A PMAC motor — permanent magnet AC motor — is a three-phase permanent magnet synchronous machine driven from an inverter, sized and mounted to go where an induction motor and its drive sit today. The rotor carries magnets instead of a squirrel cage, so there is no rotor current and no slip, and the losses that heat a cage rotor simply do not occur. That is where the efficiency comes from, and it is why a PMAC motor holds its efficiency down at part load and part speed, where an induction motor falls away.
Innotec Power has built permanent magnet machines since 2005 and manufactures them at an ISO 9001:2015 plant in Faridabad, India. We publish more than 350 models with full ratings, and we wind and machine to order: no minimum quantity, 4–6 weeks standard and 6–8 weeks for a custom build, ex-works India.
PMAC, PMSM, BLDC — what the names actually mean
These three terms cause more confusion than any others in this product category, and buying the wrong one wastes weeks. All three describe a permanent magnet rotor. What differs is the supply and the current waveform.
| Term | What it usually means in practice | Typical supply |
|---|---|---|
| PMAC | PM synchronous motor driven with sinusoidal current from an AC drive, in an industrial frame. Used where an induction motor plus VFD would otherwise go. | 400 V or 565 V DC bus from an AC drive |
| PMSM | The engineering term for the machine itself. A PMAC motor is a PMSM; so is a traction motor on a battery bus. | Any |
| BLDC | The same class of machine driven with six-step (trapezoidal) commutation, usually from a battery or DC bus at 24–96 V. | 24 V, 48 V, 72 V, 96 V DC |
If you are replacing an industrial induction motor on mains supply, you want the PMAC range on this page. If you are building a battery-powered machine, go to our brushless DC motor range instead, which covers 24 V through 96 V. The underlying machines are built on the same frames in the same factory — only the winding and the drive differ.
The PMAC range: 31 models, 1 to 120 kW
Our AC-bus machines are built on the 255 and 360 frames and published for a 400 V or 565 V DC bus. The 565 V bus is the one that matches a standard 400 V or 415 V three-phase industrial supply through a drive; 460 V three-phase, the common North American industrial supply, is equally straightforward. Tell us your grid voltage and we wind the motor for it — the winding is set per order, so the motor is matched to your supply rather than to a catalogue entry.
| DC bus | Models | Continuous power | Continuous torque | Rated speed | Rotor |
|---|---|---|---|---|---|
| 400 V / 565 V | 31 | 1 – 120 kW | 19 – 912 Nm | 60 – 3,000 rpm | SPM |
Model codes follow the frame and bus, for example 255-AZZS565-002 on the smaller frame and 360-AEZS400-065 or 360-CEZS565-200 on the larger. Full ratings for every model are on the high voltage motor range, and the 400 V machines are listed separately on the 400 volt motor page.
Two things are worth noting about that speed column. The bottom of the range, 60 rpm, is a direct-drive rating — these are machines built to turn a load without a gearbox, which is a different proposition from a 4-pole induction motor and a reducer. And the top of the range is a rated speed, not a limit: because there is no rotor current, a PM machine can be wound for a speed that suits the load rather than the supply frequency.
Mounting: NEMA C-face, IEC flange, or your drawing
This is the part that decides most projects, and it is where a built-to-order manufacturer has an advantage over a catalogue. The electrical design is only half the job — the motor still has to bolt to what you have.
We build the mechanical interface to the application:
- NEMA C-face — for North American machinery where the gearbox, pump or bracket is already cut for a C-face register and bolt circle.
- IEC flange and foot — B3 foot, B5 and B14 flange, and B35 combined foot-and-flange, for European and Indian installations.
- Customer drawing — shaft diameter and extension, register, bolt circle, terminal box position and cable entry to your print.
Shaft, flange and register dimensions are set per order rather than picked from a shelf, so a PMAC motor can be specified as a mechanical drop-in for the induction motor it replaces while running at a far better efficiency. Tell us the frame the existing motor is in, or send the drawing, and we will confirm the fit before you order.
NEMA C-face mounting dimensions
These are the standard NEMA MG 1 C-face dimensions. If you know the frame designation of the motor you are replacing, this table tells you the interface we build to. All dimensions in inches.
| Frame | Shaft dia. (U) | Shaft length (N-W) | Register / rabbet (AK) | Bolt circle (AJ) |
|---|---|---|---|---|
| 56C | 0.625 | 1.875 | 4.500 | 5.875 |
| 143TC, 145TC | 0.875 | 2.250 | 4.500 | 5.875 |
| 182TC, 184TC | 1.125 | 2.750 | 8.500 | 7.250 |
| 213TC, 215TC | 1.375 | 3.375 | 8.500 | 7.250 |
| 254TC, 256TC | 1.625 | 4.000 | 8.500 | 7.250 |
| 284TC, 286TC | 1.875 | 4.625 | 10.500 | 9.000 |
Frames above 286TC — 324TC, 326TC, 364TC, 365TC and larger — are built to order. Send us the frame designation and we will confirm the interface dimensions before you commit.
