Анонс нового обладнання Група продуктів: Інвертор Лінійка продуктів: опції EFR (дроселі змінного струму, реактори DV/DT, синусні фільтри) Частина 2
We are pleased to announce the release of new inverter options from the Inverter family.
4. EFR-HAL – AC Reactors (Input Chokes)
4.1 Role of AC Reactors in Drive Systems
AC reactors (input chokes) are installed on the supply side of the inverter. Their primary function is the reduction of current harmonics (THDi) drawn from the power supply.
4.2 Reduction of Current Harmonics (THDi)
AC reactors are one of the possible an cost-efficient means of reducing THDi in inverter systems. Based on internal measurements from Nagoya Works, the table below shows indicative (≈) THDi levels at 75% load for three representative inverter power ratings. Availability & Migration – Key Information
- For medium and high power inverters, a DC reactor is obligatory by design, therefore operation without any reactor is not applicable.
- Adding an AC reactor on top of the DC reactor provides a further, measurable reduction of THDi.
- Values shown are orientative, intended for comparison and application guidance.
4.3 Large Transformers and Power Factor Correction Capacitors
Installation of an AC reactor is strongly recommended or mandatory in the following cases:
- The inverter is supplied from a large-capacity power transformer (typically ≥ 1000 kVA)
- The power supply is considered stiff
- Power factor correction capacitors are installed upstream of the inverter and may be switched
In these configurations, excessive peak currents can occur, potentially damaging the inverter rectifier. Application limits and transformer-to-inverter power ratios are defined in the inverter documentation (e.g. FR-F800 series), where AC reactor usage is explicitly required beyond defined thresholds.
When the inverter is connected near a large-capacity power transformer (1000 kVA or more) or when a power factor correction capacitor is to be switched over, an excessive peak current may flow in the power input circuit, damaging the converter circuit. To prevent this, always install an AC reactor which is available as an option. 
4.4 Additional Benefits of AC Reactors
In addition to THDi reduction, AC reactors provide:
- Reduced electrical stress on the inverter rectifier
- Increased inverter lifetime
- Improved overall power factor
- Higher robustness of the inverter in demanding supply conditions
4.5 Sample Nameplate
4.6 Technical data table
4.6 EFR-HAL Material List
