S1A Belimo Auxiliary Switch — Add-On SPDT Accessory for Damper & Rotary Actuators

Overview

The Belimo S1A Auxiliary Switch is a compact add-on designed for use with Belimo damper and rotary actuators. It provides accurate position feedback or triggers external devices when a damper reaches a specific angle. Featuring a single SPDT contact, the switching point is adjustable across the full actuator rotation range (0–100%). This makes the S1A a flexible accessory for building automation systems and control applications.

Key Features

• Single SPDT contact (changeover switch)

• Adjustable switching point over full actuator travel (0–100%)

• Switching capacity: 1 mA up to 3 A (0.5 A inductive) at AC up to 250 V

• DC switching range: 5 V to 110 V

• Factory-wired 3 ft (1 m) cable, 3 × 0.75 mm²

• IP54 / NEMA 2 enclosure protection

• Operating temperature: –22 °F to 122 °F (–30 °C to +50 °C)

• Compact, robust, and maintenance-free design

Technical Specifications

Applications

• Position Feedback: Provides a signal to building automation systems when an actuator reaches a specific position.

• Interlocks: Activates external devices such as fans or pumps based on damper position.

• Retrofit Use: Adds auxiliary switching capability to existing Belimo actuators.

• Safety & Monitoring: Offers redundancy or secondary confirmation of actuator position.

Installation & Mounting

1. Disconnect power before installation.

2. Remove the actuator position indicator if present.

3. Engage manual override and rotate actuator to a reference position.

4. Mount the S1A directly onto the actuator using the built-in guide grooves.

5. Adjust the switch setting dial to the desired switching point (0–100%).

6. Connect the wiring to terminals S1, S2, and S3 based on control requirements.

7. Restore power and test the switch operation.

Benefits

• Full-range adjustable switching point for maximum flexibility.

• Provides reliable, consistent position feedback.

• Easy installation on compatible Belimo actuators.

• Compact accessory that adds functionality without replacing actuators.

• Increases control accuracy in HVAC and building automation systems.

Ordering Information

• Model: Belimo S1A

• Type: Auxiliary Switch / Actuator Accessory

• Contacts: 1 × SPDT

• Category: Damper and Rotary Actuator Accessories