Mitsubishi Electric FR-CS84-012 Instruction Manual page 57

 Calculation of equivalent capacity P0 of harmonic generating equipment
"Equivalent capacity" is the capacity of a 6-pulse converter converted from the capacity of consumer's harmonic generating
equipment and is calculated by the following equation. If the sum of equivalent capacities is higher than the limit (refer to the
list of the equivalent capacity limits), harmonics must be calculated by the equation in next subheading.
P0 = Σ (Ki × Pi) [kVA]
Ki: Conversion coefficient (Refer to the list of the conversion
factors.)
Pi: Rated capacity of harmonic generating equipment
i: Number indicating the conversion circuit type
 Calculation of outgoing harmonic current
Outgoing harmonic current = fundamental wave current (value converted from received power voltage) × operation ratio ×
harmonic content
• Operation ratio: actual load factor × operation time ratio during 30 minutes
• Harmonic content: Refer to the list of the harmonic content.
 Rated capacities and outgoing harmonic currents of inverter-driven motors
Fundamental
wave current (A)
Applicable
motor (kW)
200 V
0.4 1.61
0.75 2.74
1.5 5.50
2.2 7.93
3.7 13.0
5.5 19.1
7.5 25.6
11 36.9
15 49.8
 Determining if a countermeasure is required
A countermeasure for harmonics is required if the following condition is satisfied: outgoing harmonic current > maximum value
per 1 kW contract power × contract power.
 Harmonic suppression techniques
No. Item
Reactor installation
1
(FR-HAL)
High power factor
2
converter (FR-HC2)
Installation of power factor
3
improving capacitor
Transformer multi-phase
4
operation
5 Passive filter (AC filter)
Active filter
6
(Active filter)
56
3. PRECAUTIONS FOR USE OF THE INVERTER
3.2 Power supply harmonics
Fundamental
wave current Rated
converted capacity
from 6.6 kV (kVA)
400 V
(mA)
0.81 49 0.57
1.37 83 0.97
2.75 167 1.95
3.96 240 2.81
6.50 394 4.61
9.55 579 6.77
12.8 776 9.07
18.5 1121 13.1
24.9 1509 17.6
Description
Install an AC reactor (FR-HAL) on the AC side of the inverter to suppress outgoing harmonic currents.
This converter trims the current waveform to be a sine waveform by switching the rectifier circuit
(converter module) with transistors. Doing so suppresses the generated harmonic amount significantly.
Connect it to the DC area of an inverter. Use the high power factor converter (FR-HC2) with the
accessories that come as standard.
When used with a reactor connected in series, the power factor improving correction capacitor can
absorb harmonic currents.
When two transformers are installed with a phase angle difference of 30° in
∆ connection, the combination of the two transformers are equivalent to a 12-phase rectifier, reducing
low-degree harmonic currents.
A capacitor and a reactor are used together to reduce impedances at specific frequencies. Harmonic
currents are expected to be absorbed greatly by using this technique.
This filter detects the current in 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 the
harmonic current at the detection point. Harmonic currents are expected to be absorbed greatly by using
this technique.
*1 Rated capacity: Determined by the capacity of the applied
motor and found in the table "Rated capacities and outgoing
harmonic currents of inverter-driven motors". The rated
capacity used here is used to calculate the generated
*1 harmonic amount and is different from the power supply
[kVA]
capacity required for actual inverter drive.
Outgoing harmonic current converted from 6.6 kV (mA) (No reactor, 100%
5th 7th 11th
31.85 20.09 4.165
53.95 34.03 7.055
108.6 68.47 14.20
156.0 98.40 20.40
257.1 161.5 33.49
376.1 237.4 49.22
504.4 318.2 65.96
728.7 459.6 95.29
980.9 618.7 128.3
operation ratio)
13th 17th 19th
3.773 2.107 1.519
6.391 3.569 2.573
12.86 7.181 5.177
18.48 10.32 7.440
30.34 16.94 12.21
44.58 24.90 17.95
59.75 33.37 24.06
86.32 48.20 34.75
116.2 64.89 46.78
and ∆ connection or ∆ and
23rd 25th
1.274 0.882
2.158 1.494
4.342 3.006
6.240 4.320
10.24 7.092
15.05 10.42
20.18 13.97
29.15 20.18
39.24 27.16