Mitsubishi Electric FR-A800, Instruction Manual

Page: 135 / 1042

Precautions for use of the inverter Power supply harmonics
FR-A800 3 - 13
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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 in tab. 3-9, harmonics must be calculated with
the following procedure:
P0 = ∑ (Ki × Pi) [kVA]
Ki: Conversion coefficient (refer to tab. 3-8)
Pi: Rated capacity of harmonic generating equipment
[kVA]
i: Number indicating the conversion circuit type
Rated capacity: Determined by the capacity of the applied motor and found in tab. 3-11. The
rated capacity used here is used to calculate the generated harmonic amount and is different
from the power supply capacity required for actual inverter drive.
Classification Circuit type Conversion coefficient Ki
3
Three-phase bridge
(Capacitor smoothing)
Without reactor K31 = 3.4
With reactor (AC side) K32 = 1.8
With reactor (DC side) K33 = 1.8
With reactors (AC, DC sides) K34 = 1.4
5
Self-excitation three-phase
bridge When a high power factor converter is
used
K5 = 0
Tab. 3-8: Conversion factors
Received power voltage Reference capacity
6.6 kV 50 kVA
22/33 kV 300 kVA
66 kV 2000 kVA
Tab. 3-9: Equivalent capacity limits
Reactor 5th 7th 11th 13th 17th 19th 23rd 25th
Not used 65 41 8.5 7.7 4.3 3.1 2.6 1.8
Used (AC side) 38 14.5 7.4 3.4 3.2 1.9 1.7 1.3
Used (DC side) 30 13 8.4 5.0 4.7 3.2 3.0 2.2
Used (AC, DC sides) 28 9.1 7.2 4.1 3.2 2.4 1.6 1.4
Tab. 3-10: Harmonic content (Values of the fundamental current is 100%)