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EMC and leakage currents
Class
Three-phase bridge
3
(Capacitor smoothing)
Table 3 Equivalent Capacity Limits
Received Power Voltage
6.6kV
22/33kV
66kV or more
Table 4 Harmonic content (Values of the fundamental current is 100%)
Reactor
Used (AC side)
1) Calculation of equivalent capacity P0 of harmonic generating equipment
The "equivalent capacity" is the capacity of a 6-pulse converter converted from the capacity of consumer's harmonic
generating equipment and is calculated with the following equation. If the sum of equivalent capacities is higher than
the limit in Table 3, harmonics must be calculated with the following procedure:
P0 = Σ (Ki × Pi) [kVA]
Ki: Conversion factor(According to Table 2)
Pi: Rated capacity of harmonic generating equipment
i : Number indicating the conversion circuit type
2) Calculation of outgoing harmonic current
Outgoing harmonic current = fundamental wave current (value converted from received power voltage) × operation
⋅ Operation ratio: Operation ratio = actual load factor × operation time ratio during 30 minutes
⋅ Harmonic content: Found in Table 4.
Table 5 Rated capacities and outgoing harmonic currents of inverter-driven motors
Rated Current
Applied
(A)
Motor
(kW)
200V
400V
5.5
19.1
9.55
7.5
25.6
12.8
11
36.9
18.5
15
49.8
24.9
18.5
61.4
30.7
22
73.1
36.6
30
98.0
49.0
37
121
60.4
45
147
73.5
55
180
89.9
3) Harmonic suppression technique requirement
If the outgoing harmonic current is higher than the maximum value per 1kW (contract power) × contract power, a
harmonic suppression technique is required.
4) Harmonic suppression techniques
No.
Item
Installation of power factor
1
improving capacitor
Transformer multi-phase
2
operation
Passive filter
3
(AC filter)
4
Active filter
40
Table 2 Conversion factors for FR-A701 series
Circuit Type
With reactor (AC side)
Reference Capacity
50kVA
300kVA
2000kVA
5th
7th
11th
38
14.5
ratio × harmonic content
Fundamental
Wave Current
Rated
Converted
Capacity
from 6.6kV
(kVA)
(mA)
579
6.77
776
9.07
1121
13.1
1509
17.6
1860
21.8
2220
25.9
2970
34.7
3660
42.8
4450
52.1
5450
63.7
When used with a series reactor, the power factor improving capacitor has an effect of
absorbing harmonic currents.
Use two transformers with a phase angle difference of 30° as in
to provide an effect corresponding to 12 pulses, reducing low-degree harmonic currents.
A capacitor and a reactor are used together to reduce impedances at specific frequencies,
producing a great effect of absorbing harmonic currents.
This filter detects the current of a circuit generating a harmonic current and generates a
harmonic current equivalent to a difference between that current and a fundamental wave
current to suppress a harmonic current at a detection point, providing a great effect of
absorbing harmonic currents.
13th
17th
7.4
3.4
3.2
* Rated capacity: Determined by the capacity of the applied
motor and found in Table 5. It should be noted that the rated
capacity used here is used to calculate generated harmonic
[kVA]
*
amount and is different from the power supply capacity
required for actual inverter drive.
Outgoing Harmonic Current Converted from 6.6kV (mA)
(With reactor, 100% operation ratio)
5th
7th
11th
220.0
83.96
42.85
294.9
112.5
57.42
426.0
162.5
82.95
573.4
218.8
111.7
706.8
269.7
137.6
843.6
321.9
164.3
1129
430.7
219.8
1391
530.7
270.8
1691
645.3
329.3
2071
790.3
403.3
Description
Conversion Factor (Ki)
K32 = 1.8
19th
23rd
1.9
1.7
13th
17th
19th
19.69
18.53
11.00
26.38
24.83
14.74
38.11
35.87
21.30
51.31
48.29
28.67
63.24
59.52
35.34
75.48
71.04
42.18
101.0
95.04
56.43
124.4
117.1
69.54
151.3
142.4
84.55
185.3
174.4
103.6
-
,
-
25th
1.3
23rd
25th
9.843
7.527
13.19
10.09
19.06
14.57
25.65
19.62
31.62
24.18
37.74
28.86
50.49
38.61
62.22
47.58
75.65
57.85
92.65
70.85
combination

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