Synchronous Motors
Salient-pole synchronous motors for large compressors, mills and pump sets where constant speed and power-factor correction are both required.
- Rated power
- 630 – 12 500 kW
- Voltage
- 6 000 – 10 500 V
- Poles
- 4 – 12
- Speed
- 300 – 1 500 rpm
- Cooling
- IC 611 / IC 81W
- Insulation
- Class F
Above roughly 1 MW, a synchronous machine is often the cheaper answer over its life: it runs at exactly synchronous speed regardless of load, and its excitation can be used to supply reactive power back into the plant network.
That second property is usually what pays for the machine. A synchronous drive on a large compressor can hold the plant power factor without a separate capacitor bank.
Brushless and static excitation systems are both offered. Starting is by asynchronous cage with automatic field application at sub-synchronous speed.
Key characteristics
Speed independent of load
Shaft speed is fixed by supply frequency and pole count, which matters for process consistency on mills and compressors.
Reactive power on demand
Over-excitation lets the machine act as a synchronous condenser, correcting plant power factor without additional equipment.
Efficient at partial load
Efficiency stays high across the load range rather than falling away below 60 % load.
High air-gap tolerance
Salient-pole construction with a generous air gap tolerates foundation settlement better than an equivalent induction machine.
Construction
- Salient-pole rotor with damper winding for asynchronous start
- Brushless exciter with rotating rectifier bridge
- Sleeve or anti-friction bearings depending on rating and speed
- Air-to-water heat exchanger (IC 81W) for indoor installation
- Class F insulation with vacuum-pressure impregnation
Available configurations
- Brushless or static excitation
- Horizontal or vertical construction
- Air-to-air or air-to-water cooling
- Sleeve bearings with forced lubrication
- Synchronous condenser mode
Monitoring options
- Winding and bearing Pt100 sensors
- Field current and voltage measurement
- Vibration monitoring, proximity or seismic
- Air and water temperature at the heat exchanger
1 series, 4 models
A series shares one design; the variants below differ by frame size and rating. This table is generated from the series definition — the variant list is never maintained by hand.
SD — synchronous motor series
Salient-pole synchronous motors with brushless excitation for compressor, mill and large pump drives.
Offered against: SDN-2 · STD · SDS — replacement finder
| Frame | Rated powerkW | Rated voltageV | Rated speedrpm | Number of poles | Efficiency class | Rotor type | Masskg | |
|---|---|---|---|---|---|---|---|---|
| SD-630-6 | 630 | 6000 | 1000 | 6 | IE4 | Salient pole | 4200 | Details → |
| SD-1600-8 | 1600 | 6000 | 750 | 8 | IE4 | Salient pole | 8600 | Details → |
| SD-4000-10 | 4000 | 10000 | 600 | 10 | IE4 | Salient pole | 19500 | Details → |
| SD-8000-12 | 8000 | 10500 | 500 | 12 | IE4 | Salient pole | 34000 | Details → |
Principal applications
Suitable industries
Documentation for this family
PDFs supplement the pages above. Nothing here is required to establish whether a machine is a candidate.
- Download (mock)CatalogueSynchronous Motors — Technical CataloguePDF · 6.1 MB · Rev. 02 · updated 2025-11 · EN
- Download (mock)Data sheetSD Synchronous Series — Data SheetPDF · 1.2 MB · Rev. 02 · updated 2025-11 · EN
- Download (mock)DrawingSD Synchronous — Outline DrawingsRegistrationPDF · 6.9 MB · Rev. 02 · updated 2025-11 · EN
- Download (mock)QuestionnaireTechnical Questionnaire — Electric MotorsPDF / online form · 0.3 MB · Rev. 02 · updated 2026-06 · EN, RO
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