Fuji Electric Frenic-Mini - Page 346

A-16
Correction coefficient according to contract demand level
Since the total availability factor decreases if the scale of a building increases, calculating reduced
harmonics with the correction coefficient β defined in Table B.7 is permitted.
Table B.7 Correction Coefficient according to the Building Scale
Contract demand
(kW)
Correction
coefficient β
300 1.00
500 0.90
1000 0.85
2000 0.80
Note: If the contract demand is between two specified values listed in Table B.7, calculate the value
by interpolation.
Note: The correction coefficient β is to be determined as a matter of consultation between the
customer and electric power supplier for the customers receiving the electric power over 2000
kW or from the special high voltage lines.
(4) Degree of harmonics to be calculated
The higher the degree of harmonics, the lower the current flows. This is the property of harmonics
generated by inverters so that the inverters are covered by "The case not causing a special hazard" of
the term (3) in the above Appendix for the 9th or higher degrees of the harmonics.
Therefore, "It is sufficient that the 5th and 7th harmonic currents should be calculated."
[ 3 ] Examples of calculation
(1) Equivalent capacity
Example of loads
Input capacity and
No. of inverters
Conversion factor Equivalent capacity
[Example 1] 400V, 3.7 kW, 10 units
w/- AC reactor and DC reactor
4.61 kVA×10 units K32 = 1.4 4.61 × 10 × 1.4
= 64.54 kVA
[Example 2] 400V, 1.5 kW, 15 units
w/- AC reactor
2.93 kVA×15 units K34 = 1.8 2.93 × 15 × 1.8
= 79.11 kVA
Refer to Table B.2. Refer to Table B.3.
(2) Harmonic current every degrees
[Example 1] 400V, 3.7 kW, 10 units, w/- AC reactor, and maximum availability: 0.55
Fundamental current
onto 6.6 kV lines (mA)
Harmonic current onto 6.6 kV lines (mA)
5th
(38%)
7th
(14.5%)
11th
(7.4%)
13th
(3.4%)
17th
(3.2%)
19th
(1.9%)
23rd
(1.7%)
25th
(1.3%)
394×10= 3940
3940×0.55= 2167
823.5 314.2
Refer to Tables B.4 and
B.6.
Refer to Table B.5.
[Example 2] 400V, 3.7 kW, 15 units, w/- AC reactor and DC reactor, and maximum availability: 0.55
Fundamental current
onto 6.6 kV lines (mA)
Harmonic current onto 6.6 kV lines (mA)
5th
(28%)
7th
(9.1%)
11th
(7.2%)
13th
(4.1%)
17th
(3.2%)
19th
(2.4%)
23rd
(1.6%)
25th
(1.4%)
394×15= 5910
5910×0.55= 3250.5
910.1 295.8
Refer to Tables B.4 and
B.6.
Refer to Table B.5.