Compact Electric Motors

The compact series consists of three-phase motors that deliver familiar power and speed ratings in an IEC frame one size smaller. The electrical data on the nameplate stay the same as the standard counterpart; what changes are the outer dimensions and the points where the motor connects to the machine.

What does the compact series mean?

The size of an electric motor is referred to by its IEC frame number. The figure in that number gives the height of the shaft centre above the foot base in millimetres. The standard table assigns a specific frame to each power and speed.

In a compact model this pairing is shifted down by one step. The HEM Motor compact series covers these three pairings:

• 11 kW and 1500 rpm: standard frame 160M, compact frame 132M.
• 5.5 kW and 1500 rpm: standard frame 132S, compact frame 112M.
• 3 kW and 3000 rpm: standard frame 100L, compact frame 90L.

The letter “K” at the end of the model code marks the compact design. For example, 132M-4K is a four-pole compact motor in frame 132M with a power of 11 kW. It should not be confused with an ordinary four-pole motor carrying the same frame number.

In short, a compact motor fits a familiar power class into a tighter outer envelope. The practical consequence is clear: when it is put in place of an existing standard motor, the mounting dimensions do not match. The rest of this page shows that difference with concrete figures.

Compact models available

Three compact models are currently listed. Each product page shows the nameplate data, the B3 dimensions and an order link.

• 132M-4K compact motor: 11 kW (15 HP), four poles, synchronous speed 1500 rpm, aluminium frame, IEC 132M.
• 112M-4K compact motor: 5.5 kW (7.5 HP), four poles, synchronous speed 1500 rpm, aluminium frame, IEC 112M.
• 90L-2K compact motor: 3 kW (4 HP), two poles, synchronous speed 3000 rpm, cast iron frame, IEC 90L.

To compare all options at the same speed, see the 1500 rpm electric motors and 3000 rpm electric motors pages. The current price is shown on the cards and on the product page; you can also request a quote via WhatsApp from the section below.

Standard versus compact: dimension comparison

The table places each compact model next to its standard counterpart of the same power and speed. Dimensions apply to the foot-mounted (B3) design and are in millimetres. Cable entry and front bearing data are included as well.

The letters mean: H shaft height, A×B transverse and longitudinal distance between the foot holes, D×E shaft diameter and shaft length, K number and diameter of the foot holes, L overall motor length, and AC frame diameter. You can read how a frame number is interpreted in the question on frame number and shaft size.

In the 11 kW pair the shaft height drops from 160 mm to 132 mm. The shaft becomes Ø38 × 80 mm instead of Ø42 × 110 mm, and the overall length falls from 608 mm to 476 mm. The cable entry is 2 × M32×1.5 instead of 2 × M40×1.5, and the front bearing is 6208-ZZ-C3 instead of 6309-C3.

In the 5.5 kW pair the shaft height goes from 132 mm to 112 mm, and the shaft from Ø38 × 80 mm to Ø28 × 60 mm. The transverse foot spacing is 190 mm instead of 216 mm. The longitudinal spacing stays at 140 mm, yet the overall length shortens from 438 mm to 394 mm.

In the 3 kW pair the shaft height drops from 100 mm to 90 mm. The foot holes become 4–Φ10 instead of 4–Φ12, and the foot spacing 140 × 125 instead of 160 × 140. The frame diameter is 182.4 mm instead of 205.4 mm.

As you can see, several mounting dimensions change in every pair. One matching value does not mean the motor will sit correctly on the machine.

Same electrical data, different mechanics

When choosing a compact model, no new electrical calculation is needed. Rated speed, current, torque, power factor and starting ratios are the same as the standard counterpart. Summary of the three pairs:

• 132M-4K and the standard 160M-4 aluminium: rated speed 1465 rpm, 20.4 A at 400 V, rated torque 71.7 Nm, cos φ 0.85, Is/In 7.7.
• 112M-4K and the standard 132S-4 aluminium: rated speed 1460 rpm, 10.7 A at 400 V, rated torque 36 Nm, cos φ 0.83, Ts/Tn 2.
• 90L-2K and the standard 100L-2 cast iron: rated speed 2895 rpm, 5.71 A at 400 V, rated torque 9.9 Nm, cos φ 0.87, Ts/Tn 2.2.

