1000 rpm Electric Motors

A 1000 rpm electric motor is a three-phase induction machine whose stator carries six magnetic poles. With a 50 Hz supply this winding layout fixes the rotating field at 1000 revolutions per minute, while the shaft turns slightly below that under load. HEM Motor offers this group with both aluminium and cast iron frames. All of them come with IP55 protection and class F insulation. Where a drive needs low speed and high shaft torque at the same time, this group is usually the first one to look at.

Six poles, a thousand turns a minute: how the speed group works

In an induction motor, speed is governed first of all by how many poles the winding forms. The relation is short: synchronous speed = 120 × frequency / number of poles. For 50 Hz and six poles the result is 120 × 50 / 6 = 1000 rpm. As the pole count rises the rotating field slows down; the motor delivers the same power at a lower speed and therefore with a larger turning moment.

For this reason a 6-pole electric motor transfers more torque to the shaft than a two- or four-pole motor of the same kW rating. The price is that the winding and rotor need more material. As a result the frame often grows by one or two IEC steps at the same power. When selecting, it is therefore important to look not only at kW but also at the frame number.

Synchronous speed and the rated speed on the nameplate

1000 rpm is the theoretical speed of the rotating field. For the rotor to produce torque it has to lag the field a little; this difference is called slip. The rated speed on the nameplate is the real shaft speed measured at full load and is always below the synchronous value.

The real data in this group clearly show that slip decreases as power increases:

• The smallest model, 71M2-6 (0,25 kW), runs at 855 rpm at full load; slip is noticeable at this size.
• At medium power, for example 132S-6 (3 kW), the rated value is 968 rpm.
• In the large cast iron models the value rises to 990 rpm; 355M2-6 (200 kW) is an example.

The rated range is 855–970 rpm for aluminium frames and 890–990 rpm for cast iron frames. For 355M-6 (185 kW), 355L-6 (315 kW) and 400L-6 (355 kW) our data file holds no rated speed value; speed and torque for these models are confirmed with the order. Use the rated value of your chosen model in calculations, not the figure 1000. For more detail, see the question page explaining why the actual speed differs.

Power range, frame material and IEC steps

The group is distributed by frame material as follows. The values in the table are taken directly from the product data.

Two details stand out. First, the 400L frame exists only in this speed group: delivering 355 kW with six poles requires more active material than a 355 frame can hold. Second, in the aluminium series the 11 kW model sits in a 160L frame, whereas its four- and two-pole counterparts stay in the 160M frame.

On the voltage side the rule is the same across the series: up to 3 kW the connection is 230/400 V (Δ/Y); from 4 kW upward it becomes 400/690 V (Δ/Y). For light construction and small power see the aluminium frame motors, for heavy duty and high power the cast iron frame motors categories.

Six models selected from the list and their technical values

The models below show how the group progresses from small to large. Each link leads to the relevant product page, where the dimension drawing and detailed data are available.

• 90L-6 aluminium frame: 1,1 kW; rated speed 945 rpm; torque 11,1 Nm; 230/400 V.
• 132M1-6 cast iron frame: 4 kW; rated speed 968 rpm; torque 39,5 Nm; the first step with 400/690 V connection.
• 160L-6 aluminium frame: 11 kW; rated speed 970 rpm; torque 108,3 Nm; the most powerful member of the aluminium series.
• 225M-6 cast iron frame: 30 kW; rated speed 980 rpm; torque 292,3 Nm.
• 315M-6 cast iron frame: 90 kW; rated speed 988 rpm; torque 869,9 Nm.
• 400L-6 cast iron frame: 355 kW; the largest frame of the group and of the whole range. Rated speed and torque for this model are confirmed at the quotation stage.

Three speed groups at the same power: torque, frame and current

Torque is the ratio of power to shaft speed. As speed falls, the same kW turns into a larger moment. The table below places real models of equal power side by side:

Three conclusions follow from the table. The torque of the six-pole model is roughly three times that of the two-pole model of equal power and around one and a half times that of the four-pole one. The frame number grows in every row: at 4 kW 132M replaces 112M, at 30 kW 225M replaces 200L. Rated current also rises somewhat; at 11 kW the 400 V current of 160L-6 is 22,0 A, compared with 20,4 A for the four-pole 160M-4 and 19,6 A for the two-pole 160M1-2. This difference should be taken into account when sizing cables and protective devices.

