The motor and inverter experts

What types of electric motors are available?

RJW Motors and Inverters supply single-phase units running 0.12kW to 3kW on a standard 230V supply and three-phase motors that extend to 7.5kW, with TEC starting at 0.18kW and Brook Crompton covering the full range.

B56 imperial frames suit machine tools with rolled steel casings in drip-proof or totally enclosed options. Mounting styles include foot (B3), C face (B14), and D flange (B5) configurations.

How do I specify the correct motor for my application?

Electric motors have kW ratings you can match to your load demands, with single-phase limited to 3kW whilst three-phase extends to higher power outputs.

Environmental factors matter, too, with food processing needing washdown protection, dusty locations requiring totally enclosed fan cooling, and space constraints influencing mounting choices between foot, face or flange configurations.

Single-phase vs three-phase motors?

230V domestic supply restricts single-phase motors to 3kW maximum output. 400V industrial connections let three-phase units deliver consistent torque above 0.75kW with superior efficiency.

Capacitors complicate single-phase starting, especially on larger motors. Three-phase designs start directly, maintain cooler temperatures, and handle continuous duty without additional components.

What is the life expectancy of an electric motor?

It’s normal for an electric motor to last 15-20 years when it is appropriately specified for your application.

Aggressive environments significantly reduce lifespan – chemical vapours attack windings, dust blocks cooling vents. Choosing the correct enclosure type from the start protects your investment better than any maintenance routine.

How do I select the appropriate motor speed?

Your driven equipment determines pole selection – fans typically need 2800-3000rpm two-pole motors, pumps suit 1400-1500rpm four-pole units, and conveyors often use 950-1000rpm six-pole designs. Direct coupling requires exact speed matching.

Variable speed drives offer flexibility when fixed speeds won’t suffice. Belt reduction from faster motors sometimes provides better control than direct-drive arrangements.

Where can I find more information or assistance?

RJW Motors and Inverters provide technical support on 0800 999 0200. Our facility stocks the electric motors covered above, plus compatible drives and accessories.

What is the difference between an inverter and a VFD?

There is no difference, just different terminology. Variable Frequency Drive (VFD) is the technical term; inverter is what everyone calls them in practice.

Both convert fixed mains frequency into a variable output to control motor speed. Whether you see an Invertek Optidrive E3 labelled as an inverter or VFD, it performs the same function.

How do I select the right VFD for my motor?

Check your motor nameplate for kW rating, voltage, and phase type first. Match these exactly to VFD specifications – a 2.2kW motor needs at least a 2.2kW drive.

Environmental conditions determine enclosure rating: IP20 for clean panels, IP66 for washdown areas. Application type matters too – pumps need different control modes than fans or conveyors.

Why match the voltage ratings between the VFD and the motor?

Mismatched voltages destroy equipment rapidly – a 400V drive outputting to a 230V motor burns windings, and 400V motors on 230V drives have insufficient torque and overheat.

Supply voltage must also align: UK three-phase runs 400V, single-phase uses 230V. The Optidrive E3 three-phase accepts 380-480V input, covering standard UK industrial supplies perfectly.

Can a single-phase VFD drive a three-phase motor?

Not properly — you’ll get poor performance and early failure. Single-phase drives output single-phase power regardless of the motor type connected.

Some converters claim to run three-phase motors from a single-phase supply but deliver reduced power and reliability. Buy the right equipment initially instead of bodging incompatible combinations.

What are the benefits of using a VFD?

Energy savings pay for drives quickly — running pumps and fans at 80% speed uses half the power. Soft starting eliminates mechanical shock and electrical spikes during motor startup.

Process control improves dramatically with variable speed instead of throttling valves or dampers. Reduced wear on mechanical components extends equipment life significantly beyond fixed-speed operation.

Single-phase inverter vs three-phase — what’s the difference?

Power capacity separates them — single-phase handles up to 3kW on a 230V domestic supply. Three-phase systems manage much larger loads using 400V industrial power, with better efficiency throughout.

Installation differs too: single-phase plugs into standard sockets, whilst three-phase needs proper industrial wiring. Cost and complexity increase with the three-phase but so does capability and reliability.

Where can I purchase high-quality VFDs?

RJW Motors and Inverters stock Invertek Optidrive E3 and Commander C200 ranges in both single and three-phase versions. Ring 0800 999 0200 for expert sizing guidance.

Download technical data from our website. Email [email protected] with your details for accurate quotations and availability.