Limit Switches, Their working principle, Application, and Types

 Limit switch are switches operated by a machine part's motion of an object's presence.

Limit switches use control machinery as a security interlock, a part of an impact system, or to count objects passing to some extent. Limit switches are electromechanical equipment containing an actuator mechanically connected to a group of contacts; when an object comes in-tuned with the actuator, the machine operates the contacts to form or cut an electrical connection.

Limit switches are applied in multiple applications and environments due to their ruggedness, simple fitting, and operation reliability. Limit switches can ascertain the proximity or absence, passing, positioning, and travel of an object. Limit switches were first wont to define the limit of travel of an object, hence the name "Limit Switch."

Working Principle

Limit switches with a roller-lever operator; are connected to a gate on a canal lock and indicate a gate's position to an impact system. Limit switches are industrial control elements produced with multiple operator types, including the whisker, roller plunger, and lever type. The motion of the operating lever may mechanically operate limit switches. A reed switch indicates the proximity of a magnet attached to a moving part. Proximity switches work by changing an electromagnetic field, capacitance, or sensing a magnetic flux.

Sometimes a final operating device like a solenoid valve or lamp will be directly managed by an industrial limit switches contacts. The limit switches are customarily wired within a motor contactor circuit or an impact relay. Limit switches are often present as an input to a programmable logic controller.

Application Of Limit Switches:

Limit Switches application includes Injection molding, Hydraulic machines, Special purpose machines, Machine tools, conveyors, lifts and escalators, EOT cranes, Material Handling, Food & Beverages packaging machinery, Textile machinery, Heating Ovens, Drilling machines, Tapping machines. Limit Switches are also used in load tap changers of transformers, HV Disconnector & circuit breakers, swing doors, Valves applications. BCH Electric Limited is the most reliable producer of Limit switches in India. BCH limit switches are highly reliable & preferred in power plants, cement plants, mining, automotive, Pulp & Paper industries.

BCH Limit Switches are used in a wide range of applications and have various types mentioned below.

Types Of Limit Switches: 

1. Heavy Duty Limit Switches: Heavy Duty Limit Switches are designed to work in adverse industrial conditions. Heavy Duty Limit Switches deliver faultless & steady production even in a highly contaminated atmosphere, high shock & vibration applications. 

Specification and Features of Heavy Duty Limit Switches are as follows:

• Conforms to IEC- 60947-5-1
•  Marking
• Contacts : 1 NO + 1NC, and 2NO +2NC
• Heavy Duty Zinc Die-cast body
• Rugged and reliable design
• Choice of 18 operating heads
• Oil Tight, Water Tight, and Dust Proof (IP67)
• Screw terminal / prewired.

2.Mini Limit Switches:

Mini limit switches are designed to improve productivity with less production downtime. Mini limit switches have a wide array of operating heads and meet the specifications of Machine Tools, Lifts and Escalators, Food and Beverages, Textile Machines, Packaging & Printing Machines applications.

Specification and Features

• Conforms to IEC – 60947-5-1
• Compact design requiring less mounting space
• Unique Crossbar contacts to enhance reliability
• Zinc Die-cast base & high-end polyamide cover
• Dustproof, waterproof, and oil resistant
• Long mechanical & electrical life
• Wide Range of operating heads
• Frequency of operation 7200 operations/hr

3.Precision Limit Switches: 

Precision Limit Switches are best suited for applications where space is a priority. These are compact in size, reliable in operation, has an exceptionally very high life.

 Specification and Features

• Conforming to IEC 60947-5-1
• Variety of operating heads: Top Pushbutton, Top Push Roller, Roller Lever, 6 "long lever
• Dustproof, Waterproof & Oil resistance construction
• Quick make & quick break action
• Long-life on high load applications
• Frequency of operation 2500 operations/hr