What is a Cam Switch : Working, Types & Its Applications

Cam switches are electrical devices used mainly for switching in both AC & DC electrical currents and particularly used for controlling motors. These switches are made with high-quality conductive & insulating materials and these are characterized based on their size, good switching capabilities, etc. To guard them against short-circuit current within the circuits, you must use fuses through fuse links. This article discusses an overview of a cam switch – working with applications.


What is Cam Switch?

Cam switch definition is; a switch that is used to transmit electrical energy from one end to another by turning a handle & shaft at different angles. The switch contacts can also be changed by rotating the handle. The cam switch symbol is shown below.

Cam Switch Symbol
Cam Switch Symbol

This switch is used within industrial automation to automate, control, monitor & count work finished through machines known as cam switches. This is a versatile device that uses a rotation of the camshaft to control several switches at once.

The features of the cam switch include compact size, reliable design, multi pole, quick and easy installation, etc.

Working Principle

The working principle of the cam switch is to make & break operations in a sequential way by turning the switch to various positions. This type of switch has rotating movement to several positions, so several circuit functions can be easily controlled.

Many features need to consider while selecting this switch like the number of contacts, positions, voltage, and the poles it has. Here, the number of poles & contacts of this switch simply determines how many functions the device can control.

Cam Switch Wiring Diagram

The wiring diagram of the cam switch is shown below. Here, the type of cam switch used in this circuit is a voltmeter selector switch. This circuit is used to find out the voltage between three phases RY, YB, and BR by using a voltmeter. For that, a selector switch is used with a voltmeter.

Voltmeter Selector Switch or Cam Switch Wiring
Voltmeter Selector Switch or Cam Switch Wiring

The connections of this wiring can be done as per the diagram shown above. In this wiring connection, a voltmeter, a selector switch, and an MCB are used. Here the three phasings is given by connecting R, Y, and B terminals of the selector switch to MCQ. The positive and negative connections of the voltmeter are given to the V+ and V- terminals of the switch.

Once the power is given to the selector switch, the circuit will be activated. Once the knob of the switch is turned to the RY position then the voltage between the RY is shown on the voltmeter. When the knob of the switch is turned to YB then the voltage between YB is shown on the voltmeter. Similarly, when the switch knob is turned to BR, then the voltage between BR is shown on the voltmeter.

Types of Cam Switch

There are different types of cam switches available in the market like isolator, changeover, multistep, voltmeter selector, ammeter selector, motor control, and control switches.

Multistep Switches

Multi-Step switches are used to connect various circuits to a common power supply. The switches including single poles, double poles, and three poles are very famous for single, two, and three-phase power supplies. These types of switches can be used as a tap changing switch, particularly for stabilizers or Transformer, etc.

Multistep Switches
Multistep Switches

Isolator Switches

Isolator switches are also called ON-OFF switches that are mainly used to isolate the power to a particular operating region. These switches are applicable for switching of main or controlling of main, motor ON-OFF in instrumentation circuits, etc.

Isolator Switch
Isolator Switch

Voltmeter Selector Switches

Voltmeter selector switches are mainly used for switching in between phases for measurement on a 3-phase system. And also these types of switches also measure voltages in between phases & phase and neutral.

Voltmeter Selector
Voltmeter Selector

Changeover Switches

Changeover switches are very helpful in operating two different circuits by using a different no. of inputs & outputs. These switches are applicable in changeover from power supply to generator manual or auto changeover, remote or auto changeover, etc. These switches are particularly used in UPS, distribution panels, etc.

Changeover Switch
Changeover Switch

Ammeter Selector Switches

Generally, the ammeter selector switch is a typical 3- position switch. These switches are used for measuring currents within various circuits which include an analog ammeter, a switch & a current transformer, or in order to monitor current within a 3–phase system, ammeters are used within every separate line. This switch is used to decrease the number of ammeters used in a three-phase system by placing current transformers on each line & the output of the current transformer is connected to the ammeter selector switch.

Ammeter Selector
Ammeter Selector

Control Switches

Control switches are mainly used for strengthening contractors to control motor operations. These switches provide a unique option to several Push Button Stations when a single switch controls rather than several push buttons. A control switch including numerous positions can be offered for an appropriate combination.

Control Switches
Control Switches

Motor Control Switches

These switches are normally used for controlling a motor in Two Speed Forward-Reverse, Star-Delta & Forward-Reverse. These switches are mainly designed to control with a contactor which have an in built tripping feature when overload and power failure occurs.

Motor Control Switches
Motor Control Switches

Advantages & Disadvantages

The advantages of the cam switch include the following.

  • The operation of this switch is simple.
  • These switches are very simple to use.
  • This switch functions like a transfer switch that transfers energy from one position to another.
  • It is less costly.
  • Its size is compact.
  • It doesn’t require maintenance.
  • It is used in AC & DC-based applications.
  • It has high IP security.
  • This switch can be connected to the panel door or within the enclosure.
  • It can work in high & low temperatures without de-rating.
  • Its installation takes less time.
  • These switches have long mechanical & electrical life.

The disadvantages of cam switch include the following.

  • This switch can be controlled only manually not remotely.
  • This type of switch cannot switch extremely high currents.
  • It does not contain any security function from magnetic & thermal currents.
  • A physical rotating power should be applied to activate it.

Applications

The applications of cam switch include the following.

  • Stamping machines.
  • Forging presses.
  • Sheet metal forming machines.
  • Presses.
  • Transport equipment.
  • Mining equipment.
  • Assembly machinery.
  • Packaging machinery.
  • Construction machinery.
  • Auto machinery.
  • Air conditioners.
  • Electrical switchboards.
  • Oil & gas.
  • Panel builders.
  • Electrical enclosure.
  • Machine tools.
  • Wood industry.
  • Packaging.
  • Vegetable cutting machine.

Thus, this is all about an overview of a cam switch – types, advantages, disadvantages & its applications. These switches are applicable in daily life so used in river shipping, industrial production, on vessels of sea, in-floor rail-less electric vehicles, etc. Here is a question for you, what is the rotary switch?

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