Environmental Engineering Reference
In-Depth Information
TABLE 7.1
Wire size, Copper, 480 V, Three-Phase, 2% Voltage Drop
Overhead
Load,
Type
Bare,
amps
Insulated
Covered
30
46
60
76
91
107
122
137
152
168
183
5
12
10
12
12
12
12
12
12
12
12
12
12
12
7
12
10
12
12
12
12
12
12
12
12
10
10
10
10
12
10
12
12
12
12
12
10
10
10
10
8
8
15
12
10
12
12
12
10
10
10
8
8
8
8
6
20
12
10
12
12
10
10
8
8
8
6
6
6
6
25
10
10
12
10
10
8
8
6
6
6
6
4
4
30
10
10
12
10
8
8
6
6
6
6
4
4
4
35
8
10
10
10
8
6
6
6
4
4
4
4
4
40
8
10
10
8
8
6
6
4
4
4
4
3
3
45
6
10
10
8
6
6
6
4
4
4
3
3
2
50
6
10
10
8
6
6
4
4
4
3
3
2
2
60
4
8
8
6
6
4
4
4
3
2
2
2
1
70
4
8
8
6
4
4
4
3
2
2
1
1
1
80
4
6
8
6
4
4
3
2
2
1
1
0
0
90
3
6
6
6
4
3
2
2
1
1
0
0
0
100
3
6
6
4
4
3
2
1
1
0
0
00
00
115
2
4
6
4
3
2
1
1
0
0
00
00
000
130
1
4
6
4
3
2
1
0
0
00
00
000
000
150
0
2
4
3
2
1
0
0
00
00
000
000
4/0
175
00
0
4
3
1
0
0
00
000
000
4/0
4/0
4/0
200
000
00
4
2
1
0
00
000
000
4/0
4/0
250
250
250
250
00
3
1
0
00
000
4/0
4/0
250
250
300
300
Source:
From
Agriculture Wiring Handbook
. 3rd Ed, 1993. National Food and Energy Council, Colombia, Missouri.
Note:
First column is the current; the next two columns give minimum size of wire to use for type of insulation and for bare
wire. With longer wire runs, a larger-diameter wire is needed. The length of the total wire run is in bold, m. Other numbers
are size of wire. 4/0 means 0000 size. A smaller number means a larger-diameter wire, and more zeros mean larger-diameter
wire. After 4/0, the number is a thousand, circular mills.
7. 3 P O W E R Q UA L I T Y
Wind turbines and especially wind farms, which in reality are wind power plants, must provide the
power quality [10, 11] to ensure the stability and reliability of the system, which include power qual-
ity for other customers on the grid. The four types (
Figure 7.12
) of connection depend on the electri-
cal conversion, generator, and connection (direct or partial and full converter). Induction generators
require reactive power from the grid, and capacitor compensation is often used, at the wind turbine
or at the substation. The power output of variable-rpm wind turbines is smoother, less flicker, than
constant-rpm wind turbines because rapid changes in the power are smoothed out by rotor inertia. If
the converter is large enough, variable-rpm wind turbines can also be used for voltage and frequency
control in the grid. Power electronic converters produce harmonics that may need to be filtered.
The voltage at each wind turbine with the wind farm varies independently, and they may be shut
down for various faults (see
Section 5.6.2
) or maintenance. The capacitor compensation may lead
to the possibility of harmonics and self-excitation, with the constant-rpm, induction generators [10];
Search WWH ::
Custom Search