90S and 90L Frame Motors: Dimensions

DRG Motor offers 13 three-phase models in IEC frame 90: in 90S, 0.75 kW (6-pole), 1.1 kW (4-pole) and 1.5 kW (2-pole); in 90L, 1.1 kW (6-pole), 1.5 kW (4-pole), 2.2 kW (2-pole) and a compact 3 kW 2-pole unit (DRG-90L-2K-GG). Both lengths share a 90 mm shaft height, a 24 × 50 mm shaft and the same B5 flange (P 200 / N 130 / M 165 mm); what separates S from L is the lengthwise foot-hole spacing B (100 / 125 mm) and the overall length (336 / 361 mm).

Grey DRG three-phase electric motor – example image for 90S and 90L frame motor selection

You can filter every model in this frame by power and speed in the DRG electric motor shop, or see the full range on the three-phase asynchronous electric motors page. Each standard 90S/90L model is available with an aluminium frame and with a cast iron frame; the compact 3 kW comes in cast iron only.

90S vs 90L: foot length and body length

This is where maintenance teams replacing a frame 90 motor most often go wrong. The number “90” is the shaft height; the letter is the body length. In the DRG catalogue, 90S and 90L share the transverse foot spacing (A), the distance from shaft shoulder to front foot hole (C), the foot hole (K), and all shaft and flange dimensions. Only two figures change: the rear foot hole sits 25 mm further back and the motor grows by 25 mm. Put a 90L on a base drilled for a 90S and the front holes line up while the rear ones do not; the same happens the other way round.

Dimension	90S	90L	Meaning
H – shaft height	90 mm	90 mm	Floor to shaft centre; the frame number comes from it
A – foot holes across	140 mm	140 mm	Transverse hole spacing on the base
B – foot holes lengthwise	100 mm	125 mm	The only foot difference between S and L (25 mm)
C – shaft shoulder to front foot hole	56 mm	56 mm	Sets coupling/pulley alignment
K – foot hole	4–Φ10	4–Φ10	Four holes; limits bolt diameter
D × E – shaft	24 × 50 mm	24 × 50 mm	Key width F = 8 mm
L – overall length	336 mm	361 mm	90L is 25 mm longer than 90S

In practice: for a foot-mounted (B3) motor, measure the old motor’s foot holes lengthwise. If you read 100 mm, look for a 90S; 125 mm means a 90L. When the nameplate only says “90”, this measurement is the quickest way to find the letter.

Power and pole table: which kW in 90S, which in 90L?

Within one frame length, power drops as the pole count rises, because at lower speed the same body carries more torque. Torque values in the tables are calculated from the rated speed with T = 9550 × P / n; for example 2.2 kW at 2895 rpm gives 9550 × 2.2 / 2895 ≈ 7.26 Nm. All frame 90 models are connected 230/400 V (Δ/Y).

Frame 90S models

Power and poles	Aluminium frame	Cast iron frame	Rated speed / current / torque
0.75 kW (1 HP) – 6 pole, 1000 speed class	DRG-90S-6-AL	DRG-90S-6-GG	935 rpm / 1.93 A / 7.66 Nm
1.1 kW (1.5 HP) – 4 pole, 1500 speed class	DRG-90S-4-AL	DRG-90S-4-GG	1445 rpm / 2.48 A / 7.27 Nm
1.5 kW (2 HP) – 2 pole, 3000 speed class	DRG-90S-2-AL	DRG-90S-2-GG	2895 rpm / 3.06 A / 4.95 Nm

Frame 90L models

Power and poles	Aluminium frame	Cast iron frame	Rated speed / current / torque
1.1 kW (1.5 HP) – 6 pole, 1000 speed class	DRG-90L-6-AL	DRG-90L-6-GG	945 rpm / 2.69 A / 11.1 Nm
1.5 kW (2 HP) – 4 pole, 1500 speed class	DRG-90L-4-AL	DRG-90L-4-GG	1445 rpm / 3.3 A / 9.91 Nm
2.2 kW (3 HP) – 2 pole, 3000 speed class	DRG-90L-2-AL	DRG-90L-2-GG	2895 rpm / 4.35 A / 7.26 Nm

“1000 / 1500 / 3000 rpm” is the synchronous speed class; the rated speed under load is slightly lower (935, 1445, 2895 rpm and so on). Use the rated speed for pulley or ratio calculations; the electric motor calculator is handy for a quick check.

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Same kW, different frame: the S/L trap at 1.1 and 1.5 kW

In frame 90 the same power appears in two lengths. 1.1 kW is a 90S at 4 poles but a 90L at 6 poles. 1.5 kW is a 90S at 2 poles but a 90L at 4 poles. An order that says only “1.5 kW, frame 90” is therefore incomplete: the 2-pole 1.5 kW has 100 mm foot spacing, the 4-pole 1.5 kW has 125 mm. The shaft (24 × 50 mm) is common, so the coupling is not the issue; the base holes and the space behind the motor are.

Torque matters as well. The 2-pole 1.5 kW motor delivers 4.95 Nm, while the 4-pole 1.5 kW motor delivers 9.91 Nm. Keeping the kW but changing the speed changes both the speed and the load of the driven machine. For similar power ranges see also 1.5 kW flange motor and 2.2 kW flange motor.

