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 list of the equivalent capacity limits), harmonics must be calculated by the equation in next subheading. equipment and is calculated by the following equation. If the sum of equivalent capacities is higher than the limit (refer to the P0 = Σ (Ki Ч Pi) [kVA] *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 harmonic amount and is different from the power supply capacity required for actual inverter drive. Ki: Conversion coefficient (Refer to the list of the conversion factors.) Pi: Rated capacity of harmonic generating equipment *1 [kVA] i: Number indicating the conversion circuit type Calculation of outgoing harmonic current harmonic content Outgoing harmonic current = fundamental wave current (value converted from received power voltage) Ч operation ratio Ч • Operation ratio: actual load factor Ч 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 Determining if a countermeasure is required per 1 kW contract power Ч contract power. A countermeasure for harmonics is required if the following condition is satisfied: outgoing harmonic current > maximum value Harmonic suppression techniques 56 3.
PRECAUTIONS FOR USE OF THE INVERTER 3.2 Power supply harmonics 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) (No reactor, 100% operation ratio) 200 V 400 V 5th 7th 11th 13th 17th 19th 23rd 25th 0.4 1.61 0.81 49 0.57 31.85 20.09 4.165 3.773 2.107 1.519 1.274 0.882 0.75 2.74 1.37 83 0.97 53.95 34.03 7.055 6.391 3.569 2.573 2.158 1.494 1.5 5.50 2.75 167 1.95 108.6 68.47 14.20 12.86 7.181 5.177 4.342 3.006 2.2 7.93 3.96 240 2.81 156.0 98.40 20.40 18.48 10.32 7.440 6.240 4.320 3.7 13.0 6.50 394 4.61 257.1 161.5 33.49 30.34 16.94 12.21 10.24 7.092 5.5 19.1 9.55 579 6.77 376.1 237.4 49.22 44.58 24.90 17.95 15.05 10.42 7.5 25.6 12.8 776 9.07 504.4 318.2 65.96 59.75 33.37 24.06 20.18 13.97 11 36.9 18.5 1121 13.1 728.7 459.6 95.29 86.32 48.20 34.75 29.15 20.18 15 49.8 24.9 1509 17.6 980.9 618.7 128.3 116.2 64.89 46.78 39.24 27.16 No.
Item Description 1 Reactor installation (FR-HAL) Install an AC reactor (FR-HAL) on the AC side of the inverter to suppress outgoing harmonic currents. 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 When two transformers are installed with a phase angle difference of 30° in and ∆ connection or ∆ and ∆ connection, the combination of the two transformers are equivalent to a 12-phase rectifier, 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.