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Frequency converters 3.7 kW

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3.7 kW Variable Frequency Drives — Motor Control at the Small-to-Medium Power Boundary

The 3.7 kW power rating is a standard frame size across most VFD manufacturers and corresponds to motors widely used in industrial and utility equipment. Variable frequency drives (VFDs) at this rating typically operate on 3×380 V supply, deliver output current in the 8–10 A range, and provide soft start, precise speed control, and motor overload protection.

Applications for 3.7 kW VFDs

This power class covers a wide range of industrial tasks:

  • Water supply and irrigation pumps — reduced inrush current, pressure control via PID regulator.
  • Fans and exhaust systems — scalar U/f control enables significant energy savings at partial loads.
  • Conveyors and belt systems — smooth start and adjustable conveying speed without jerking.
  • Small compressors — stable pressure maintenance under variable load.
  • Mixers and agitators — precise RPM control for process requirements.
  • Machine tool auxiliaries — coolant pumps, secondary drives.

3.7 kW VFD Models

The chastotnik.ua catalog lists 13 models rated at 3.7 kW from leading manufacturers. Below is a comparison of key parameters based on real sales data:

ModelBrand / SeriesSupplyCurrent, AKey Feature
Delta VFD037E43ADelta Electronics / VFD-E3×380 V8.2Built-in PLC, PID, encoder input
Delta VFD037EL43ADelta Electronics / VFD-EL3×380 V8.2Compact, built-in EMC filter, Modbus
Mitsubishi FR-D740-080SC-ECMitsubishi Electric / FR-D3×380 V8.0Vector control, built-in brake chopper
Mitsubishi FR-F840-00083-E2-60Mitsubishi Electric / FR-F3×380 V6.9Optimised for fans/pumps, IP20, RS-485
Danfoss 195N0074Danfoss / VLT 28001×220 V16.0Single-phase 220 V input, IP20

How to Choose a 3.7 kW VFD

Key selection criteria:

  • Supply voltage: most models require 3×380 V. For single-phase 220 V connection, Danfoss VLT 2800 (195N0074) is the right choice.
  • Load type: for pumps and fans (quadratic torque load) scalar U/f control is sufficient; for conveyors and machine tools with dynamic loads, vector control is recommended — such as Mitsubishi FR-D740 or Delta VFD-E.
  • Communication interface: for SCADA or PLC integration, select models with Modbus RTU or RS-485.
  • Enclosure rating: all catalog models are rated IP20; for wet or dusty environments, mount inside a protective enclosure or consider 5.5 kW models with higher IP ratings.

Other Power Ratings

Browse adjacent power categories: 2.2 kW · 3.0 kW · 5.5 kW · 7.5 kW. Full catalog available at Variable Frequency Drives.

Warranty and Support

All 3.7 kW VFDs in the chastotnik.ua catalog are supplied with official manufacturer warranty. Delivery across Ukraine via Nova Poshta. Cash on delivery or bank transfer for legal entities. Contact our technical team for selection guidance and connection support.

Frequently Asked Questions

What is a variable frequency drive and how does it work?

A VFD is an electronic device that converts AC mains voltage to DC (rectifier stage), then back to AC with adjustable frequency and amplitude (inverter stage). By varying the output frequency from 0 to 600 Hz, it smoothly controls the rotational speed of an AC induction motor from standstill to rated speed and beyond, while limiting starting current to 1.5× rated.

How do I size a VFD for my motor?

The VFD power rating should equal or exceed the motor nameplate power. For pumps and fans (variable torque), select based on the motor rating. For conveyors, cranes, and crushers (constant torque or heavy starting), choose one power step above — for example, for a 4 kW conveyor motor, we recommend a 5.5 kW VFD. Also verify that the motor's rated current does not exceed the VFD's current rating.

Can I run a three-phase 380V motor from a single-phase 220V supply?

Yes, you need a VFD with single-phase 220V input and three-phase 380V output, such as the Veichi AC70E or AC10 T/S2 variant. Power is limited to 2.2–4 kW depending on the series. The VFD not only starts the motor but also provides soft starting, speed control, and overload protection.

What is the difference between scalar and vector control?

Scalar control (V/f) maintains a constant voltage-to-frequency ratio — a simple, reliable method for pumps, fans, and compressors. Vector control (SVC, FOC) calculates motor current and flux vectors in real time, delivering 150–200% rated torque at low frequencies. Vector control is essential for conveyors, elevators, extruders, cranes, and CNC machine tools.

Why do I need an EMC filter in a VFD?

An EMC (electromagnetic compatibility) filter reduces high-frequency interference that the VFD generates in the power supply and airwaves. It is mandatory for facilities with sensitive equipment (medical, laboratories, server rooms), residential buildings, and when the cable between VFD and motor exceeds 25 m. The Veichi AC10, Delta VFD-E, and INVT GD20 models include a built-in Class C3 EMC filter.

How much energy does a VFD save?

On pumps and fans, savings range from 20% to 60% depending on the load profile. Power is proportional to the cube of speed (P∝n³): reducing speed by 20% halves energy consumption. If equipment typically operates at 70–80% of rated speed, average savings are approximately 40%. Payback period for a VFD on a pumping station is 6 to 18 months.