Control speed.
Cut energy. Protect machines.
A VFD lets a standard AC motor run at exactly the speed the process needs. We select, supply, program and commission drives from 0.4 kW to 710 kW — and build the panels they live in.
How a drive works
A VFD takes fixed 50 Hz mains, converts it to DC, then rebuilds a new AC supply at whatever frequency and voltage the motor needs. Motor speed follows frequency — so 25 Hz gives roughly half speed.
- Rectifier — diodes convert 3-phase AC into DC.
- DC bus — capacitors (and often a DC reactor) smooth and store energy.
- IGBT inverter — switches the DC thousands of times a second (PWM) to synthesise variable-frequency AC.
- Control — V/f, sensorless vector or closed-loop vector control keeps torque where it's needed.
Why fit a VFD?
Large energy savings
On pumps and fans, power falls with the cube of speed — run at 80% speed and the motor draws about half the power.
Soft start, low inrush
No 6–7× starting current. Smaller gensets and cables, no voltage dips for the rest of the plant.
Less mechanical wear
Smooth acceleration protects gearboxes, couplings, belts and pipework from shock and water hammer.
Precise process control
Built-in PID holds pressure, flow, level or tension automatically from a sensor signal.
Motor protection
Overload, phase loss, stall, over/under-voltage and PTC thermistor protection in one device.
Connected
Modbus RS-485 as standard, with BACnet, CANopen and Ethernet options for PLC, BMS and IoT.
Drives we supply & support
Fuji Electric FVR series — from simple micro-inverters to multi-function drives for heavy industry.
Small conveyors, fans, mixers and OEM machines.
- SUPPLY
- 1-ph 200 V · 3-ph 400 V
- I/O
- 5 DI · 1 transistor out · 1 relay · 2 AI · 1 AO
- COMMS
- Modbus RS-485
- OVERLOAD
- 150% 1 min · 200% 0.5 s
Pumps, blowers and general machinery needing PID.
- SUPPLY
- 1-ph 200 V · 3-ph 400 V
- I/O
- 5 DI · 1 transistor out · 1 relay · 2 AI · 1 AO
- COMMS
- Modbus RS-485
- CONTROL
- V/f & dynamic torque vector
Conveyors, extruders, compressors, cranes and process lines.
- SUPPLY
- 1-ph 200 V · 3-ph 230 V · 3-ph 400 V
- I/O
- 7 DI · 2 transistor out · 1 relay · 2 AI · 1 AO
- COMMS
- Dual-channel Modbus RS-485
- DUTY
- Heavy & normal duty ratings
Heavy industry: mills, large fans and pumps, hoisting.
- SUPPLY
- 3-ph 230 V · 3-ph 400 V
- I/O
- 9 DI · 4 transistor out · 2 relay · 2 AI · 2 AO
- COMMS
- Modbus RS-485 · 3 option ports
- OVERLOAD
- HD 200% 3 s / 150% 1 min · ND 120% 1 min
Purpose-built for the job
HVAC & Buildings
- 0.75–710 kW, built-in EMC filter
- BACnet MS/TP, Modbus RTU, Metasys N2
- Fan macros, real-time clock, 4 PID sets
- IP55 option
Water & Pumps
- Multi-pump control — up to 9 pumps
- Anti-jam & pipe-fill modes
- Fire mode (forced run)
- Dry-run & flow detection
Elevators
- 200% 0.5 s / 150% 60 s overload
- 6 S-curves for ride comfort
- ARD rescue on 240 V single phase
- STO, SIL 3 · CANopen
Solar Pumping
- True MPPT for maximum water output
- Dry-pump & tank-level detection
- Sleep function, low-power signal
- Modbus for remote monitoring
What could a VFD save you?
For centrifugal pumps and fans the affinity laws apply: flow ∝ speed, pressure ∝ speed², power ∝ speed³. Throttling a valve or damper wastes that difference as heat and noise; a drive simply slows the motor down.
| Speed | Flow | Power |
|---|---|---|
| 100% | 100% | 100% |
| 90% | 90% | 73% |
| 80% | 80% | 51% |
| 70% | 70% | 34% |
| 60% | 60% | 22% |
Indicative estimate for centrifugal loads, 300 days/year, compared with valve/damper control at ~85% of rated power. Actual savings depend on your duty profile — we'll measure it for you.
Choosing the right drive
Getting these right at the start avoids nuisance trips, overheating and early failures.
| Check | What to look at | Why it matters |
|---|---|---|
| Load type | Variable torque (pumps, fans) or constant torque (conveyors, hoists, extruders) | Sets normal-duty vs heavy-duty rating — constant-torque loads often need a size up |
| Motor current | Size by motor nameplate amps, not just kW | Old or multi-pole motors can draw more current than a "same kW" drive allows |
| Overload & starting | Breakaway torque, acceleration time, peak loads | Crushers, mixers and hoists need 150–200% torque for short periods |
| Braking | Deceleration time, overhauling loads (cranes, inclined conveyors) | May need a braking resistor, braking unit or regenerative solution |
| Control mode | V/f, sensorless vector or closed-loop with encoder | Low-speed torque and speed accuracy for hoists, winders and positioning |
| Environment | Ambient temperature, dust, humidity, altitude | Derating above 40–50 °C; IP rating and panel ventilation must match |
| Cable length | Drive-to-motor distance | Long runs need output reactors or dV/dt filters to protect motor insulation |
| Harmonics & EMC | Supply transformer size, other sensitive loads, IEEE 519 limits | DC/AC reactors, EMC filters or active front ends keep the network clean |
| Communication | PLC, SCADA, BMS or IoT integration | Choose Modbus, BACnet, CANopen or Ethernet options up front |
Beyond the box
- Site survey & sizing — load study and drive/motor matching.
- VFD panels — with bypass, reactors, filters and ventilation designed in.
- Programming & commissioning — auto-tuning, PID loops, multi-pump and network setup.
- Retrofits — replace star-delta, DOL or damper control with a VFD.
- Repair, spares & AMC — fault diagnosis, parameter backups and preventive maintenance.
- Harmonic studies — measurement and mitigation for multi-drive installations.
Common questions
Can I add a VFD to my existing motor?
Usually yes. Most modern induction motors work well on a drive. For very old motors, long cables or extended low-speed running we check insulation class, cooling and may recommend an output filter or a forced-cooling fan.
Will a VFD save energy on a conveyor?
Less than on pumps and fans — conveyors are constant-torque, so power falls only in proportion to speed. The bigger benefits are soft starting, adjustable throughput and reduced belt and gearbox wear.
What causes VFD overvoltage trips?
Decelerating a high-inertia or overhauling load faster than the drive can absorb the returning energy. Longer decel times, a braking resistor or a regenerative unit fixes it.
Do VFDs cause harmonics?
Yes — the rectifier draws non-sinusoidal current. For most sites a built-in DC reactor and EMC filter are enough; large multi-drive installations may need AC line reactors, passive filters or active front-end drives.
Can the drive run a motor above 50 Hz?
Yes, within motor and load limits. Above base speed the motor enters field-weakening and available torque drops, so we check mechanical limits and the load curve first.
Need a drive sized?
Send the motor nameplate and application — we'll recommend the drive, options and panel.