Compact DRG-90L-2K-GG: 3 kW in a 90L frame

In the standard sequence, a 3 kW 2-pole motor moves up to frame 100L. The DRG-90L-2K-GG delivers the same power in a 90L frame. That helps when space is tight, but as a replacement for a 100L the dimensions do not match. The comparison below is taken from the product data:

Item	DRG-90L-2K-GG (compact)	DRG-100L-2-GG (standard)
Power / poles	3 kW / 2	3 kW / 2
IEC frame	90L	100L
Shaft height H	90 mm	100 mm
Shaft D × E	24 × 50 mm	28 × 60 mm
Feet A × B	140 × 125 mm	160 × 140 mm
Overall length L	361 mm	406 mm
Current at 400 V / torque	5.71 A / 9.9 Nm	5.71 A / 9.9 Nm
Bearing	6205-ZZ-C3	6206-ZZ-C3

The electrical values (current 5.71 A, torque 9.9 Nm) look the same, but the shaft drops from 28 mm to 24 mm and the shaft height from 100 mm to 90 mm. Coupling hub, pulley bore and base height need to be reviewed accordingly. Do not pick the compact model from a “3 kW” filter alone; the letter K in the code marks the difference. For the 100L options, see the 3 kW flange motor article.

24 × 50 mm shaft and B5 flange dimensions

The IM B5 (large flange) rows in the DRG catalogue give the same flange for 90S and 90L; only the overall length changes. Check outside diameter P, spigot diameter N, bolt circle M and hole diameter S one by one; a matching outside diameter alone is not enough.

Dimension	90S and 90L	Description
P	200 mm	Flange outside diameter
N	130 mm	Spigot (pilot) diameter
M	165 mm	Bolt circle diameter
S	12 mm	Flange hole diameter
T	3.5 mm	Spigot depth
LA	12 mm	Flange thickness
D × E	24 × 50 mm	Shaft diameter × length
F	8 mm	Key width
G	20 mm	Shaft to key bottom
DH	M8×19	Shaft end thread
L	336 mm (90S) / 361 mm (90L)	Overall length (B5)

For frame-by-frame comparison, use the B5 motor flange dimensions table; for shaft sizes by power, the motor shaft diameter by kW table. If you are working on a drawing, the files on the 2D technical drawings page will help.

B14, B34 and gearbox inputs: what to know

The DRG catalogue has no B14 small-flange dimension table, so no B14 figures are given here. If you need B14 or a foot-and-small-flange (B34) motor, measure the flange outside diameter, bolt circle, spigot diameter and thread size and send them via WhatsApp so we can confirm. Mounting arrangements are compared in B3, B5, B14 and B35 mounting types and B34 ordering dimensions.

A frame 90 motor is often bolted to a gearbox input. The gearbox size code alone is not enough: input flange dimensions, input bore (compare with the 24 mm shaft), key width (8 mm), ratio and permitted load must be read from the gearbox nameplate and documents. DRG does not sell gearboxes; it supplies the motor only. See choosing a flange motor for a gearbox and electric motors for worm gearboxes.

Aluminium or cast iron?

In frame 90 both materials are listed with the same kW, poles and catalogue dimensions, so the choice depends on the working environment more than on the mounting. Aluminium is lighter; cast iron offers a sturdier body where vibration and shocks are present. The compact 3 kW is cast iron only. Both use 6205-ZZ-C3 bearings and a 1 × M25×1.5 cable entry, with IP55 protection, class F insulation and IC411 cooling. The details are in aluminium vs cast iron housing.

Six checks before ordering

Nameplate power (kW) and rated speed: the pole count decides whether a given kW is 90S or 90L.
Lengthwise foot spacing B: 100 mm (90S) or 125 mm (90L); A = 140 mm on both.
Shaft: 24 × 50 mm, key 8 mm. If the old motor is a 100L, its shaft is 28 × 60 mm.
For flange mounting, P, N, M and S each on their own.
Rear clearance: a 90L is 25 mm longer than a 90S.
Current and cable: 400 V currents are in the tables; use the motor cable size calculator and the motor current chart.

Send a photo of the old motor’s nameplate together with the shaft/flange dimensions, and we will confirm the choice between 90S, 90L and the compact model with you.

Send a photo of your current motor nameplate and we will find the suitable DRG model together.Send on WhatsApp

Browse the 90S and 90L frame motors and their current prices in the shopSEE PRICES

Frequently asked questions

Can I bolt a 90L motor onto a 90S base?

The front foot holes and shaft height are the same, but the rear holes differ by 25 mm. Without drilling new holes or using an adapter plate, the rear bolts will not seat.

Do 90S and 90L motors have the same shaft?

In the DRG catalogue both lengths and all pole counts have a 24 × 50 mm shaft, 8 mm key and M8×19 shaft-end thread, so there is no dimensional difference between S and L on the coupling or pulley side.

How do I choose between DRG-90L-2K-GG and DRG-100L-2-GG?

Power (3 kW) and speed class are the same. On a new machine with limited space, the compact 90L suits. When replacing an existing 100L motor, the standard 100L keeps the 28 mm shaft and 100 mm shaft height, so it is the better choice.

Where can I find B14 flange dimensions for a frame 90 motor?

The DRG catalogue has no B14 table. Send the outside diameter, bolt circle, spigot diameter and thread size of your current flange via WhatsApp and we will confirm suitability.

DRG Motor is a manufacturer, supplier and seller of electric motors. To compare with other frames, read the electric motor price list by frame size and the motor frame size order guide.

Electric Motors Related to This Topic — Models and Current Prices

Suitability is not decided by power alone: compare the speed, voltage, mounting, shaft and fixing dimensions of your machine with the product data; if unsure, send us the nameplate of your current motor.