Mitsubishi Electric FR-A842-07700, Instruction Manual

Page: 82 / 128

Power supply harmonics
PRECAUTIONS FOR USE OF THE INVERTER
81
3
• 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 (refer to
page 80 ), harmonics must be calculated with the following procedure:
• Calculation of outgoing harmonic current
Outgoing harmonic current = fundamental wave current (value converted from received power voltage) × operation ratio ×
harmonic content
• Operation ratio: Operation ratio = actual load factor × operation time ratio during 30 minutes
• Harmonic content: Found in page 80 .
• Rated capacities and outgoing harmonic currents of inverter-driven motors
• 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
P0 = ∑ (Ki
×
Pi) [kVA] ∗2
Rated capacity: Determined by the capacity of the
applied motor and found in Table 5. 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.
Ki: Conversion coefficient (Refer to page 80 )
Pi: Rated capacity
∗2
of harmonic generating equipment [kVA]
i: Number indicating the conversion circuit type
Applicable
motor
(kW)
Fundamental
wave current
(A)
Fundamental
wave current
converted
from 6.6 kV
(mA)
Rated
capacity
(kVA)
Outgoing harmonic current converted from 6.6 kV (mA)
(With a DC reactor, 100% operation ratio)
400 V 5th 7th 11th 13th 17th 19th 23rd 25th
75 123 7455 87.2 2237 969 626 373 350 239 224 164
90 147 8909 104 2673 1158 748 445 419 285 267 196
110 179 10848 127 3254 1410 911 542 510 347 325 239
132 216 13091 153 3927 1702 1100 655 615 419 393 288
160 258 15636 183 4691 2033 1313 782 735 500 469 344
220 355 21515 252 6455 2797 1807 1076 1011 688 645 473
250 403 24424 286 7327 3175 2052 1221 1148 782 733 537
280 450 27273 319 8182 3545 2291 1364 1282 873 818 600
315 506 30667 359 9200 3987 2576 1533 1441 981 920 675
355 571 34606 405 10382 4499 2907 1730 1627 1107 1038 761
400 643 38970 456 11691 5066 3274 1949 1832 1247 1169 857
450 723 43818 512 13146 5696 3681 2191 2060 1402 1315 964
500 804 48727 570 14618 6335 4093 2436 2290 1559 1462 1072
560 900 54545 638 16364 7091 4582 2727 2564 1746 1636 1200
No. Item Description
1
Reactor installation
(FR-HAL)
The converter unit (FR-CC2) is equipped with the DC reactor on its DC side, and outgoing harmonic
current can be suppressed. By installing an AC reactor (FR-HAL) on the AC side of the inverter, the
outgoing harmonic current suppression performance can be improved.
2
high power factor
converter
(FR-HC2)
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.
3
Installation of power
factor improving
capacitor
When used with a reactor connected in series, the power factor improving correction capacitor can
absorb harmonic currents.
4
Transformer multi-phase
operation
Use two transformers with a phase angle difference of 30° as in -
Δ
and
Δ
-
Δ
combinations to provide an
effect corresponding to 12 pulses, reducing low-degree harmonic currents.
5
Passive filter
(AC filter) 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.
6
Active filter
(Active filter)
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.