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How Do Float Switches Work?

Views: 34     Author: China Micro Switch Manufacturer     Publish Time: 2020-08-11      Origin: https://www.unionwells.com/

In the switch industry, float switches have been remarkably appreciated and widely used. They are highly reliable, which explains why they still remain the basic principle behind the field of level monitoring. The popularity of float switches have cut across standard devices such as pumps, alarms, indicators, controls, as well as other related devices. A float switch has a simple mechanism that can be understood by anybody. That makes it easy for us to answer the question - how does a float switch work? Read the remaining part of the post carefully and learn what you need to know about float switches. 

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Float switch history

The use of float switches didn’t start today. It had actually started centuries ago. The same basic principle used for operating float switches have been similarly applied in controlling the flow of water in fields and mills. Funny enough, it has remained one of the most applied technology in the history of mankind today. The level monitoring will be done by a float that has low density and adequate buoyancy, allowing it to rise and fall anytime there is a change in the height of the liquid inside a container. 

You can make this work as a mechanical switch by introducing some sort of mechanical lever to orchestrate the float’s movement, just like the flap controls that are employed in irrigation channels. 

How float switches look today

Float switches have evolved over time and gone through so many transitions. They are now referred to as the contemporary float switches, and are used for making and breaking an electric circuit. Float switches of nowadays are now privy to more sophisticated designs. 

Another elementary look at a float switch will indicate that it has a float body, coupled with a magnet inside of it, a tube that will be guiding the float body, adjustable collars for limiting the float’s movement, as well as reeds on the side of the contacts. In the past, float switches had limitations with the kind of liquids you can use them with. Thankfully, the recently designed models have made sure none of that is a challenge. In other words, contemporary float switches can now be used to detect the level in any type of liquid. 

This is how it works

The float switch is normally left to float on top of the liquid in question. Whenever there is a change in the level of the liquid, that is, either up or down, the float switch moves accordingly with the changing level. Based on the counter weight and pre-set trigger of the float switch, the mechanical switch contacts would remain open or closed so that current can flow through a device that connected to the circuit. In most scenarios, the job of the connected device is to ensure that the liquid is pumped to the container or stopped from going in when certain levels are attained. 

A broader definition

Therefore, a float switch consist of some kind of hollow floating item and an internal switch.  The internal switch is usually known as a sensor. The most popular type of internal switch happens to be a reed switch. The reed switch comprises a magnet within. However, the reed switch is not the only form of internal switch, as there are other forms, operating firmly on the principle of gravity to move the float in a vertically upward or downward movement. 

For the reed type of internal switch, it is pretty easy to understand. Anytime the reed switch is in close proximity with the magnet, the electrical circuit becomes closed, thereby allowing current to flow through. And if the reed switch moves away from the magnet, the circuit becomes open, and current will no longer pass through the device. 

The switch does have its max switching voltage and current. You really have to be careful so you do not exceed those values. That way, the switch will not be damaged much sooner than you had expected. Another thing noteworthy is the angle of the magnet in the switch. That angle is determined by the float switch, which happens to be further influenced by the level of the liquid.  

The installation of the float switch will either have an external counter weight or a fixed point. This is applied in setting the internal mechanical switch pre-set level, so it can properly switch between the open and closed states. 

Generally, when water flows to a certain extent inside a tank, the float switch will help turn off the water so that it doesn’t overflow the container. The floating body rises as the water rises, bringing the magnet and reed switch closer together. And the moment both of them touch, a contact is created and the circuit is completed (at this instance, current can now flow through it). When the circuit is closed, the pump will no longer pump water into the tank. When there is a reduction in the water level inside the tank, the float moves away from the magnet, and the circuit becomes open. The open circuit will then trigger the activation of the pump to send pumping water into the tank. 

How they are wired

Float switches have to be properly wired for electrical signals to move around it, so that their open and closed states can be rightly defined. The wiring configuration can only be in any of these two states. The normally closed type of float switch connection is different from the normally open type of float switch connection. 

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Float switches have been around longer than you know it. Their designs have almost become perfect over time. They are basically used to control the level of liquid inside containers. A very practical example is in the pumping of water into tanks. They are made of different types, although they all have almost the same working principle. The floating switch gets the leveling job done by creating a closed or open circuit as at when due with the concerned circuit.

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