Frequency converters Mitsubishi Electric FR-D

The key parameter is the motor's rated current in amps (from the nameplate), not kilowatts. The VFD's rated current must equal or exceed the motor current. Power in kW is a secondary guide: at the same rating, an older 6-pole motor draws more current than a modern 4-pole. For heavy-start loads (crushers, high-inertia belt conveyors, screw compressors) go one frame size up. For pumps and fans no margin is needed — torque drops quadratically with speed, so the VFD never sees overload during ramp-up.

A soft starter limits inrush current and removes mechanical jerk; once the motor is up to speed it is either bypassed or simply holds the motor at full voltage — it cannot vary speed during operation. A VFD does both smooth starting and speed control from zero to 400–600 Hz, plus PID control of pressure or flow. The choice is straightforward: if motor speed is always constant, use a soft starter (cheaper, smaller cabinet); if any speed adjustment is needed during operation, use a VFD.

Scalar V/f control maintains a fixed voltage-to-frequency ratio and works well for pumps and fans (quadratic torque M∝n²) where speed regulation accuracy under load is not critical. Sensorless vector (SVC) is needed when the motor drives a conveyor, extruder, or hoist: full torque is required from as low as 3–5 Hz with a stiff speed characteristic. Closed-loop FOC with an encoder gives ±0.01% speed accuracy — used in cutting lines, winding, and lifting equipment. Most series in the catalogue (Veichi AC10/AC310, INVT GD20) include both modes in one unit; pure scalar-only models are INVT GD10 and GD200A.

Yes, with one important note. A single-phase input produces a three-phase output at roughly 220 V, not 380 V — that is a physics constraint, not a device limitation. The motor will deliver approximately 60–70% of its rated power due to the lower voltage. If the motor is wound for star-connection at 220 V it will run at full power. Models in our catalogue with single-phase 220 V input and three-phase output: Veichi AC10-S2, Veichi AC01-S2, INVT GD10-S2, INVT GD20-S. To drive a 380 V three-phase motor from a single-phase supply you need either a step-up transformer or a VFD with a built-in boost stage.

Over 1,720 models from 14 manufacturers in stock. Largest selections: Danfoss (225 SKUs: VLT FC102/FC202/FC302), Schneider Electric (218: Altivar 12/310/320/610/650/950), Siemens (182: Sinamics G120/G130), Bosch Rexroth (159: EFC/VFC 3610/5610), INVT (138: GD10/GD20/GD200A/GD350), ABB (123: ACS355/ACS580/ACS880), Veichi (123: AC01/AC10/AC310/AC70). By sales volume 2025–2026 Veichi AC10 and AC310 lead — primarily because of their price-to-feature ratio and available Ukrainian service centre. Warranty is 12 months on all series, 24 months on Veichi AC10/AC310 and INVT GD20.

Four factors. Power: price scales roughly linearly with kW. Control type: scalar VFDs cost 15–30% less than vector models at the same power. Features: built-in PLC, Profinet/EtherCAT interface, braking chopper, EMC filter, STO certificate — each option adds to the price. Brand: Japanese and European series (Mitsubishi FR, Siemens G120, Danfoss FC302) cost more than Asian brands at the same rating. Reference prices: budget 1.5 kW — from UAH 3,500; mid-range 5.5 kW — from UAH 9,000; industrial 37 kW with Profinet — from UAH 65,000.

A braking resistor is needed when the motor brakes frequently or decelerates a high-inertia load: hoists, centrifuges, cutting lines. During regenerative braking the VFD feeds energy back into the DC bus; without a resistor the bus voltage climbs until the OV protection trips. An input reactor (line choke) is recommended for drives 22 kW and above, or when powering from a generator: it reduces capacitor inrush peaks and cuts harmonic THDi from 80–120% down to 30–40%. On sites with sensitive equipment, fit both a reactor and an EMC filter together.

First localize the source. Disconnect the motor from outputs U/V/W and run the drive with no load. If the fault clears, the problem is in the motor or cable (shorted turns, a damaged cable, a damp terminal box). If E.OC persists even without a motor, the output power module (IGBT) is damaged: measure resistance between the DC+/DC- bus terminals and outputs U, V, W — zero resistance confirms a breakdown. A special case for drives above 40 kW: dried-out thermal paste under the heatsink lets the module overheat locally within milliseconds, faster than the temperature sensor can react — inspection and re-pasting fixes it.

No. A VFD is neither a stabilizer nor a step-up transformer — its output will never exceed the voltage coming in. For 220 V-class drives the motor rated voltage (parameter F02.05 on Veichi) is kept within ~253 V: that is the ceiling of a 230 V +10% supply, above which you risk the DC-bus capacitors. If the motor really lacks torque at low speed, the answer is not «more voltage» but the correct control mode (vector SVC instead of scalar V/f) and torque boost — not inflating the voltage figure.

Yes — stray voltage on the housing is both a safety issue and the reason nearby electronics (scales, controllers, sensors) misbehave. First rule: the motor ground wire must go directly to the VFD PE terminal, not to a shared building bus — otherwise high-frequency PWM currents return through «earth» and induce a potential on the housings. If you measure more than 5 V between neutral «0» and protective earth, the grounding loops must be separated. Ground the shield of signal cables (4-20 mA sensors) at one end only — at the VFD side — otherwise the shield itself becomes an antenna.