IEC B5 flange mounting dimensions
For IEC installations, the B5 flange interface by frame size. All dimensions in millimetres.
| Frame | Shaft dia. (D) | Shaft length (E) | Spigot / register (N) | Bolt circle (M) | Flange OD (P) |
|---|---|---|---|---|---|
| 71 | 14 | 30 | 110 | 130 | 160 |
| 80 | 19 | 40 | 130 | 165 | 200 |
| 90S, 90L | 24 | 50 | 130 | 165 | 200 |
| 100L, 112M | 28 | 60 | 180 | 215 | 250 |
| 132S, 132M | 38 | 80 | 230 | 265 | 300 |
| 160M, 160L | 42 | 110 | 250 | 300 | 350 |
| 180M, 180L | 48 | 110 | 250 | 300 | 350 |
| 200L | 55 | 110 | 300 | 350 | 400 |
| 225S, 225M | 60 | 140 | 350 | 400 | 450 |
| 250M | 65 | 140 | 450 | 500 | 550 |
| 280S, 280M | 75 | 140 | 450 | 500 | 550 |
| 315S, 315M | 80 | 170 | 550 | 600 | 660 |
Two-pole machines at frame 225 and above take a smaller shaft than the four-pole and slower designs, so confirm the pole count when you specify. B14 face mounting, with tapped holes instead of clearance holes, is available on the smaller frames.
Efficiency, and how we prove it
The efficiency argument for permanent magnet machines is straightforward: no rotor current means no rotor copper loss. In our own measurements, inverter-fed machines in this range run at around 95% efficiency. Peak efficiency differs from model to model and rating to rating — the larger, faster machines do better than the small ones, and every motor has an operating point where it is at its best. Two qualifications go with any figure we quote: it is the motor alone rather than the motor and drive together, and it applies at a stated operating point rather than across the whole speed and load range. Ask us for the number on the specific model you are considering and we will give you the measured one.
Every motor we ship is tested individually, not batch-sampled. The routine covers winding resistance, insulation resistance, hipot, back-EMF constant, no-load run, loaded run and temperature rise, and the test report is issued on request. If you need efficiency verified to a particular standard for a tender, tell us at the enquiry stage and we will confirm what we can supply.
Where PMAC motors earn their place
A PMAC motor is worth specifying where the motor runs long hours, where it runs at part load a lot of the time, or where the physical envelope is tight. It is not usually worth it for an intermittent load that runs a few minutes a day.
- Pump drives, including servo-pump conversions on injection moulding machines and presses, where the duty cycle swings and a PM machine holds efficiency at part load.
- HVAC and air handling, and HVLS fans, where a direct-drive PM motor removes the belt drive and the losses that go with it.
- Cooling tower fans, where a direct-drive motor replaces the gearbox and driveshaft entirely.
- Traction and material handling, where torque density decides the packaging.
- Low-speed direct drives, where the gearbox can be designed out rather than specified.
Where a brake is part of the machine function rather than a safety afterthought, we build it in — see the brake motor range.
Drives
A PMAC motor needs a drive that can commutate a permanent magnet machine; a general-purpose V/f drive will not do it properly. We supply matched controllers with the motors, and the standard position feedback is an RLS Sin/Cos encoder. If you are pairing our motor with a third-party drive, send us the model and we will confirm the parameters it needs.
What we need to quote
The fastest route to a real number is these five things:
- Continuous power or torque, and the speed you need it at.
- Supply voltage, and whether you are using our drive or your own.
- The mounting — NEMA frame, IEC frame, or a drawing.
- Duty cycle, and the ambient the motor sits in.
- Annual quantity, so we quote the right price break.
If you are replacing an existing motor, a photo of the nameplate plus the mounting dimensions is usually enough to start. Send us the details and we will come back with a model and a price.
PMAC motors: common questions
What is a PMAC motor?
A permanent magnet AC motor: a three-phase synchronous machine with magnets on the rotor, driven with sinusoidal current from an AC drive. It does the job of an induction motor and VFD, at a higher efficiency and in a smaller frame.
What is the difference between a PMAC motor and a BLDC motor?
The machine is the same class. The difference is the drive: a PMAC motor is driven with smooth sinusoidal current, a BLDC motor with six-step commutation. Sinusoidal drive gives lower torque ripple and quieter running, which is why industrial and servo applications use it. BLDC is usual on low-voltage battery systems.
Can a PMAC motor replace an induction motor?
Usually yes, but it is not a direct swap on the electrical side — a PM motor cannot start across the line and always needs a drive. Mechanically it can be a drop-in, because we build the shaft, flange and mounting to match the motor you are replacing.
Do you build PMAC motors in NEMA and IEC frames?
Yes. We build NEMA C-face, IEC B3, B5, B14 and B35 mounting, and to customer drawings. The mechanical interface is made to order rather than chosen from stock — see the dimension tables above for the standard interfaces.
What supply voltage do your PMAC motors run on?
They are wound to your grid voltage. The published range covers a 400 V or 565 V DC bus, which corresponds to 400 V and 415 V three-phase mains through a drive; 460 V three-phase for North America is equally standard. Tell us the supply and we wind for it.
What is the largest PMAC motor Innotec makes?
The published AC-bus range runs to 120 kW and 912 Nm on the 360 frame. Above roughly 75 kW we treat it as a custom build rather than a standard product.