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+A load curve is plot ofthe load demand (on the y-axis) versus
| the time (on the x-axis), Connected load: A consumer, for example a domestic com
may have several appliances rated at different wattages. The
‘gum of these ratings (s his or her connected load,
; Maximum demand: It is the maximum load used by a consumer
at any time. It can be less than or equal to the connected load
The maximum demand is usually measured in units of kW or MW
bya maximum demand indicator. (Usually, in the case of HT
consumers, the MD is measured In terms of kVA or MVA.)
|. Load factor of a power station is defined as
a. maximum demand/average load
b. average load x maximum demand
. average load/maximum demand
d. (average load x maximum demand)x365
lAns: c. average load/maximum demand
1 Load factor:- The ratio of average load to the maximum demand
during a given period is known as
Loud factor = “Niax, demand
ifthe plant isin operation for T hour
Lond fictor = . 35.1 % ; 46.5 %
. 55.1 % ; 36.5 %
36.5 % : 55.1 %
b, 35.1 % ; 46.5 %
fed increased penalty factor between a generating plai i
system load current is to i
. decrease load on the generating plant
p. increase load on the plant
hold the plant load constant
increase power factor
ns: a. decrease load on the generating plant
4.Which of the following is considered as an operational cost
for a power system?
fa. Fuel Cost
fb. Insurance
fc
fd.
. Initial cost
Taxes and Interest
Ans: a. Fuel Cost
[25.The load curve is useful in deciding
/.. The operating schedule of generating units
2. The total installed capacity
hich of the above statement is/are correct?
Ja. 1 only
fb. 2 only
Ic. Both 1 and 2
ld. Neither 1 and 2
{Ans: c. Both 1 and 2
I26.Which of the following is the ratio of the area under the
load curve to the time?
Peak demand
. Average demand
. Difference between the average and the peak demand
None of these
lAns: b. Average demand
127. Determine the average load from the load curve.
thermal power station Is 72]
Se and
Share every moment with friends! Bee
= j
.The daily energy produced in a thermal power sta
MWh ata load factor of 0.6. What is the maximum
of the station?
. 40 MW
. 72. MW
30 MW
50 MW
9.1f a power plant has no reserve capacity, then the plant
capacity factor is equal to the
demand factor
. diversity factor
lc. load factor
. plant use factor
fans: c. load factor
130.The maximum demand on a power station is 200 KW. If the
annual load factor is 50%, calculate the total energy
generated in a year.
fa. 876 « 10° kWh
fb. 438 « 10° kWh,
Jc. 876 x 10° kWh
id. 438 « 10° kWh
Ans: a. 876 « 10° kWh
Utilization factor of a power station is the ratio of:
. Maximum demand of a power station to the sum of
individual maximum demands.
lb. Average demand to the rated capacity of the power station.
Sum of individual maximum demands to maximum
demand of a power station.
Maximum demand on the power station to the rated
capacity of the power station.
ns: d.
jaximum demand on the power station
Rated capacity of the power station
A generating station has a maximum demand of 35 MW and]
has connected load of 60 MW. The annual generation of
units is 24 » 107 kWh. Calculate the load factor any
demand factor respectively.
- 56.3% he 78.28 %
Ib. 78.28 % & 58.3%
Utilization Factor Cer)
he total expenditure to be incurred annually is called the ‘ani
economy of the project is judged from this cost (but not from
jotal investment)
i) The running cost or operating cost
% The cost of fuel: The higher the number of units (kWh) generated,
the higher is the fue! consumption
The maintenance and repair cha
9s of the equipment in all the
sam) and the cost of the
{ii) The fixed charges (not fixed capital)
Huge investment running into, maybe, several hundreds of crores
Normally, a part of this
m the public, offering them a certain rate
est has to be paid annually, whether or not
rent and clerical staff.
Block-Rate Tariff
(iv) Two-Part Tariff
+(v) Maximum Dema
+ (vi) Power Factor
(vil) Three Part Tariff
Tart
wh
% When there is a fixed rate per unit of energy consumed, itis
called a simple tariff or uniform rate tariff. The price charged
annual running charges + annual fixed charges
the fotal number of units supplied to the g
|# Advantage:
+The only merit of this tariff is simple in calculations to un
yall the consumers.
ic rar t onrgrar
i= LS Ching te ater the
e lower will
nes more
o increase the load ff
of generation.
a measure for the
y for residential and
tal energy charges = Rs. (a = KW +b x kWh)
aree of connected load and bi
° med.
