Page 31 - Handbook of Electrical Engineering

10 HANDBOOK OF ELECTRICAL ENGINEERING

Table 1.10 shows the values of the load factor F i and the overload factor F o for a range of
typical power consumptions P l . The values of P g are the site requirements and relate approximately
to the ratings of gas-turbine generators that are available and used in the oil industry i.e. 2.5 to
40.0 MW.
The table was compiled by constraining F i and F o to be within good practical limits,

66.7% F i 90.0%

and
80 F o 125%

Table 1.10. Selecting generator ratings on the basis of N − 1 capacity with tolerance of overloading
Power Initial Number of Generator rating at Turbine ISO ratings Final load
consumption load factor installed site conditions for a site amb. temp factor
◦
(%) generators (MW) of 40 C(MW) (%)
(MW) P l
F i N P g P iso40 F o
10 66.7 4 5.0 5.9 100.0
10 74.1 4 4.5 5.3 111.1
10 83.3 4 4.0 4.7 125.0
10 71.4 5 3.5 4.1 95.2
10 83.3 5 3.0 3.5 111.1
10 66.7 6 3.0 3.5 83.3
10 80.0 6 2.5 2.9 100.0
15 66.7 4 7.5 8.8 100.0
15 75.0 5 5.0 5.9 100.0
15 83.3 5 4.5 5.3 111.1
15 66.7 6 4.5 5.3 83.3
15 75.0 6 4.0 4.7 93.8
15 85.7 6 3.5 4.1 107.1
20 66.7 4 10.0 11.8 100.0
20 66.7 5 7.5 8.8 89.9
20 80.0 6 5.0 5.9 100.0
20 88.9 6 4.5 5.3 111.1
25 69.4 4 12.0 14.1 104.2
25 83.3 4 10.5 11.8 125.0
25 83.3 5 7.5 8.8 111.1
25 66.7 6 7.5 8.8 83.3
30 71.4 4 14.0 16.5 107.1
30 83.3 4 12.0 14.1 125.0
30 75.0 5 10.0 11.8 100.0
30 80.0 6 7.5 8.8 100.0
40 66.7 4 20.0 23.5 100.0
40 74.1 4 18.0 21.2 111.1
40 83.3 4 16.0 18.8 125.0
40 71.4 5 14.0 16.5 95.2
40 83.3 5 12.0 14.1 111.1
40 66.7 6 12.0 14.1 83.3