For the faster alternatives, see the 1500 rpm group and the 3000 rpm group. The effect of pole count on selection is also covered by the 2, 4 or 6 poles at the same power question.

The effect of a six-pole motor in geared drives

The output speed of a gearbox is found by dividing the motor's rated speed by the gear ratio. If a six-pole motor is connected to the same gearbox instead of a four-pole one, the input speed drops to roughly two thirds; the output speed falls in the same proportion, while output torque rises.

This should be considered from both sides:

• If the target output speed is fixed, a gearbox with a smaller ratio may be sufficient with a six-pole motor.
• If the gearbox stays unchanged, check whether the higher output torque remains within the permissible moment and thermal capacity of the gear unit.
• Because the motor frame grows, the gearbox input flange and shaft size must suit the new motor.

For a worked explanation, read the question page about the resulting output speed once a 1000 rpm motor drives the same gearbox.

Mounting dimensions and electrical connection check

Listed prices refer to the plain B3 version with feet. Choosing B5, B14 or B35 instead can alter the price; this is settled when you order. If you are replacing an existing motor with a 1000 rpm three-phase motor, make the following comparison:

• Mounting: feet only, flange only, or both.
• Shaft: diameter, length and keyway.
• Distance between the fixing holes in the feet, plus the centre height of the shaft.
• For flange designs: flange outer diameter, spigot diameter and bolt circle.
• Winding connection for 230/400 V, alternatively 400/690 V, in delta or star; together with the plant supply and the starting method.

Matching IEC frame numbers are merely a starting point; shaft and flange details must be verified separately. Especially when moving from a four-pole to a six-pole motor, the frame may step up, so base and coupling dimensions can change. The frame number question page explains what the frame code tells you. Sending us, over WhatsApp, pictures of the existing nameplate and of the wiring inside the terminal box removes most doubts.

Machines that often call for a six-pole drive

The machines below are examples where a 6-pole motor is often evaluated. A machine type on its own proves nothing about fit; what decides is the load profile, the shaft speed you actually need, how power is transmitted (via coupling, belts and pulleys or a gearbox) and the conditions on site.

• Some belt and chain conveyors: when high starting torque is needed at a slow line speed.
• Agitators and mixers: when dense products require a low mixing speed.
• Crusher and mill drives: when a large inertia mass has to be turned.
• Large-diameter fans: when blade tip speed has to be kept limited.

In these applications a four-pole motor driving through a belt reduction can sometimes give the same result. We can assess together which is more suitable once we know your drive layout.

What to prepare when requesting a quotation

For a fast and accurate quotation, simply send the following information to our WhatsApp line. You can also reach us by phone.

• Required power (kW) and speed group.
• Mounting type: B3, B5, B14 or B35.
• Supply voltage and connection (230/400 V, alternatively 400/690 V).
• Housing: aluminium or cast iron, whichever you prefer.
• How many units you need.
• If replacing a unit, a nameplate picture of the motor being removed.

You will find the up-to-date price on every model card and on the matching product page; prices follow the IE3 list dated 24.09.2026 and are displayed in USD (EUR). To see other speeds and powers at a glance, have a look at the three-phase motor model map.

Frequently Asked Questions

How many revolutions per minute does a 1000 rpm motor make at full load?

The synchronous speed is 1000 rpm, but because of slip the shaft turns slightly slower. In this group the rated values range from 855 to 990 rpm depending on the model; the difference is larger at small powers. The exact value is stated in each product's technical data.

Can a 6-pole unit rated at an equal kW take the place of a four-pole one?

Electrically it is possible, but the shaft speed drops to roughly two thirds and torque increases. The frame also often grows; at 4 kW, for example, 132M comes instead of 112M. The machine speed, base dimensions and transmission parts must be checked accordingly.

What power is the 400L frame model and why is it only in this group?

The 400L frame is used in the 400L-6 model rated at 355 kW. Because delivering this power with six poles needs more winding and rotor material, the power that fits a 355L frame in the four- and two-pole groups moves up one frame here.

Why is the rated speed not given for some large models?

For 355M-6 (185 kW), 355L-6 (315 kW) and 400L-6 (355 kW) our data set contains no rated speed or torque value. For these models we confirm the technical values via WhatsApp or phone before the order.

Where can I see 1000 rpm motor prices?

The current price is shown on each model's card and product page. Listed prices refer to the plain B3 version with feet; for a different mounting arrangement or volume purchase, simply request a quotation.