Crane overload limiter

Overview of QCX Crane Overload Limiter

The QCX Crane Overload Limiter is one of the most commonly used safety devices on double-girder cranes. It is designed to enhance operational safety by preventing overloading, thus protecting both equipment and personnel. The system typically consists of three main components: a sensor, a junction box (amplifier box), and a control instrument.

Key Features

1. Versatile Sensor Compatibility:
   • The QCX instrument can work with various types of sensors and support custom non-standard functions to meet diverse user requirements.
2. High Accuracy:
   • Measurement accuracy: ≤5% F.S.
3. Warning and Alarm Mechanisms:
   • 90% Load: Pre-warning alert.
   • 105% Load: Alarm activates.
   • 130% Load: Immediate control, outputs a relay contact to cut off the lifting motor circuit.
4. Robust Electrical Specifications:
   • Relay capacity: 10A, 380V
   • Power supply: AC380V or 220V/50Hz
5. Environmental Adaptability:
   • Operating temperature: -20℃ to +60℃
   • Humidity tolerance: 90% RH
6. Protection Ratings:
   • Sensor: IP65
   • Instrument: IP42
7. Optional Features:
   • 4-20mA Interface: For seamless integration with external systems.
   • Large Screen Display: To enhance visibility of operational data.
   • Additional Control Outputs: For extended functionality.

Key Functions

• Load Monitoring: Displays the weight of lifted loads in real time.
• Alarm System:
  • Visual and audible warnings for overloading conditions.
  • Automatic cutoff of the lifting motor circuit at critical load thresholds.
• Enhanced Safety: Prevents equipment damage and accidents caused by overload.

Working Principle

1. Weight Measurement:
   • When the crane lifts a load, the sensor detects the weight.
   • The sensor converts the weight into a small voltage signal.
2. Signal Amplification and Processing:
   • The signal is amplified in the junction box and transmitted to the control instrument.
   • A high-resolution A/D converter converts the amplified signal into a digital format.
3. Data Analysis:
   • The microcontroller processes the digital signal, calculates the weight, and compares it with the rated capacity.
4. Safety Actions:
   • If the weight reaches 110% of the rated capacity, the system outputs a normally closed relay contact signal.
   • This signal cuts off the lifting motor’s power supply to prevent further operation.
5. Display and Alerts:
   • The system displays the weight and triggers alarms (visual and audible) for pre-warning and overloading conditions.

Applications

The QCX Crane Overload Limiter is essential in industries where safety is critical, including:

• Metallurgy
• Machinery
• Mining
• Railways
• Ports
• Warehousing

Its ability to prevent overloading ensures modernized and safe operations in these sectors.

Conclusion

The QCX Crane Overload Limiter is an indispensable safety mechanism for double-girder cranes. By offering accurate load monitoring, reliable alarms, and automatic motor cutoffs, it minimizes risks associated with overloading and contributes significantly to modern industrial safety standards.