Last Updated on October 22, 2023 by Kevin Chen
Micro switches are small and compact electrical components used in a variety of applications. They are also known as micro-momentum switches, micro-momentum contacts, micro-switch contacts, micro-resistance contacts, and micro plunger switches.
These devices have many applications because they combine the functions of several different types of switches in one compact device. These electrical components can be used in a wide range of applications including robotics, medical equipment, vending machines, security systems, and even toys.
In this blog post, you will learn everything you need to know about micro switches including their different types, operation principles, standard specifications, and more.
Components of a Micro Switch
A typical micro switch comprises of a plunger or actuator, a cover, moving piece, a support system, case, NO terminal, an NC terminal, contact, and a moving arm.
The actuator is the movable piece of the micro switch that is used to make or break the circuit. The moving piece is attached to the actuator and moves when the actuator moves. The moving arm is attached to the moving piece and extends through a hole in the case.
The support system holds everything together and makes sure that all components are working properly.
The NO terminal is connected to a circuit that should be made when the micro switch is activated. The NC terminal is connected to a circuit that should be made when the micro switch is activated.
The contact connects to wires that are attached to either one or both terminals. When these wires are connected, current will flow through them, but this flow can be interrupted by pressing down on the micro switch plunger with a finger or another object.
The case holds all of these components together in one place and protects them from outside forces, such as heat, water, dirt, etc.
Operating Principle of Micro Switches
The operation of a microswitch is pretty simple and straightforward. It basically consists of a spring-loaded plunger which is made of a material called beryllium copper.
As the name suggests, this material has high elasticity so it has the ability to spring back to its original shape after the load is removed. The plunger is connected to a lever arm that can move in two different directions. This lever arm can be made of plastic or metal, depending on the application.
As you press the micro switch, the plunger gets pushed into its electrical contact.
When you remove your finger from the micro switch, it springs back and breaks all electrical contact with its electrical contacts. In some applications, there may be multiple switches in series so pressing one switch will break all other switches in series.
Types of Micro Switches
There are a number of different types of micro switches available. Each type has a different design and application. You should select the right type of micro switch for your application to ensure proper performance.
-Pin plunger: This type of switch is designed to be used with the solenoid. It has a pin that projects from its plunger. This pin is connected to a lever arm and it makes electrical contact with a fixed spring-loaded contact on the other side of the plunger.
-Lever arm: This type of switch has a lever arm that is connected to its plunger. The lever arm makes electrical contact with two fixed spring-loaded contacts on either side of the lever arm.
-Toggle: A toggle switch has an actuator that can be pulled in both directions, which breaks and re-establishes electrical contact as it moves back and forth.
-Momentary: A momentary switch only allows current to pass through it for as long as you hold your finger on it, otherwise no current passes through it.
-Leaf spring: A leaf spring switch is a lever arm switch with a spring that acts as the other contact. The spring is connected to the lever arm and it makes electrical contact with two fixed contacts on either side of the spring.
-Spring pin plunger: A spring pin plunger switch is a lever arm switch with a spring that acts as the other contact. The spring is connected to the plunger and it makes electrical contact with two fixed contacts on either side of the spring.
-Roller-lever: A roller-lever switch is a lever arm switch with a roller that acts as the other contact. The roller is connected to the lever arm and it makes electrical contact with two fixed contacts on either side of the roller.
-Ball bearing: A ball bearing switch has a ball bearing that acts as the other contact. The ball bearing is connected to the plunger and it makes electrical contact with two fixed contacts on either side of the ball bearing.
Standard Specifications of Micro Switches
The standard specifications of micro switches depend on the type of micro switch you select. With the wide variety of micro switches available, you can find the right switch for your application.
– Contact Rating – This refers to the maximum amount of current that the switch can handle. You should select a switch with a higher rating if you need to pass a lot of current.
– Maximum Momentary Discharge – This is the maximum amount of energy that the switch can discharge when pressed. This energy is also known as impulse current or breaking current. This specification is important for applications where you will be pressing the switch many times.
– Operating Temperature – This refers to the maximum temperature the switch can withstand without being damaged.
– Full-On Current – This is the maximum amount of current that flows through the circuit when the switch is pressed. It is also known as operating current. This current does not depend on the resistance of the circuit. It only depends on the amount of current that flows through the switch.
– Full-Off Current – This is the maximum amount of current that flows through the circuit when the switch is released. It is also known as release current. This current depends on the amount of resistance in the circuit when the switch is pressed.
– Insulation Resistance – This is the amount of current that can flow through the switch once it has been closed. – Contact Resistance – This is the amount of current that flows through the switch when it is in the closed position.
– Contact Travel – This is the distance the micro switch plunger travels to make or break the electrical circuit.
– Momentary-Make/Break Ratio – This is the ratio between the full-on current and the full-off current.
– Maximum Break Time – This is the maximum amount of time the switch can remain closed. It is also known as make-break time.
– Operating Temperature – This is the maximum temperature the switch can withstand without being damaged.
– Operating Voltage – This is the maximum voltage that can pass through the switch without being damaged.
– Connection Type – This refers to the type of connectors the switch has on its terminals.
– Seal Rating – This is the amount of pressure the switch can withstand before being damaged.
– Lifetime – This is the amount of time the switch is guaranteed to work before being damaged.
Limitations of Micro Switches
You should be aware of the limitations of micro switches before choosing them for your application.
Micro switches are small in size and can only handle a limited amount of current. You should select a micro switch with a higher contact rating if you plan to pass a lot of current through the switch.
Another limitation is the operating temperature. A micro switch is designed to be used in a specific temperature range. If you plan to operate the micro switch outside of this temperature range, you should select a micro switch with higher heat resistance.
Micro Switch Maintenance
How do I keep a microswitch in perfect working condition? There are various maintenance tips that you can easily implement on your microswitch.
One of them is lubrication. Lubrication is very important to ensure that the microswitch will continue to work smoothly. You should regularly spray a small amount of lubricant onto the microswitch to keep it in good condition.
Another tip is inspection. You should inspect your microswitch on a regular basis, and replace it if you find that it has been damaged.
Also, don’t use the switch in applications where it may be exposed to water.
You should also ensure that the microswitch is not over-pressurized, as this may damage the switch.
Where are microswitch used? You may ask. From the working principle, you can tell that they are used in a wide range of applications including:
-Timing devices such as triggering sensors, switches, and relays.
-Position sensors such as proximity switches, doorbells, and proximity cards.
-Insulation devices such as fuses and relays.
-Electronic parts such as power supplies, voltage converters, current transformers etc.
-Industrial applications such as high-temperature circuit breakers (HTCB), electrical switchgear.
-Medical applications such as pacemakers and cardiac resynchronization devices (CRDs).
When it comes to buying microswitches, ensure you buy from reputable and reliable suppliers.
You should also ensure that the microswitch you buy is of the correct size.
Also, when buying microswitches, make sure you look for a good quality product and one that will not be easily damaged.
You can also seek the help of a sourcing agent when purchasing microswitches.
For example, if you are looking for a microswitch that is used in medical applications, you should consider buying from a medical device manufacturer.
The reason is they will have access to the latest products and specifications. This is exactly what we at ICRFQ will do for you.
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