Product Overview
A synchronous reluctance motor runs at exact synchronous speed under load — no slip — using a specially-shaped steel rotor that contains no magnets at all. That makes the rotor as robust as an induction rotor while delivering exact speed, with no rare-earth dependency. Reuland builds these to 50 HP and 12,000 rpm on standard NEMA frames, engineered to order with no minimum quantity — the choice when you want slip-free synchronous speed and rugged simplicity without committing to a magnet supply.
Related Reuland synchronous & specialty motors
Line-Start & AC Synchronous PM — PM efficiency — ~20% higher efficiency, across-the-line or inverter
Inverter-Driven PM (IPM & SPM) — high-power flux-vector PM — IPM to 1,000 HP, SPM to 30,000 rpm
NEMA Design D High-Slip — the high-slip induction alternative for shock and pulsating loads
Key Features & Benefits
- Exact speed under load — zero slip — a synchronous machine locks to the supply frequency and holds rated speed regardless of load, where an induction motor always slips a few percent. The reason to choose synchronous: the process speed does not wander as the load changes.
- Built to your exact spec, not pulled off a shelf — every Reuland synchronous motor is engineered from the ground up to your electrical and mechanical requirements — voltage, speed, frame, mounting, shaft, enclosure — and built foundry-to-test in-house. No minimum quantity: one motor or a production run.
- Process synchronization and tension control — because every motor on a line holds the same exact speed, multiple drives stay in step section to section — the basis for web-tension and line-synchronization control in fiber, glass, wire, and converting. What you reach for when several drives must track one another precisely.
- High-speed-capable construction — M-19/M-36 laminations, hand-wound stators, Class H insulation, and ABEC-7 precision bearings give the platform the headroom for high-speed and high-duty service (the speed envelope is in the specifications). The same construction that serves test-stand and spindle duty.
Specifications
- Operating principle
- Synchronous AC machine — runs at exact synchronous speed under load (no slip). The rotor contains no magnets, so it is as robust as an induction rotor with no rare-earth dependency.
- Rotor & excitation
- Reluctance rotor — no magnets and no rotor windings. A specially-shaped steel rotor follows the rotating stator field at synchronous speed; torque comes from the rotor’s magnetic reluctance, not from magnets.
- Power range (HP)
- Up to 50 HP.
- Speed range
- Up to 12,000 rpm (higher speeds available — consult factory).
- Voltage
- Up to 600 V.
- Phase
- 3-phase.
- Frequency
- 50/60 Hz across-the-line; to nominal 1,000 Hz on an inverter.
- Poles
- 2, 4, 6, and 8-pole.
- Control method
- Across-the-line; open-loop and flux-vector.
- Stator construction
- M-19 or M-36 electrical-steel laminations (other lamination grades on request), hand-wound for balanced, symmetrical windings.
- Rotor construction
- Specially-shaped steel rotor on M-19 or M-36 electrical-steel laminations; a die-cast cage is added on line-start builds for across-the-line starting. No magnets and no rare-earth content.
- Frame
- Standard NEMA frames 56–326.
- Enclosure / cooling
- Fan-cooled (TEFC/DPFC), auxiliary-fan-cooled (A-TEFC/A-DPFC), and non-ventilated (TENV/ODP).
- Insulation class
- Class H insulation throughout — the high-temperature class Reuland uses on its synchronous and high-speed machines for thermal headroom and for the voltage stress a fast-switching inverter waveform imposes.
- Bearings
- High-precision ABEC-7 — steel-ball, ceramic-ball, or roller bearings, selected to the speed and duty.
- Build & lead time
- Every Reuland motor is custom-built to your exact electrical and mechanical requirements — foundry through final test in-house, with no minimum quantity (one motor or thousands). No published price list; quote-only, lead time set per job. Expedited lead times are available based on factory capacity.
Common Applications
- High-speed process machinery — exact, slip-free speed
- Line-synchronization drives — multiple motors holding the same exact speed
- Compressors and pumps where rare-earth magnet supply or cost is a concern
- Spindles and machine tools requiring repeatable speed without magnets
Fit guide: choose synchronous reluctance when you want exact synchronous speed and a rugged, magnet-free rotor. Where efficiency and power density are paramount and a magnet supply is acceptable, see the line-start PM or the high-power inverter-driven IPM/SPM class.
Design & Selection Considerations
- Decide the start method before the rotor type — a line-start PM motor starts across-the-line on its die-cast cage and then pulls into synchronism; a pure-synchronous, IPM, or SPM machine needs an inverter to start and run. Settle whether the motor must start direct-on-line or will always run on a drive — it determines the class. The single question that picks PM line-start vs. inverter-driven.
- Inverter-fed windings see extra voltage stress — a VFD’s fast-switching waveform stresses winding insulation; Reuland’s Class H system is specified for it, and on a drive the motor can be wound for the drive’s actual output voltage rather than full line voltage to cut drive and feeder cost. Use the input form to tell us the drive model and how it will be operated.
- Protect bearings against VFD shaft currents — inverter operation can drive circulating currents through the bearings; bearing protection — and where needed insulated or ceramic bearings — addresses it, which is why the bearing option is specified with the drive. Easy to overlook on a high-speed PM machine, expensive to discover as fluting.
- Match the cooling to the power density — fan-cooled (TEFC/DPFC) and non-ventilated (TENV/ODP) builds suit the air-cooled NEMA-frame classes; water-cooled (TEWC) and oil-cooled (TELCW) builds are how the high-power IPM/SPM classes shed heat in a small frame. Power density and the available coolant set the enclosure, not the other way round.
- Rare-earth supply is a design input — PM classes depend on samarium-cobalt or neodymium magnets; where magnet supply, cost, or temperature is a concern, the synchronous-reluctance class gives exact speed with no magnets at all. If a magnet-free rotor matters to you, say so up front — it changes the class, not just the price.
To spec the right Reuland synchronous reluctance motor:
Use the input form to send your horsepower and speed (or poles), the voltage, phase and frequency available, the duty cycle, mounting and frame constraints, the enclosure environment, and how the motor will be driven (across-the-line or on a specific VFD/drive model) — plus any governing standards — and we’ll spec the right Reuland synchronous motor & control package for your application.
Specialty Motors Application Sheet ›Talk to an engineer directly — Scott Prater, Principal · 917-580-0878 · scott@pratertechnical.com
Specifications compiled by Prater Technical Partners from Reuland Electric published product specifications.