The Belimo NMCB24-SR is a fast-running non-spring-return damper actuator delivering 90 in-lb [10 Nm] of torque with modulating 2-10 VDC control on AC/DC 24 V power. It direct-couples to round or square damper shafts up to 1.05 in. with a universal clamp and holds its last position on loss of power (non-fail-safe, no spring return), making it a member of the NMB platform for large commercial HVAC dampers. A faster 45-second running time speeds damper response.
Specifications sourced from the official Belimo NMCB24-SR technical data sheet (rev 2025-10-06).
Overview
Belimo NM-Series actuators are non-spring-return drives for commercial HVAC control dampers — they position the damper under power and hold the last commanded position when power is removed (there is no spring-return fail-safe). The NMCB24-SR produces 90 in-lb [10 Nm] and mounts directly to round or square damper shafts up to 1.05 in. with its universal clamp (a crank arm and brackets are available for jackshaft and linkage applications); manual positioning uses an external push button. This NMC model uses a faster 45-second motor for quicker damper response. A 2-10 VDC signal (or 4-20 mA with the ZG-R01 resistor) modulates the damper, with 2-10 VDC position feedback.
Best for
- Modulating damper control (90 in-lb)
- Non-spring-return applications (no fail-safe required)
- Outdoor-air, mixing-box and zone dampers
- Faster (45-second) damper actuation
Key Features
90 in-lb Torque
Sized for commercial HVAC dampers; direct-couples to round or square damper shafts up to 1.05 in. with a universal clamp.
Non-Spring-Return Design
Holds the last commanded position when power is removed (non-fail-safe). Lower cost and power draw than a spring-return where fail-safe is not required.
Modulating 2-10 VDC
Accepts a 2-10 VDC (or 4-20 mA with ZG-R01) signal with 2-10 VDC position feedback.
Fast 45-Second Running Time
A faster motor drives 90° in about 45 seconds — quicker than the standard 95-second NM actuator.
Push-Button Manual Override
An external push button declutches the gear train so you can position the damper by hand for setup or service.
cULus Listed
Double-insulated (Class 2), cULus listed and ISO 9001 built for long, maintenance-free service.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Belimo |
| Part Number | NMCB24-SR |
| Actuator Type | Non-Spring-Return (Non Fail-Safe) Damper Actuator |
| Nominal Voltage | AC/DC 24 V |
| Nominal Frequency | 50/60 Hz |
| Power Consumption (Running) | 2.5 W |
| Torque | 90 in-lb [10 Nm] (minimum) |
| Control Signal | Modulating |
| Operating Range (Y) | 2-10 VDC (4-20 mA with ZG-R01 resistor) |
| Position Feedback (U) | 2-10 VDC (max. 1 mA) |
| Shaft Range | Up to 1.05 in. [26.7 mm] via universal clamp; crank arm available |
| Angle of Rotation | 95° (adjustable mechanical stops) |
| Running Time (Motor) | 45 s / 90° |
| Behavior on Power Loss | Holds last position (non-spring-return) |
| Manual Override | External push button (self-locking gear) |
| Direction of Motion | Selectable with 0/1 switch |
| Electrical Connection | 18 AWG plenum cable, 3 ft [1 m], 1/2" NPT connector |
| Overload Protection | Electronic, full 0-95° rotation |
| Electrical Protection | Double insulated (Class 2) |
| Enclosure Rating | NEMA 2 / UL Type 2 |
| Ambient Temperature | -22 to 122°F [-30 to 50°C] |
| Agency Listing | cULus (UL60730-1A/-2-14, CAN/CSA) |
| Quality Standard | ISO 9001 |
| Plenum Rated | UL 2043 (suitable for air plenums) |
| Weight | 2.1 lb [0.94 kg] |
| Warranty | 5 Years |
Documentation
Related Products
Accessories & Mounting
Common Belimo accessories for mounting, linkage, signaling and powering the NMCB24-SR, drawn from the actuator datasheet. All are stocked by ZOT Supply as an authorized Belimo distributor.
Mounting & Linkage
Electrical Add-Ons
Frequently Asked Questions
What is the Belimo NMCB24-SR?
The Belimo NMCB24-SR is a non-spring-return (non-fail-safe) damper actuator for commercial HVAC. It produces 90 in-lb [10 Nm] of torque, uses modulating 2-10 VDC control on AC/DC 24 V power, and holds its last position on loss of power. Its housing is rated NEMA 2.
Is the NMCB24-SR a spring-return (fail-safe) actuator?
No. The NMCB24-SR is non-spring-return: on power loss it holds its last position rather than driving to a fail-safe position. For fail-safe operation choose a spring-return Belimo actuator (such as the EF-Series) instead.
How much torque does the NMCB24-SR provide?
It delivers 90 in-lb [10 Nm] of torque, sizing it for commercial HVAC dampers.
What shaft sizes does the NMCB24-SR fit?
It direct-couples to round or square damper shafts up to 1.05 in. using its universal clamp (K-NA). For jackshafts or off-shaft mounting, a crank arm and brackets (ZG-NMA, ZG-JSL) are available.
What control signal does the NMCB24-SR use?
It uses modulating 2-10 VDC control. The 2-10 VDC input also accepts 4-20 mA with the ZG-R01 resistor and provides 2-10 VDC feedback.
What is the difference between NMC and NMB actuators?
The NMC uses a faster motor — about a 45-second running time for 90 degrees, versus 95 seconds on the standard NMB/NMX. Both are 90 in-lb non-spring-return actuators.
How do you manually position the NMCB24-SR?
Press the external manual-override push button to declutch the gear train, then turn the damper by hand for setup or service.
Is the Belimo NMCB24-SR available from an authorized Belimo distributor?
Yes. ZOT Supply is an authorized Belimo distributor and carries the NMCB24-SR. Every unit ships factory new with Belimo's full 5-year warranty and application support.
- Actuator Type:
- Non-Spring-Return
- Torque:
- 90 in-lb
- Control Signal:
- Modulating
- Voltage:
- 24 VAC/DC
- Auxiliary Switch:
- No
- Enclosure:
- NEMA 2
- Series:
- NMC
- Running Time:
- Fast (45 s)
- Feedback Signal:
- 2-10 VDC
