For plants running pumps, fans, conveyors and process equipment for long shifts, motor losses are a recurring operating cost rather than a minor nameplate detail. This ABB synchronous reluctance motors review examines where ABB SynRM technology is a sound engineering choice, where it needs careful application work, and what to confirm before replacing an existing induction motor.
ABB synchronous reluctance motors are designed to operate with a variable speed drive. They use a magnet-free salient rotor rather than the squirrel-cage rotor used in a conventional induction motor. That change reduces rotor losses and supports high efficiency across a useful portion of the speed and load range. For duty with substantial annual running hours, the potential reduction in energy consumption can be commercially meaningful.
ABB synchronous reluctance motors review: the practical verdict
ABB SynRM motors are a strong option for variable-speed applications where energy efficiency, controllability and lifecycle cost matter more than the lowest possible purchase price. The technology is particularly well suited to centrifugal loads, including pumps and fans, but can also be effective on selected compressors, mixers, extruders and conveying systems when the torque profile and drive selection have been checked.
The central qualification is straightforward: this is not a direct-on-line motor replacement. The motor and drive should be treated as a matched system. Correct commissioning parameters, cable arrangements, protective functions and process control are part of the outcome. A plant that simply substitutes a motor without reviewing the drive and application may not realise the expected performance or efficiency benefit.
For industrial buyers, ABB is an established supplier with a broad drive portfolio and well-developed motor package capability. That matters where a project needs a known equipment platform, documentation, spares planning and technical support over a long operating life.
Why the technology performs differently
An induction motor creates rotor current to produce torque. Those currents create heat in the rotor, which contributes to overall losses. A synchronous reluctance rotor is shaped so it aligns with the rotating magnetic field produced by the stator. Because there is no rotor cage carrying induced current in the same way, rotor losses are lower.
In practical terms, lower losses can reduce motor heating and improve efficiency. ABB SynRM motor and drive packages are commonly specified for high-efficiency performance, including IE5-class performance in applicable configurations. The exact result still depends on the motor size, speed, load point, selected drive and operating conditions. Efficiency class alone should not be used as a proxy for site energy savings.
The synchronous operating principle also gives the drive precise control of speed and torque. This is valuable where stable process control is needed, such as maintaining pump pressure, fan airflow or web tension. The motor typically has lower rotor inertia than a comparable induction machine, which can improve response in applications involving frequent speed changes. That benefit is useful, but it should not be overstated for large high-inertia loads where the driven equipment dominates the system inertia.
Efficiency at the real duty point
The best SynRM business cases are rarely based on motor efficiency at one nominal point. They are based on the annual load profile. A continuously operated pump with a variable flow requirement may benefit from both the motor efficiency and the energy reduction delivered by speed control.
Fan and pump applications are particularly attractive because reducing speed can sharply reduce absorbed power. If a damper or throttling valve is currently controlling flow, a variable-speed solution may provide a far greater saving than a motor-only upgrade. The motor choice remains relevant, but the complete control method determines the result.
For a constant-speed, lightly loaded machine that runs only occasionally, the energy case may be less compelling. In those situations, a conventional high-efficiency induction motor may be the better commercial decision. Capital cost, outage time and available drive infrastructure need to be considered honestly.
Where ABB SynRM motors fit best
Pumps in water, wastewater, mining and process facilities are a natural fit, especially where flow or pressure varies over the operating cycle. Fan systems in ventilation, dust extraction, cooling and HVAC duty are similarly suitable. In both cases, the drive can control the process directly rather than wasting energy across a mechanical restriction.
The motors can also suit production machinery that benefits from accurate speed control, low heat losses and repeatable operation. Examples include selected material handling systems, mixers and process machinery. For conveyors, the key question is not simply whether variable speed is wanted. It is whether the application requires high breakaway torque, controlled starts under load, regenerative operation, or specialist mechanical protection. These requirements influence drive sizing and control strategy.
In harsh Australian industrial environments, ambient temperature, dust, washdown exposure, elevation, enclosure rating and mounting arrangement remain fundamental. A high-efficiency motor still needs to be specified for the site. Mining and remote infrastructure applications may also place greater value on standardisation, maintainability and availability of technical support than on the calculated energy saving alone.
Drive compatibility is not optional
A SynRM motor requires a compatible variable speed drive with the appropriate motor control capability. ABB drives are designed to support ABB SynRM motors, allowing the package to use motor data and control functions intended for the technology. This simplifies selection compared with attempting to pair an unfamiliar motor type with a drive that has not been configured for it.
The drive must still be sized for the application, not just matched to the motor nameplate kilowatts. Consider the required overload, starting torque, speed range, acceleration time, number of starts, supply conditions and expected operating mode. A mixer with changing product viscosity will have different demands from a clean-water pump, even where the motor power rating is similar.
Long motor cables, reflected-wave voltage, harmonic mitigation, earthing and electromagnetic compatibility should also be reviewed during design. These are normal variable speed drive considerations, but they are often missed in retrofit projects. On larger motors or difficult supply networks, an input reactor, harmonic solution, output filter or insulated bearing arrangement may be appropriate depending on the selected equipment and installation conditions.
Low-speed and process-duty checks
Low-speed operation deserves specific attention. Motor cooling, torque requirements and process stability can change materially below base speed. A fan-cooled motor may require derating in prolonged low-speed, high-torque duty, while a separately forced ventilation arrangement may be appropriate for demanding applications.
Confirm the required speed range and torque curve with the equipment supplier or system integrator. Also check whether the motor must hold torque at zero or near-zero speed, whether it will cycle rapidly, and whether the driven machine can tolerate the available acceleration and deceleration profile. These questions prevent a technically efficient package from becoming a process bottleneck.
Installation and replacement considerations
For an existing motor replacement, begin with the mechanical details: frame size, mounting, shaft dimensions, coupling arrangement, terminal box orientation and available clearance. Electrical details follow closely, including supply voltage, cable condition, drive rating, protection settings and control interface. A review of the existing duty cycle is essential, particularly if the old motor has been oversized or has been operating outside its intended load range.
Commissioning should verify motor identification data, rotation, current, speed feedback where used, ramp settings, minimum and maximum speed limits, and trip behaviour. The control system should also be tested against realistic process conditions rather than only a no-load run. A pump that appears satisfactory during commissioning can still operate poorly if minimum-flow requirements, suction conditions or pressure-control tuning are not addressed.
Maintenance requirements are generally familiar to teams accustomed to industrial motors and drives. Bearings, cooling paths, terminal connections, alignment and drive fault history still require routine attention. The benefit of reduced rotor losses does not remove the need for condition monitoring or proper installation practice.
Assessing the return on investment
A useful review compares the proposed package with the actual baseline, not an assumed worst-case motor. Record operating hours, measured kW, average loading, speed profile, production demand and electricity tariff. Include expected downtime, installation labour, control changes and any switchboard or cable upgrades.
The result may support a rapid payback on a continuously operating variable-load asset. It may also show that the project should be scheduled with a planned shutdown, bundled with a drive upgrade, or limited to the highest-energy motors first. Both are valid outcomes. The objective is to direct capital toward assets where efficiency and process improvements are measurable.
For projects requiring ABB SynRM motors and drives, Tech Source can assist with application-based selection rather than a nameplate-only substitution. The most productive starting point is a clear duty description, existing motor and drive details, operating hours, load behaviour and the site constraints that could affect installation. That information turns a motor review into a reliable specification decision.