The ‘Pull cord switch in conveyor’ is a safety feature that is very important for the safety of people working on the conveyor belt. It is a simple device, but its role is very big.
What is a pull switch cord?
Conveyor belts are used in coal plants to move huge quantities of coal from one place to another. These belts keep moving continuously. To ensure safety, a pull cord switch is installed on or near these belts. If for some reason a person gets stuck in the belt or feels any danger near the belt, he can pull this cord. As soon as the cord is pulled, an automatic system gets activated and the conveyor belt stops immediately, thus preventing any accident.
Pull cord switch working principle
A pull cord switch is a safety device used to bring the belt to an immediate stop. It is a special type of switch that is protected from bad weather or dirt.
This switch is not used very often, so it is made in such a way that it can work immediately even after being unused for a long time. It is a strong connection that lasts a long time.
Pull cord switches are used on the edge of the runway portion of the belt, usually after every 20-25 meters. When a cube is pulled from any side, the switch is triggered. It remains on until the switch is brought back to the normal position by hand.
All the pull cord switches on a conveyor belt are connected together and connected to the control center through a two-wire cable. Therefore, pulling any one of these switches will stop the conveyor belt completely until that particular switch is brought back to the normal position.
Construction
As you can see in the pictures below, a pull cord switch has several parts:
- Name plate: This plate contains details such as the switch type, contacts, rating, serial number, etc.
- Cable entry: The power cable can be entered through the cable entry gland, which is sealed with a rubber cover.
- Operating spindle: The operating spindle has steel rings to fix the rope. The worker can operate the switch by pulling the rope.
- Mounting mechanism: The user can mount the switch using the mounting bolts on the side of the conveyor.
- Electrical terminals: The maintenance worker can use normally open or normally closed contacts depending on the logic used by the designer.
Connections:
Parallel Connection: In this method, all the pull cord switches are connected together. If any of these switches is activated, the conveyor belt stops.
Series Connection: In this method, the switches are connected one after the other. The conveyor belt will stop only if all the switches are activated.
PLC Logic:
- PLC Logic for Parallel Connection: The inputs of all the switches are connected to OR gates, and the output controls the conveyor belt.
- PLC Logic for Series Connection: The inputs of all the switches are connected to AND gates, and the output controls the conveyor belt.
Uses:
- Conveyor Belt Systems in Steel, Cement, Coal Industries, Power Plants etc.
- Food and Beverage Industries
- Packaging Industries
- Finally:
Hope you got complete information about Pull Cord Switches. If you have any further questions, please comment below. Your every comment is important to us and encourages us to share more ideas with you.
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