Short answer: ST30 and LT30 are labels Somfy prints on 30 mm class hardware, the drive stops and drive wheels that go with Sonesse 30 motors. For a 50 mm tube, the motors to look at are the Sonesse 50 and Sonesse ULTRA 50, which run on LT50 hardware and need at least a 1.85 in (47 mm) inside diameter. Order by the part number on the label.
The ST30, LT30 and ST50 shorthand turns up on old quotes, parts lists and shade labels. It points at a size class. The part you order is a Somfy motor with a family name and a seven-digit reference, and your tube measurement narrows the family.
The number in ST30 and LT30 is the tube class
Somfy's 24V DC Low-voltage Motor Range Databook (L-0290) uses ST30 on the Sonesse 30 hardware. It lists an ST30 Series Drive Stop and Screw, included with the crown and drive, and recommends it to keep the drive wheel quiet and seated on the motor shaft. The same book lists a soft drive wheel as "ST30/LT30 type" for the Acmeda 44 mm tube.
The 50 mm hardware in that databook carries LT50 labels instead: an LT50 stop wheel, LT50 motor mounting screws, and end caps that fit tubes with LT50/60 crown and drive sets. Read the digits as a diameter class. Thirty means the 30 mm motor family. Fifty means the 50 mm family.
The motors themselves carry Somfy family names. A 30 mm class motor is a Sonesse 30 or Sonesse ULTRA 30. A 40 mm class motor is a Sonesse 40 or an LS40. A 50 mm class motor is a Sonesse 50, a Sonesse ULTRA 50 or an LT50 exterior motor such as the Altus. Put the class next to your tube measurement and the list of candidates gets short.
Somfy motors in the 30 mm class
The Somfy Sonesse 30 RTS 24V DC Motor (1241142) is the wired, low-voltage 30 mm motor for interior roller shades on narrow tubes. Somfy rates it at 2 Nm (17.7 in-lb) and 25 rpm with a round head, and it needs a tube with at least a 1.13 in inside diameter. It runs on 24V DC from a regulated supply, draws 0.625 A, and holds 12 RTS channels.
The Somfy Sonesse 30 RS485 24V DC (1241144) is the same 30 mm class on a wired RS485 bus, for projects that run Somfy SDN through a keypad or a control system.
The battery choice is the Somfy Sonesse ULTRA 30 WireFree 12V Li-ion RTS Motor (1003310). Somfy rates it at 2 Nm and 42 dB, with a built-in rechargeable lithium-ion battery, IP 20 and 656.2 ft of open-field RTS range. Somfy lists crowns and drives for 44 mm Acmeda type tubes and 1.5 in tubes for it.
| Sonesse 30 RTS 24V DC (1241142) | 2 Nm (17.7 in-lb), 25 rpm, 24V DC, round head, 1.13 in minimum tube ID, 47 dB, IP 30 |
| Sonesse 30 RS485 24V DC (1241144) | 30 mm class, 24V DC, wired RS485 for SDN |
| Sonesse ULTRA 30 WireFree RTS Li-ion (1003310) | 2 Nm (17.7 in-lb), 12V DC Li-ion, 42 dB, IP 20, 433.420 MHz RTS |
| Sonesse 40 RTS 404S2 (1240380) | 4 Nm (35.4 in-lb), 36 rpm, 1.46 in (37 mm) minimum tube ID, 42 dB |
| Sonesse 50 506S2 RTS (1001809) | 6 Nm (53.1 in-lb), 32 rpm, 1.85 in (47 mm) minimum tube ID, 45.1 dB |
| Sonesse ULTRA 50 506A2 RTS (1002562) | 6 Nm (53.1 in-lb), 24 rpm, 1.85 in (47 mm) minimum tube ID, 38 dB |
The 50 mm class and an ST50 search
A Somfy ST50 motor search lands on the 50 mm family. In Somfy's databooks the 50 mm interior motors carry the Sonesse 50 and Sonesse ULTRA 50 names, and the matching hardware carries the LT50 label. Somfy's Sonesse 50 specification catalog sets the tube rule: the inside diameter has to exceed 47 mm.
The Somfy Sonesse 506S2 RTS 120V Motor (1001809) is the standard choice here, 6 Nm at 32 rpm and 45.1 dB on 120V AC. For a bedroom or a conference room, the Somfy Sonesse ULTRA 506A2 RTS 120V Motor (1002562) keeps the 6 Nm rating and drops to 38 dB, at 24 rpm.
