Variable Frequency Drives (VFD) — Motor Speed Control for Industry and Utilities
A Variable Frequency Drive (VFD, frequency inverter, AC drive) is an electronic device that controls the speed of an AC induction motor by varying the frequency and voltage of its power supply. Instead of direct-on-line starting with inrush current of 5–7× rated, the VFD provides smooth acceleration with starting current limited to 1.5× rated, dramatically extending the service life of motors, contactors, and mechanical transmissions.
The Chastotnik.ua catalog features over 1,300 VFD models rated from 0.4 to 630 kW for single-phase 220V and three-phase 380V supply. Key applications include pump control for water supply and HVAC, fan drives for ventilation systems, conveyors, compressors, and motor drives for industrial machinery and packaging lines. Implementing variable frequency control reduces energy consumption by 20–60% on variable-torque loads and eliminates water hammer in piping systems.
Where Variable Frequency Drives Are Used
VFDs work wherever an electric motor needs to change speed or start smoothly. Over 12 years we have supplied equipment to hundreds of facilities — from small wells to industrial plants with dozens of drives.
- Water Supply & Sewage — controlling pumps for wells, booster stations, and sewage lift stations. The VFD maintains stable pressure via a built-in PID controller, eliminates water hammer, and saves 30–50% on electricity.
- HVAC & Ventilation — supply and exhaust systems for commercial and industrial buildings. The drive adjusts fan output based on demand, reducing noise and energy consumption at partial loads.
- Conveyors & Transporters — soft start prevents belt slippage. Vector control provides constant torque at low speeds for precise dosing.
- Compressors — maintaining set pressure without start-stop cycles extends equipment life by 40–60%.
- CNC Machines & Spindles — spindle drives up to 600 Hz for high-speed machining, precise positioning with vector control and encoder feedback.
- Elevators & Hoists — smooth acceleration and deceleration, regenerative braking returns energy to the grid.
- Packaging Lines & Extruders — multi-drive speed synchronization with constant torque.
Benefits of Variable Frequency Control
Installing a VFD typically pays for itself within 6–18 months through direct energy savings and reduced maintenance costs.
- 20–60% Energy Savings — reducing speed by 20% cuts consumption by 50% due to the cubic power-speed relationship.
- Soft Start Without Current Spikes — starting current limited to 1–1.5× rated vs. 5–7× with direct-on-line starting.
- Extended Motor & Mechanical Life — eliminating startup shocks extends bearing, coupling, and seal lifespan. Eliminates water hammer in piping systems.
- Precise Process Control — built-in PID controller automatically maintains pressure, temperature, or level.
- Motor Protection — monitors current, temperature, overvoltage, and phase loss, stopping the motor faster than any protection relay.
- Noise Reduction — running at reduced speed significantly lowers aerodynamic and mechanical noise.
How to Choose a Variable Frequency Drive
VFD selection starts with four key parameters:
- Motor power and current — the most accurate selection parameter is the motor's rated current in amps. The VFD's rated current must equal or exceed the motor's rated current. Any motor with power below the VFD's rated power can be connected without restrictions. For heavy-start applications (crushers, presses), choose one power step above.
- Supply voltage — 1×220V for light-duty applications up to 2.2 kW, 3×380V for industrial installations. To run a three-phase motor from single-phase mains, use a 220V → 380V converter.
- Load type — variable torque (pumps, fans — quadratic M∝n²) or constant torque (conveyors, extruders, hoists — M=const).
- Control method — scalar (V/f) is sufficient for pumps and ventilation, vector (SVC/FOC) is required for precise positioning and full-torque operation at low frequencies.