This type 0 medium industrial o
Acartage:
= Thee mca of this tartare that it can easily be understood,
ccumsumers ane Gepends upon the maximum demand it recovers the fixed Advantage: j
The advantages of this tariff are that it can easily be understoot
Consumers and depends upon the maximum demand it recov
charges.
J+ The drawbacks of this tariff are that it lacks a measure for the demand of
the consumer and itis suitable only for residential and small commercial
‘consumers,
DTS
% Intthis tarif, the maximum demand of the consumer is actually
‘measured by installing a ‘maximum demand meter’ in the consumer's
premises,
Thus, the fixed charges component will be proportional to the (ac
maximum demand rather than to the connected load,
Total energy charges = Rs. (a x kW + b x kWh)
Where ‘of connected load and
Wh of energy consumed
This type of tariffs suitable for big industrial consumers.
MS a i
(@) kVA maximum demand tariff
(b) kWh and KVArh tariff
rfactor tari
(Doherty Rate)
% In this type of tariff, the total charge to be made from the consumer is
split into three parts:
% Thus, the fixed charges component will be proportional tothe (actual)
maximum demand rather than to the connected load.
Total eneray charges = Rs. (a+b KW +c x kWh)
where. made during billing period, b is the charge
per KW of connected demand, and of energy
consumed
ee
‘The average motor load of a consumer is 250 kW at a pf 0.85
Jag. The consumer is charged electricity at the tariff of 50
Rs,/kVA of maximum demand plus 10 paise per unit
‘consumed. Determine the consumer's annual bill for a load
factor of 70%.
‘Tariff on electrical energy where the consumer is
according to his maximum demand and energy
consumption is expressed as z = a + by is known a BB wih
Advantage: j
‘The advantages of this tariff are that it can easily be understoo
consumers and depends upon the maximum demand it recove
charges.
+ The drawbacks of this tariff are that it lacks a measure for the demand of
the consumer and itis suitable only for residential and small commercial
consumers.
CSE
Jn this tariff, the maximum demand of the consumer is actually
measured by installing a ‘maximum demand meter, in the consumer's
premises.
Thus, the fixed charges component will be proportional to the (actual)
maximum demand rather than to the connected load
Total energy charges = Rs. (a x kW +b x kWh)
Where ‘of connected load and
of energy consumed,
% This type of tariff is suitable for big industrial consumers,
% (a) KVA maximum demand tariff
% (b) kWh and kVArh tariff
(Doherty Rate)
In this type of tarif, the total charge to be made from the consumer is
split into
ree parts:
i) fixed charg
& (ji) semifixed chi
© Thus, the fixed charges component will be proportional to the (actual)
maximum demand rather than to the connected load
% Total energy charges = Rs. (a+b » KW +c x kWh)
% where made during billing period, b is the charge
per kW of connected demand, and of energy
consumed
|. The average motor load of a consumer is 250 kW at a pf 0.85
lag. The consumer is charged electricity at the tariff of 50
Rs./KVA of maximum demand plus 10 paise per unit
consumed. Determine the consumer's annual bill for a load
factor of 70%.
. Tariff on electrical energy where the consumer is,
according to his maximum demand and energy
‘consumption is expressed as z = a + by is known a
. Doherty rate
». Fla
snr ft are
LS Nee SD aT Ee
.. Doherty rate
. Flat demand rate ,
. Straight meter rate
Hopkinson demand rate
ins: d. Hopkinson demand rate
Total charge 2 = a+ by
a= charge of the Maximum Demand
by = charge of the Energy Consumption by the load
The bill of power consumption depends only on.
the Maximum Demand of the load.
The total bil is divided into two parts. The fixed charge
is because of the maximum demand and the second
TTwevpart fate depends on the energy consumption by the
load.
tariff
Zaa+by
The total costs are divided into 3 sections: Fixed cost,
‘semi-fixed costs, and running costs—» energy
consumption.
The generation of the bills depends on the energy
‘consumption of the load,
Z=by,
1Q. The data of a power station as follows:
capital cos
Rate of interest and depreciation = 20%.
Jannual cost of fuel oil, salaries, and taxation = Rs. 40 * 10%
Load factor = 0.5.
Determine the cost of generation and the cost of saving per
Wh if the annual load factor is raised to 0.6.
Q. The annual load duration curve of a certain power station
can be considered as a straight line from 20 MW to 4 MW.
To meet this load, three turbine-generator units, two rated
at 10 MW each and one rated at 5 MW are installed.
Determine (i) installed capacity (li) plant factor (i
generated per annum (Iv) load factor and (v) util fannual load factor is 45%. Calculate the diversity factor and
the number of units generated annually.
MCS care