The same catalog lists 50 mm accessories that serve LT50 RS485, Sonesse ULTRA 50 RTS, Sonesse 50 RTS, Sonesse 50 RS485 and Altus 50 RTS motors. Interior and exterior motors share that 50 mm platform. Torque and speed still differ by model, and the model code on the label gives you both. In 506S2, the 06 is 6 Nm.
ST40, LS40 and the 40 mm class
Between the two sits the 40 mm family. The Somfy Sonesse 404S2 RTS Motor with Fast Connector (1240380) delivers 4 Nm at 36 rpm, runs at 42 dB and needs a 1.46 in (37 mm) minimum inside diameter. The wired LS40 412R2 reaches 12 Nm in the same tube class.
Step up to the 40 mm class once the fabric outweighs a 2 Nm rating and the tube bore clears 1.46 in. Wide blackout shades often land here.
Identify the motor you already have
Before you order a replacement, pull the old motor and read its label. Somfy prints the reference, model code and voltage there. An old invoice holds less.
- Seven-digit reference. A number such as 1241142 or 1001809 names one exact Somfy motor. Search it and you have the replacement or its successor.
- Model code. A string such as 506S2 or 404S2 gives the platform, the torque in Nm and the speed band.
- Somfy address. The 74300 Cluses line confirms a Somfy motor. Our guide to the 74300 motor label walks through the rest of the label.
- Voltage and cable. 120V AC motors carry a 3-wire or 4-wire cable. 24V DC motors need a regulated power supply.
No label? Measure the tube's inside diameter and check the head shape. Round, star and square heads take different brackets. A 1.13 in bore points to the 30 mm class, 1.46 in opens the 40 mm class and anything over 47 mm (1.85 in) takes a 50 mm motor. Our Sonesse 28, 30, 40 and 50 comparison lays out the torque options inside each size.
Order crowns and drives by class
A crown and drive set adapts a motor to one tube profile, so it belongs to one motor class. For the Sonesse 30 RTS 24V DC, Somfy lists the Somfy RollEase 1.5" Crown & Drive (9020674) for RollEase 1.5 in tubes, plus sets for Acmeda 45, Louvolite 40 mm and 45 mm, Hunter Douglas 37 mm, RollEase/ZMC 2 in profiled tube and a 40 mm octagonal tube. The ST30 drive stop and screw ships with the crown and drive.
Keep the classes apart. A 30 mm crown will not seat on a 50 mm motor, and LT50 crowns and drives will not fit a Sonesse 30. Our crowns, drives and brackets guide covers tube profiles and head types in detail, and the motor's install guide in the Somfy spec library lists the sets Somfy approves for it. You can compare the full range of Somfy Sonesse motors by tube size and torque.
Common questions
Is a Somfy ST30 motor the same as a Sonesse 30?
ST30 is the series label Somfy uses on Sonesse 30 hardware, such as the ST30 drive stop and screw that comes with the crown and drive. The motor you order is a Sonesse 30, for example the Sonesse 30 RTS 24V DC (1241142), or the battery Sonesse ULTRA 30 WireFree RTS (1003310). Match it by the reference on your label.
Does LT30 mean a different motor from ST30?
Somfy's databook lists a soft drive wheel as "ST30/LT30 type" for the Acmeda 44 mm tube, so the two labels share 30 mm class hardware. On the motor side, look for the Sonesse 30 family. Check the tube's inside diameter against Somfy's 1.13 in minimum for the Sonesse 30 RTS 24V DC before you order.
Can a 50 mm Somfy motor go in a 1.5 in tube?
No. Sonesse 50 and Sonesse ULTRA 50 motors need a tube with an inside diameter over 47 mm (1.85 in). A RollEase 1.5 in tube takes a 30 mm class motor such as the Sonesse 30 RTS 24V DC with the RollEase 1.5 in crown and drive (9020674). Move to a larger tube if the shade needs more torque than that class delivers.
Do I need a new crown and drive if I change motor class?
Yes. Crowns and drives are sized to one motor class and one tube profile. A switch from a Sonesse 30 to a Sonesse 40 or 50 means new crown and drive parts and often a new bracket, because head types differ. The motor's install guide lists the sets Somfy approves for it.
Sources: Somfy 24V DC Low-voltage Motor Range Databook L-0290 (ST30 drive stop and screw, ST30/LT30 soft drive wheel, LT50 hardware); Somfy Sonesse 50 specification catalog B11EN (47 mm minimum tube ID, shared 50 mm accessories); somfypro.com product records for 1241142, 1240380, 1001809 and 1002562; somfysystems.com product page for 1003310.
Shade Motors Direct is an authorized source for genuine Somfy motorized window shade, blind, and drapery parts.
