What Is a Cam Switch?
A cam switch is a manually operated switch, typically activated by twisting a handle. It primarily refers to switches used for changing electrical contacts. Notably, it includes devices like front door locks within its broader classification due to the cam mechanism employed.
The cam mechanism, integral to cam switches, changes the motion direction of an object when attached to a rotating shaft. This mechanism finds applications in diverse products, including merry-go-rounds and automobile exhaust valves.
Uses of Cam Switches
Cam switches have industrial applications, such as:
- Operating high-voltage circuit breakers, including vacuum circuit breakers.
- Selecting devices for operation.
- Switching current indicators’ phase.
- Controlling the power supply of industrial equipment.
- Starting large motors.
Due to their durability and resistance to damage, cam switches are preferred for manual switching of high-voltage circuit breakers in power generation. They are designed to prevent accidental operation.
Additionally, cam switches are essential for phase switching in current indicators, requiring a closed-circuit configuration when connected to current transformers.
Principle of Cam Switches
A cam switch comprises three main components: an actuator, a mechanism, and contacts.
1. Actuator
The actuator, functioning as the handle, is usually made from durable synthetic resin and connects to the mechanism. It is marked with white lines and arrows to indicate the cam’s position alongside the mechanism’s nameplate.
2. Mechanism
The mechanism alters the contact configuration based on the handle’s position. Attached to the spindle and handle, the cam opens and closes the contacts. It’s possible to adjust the number of cams and contacts as needed.
3. Contacts
Contacts are the electrical points that complete the circuit. Typically, a terminal block is affixed to the cam switch’s rear, allowing for connection with processed terminals.
Types of Cam Switches
Cam switches are available in various types, catering to specific applications:
1. Handle Type
This type features a grip on the actuator and is commonly used for starting motors and manual circuit breaker operations. It includes models designed for pull operation, suitable for high-capacity equipment.
2. Keylock Type
Equipped with a lock to prevent unauthorized use, the keylock type is often employed to control the main power supply of industrial machinery.
3. 360° Type
The 360° type can rotate fully and is primarily used for selecting and operating industrial equipment. It may feature various handle designs and complex contact configurations.
Other Information on Cam Switches
Types of Cams
Cam mechanisms are known for their durability and maintenance simplicity. They are categorized into flat and three-dimensional cams.
Flat Cam
A flat cam uses rollers to change motion direction, offering a simple, robust, and cost-effective solution widely used in cam switches.
Three-Dimensional Cam
Three-dimensional cams, with their cylindrical or spherical shapes, provide a more compact operating area than flat cams.