Industrial Automation

Pushbutton Switches & Types of Switches

Push button switch

What is a Push Button Switch?

  • A push button switch is a mechanical device to control an electrical circuit by a manual operation to energize the internal switching mechanism.
  • Push button switches are electrical actuators this switch will close or open an electrical circuit by pressing the switch.
  • Push button switches control a wide range of electronic circuits.
  • These switches are in the form of a button or a key.
  • These switches can be either momentary or maintained.
  • But, the push button is the frequent sort of momentary switch
  • Generally, A closed push button switch is known as a push-to-break switch. An open push button switch is known as a push-to-make switch.
  • The maintained push button is connected to a mechanism that holds and releases between successive alternate pushes.
  • Push buttons technically consist of two states or more, but, a push button having more than two states is not a common option.
  • These push buttons are available in a variety of shapes, sizes, and configurations, depending on the design requirements.

How Does a Push Button Switch Operate?

  • Push button switches depend on a simple in-out actuation mechanism.
  • They can be employed to break Turn Off or initiate Turn On a circuit.
  • For particular operations, push button switches provides a good user interface to start or stop a function.

Push button switches may be categorized as

1. Being Momentary:

Push button category

Here the function of the push button switch continues long as the operator is pushing the button.

2. Maintained:

Latched status of push button

Here the function of the push button switch stays latched in that status after it has been actuated.

Types of Push Button Switches

Push button switches can be classified as

  1. Normally open (NO) type “OFF” position: The switch forms the circuit when actuated.
  2. Normally closed (NC) type “ON” position: The switches break the circuit when actuated.

Based on their functionality in terms of the switching, push button switches can be further classified as

Types of push button

Single Pole, Single Throw (SPST S1):

This type of push button has two terminals, only to open and close a circuit, like turning a motor ON or OFF.

Single Pole, Double Throw (SPDT S2):

  • This type of push-button has three terminals to control two different circuits.
  • Therefore these SPDTs are used to flip powering of two separate LED’s or to move equipment from sleep mode to an active state.

Double Pole, Single Throw (DPST S3) and Double Pole, Double Throw (DPDT S4):

Both DPST and DPDT type of push button switch allows simultaneous control of two isolated circuits. One switch with max voltage, and the other switch with min voltage.

Specifications of Push Button Switch

  • Datasheets provide enough information on specific push button switch models to be compared with one another.
  • The current and voltage ratings of the switch are important to ensure compatibility.
  • In mounting push button switches these are found as surface mount, through-hole, or panel mount options.
SpecificationTypical offeringDescription
Termination StyeGull wing, wire lead,
PC pin, screw terminal.
Allow for different mounting options
Voltage RatingUp to 24 V DCMaximum voltage across the device
Current RatingUp to 14 mAMaximum current through the device
Actuator HeightFlush, 3.3 mm, 5.4 mm,Utilized in limited vertical space designs.
Pitch2.54 mm or 5.08 mmDistance between center-to-center pins
Actuator CapVariety of color options, & finishes.Selection usually comes down to application needs or user preferences.
IP RatingRated or non-ratedPush button switches endure moisture and dust entry.

Push Button Applications and Considerations

  • Push button switches are the most popular and well-recognized switches.
  • These switches are widely used in various applications such as vending machines, portable equipment, household appliances, power tools, and countless other consumer electronics and industrial controls.

Working principle of Push Button

The below figure shows the working principle of the push button switch

Construction of push button

Push Button Switch Design and Customization

  • Normally, these push-button switches are considered the most basic types of electric switches.
  • These are similar to toggle switches employed in simple circuit changes.
  • Design of both toggle switches and push button switches is simple and easy to use.
  • A push button switch is used by simply depressing the switch until it accomplishes the desired function.
  • The push button can be a Flush switch, Recessed switch, or Raised switch.
  • Flush switches are installed on the surface.
  • Recessed buttons are located beneath the base of a product to prevent accidental switching action.
  • Raised buttons are located above the surface level for easy pressing.

Relays in Electric Switches

  • In electrical structures, these relays are used for circuit management using an independent power signal.
  • In a nutshell, a relay is a low-power electrically operated switch.
  • The classic relay switch is mounted around an electromagnetic coil.
  • An electrical signal energizes the coil to attract a metal contact in a specific arrangement.
  • When a metal contact gets attracted it forms or breaks a specific contact in the process.
  • When the attraction of metal contact from the coil gets ceased, the contact returns to its normal position, i.e. the de-energized state.
  • The relay functions as a momentary switch when the coil is electrified and the metal conduct remains attracted.
  • The circuit can be opened or closed by using signals of opposite polarity.
  • Relays in electrical power supplies are used to open or close circuit breakers.
  • Relays are employed when the controlled circuit is for both ON/OFF states.

