The Application of FD500 in Lifting Equipment
Lifting equipment serves as material handling machinery that performs intermittent operations including hoisting, lowering, and horizontal movement. These operations typically follow repetitive cycles. Such equipment plays a vital role in industrial, transportation, and construction enterprises by mechanizing and automating production processes and improving labor productivity.
Lifting equipment includes hoists, winches, and cranes. Among these, the gantry crane represents a typical example due to its specific characteristics and complexity. A gantry crane mainly consists of three parts: the hoisting mechanism, the long-travel mechanism, and the cross-travel mechanism. The hoisting mechanism forms the core and most critical part of the equipment. Its importance lies in the fact that any failure during lifting—such as load slipping or dropping—could lead to severe consequences. Therefore, the frequency converter must ensure smooth starting and precise stopping to completely prevent accidents involving loads dropping in mid-air.
Implementation Solution
Based on an understanding of gantry cranes and safety control requirements, we adopt the FD500 series frequency converter to control functions such as lifting. By equipping the converter with a PN card, we establish a highly reliable communication channel with the upper-level safety control system.
Before releasing the mechanical brake, the frequency converter first generates sufficient upward torque to counteract the load's gravity. This ensures the motor securely "holds" the load before opening the brake. The system controls the timing of brake opening and closing with millisecond precision, guaranteeing seamless transition between electrical braking and mechanical braking after a command is issued, thereby completely eliminating load slipping. The independently developed PG card offers excellent anti-interference and compatibility, accurately recognizing both differential and single-ended encoder signals, thus providing reliable signal support for safety functions such as anti-slipping protection. Moreover, this frequency converter model supports closed-loop vector control, enabling precise operation of the crane and ensuring stable suspension of loads.
Application Advantages
Priority for Safety Commands: Via the PN card, the frequency converter can receive high-level safety commands from the PLC, such as emergency stop and safety limit signals, ensuring that safety actions take priority under any circumstances.
Real-Time Status Monitoring: The frequency converter uploads its internal status and fault information in real time, allowing the main control system to assess the overall health of the entire drive chain and implement predictive maintenance.
Intelligent Overload and Overcurrent Protection: The system monitors motor current in real time and responds within milliseconds to abnormal fluctuations, protecting both the drive and the motor.
Undervoltage and Overvoltage Protection: This ensures stable operation or safe shutdown during grid fluctuations, while the braking unit meets requirements for rapid braking.
Overspeed and Stall Protection: Real-time monitoring of motor status prevents equipment from running out of control due to control abnormalities.
Reduced Maintenance Costs: With comprehensive protection and diagnostic functions, the FD500 series lowers the failure rate of the motor system and reduces maintenance and repair expenses.