Comparison of popular 4–5.5 kW models from different manufacturers:
| Model | Power | Rated Current | Max Frequency | Control | Application |
|---|---|---|---|---|---|
| Veichi AC10 | 4 kW | 9.5 A | 600 Hz | V/f | Pumps, fans |
| Veichi AC310 | 4 / 5.5 kW | 10 A | 600 Hz | SVC sensorless | Conveyors, extruders |
| Delta VFD-E | 5.5 kW | 13 A | 600 Hz | V/f, SVC | Pumps, machinery |
| INVT GD20 | 4 kW | 9.5 A | 400 Hz | V/f, SVC | Ventilation, compressors |
| Danfoss FC51 | 4 kW | 9 A | 400 Hz | V/f (AMA) | Pumps with PID |
Veichi AC10 is the best-selling VFD series in Ukraine for 2025–2026: compact housing, built-in Class C3 EMC filter, frequency range up to 600 Hz for high-speed spindles, and RS-485 (Modbus RTU) interface included as standard. For constant-torque applications requiring 150% torque at 0.5 Hz, choose the Veichi AC310 series with sensorless vector control.
VFD Manufacturers
We partner with manufacturers whose equipment is proven by years of operation at industrial facilities across Ukraine. Each brand serves a distinct market segment — from budget solutions for small businesses to premium systems for critical infrastructure.
- Veichi Electric — Chastotnik.ua's top seller. Series: AC10 (scalar, 0.4–280 kW), AC70E (single-phase 220V input, 220→380V conversion), AC310 (vector SVC/FOC, 0.75–630 kW). Built-in EMC filter, extended 0–600 Hz frequency range, RS-485 port, user-friendly keypad. Best price-to-performance ratio for most industrial applications.
- Schneider Electric — French industrial leader. Series: Altivar 310 (compact general-purpose), ATV320 (enhanced with built-in filter and STO), ATV630/ATV930 (heavy industrial processes). Supports Modbus TCP, CANopen, EtherNet/IP, PROFIBUS — seamless integration with SCADA and MES systems. Global service network.
- Danfoss — Danish HVAC and water supply specialist. Micro Drive FC51 features built-in PID controller, Automatic Motor Adaptation (AMA), and cascade control for up to 4 pumps. FC51 is deployed at waterworks, district heating facilities, and shopping center ventilation systems.
- Delta Electronics — Taiwanese manufacturer with a comprehensive product range. VFD-EL (economy, fans), VFD-E (universal, 0.4–22 kW), VFD-C2000 (high-performance with STO and auto-tuning). Delta drives operate reliably at up to +50°C without derating — critical for non-air-conditioned enclosures.
- INVT — Chinese manufacturer with 22 years of experience. GD20 (universal, built-in brake module up to 30 kW), GD200A (heavy industrial duty), GD350A (servo drive). Expansion cards for PG feedback, Modbus, PROFIBUS, Ethernet — flexible adaptation to any automation protocol.
- ABB — ACS150 (micro drive), ACS310 (pumps/fans with Safe Torque Off), ACS580 (general industrial with Direct Torque Control). Built-in Flying Start for power-loss recovery.
- Siemens — SINAMICS V20 (basic), G120C (modular with Safety Integrated), G120X (infrastructure-specific). Full TIA Portal integration, PROFINET support.
- Mitsubishi Electric — FR-D (compact), FR-E (enhanced), FR-A800 (premium with positioning). Japanese reliability, particularly suited for CNC machine tools.
VFDs by Specifications
Quick selection by key parameters:
By power rating: 2.2 kW · 3 kW · 5.5 kW · 7.5 kW · 11 kW · 15 kW · 22 kW
By supply voltage: single-phase 220V · three-phase 380V · 220V → 380V (single → three-phase)
By application: for pumps · for fans · for motors · for single-phase pumps · for generator starting
By control type: vector (SVC/FOC) · scalar (V/f)
Warranty and Support
All variable frequency drives come with a manufacturer warranty of 12 to 24 months. Our engineers will help you select the right VFD for your specific motor and application at no cost: calculate the required power rating for your duty cycle, recommend the optimal series, and advise on startup and protection parameter settings.
Delivery by Nova Poshta across Ukraine: Kyiv, Kharkiv, Odesa, Dnipro, Lviv, Zaporizhzhia, and all locations. Bank transfer with VAT for corporate customers. Consultation and orders: (093) 170-14-25.