Actuator Mechanisms

  • The actuator mechanism is a mechanical component present in the push button.
  • This mechanism allows an electrical switch to function.
  • This mechanism turns on or turns off the circuit manually.
  • The actuator functions for closing and opening the circuit.
  • There are various types of actuators with the unique operation.

1. Toggle Actuator

  • A toggle actuator has a manual engaged lever.
  • Depending upon configuration the switch gets opened or closed when the lever is pulled.
  • It has a straightforward manual procedure to control an electrical switch.

2. Rotary Actuators

  • This actuator consists of a twisted handle to open or close the circuit.
  • An operator rotates this handle to open or close the circuit.
  • Till 1970 these rotary actuators were primarily used in TVs. But now they are widely used in radio control devices and measuring instruments.

3. Biased Actuators

  • Biased actuators use a spring-based mechanism to control the electrical switch
  • The actuator switch when pressed either opens or closes the circuit.
  • Biased actuators are easy to use,
  • These actuators are simple in design.
  • These actuators have a long lifespan.
  • These are popularly used by mechanical engineers and business owners.

Connectors and Contactors in Electric Switches

  • A contactor is a type of switch in an electrical circuit.
  • The function of the contactor is to initiate and terminate the contact.
  • The circuit gets closed when the contactor is in contact. The circuit gets open when the contactor is not in contact.
  • The flow of electrons within a circuit can be controlled by making or breaking a contact.
  • Conductive metals shown below are commonly used in making contactors.

Copper and Copper Alloys:

  • Copper good conductor of heat and electricity.
  • A copper alloy such as brass is popularly used in making contactors.

Silver and Silver Alloys:

  • Silver is the best since it is a good conductor of electricity.
  • Silver alloys are resistant to the effect of oxidation.

Gold and Gold Alloys:

  • Depending only on copper and silver in conductivity, Gold is also a good conductor of electricity.
  • Since gold is corrosion-resistant. 
  • Contactors made of gold are not widely used because of high cost, and lack of availability.

Platinum Group Metals:

  • Compared to the above metals, platinum is the most expensive material for use in circuitry per unit weight.
  • The specific weight of platinum is very high.

Benefits of Push Button Switches

  • Push button switches are more efficient.
  • These buttons are smaller in size.
  • These switches are compact and lightweight.
  • Push buttons save space in the switchboard
  • These switches are stronger and more user-friendly.
  • Push buttons are less expensive compared to other switches.
  • Fixing push buttons makes it easy to fit into any space.
  • The push button has high electrical conductivity.
  • The life span of the push button is more.

Drawbacks of Push Button Switches

  • The push-on switch button alone is unable to initialize a function,
  • This requires additional PCB boards for accurate functioning.
  • Frequent touching of metallic push button switch causes shrapnel to lose its elasticity and may become inoperable.

Applications of Push Button Switch

  • Push buttons are used in a wide range of applications such as computers, crosswalks, telephones, industrial machinery, security systems, ATMs, military equipment, casino games in slot machines, fitness equipment, and so on.

Push button switches in a brief

  • Push button switches on pressing either closes or opens the electrical circuits.
  • They control a wide range of electronic gadgets.
  • A push button switch is a common type of switch that consumers interact with it.
  • These come in the form of a button or a key.
  • They can be either maintained or temporary.
  • Usually, these push buttons are normally open (NO) or normally closed (NC).
  • Normally open switch completes the circuit, whereas normally closed switch breaks the circuit when they are triggered.

What is a push button switch?

  • A push button switch is a mechanical device to control an electrical circuit through the manual press by an operator to initialize internal switching actions.
  • A push button is a momentary or non-latching switch causing a temporary change in the electrical circuit only when the switch is actuated physically.

What are the basic types of switches?

Basically, there are four main types of switches.

  • Single Pole Single Throw (SPST)
  • Single Pole Double Throw (SPDT)
  • Double Pole Single Throw (DPST)
  • Double Pole Double Throw (DPDT)

What are Poles and Throws?

  • Poles and throws are the two most important components of a switch.
  • Pole: Pole is the total number of circuits that a switch can control.
  • Throw: Throw is defined as the number of positions a switch can adopt.

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