How Does a Rotary Switch Work? A Comprehensive Guide

Rotary switches are important electromechanical components used for circuit control in a wide range of industries, especially in scenarios such as automotive systems and industrial equipment where precise control of multiple positions is required. In this guide, we'll look at how they work, their types and selection criteria to help you understand their critical role in electrical systems.

What is rotary switch？

Rotary switches are multi-directional electrical switches that control multiple circuits by rotating a shaft or actuator to different positions. Unlike common switches, rotary switches can be switched in multiple directions, making them ideal for applications that require mode selection, voltage regulation, or multi-circuit management, primarily in vehicle door, appliance, medical, and industrial equipment control. In addition, these rotary switches are internally structured so that two quadrature output signals (Circuit 1 and Circuit 2) can be directly connected to the encoder processing chip.

Features

Multiple contacts: Rotary switches generally have multiple contact positions, usually 2~4 positions, but some rotary switches can reach 12 positions.

Small and robust: Rotary switches are small, compact and rugged, and the housing material is usually PC or nylon, which is highly resistant to shock and suitable for high-cycle operation. Bearings are made of corrosion-resistant alloys or stainless steel for harsh environments.

Simplified circuit: Rotary switches can be configured with poles and throw points for complex circuit wiring to simplify circuit design.

Waterproof and Dustproof: Depending on the actual use, waterproof rotary switches can also be customized with a waterproof and dustproof IP-rated design to protect the internal components from water vapor, dust, and chemicals.

Structure of Rotary Switches

Rotor: The rotor is usually a center shaft made of metal or reinforced plastic that changes position and circuitry as you turn it.

Contacts: Metal terminals configured within a disk, each terminal completes a circuit when it makes contact with the rotor contact arm.

Terminal: External connection point for wiring, generally PCB-mounted or pre-wired.

Applications

Home Appliances: In home appliances rotary microswitches are commonly used in fans, audio equipment, light switches lights.

Automotive: commercial car door detection, car instrument panel such as adjusting air conditioning, audio adjustment.

Industrial: used in the control of conveyor belts and robotic arms.

Working Principle of Rotary Switch

The operating principle depends on mechanical rotation and sequential contact engagement, primarily in “make before break” and “break before make” modes. When the knob is rotated, the rotor and its spokes move across the wafer surface, alternating between insulating and conducting segments.

Rotation: When you turns the knob, the internal rotor and its attached spokes or cams rotate.

Contact engagement: As the rotor turns, the spokes cross over the insulating part of the wafer and land on the conductive notches, closing the circuit at the corresponding terminals.

Connecting Circuit: Current flows from the common input to the selected output through the open contacts, energizing the selected circuit.

The Types of Rotary switch

• Single Position Single Throw (SPST): The most basic form of switching, consisting of a common terminal input and a terminal output, controlling the through-connection of a single circuit.
• Single-pole double-throw (SPDT): A common terminal input circuit that connects two circuits, commonly used in audio equipment, etc.
• Multi pole Multi Throw ( MPMT ): Enables a single switch to switch multiple circuits at the same time, essential in multi-phase motor control.
• Make Before Break( MBB) : Overlaps contacts during switching to maintain circuit continuity, connecting to the next contact before disconnecting the previous one to keep the contacts seamlessly connected. Suitable for sensitive signal circuits.
• Break Before Make(BBM) : The previous circuit is broken before the next circuit is closed, which prevents short circuits.

How to Choose the Rotary Switch 

Number of Positions

Determine how many different modes or circuits you need to control. For example, whether your product needs a 2-position rotary switch or a 4-position rotary switch.

Current and Voltage Rating

Ensure that the switch can handle the max electrical load of your device，to prevent short circuits. For heavy-duty applications, choose a high-current rotary switch. Also consider whether your product requires uninterrupted signal continuity and select s MBB or BBM switch as required.

Durability

Choose a durable rotary switch, if the equipment is often exposed to harsh or outdoor environments, it is necessary to select a waterproof rotary switch with an IP48 or IP67 or even higher rating to block water vapor, dust, and other contaminants from entering the internal structure of the switch and causing malfunctions.

Global Standards

Choosing a rotary micro switch that meets international safety standards such as UL, cUL, ENEC, CQC, etc., and considering a reputable micro switch manufacturer, such as Unionwell, reduces supply risk and improves the Cost effectiveness of your product.

Unionwell Rotary Switch

Unionwell manufactures two main types of rotary micro switches, including the G2 Series Rotary Micro switch and the G16 Series Swing Rotary Switch.

Rotary Micro Switch 

G2 Series rotary micro switch, with IP64 level waterproof design and small compact size. Electrical and mechanical life of at least 100,000 cycles.，At the same time, there are good electrical properties, for example, this switch has low contact resistance, the maximum initial value of 100mΩand high dielectric strength, 500VAC at 50-60Hz, can be well adapted to automotive electronics, home appliances, industrial control and other fields.

Swing Rotary Switch

The G16 series swing rotary switches are designed for precise angular positioning with a total travel position (TTP) of up to 40°. The Water and Dust Proof rating is IP67 and can withstand extreme temperatures ranging from -40°C to 85°C, allowing for a wide range of application scenarios. Customized terminals are also available, with a wide range of PCB terminals and solder terminals.Φ2.0×2.0mm posts with 9.5mm center distance, optimized for high-density layouts.

Conclusion

Rotary switches are essential components for controlling multiple circuits with a single device. Their multi-position design makes them ideal for applications requiring precise switching, such as in automotive, industrial, and home appliances. Understanding their internal structure, working principle, and types helps you to select the right switch. 

Unionwell has more than 20 years of experience in the production of micro switches and has obtained several system certifications such as ISO, IATF, and global safety certifications such as ENEC, UL, cUL, RoHS-certified. Contact us today to upgrade your rotary switches！