knjiga solarna energija dobra

INVERTERS 899
Time delay
Seconds Minutes
120
60
40
20
10
6
4
2
1
40
20
10
6
4
2
1
0.6
0.4
0.2
0.1
0.06
0.04
0.02
0.01
1 1.5 2 3 4 5 6 8 10 15 20 30
Multiple of rated current
(a)
Time delay
Seconds Minutes
120
60
40
20
10
6
4
2
1
40
20
10
6
4
2
1
0.6
0.4
0.2
0.1
0.06
0.04
0.02
0.01
1 1.5 2 3 4 5 6 8 10 15 20 30
Multiple of rated current
(b)
Figure 19.47 Current–time diagram for different fuse types: (a) characteristic left and (b) characteristic
right (DIN EN 60898, DIN EN 62019)
Power
factor
cos j
1
Power
Figure 19.48
Power factor as a function of the output power of a typical grid-connected inverter
For grid-connected inverters’ the THD of the current injected into the grid is used
to describe the inverters’ quality. The THD of the injected current, which is defined in
the same way as was done for the voltage. A high-quality grid-connected inverter shows
a THD in the current that is below 5%.