus 20 paise per kwh
C1=100 #in Rs.year/KVA
C2=20 #in paisa/kwh
KVA=FixedLoad/cosfi #in KVA
AnnualBill=KVA*C1+(C2/100)*Energy #in Rs.
print " Case (i) Annual Payment = %0.f Rs." %AnnualBill
# (ii) tarrif=Rs. 100/KW/Annum plus 20 paise per kwh plus 2 paise/KVARH
C1=100 #in Rs./year/KW
C2=20 #in paisa/kwh
C3=2 #in paisa/KVARH
tanfi=np.tan(np.arccos(cosfi)) #unitless
ReactiveKVARH=FixedLoad*tanfi*Time #in KVARH
AnnualBill=C1*FixedLoad+(C2/100)*Energy+(C3/100)*ReactiveKVARH #in Rs.
print " Case (ii) Annual Payment = %0.f Rs." %AnnualBill

 Case (i) Annual Payment = 145000 Rs.
 Case (ii) Annual Payment = 149000 Rs.

Exa 11.4 - page 293

In [13]:
from __future__ import division
import numpy as np
#Given Data :
Energy=180000 #in kwh
LoadFactor=45 #in %/year
LoadFactor=45/100 #in fraction
#Charges=Rs. 50/KW/Annum plus 8 paise per unit
C1=50 #in Rs.year/KW
C2=8 #in paisa/unit
h=365*24 #no. of hours per year
AvgLoad=Energy/h #in KW
MaxLoad=AvgLoad/LoadFactor #in KW
FixCharges=MaxLoad*C1 #in Rs.
PlusCharges=(C2/100)*Energy #in rs.
TotalTarrif=FixCharges+PlusCharges #in Rs.
print "Total Annual electricity charges = %0.2f Rs." %TotalTarrif

Total Annual electricity charges = 16683.11 Rs.

Exa 11.5 - page 293

In [15]:
from __future__ import division
import numpy as np
#Given Data :
Energy=25*10**6 #in kwh
MaxDemand=1600 #in KW
#(i) Rs. 70/KW max demand plus 2 paise per kwh
C1=70 #in Rs.year/KW
C2=2 #in paisa/unit
AnnualCost=MaxDemand*C1+(C2/100)*Energy #in Rs.
print "Case (i) Annual cost of energy = %0.f Rs." %AnnualCost
#(ii) Annual cost at a flat rate of 5p/kwh
C=5 #in paisa/kwh
AnnualCost=(C/100)*Energy #in Rs.
print "Case (ii) Annual cost of energy = %0.f Rs." %AnnualCost

Case (i) Annual cost of energy = 612000 Rs.
Case (ii) Annual cost of energy = 1250000 Rs.

Exa 11.6 - page 293

In [16]:
from __future__ import division
import numpy as np
#Given Data :
MaxDemand=20 #in KW
#(i) Rs. 180/KW/annum max demand plus 15 paise per unit
#(ii) Flat rate tarrif 40 paise/unit
C1=180 #in Rs.year/KW
C2=15 #in paisa/unit
#AnnualBill1=C1*MaxDemand+(C2/100)*x  x is the energy consumed
C=40 #in paisa/unit
#AnnualBill2=(C/100)*x  x is the energy consumed
#Puting two bills equal gives :
x=C1*MaxDemand/((C/100)-(C2/100)) #in kwh
print "No. of units to be consumed is %d or %d kwh" %(x,x)

No. of units to be consumed is 14400 or 14400 kwh

Exa 11.7 - page 294

In [18]:
from __future__ import division
import numpy as np
#Given Data :
MaxDemand=500 #in KW
LoadFactor=70 #in %/year
LoadFactor=70/100 #in fraction
cosfi=0.8 #unitless
#(i) Rs. 80/KVA of max demand
#(ii) Running chargeare  5 paise/kwh
C1=80 #in Rs./KVA
C2=5 #in paisa/kwh
AvgLoad=MaxDemand*LoadFactor #in KW
h=365*24 #no. of hours per year
Energy=AvgLoad*h #in kwh
MaxDemandKVA=MaxDemand/cosfi #in KVA
AnnualBill=MaxDemandKVA*C1+(C2/100)*Energy #in RS
print "Annual bill of consumer = %0.f Rs." %AnnualBill

Annual bill of consumer = 203300 Rs.

Exa 11.8 - page 294

In [20]:
from __future__ import division
import numpy as np
#Given Data :
MD=100 #in KW
LF=60 #in %/year
LF=60/100 #in fraction
#Tarrif Rs. 100/KW of max demand and Rs. 1/kwh
C1=100 #in Rs./KW
C2=1 #in Rs./kwh
h=365*24*12 #no. of hours
UnitsConsumed=MD*LF*h #in kwh/year
AnnualCharges=C1*MD+C2*UnitsConsumed #in RS
print "Overall Annual chrges = %0.f Rs." %AnnualCharges

Overall Annual chrges = 6317200 Rs.

Exa 11.9 - page 294

In [22]:
from __future__ import division
import numpy as np
#Given Data :
MD=250 #in KW
PF=0.8 #power factor
cosfi=PF #unitless
Energy=50000 #in units/annum
#Tarrif Rs. 50/KVA of max demand and 0.25paisa/unit
C1=50 #in Rs./KW
C2=0.25 #in Paise/kwh
MDKVA=MD/cosfi #in KVA
AnnualBill1=C1*MDKVA+C2*Energy #in RS
print "Annuall bill of industry = %0.f Rs." %AnnualBill1
#Note : If consumer raised the PF to unity.
PF=1 #power factor
cosfi=PF #unitless
MDKVA=MD/cosfi #in KVA
AnnualBill2=C1*MDKVA+C2*Energy #in RS
print "Saving by consumer in the bill = %0.f Rs."%(AnnualBill1-AnnualBill2)

Annuall bill of industry = 28125 Rs.
Saving by consumer in the bill = 3125 Rs.

Exa 11.10 - page 295

In [25]:
from __future__ import division
import numpy as np
#Given Data :
MD=10 #in KW
Energy=50000 #in kwh/year(Annual consumption)
#(i) Rs. 100/KW/year max demand plus Rs. 0.20 paise per unit
#(ii) Simple tarrif 0.30 Rs./unit
C1=100 #in Rs.year/KW
C2=0.20 #in Rs. /unit
#Case (i)
AnnualBill1=C1*MD+C2*Energy #in Rs.
print "Case(i) Annual Bill of tarrif 1 = %0.f Rs." %AnnualBill1
C=0.30 #in Rs. /unit
AnnualBill2=C*Energy #in Rs.
print "Case(ii) Annual Bill of tarrif 2 = %0.f Rs." %AnnualBill2
print "He must choose the first tarrif."

Case(i) Annual Bill of tarrif 1 = 11000 Rs.
Case(ii) Annual Bill of tarrif 2 = 15000 Rs.
He must choose the first tarrif.