The other frame materials of the standard counterparts are listed too: 160M-4 cast iron, 132S-4 cast iron and 100L-2 aluminium.

Because the currents are identical, the same figures are used when selecting protective devices. The winding voltage does not change either: the 11 kW and 5.5 kW models are wound for 400/690 V (Δ/Y), the 3 kW model for 230/400 V (Δ/Y).

The only thing that changes is how the motor attaches to the machine. Since shaft, foot and frame dimensions differ, the compact model cannot be mounted straight in place of the standard model; the dimensions must always be compared.

What to check before a changeover

If you plan to put a compact model in place of a standard motor, or the other way round, go through these items one by one:

• Shaft height and base frame: when H gets smaller, the shaft axis moves down. To avoid misalignment with the gearbox, pump or fan, the base needs a riser plate or a new mounting.
• Foot holes: A×B and K differ, so the existing bolt holes usually do not line up. Plan new holes or an adapter plate.
• Shaft diameter, shaft length and coupling or pulley hub: since D×E is smaller, the coupling half or pulley hub is selected or machined for the new shaft diameter. Check the keyway at the same time.
• Overall length and layout: when L changes, the coupling gap changes too. Leave space behind the fan cover for cooling air.
• Flange size: on flanged designs the flange diameter and bolt circle depend on the frame size. A compact B5, B14 or B35 design is specified in the order, and the dimensions are confirmed at the quotation stage. For options, see the B5 and B14 flange motors and B34 and B35 foot and flange motors pages.
• Voltage and connection: compare the nameplate voltage (400/690 V or 230/400 V) with your supply. The terminal links are then set to delta (Δ) or star (Y).
• Cable entry: on the 11 kW compact model the gland size drops to M32×1.5. Check whether your existing cable gland suits this size.
• Nameplate and photo: send a photo of the old motor's nameplate and of the terminal box wiring via WhatsApp, and we will confirm the dimensions together.

Doing these checks at the drawing stage of a new machine, or before removing the motor from a running one, makes the job easier.

When can a compact model be considered?

The compact series is not the first option for every application. It may be worth considering in the following cases:

• If space is tight: if the space reserved for the motor is limited and a standard frame does not fit, a frame one size down may be the answer.
• If a new machine is being designed: if the base, coupling and guard are not yet drawn, the compact dimensions can be used from the start.
• If the same compact motor is being renewed: if a small-frame compact motor already runs in the machine, the compact model with the same power and frame is the easiest route in terms of dimensional fit.

If you are changing a running standard motor and do not want to modify the base, choosing the standard-frame counterpart usually means less work. Before deciding, compare the table above with the dimensions on your machine.

Information needed for a quote and order

So that we can prepare the right motor quickly, please include the following in your message:

• Power (in kW or HP).
• Speed: 1500 or 3000?
• Frame: compact or standard; the IEC frame number if known.
• Mounting type: foot-mounted B3, flanged B5 or B14, foot and flange B35.
• Quantity and delivery city.

You can send these details to our WhatsApp line and attach a nameplate photo. The current price is shown on the cards and on the product page; a quote is prepared according to quantity and mounting type.

Frequently Asked Questions

Can a compact motor replace a standard motor?

Electrically it does the same job, but mechanically it cannot be mounted straight in its place. Shaft height, foot holes, shaft diameter and overall length differ; the base and coupling need adapting.

Is the power or torque of the compact model lower?

No. The 132M-4K gives the same 71.7 Nm rated torque and the same 1465 rpm rated speed as the 160M-4. The nameplate data of the other two models also match their standard counterparts.

Is the frame number on the nameplate enough on its own?

It is not. For example, a 132 mm shaft height appears both on the 11 kW compact 132M-4K and on the 5.5 kW standard 132S-4. Power, speed and model code should be read together.

Can compact models be ordered with a flange?

A B5, B14 or B35 design can be requested by stating it in the order. Because flange dimensions vary with the frame, they are confirmed separately at the quotation stage.

Which frame materials are the compact models offered in?

The 132M-4K and 112M-4K have aluminium frames, while the 90L-2K has a cast iron frame. The standard counterparts are listed in both aluminium and cast iron.

Where can I see the prices?

The current price is shown on the cards and on the product page. For quantity purchases or a special mounting type, you can request a quote via WhatsApp.