The limit switch WLCA12-2N is a type of travel switch, also known as a travel switch. It is an electrical switch used to limit the movement limit position of mechanical equipment. It is mainly composed of switch elements, wiring terminals, switch actuators, transmission parts, etc.

1. Installation position in power plant lifting equipment

In power plant lifting equipment, the installation position of the limit switch WLCA12-2N is crucial. For the horizontal movement direction of the crane’s running trolley, the limit switch is usually installed at both ends of the track. For example, when the trolley travels to the end of the track in one direction, the limit switch installed at the end will be triggered. For the lifting mechanism of the crane, the limit switch will be installed at a suitable position on the boom or a structural part connected to the lifting drum. When the hook rises to the limit height or falls to the minimum height, the corresponding limit switch will be triggered. In addition, for the lateral movement of the crane trolley (the part that moves on the track as a whole), the limit switch will also be placed on both sides of the trolley track to limit its lateral operating range.

2. Working principle details

1. Mechanical triggering process

• When the moving parts of the lifting equipment (such as the trolley, hook or trolley) gradually approach the set limit position, it will push the actuator of the limit switch WLCA12-2N. Taking the trolley as an example, when the trolley continues to move forward along the track until it is about to reach the end of the track, a structural component on the trolley (such as the small rod in front of the buffer or the limit block connected to the track, etc.) will first contact the mounting bracket of the limit switch. Then, this component will push the drive rod of the limit switch.

• For the lifting mechanism, when the hook rises to the limit height, the limit device (such as the impact rod) fixed on the hook or the lifting wire rope will hit the trigger part of the limit switch.

2. Contact action principle

• Normally closed contact (NC) and normally open contact (NO)

• The limit switch WLCA12-2N has normally closed contacts and normally open contacts inside. When there is no external force, the moving contact is closed with the normally closed contact, and the circuit is connected. For example, in the trolley motor control circuit of the crane, if this normally closed contact is connected in series in the forward or reverse circuit of the motor, the circuit remains open during the normal operation of the trolley.

• When the driving rod is pushed by an external force, the moving contact moves. It will disconnect from the normally closed contact if it was previously closed; and close with the normally open contact if it was previously open.

• Circuit control logic

• In the circuit of the lifting equipment, this change of contact will change the state of the circuit. Taking the reverse control of the trolley motor as an example, assume that when the trolley is moving in one direction, the forward circuit of the motor is connected, and the normally closed contact of the limit switch is connected in series. When the trolley approaches the end of the track, the normally closed contact of the limit switch is disconnected, and the motor will stop rotating forward due to the circuit break. At the same time, if the normally open contact of another limit switch is connected to the motor reverse circuit and is closed when the trolley hits the limit switch, the motor will start to reverse, thereby preventing the trolley from continuing to rush forward off the track.

• For the lifting mechanism, when the hook rises to the limit height, the normally closed contact of the limit switch is disconnected to prevent the motor from continuing to rise. If a similar limit switch is set during the descent process, when the hook drops to the lowest height, the motor can also be stopped from continuing to descend by the action of the contact.

3. Recovery and reset mechanism

• When the external driving force disappears, the return spring inside the limit switch will return the moving contact to the initial position, that is, the moving contact will close with the normally closed contact again and disconnect with the normally open contact. In this way, after the lifting equipment deviates slightly from the limit position (for example, due to slight vibration or error, it automatically returns to the position after crossing the boundary), the circuit can be restored to the normal initial state, and the equipment can continue to operate safely.

4. Circuit connection and feedback

• The limit switch WLCA12-2N has terminals, usually including common terminals (COM), normally closed terminals (NC) and normally open terminals (NO). These terminals are connected to the control system circuit of the lifting equipment. When the contacts are activated, the control system can make corresponding operation decisions according to different contact states (on-off relationships). For example, the control system can stop the operation of the relevant motor, or switch to other working modes according to the preset program, such as alarm status or waiting for manual instructions to restart.

The limit switch WLCA12-2N plays a vital role in the control of the motion range of the power plant lifting equipment. Through reasonable installation position selection, precise mechanical triggering and contact action principle, as well as perfect recovery and reset mechanism and circuit connection feedback method, it can effectively limit the motion range of the lifting equipment, prevent the equipment from exceeding the safety limit and causing dangerous accidents, and ensure the safe operation of the power plant lifting equipment and the normal production and operation of the entire power plant.
When looking for high-quality, reliable limit switches, YOYIK is undoubtedly a choice worth considering. The company specializes in providing a variety of power equipment including steam turbine accessories, and has won wide acclaim for its high-quality products and services. For more information or inquiries, please contact the customer service below:

E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229