Do you know what a cam switch is? It has been a well-known device in the energy market since the 1900s. Since it is first invented, most electrical professionals have used this device in their electrical projects. If you are not familiar with this unique device, keep on reading to understand the main types, applications, advantages and disadvantages of the cam switch.
What is a Cam Switch?
A cam switch is used to perform make and break operations in a sequential way by rotating the switch to different positions. The cam which closes and opens the contacts has rotary movement to multiple positions, thereby multiple circuit functions can be controlled.
A cam switch provides the transmission of electrical energy from one point to another by rotating at various angles with the help of a handle and shaft. Its contacts change position by turning the handle.
The cams are designed to make contact with stationary electrical contacts at specific points in the rotation allowing current to flow through the switch to control various functions in electrical systems.
Cam switches are commonly used in industrial machinery and control systems to control power circuits, motor circuits and lighting circuits. They are often used in applications that require a high degree of reliability and durability as the cam mechanism is less prone to wear and tear than traditional sliding or toggle switches.
Cam switches can be single-pole or multi-pole meaning they can control one or multiple circuits at the same time. They can also be designed to operate in various modes such as momentary or maintained depending on the specific application requirements.
How Does a Cam Switch Work?
A cam switch is operated by a rotating cam. The cam switch consists of a stationary contact block, a movable contact block, and a cam mechanism. The cam mechanism consists of a cam attached to a rotating shaft or wheel.
When the cam rotates, it pushes the movable contact block, which moves the contacts into different positions to open or close electrical circuits. The stationary contact block contains fixed contacts that remain in place while the movable contact block moves.
Types of Cam Switches
Cam switches have various types. Some of them are:
1. Isolator switches
Isolator switches are ON-OFF switches that are used to isolate the power to a particular area of operation. Isolator switches are used to isolate a circuit from its power supply for maintenance, repairs, or safety reasons.
Applications: Switching of main/control and instrumentation circuits motor ON-OFF and other special application circuits.
2. Changeover switches
Changeover switches are used to operate two different circuits with a different number of inputs and outputs.
Applications: Power supply to generator changeover, Auto/Manual changeover, Standby/Remote changeover and other special application circuits. Mainly used in distribution panels, UPS, etc.
3. Multistep switches
Multistep switches connect different circuits to a common supply or vice-versa. Multistep switches can be toggled between multiple positions, allowing the user to select from a range of settings or options
Applications: As tap changing switch for Transformer/Stabiliser and other special application circuits.
4. Voltmeter switches
Voltmeter switches measure voltages between phases and phase and neutral. The voltmeter switch allows the user to select different ranges of voltage to be measured. The switch typically has multiple positions or settings corresponding to different voltage ranges, such as 0-10 volts, 0-100 volts, or 0-1000 volts.
Applications: Voltage measurement
5. Ammeter switches
Ammeter switches measure currents in different circuits with a current transformer a single analog ammeter and a switch. An ammeter switch is used to connect an ammeter to an electrical circuit for the purpose of measuring the current flowing through it.
Applications: Current measurement
6. Motor control switches
Motor control switches are typically used for “Forward-Reverse”, “Star-Delta” and “Two Speed Forward-Reverse”.
“Forward-Reverse” switches allow the motor to rotate in either direction, while “Star-Delta” switches are used to start the motor in a low-voltage, low-current “star” configuration before switching to a high-voltage, high-current “delta” configuration for normal operation. “Two Speed Forward-Reverse” switches allow the motor to operate at two different speeds in either direction, typically by connecting the motor windings in different configurations.
They are also designed to operate with a contactor having a built-in tripping feature in the event of a power failure and overload.
Applications: These types of switches are commonly found in industrial and commercial settings where electric motors are used for machinery, pumps, and other applications.
7. Gang switches
Gang switches increase the capacity of circuits by ganging in serial or parallel operations for different circuit capacities. Serializing enhances the power of the battery supply and paralleling the power of the resistor.
Applications: In railway coaches for controlling the alternator and battery supply. Also in telecom panels and special application circuits.
8. Control switches
Control switches are used to energize contactors for controlling motor operations. Most switches are “Spring return” types for latching the circuit with NO contact and facilitating tripping by the tripping device.
Applications: Control switches offer a unique alternative to multiple “Push Button Stations” when one switch controls instead of many push buttons. A control switch with many positions is offered for a suitable combination.
Advantages of Cam Switch
The advantages of the cam switch include the following:
- It is very simple to use.
- It works like a transfer switch and transfers energy from one point to another.
- It is cheap and compact in size.
- It requires no maintenance.
- It can be used in AC and DC applications.
- It has a high degree of IP protection.
- It can be mounted to the panel door or inside the enclosure.
- It has lots of contact variations.
- It can operate in low and high temperatures without derating.
- It has a short installation time.
- It has a long electrical and mechanical life.
Disadvantages of Cam Switch
The disadvantages of the cam switch include the following.
- It does not have any protection function against thermal and magnetic currents.
- It cannot be controlled remotely.
- A physical rotational force must be applied to switch it.
- It cannot switch very high currents.
- It has a limited voltage and current rating.
- It is not very flexible and is usually limited to a few specific positions.
- It is difficult to automate and cannot be easily controlled by computers or other electronic devices.
Cam Switch Applications
Cam switches have a wide range of application areas. Some of them are:
1. Motor control
Cam switches are commonly used in motor control circuits to provide on-off control, forward-reverse control and overload protection for electric motors.
2. Lighting control
Cam switches can be used to control lighting in commercial, industrial and residential applications. They can be used to switch lights on and off or to control multiple lights from one location.
3. Industrial machinery
Cam switches are used in various industrial types of machinery such as conveyors, presses and packaging equipment to control the on-off operation of motors, lights and other electrical components.
4. HVAC systems
Cam switches are used in heating, ventilation and air conditioning (HVAC) systems to control the on-off operation of fans, compressors and other electrical components.
5. Power distribution
Cam switches can be used in power distribution panels to control the on-off operation of individual circuits such as lighting circuits or motor circuits.
6. Portable equipment
Cam switches are commonly used in portable equipment such as power tools to provide on-off control of the electrical power supply.
7. Marine applications
Cam switches are used in marine applications such as boats and ships to control the on-off operation of electrical components such as lights, motors and pumps.