Grab bucket cranes are commonly used lifting equipment in industry, and the industry's requirements for their speed regulation performance are increasingly high. The traditional speed regulation method of rotor series resistance in wound-rotor asynchronous motors has problems such as large on-site maintenance workload, high failure rate, and poor speed regulation indicators, which cannot meet the special needs of industrial production. FRECON FR500A vector control inverter is widely used in the lifting industry due to its excellent performance. It effectively solves the pain points of traditional speed regulation, improves the operating efficiency of equipment and production benefits, and has been widely recognized by users.
Grab bucket cranes are commonly used industrial lifting equipment with a clear overall structure where each part performs its own function. They mainly consist of a grab bucket, a hoisting mechanism, a traveling mechanism, metal structures (main beam, outriggers/bridge frame), a control system, and electrical equipment. The grab bucket is responsible for grabbing bulk materials, the hoisting mechanism enables the lifting and lowering of materials, the traveling mechanism drives the equipment to move, and the metal structure serves as the load-bearing framework of the entire machine. Equipped with a dedicated control system for operation, it has a compact overall structure, is suitable for scenarios such as bulk cargo loading and unloading and material handling, and features efficient operation and strong practicality.
Grab bucket cranes mainly complete bulk material operations through the cooperation of machinery and electricity. They rely on the hoisting mechanism to drive the steel wire rope and control the grab bucket to complete the opening and closing actions: when closing, the grab bucket goes deep into the material pile to complete grabbing; the hoisting mechanism lifts the grab bucket and the materials, then moves to the unloading position through the trolley and cart running mechanisms, and then the grab bucket opens to complete unloading. The entire process is carried out cyclically. With precise electrical control, it can smoothly complete lifting, moving, grabbing and unloading, and is suitable for the handling and loading/unloading of various bulk materials such as sand, gravel, and coal.
The traditional electric drive system of grab cranes mainly includes the opening and closing of the grab, the lifting of materials, and the translation mechanisms of the trolley and the large car. It mostly adopts the speed regulation of rotor resistance in series of wound-rotor asynchronous motors and relies on CAM controllers, relays and contactors for control.
The equipment adjusts its speed by relying on resistors, resulting in poor operational stability, and the resistors are prone to burning out and breaking. It belongs to energy-consuming speed regulation, with high power consumption, a small speed regulation range, and unsmooth speed changes. The impact during startup and shutdown is large, causing significant wear on the reducer and steel wire rope. The contactor switches frequently, the starting current is large, the contacts and motor are easily damaged, the overall failure rate is relatively high, and the maintenance workload is heavy.
The traditional electric drive system of grab cranes mainly includes the opening and closing of the grab, the lifting of materials, and the translation mechanisms of the trolley and the large car. It mostly adopts the speed regulation of rotor resistance in series of wound-rotor asynchronous motors and relies on CAM controllers, relays and contactors for control.
For this renovation, the FRECON FR500A vector control inverter is selected, which is equipped with a dedicated DSP control chip and low-power IGBT devices. The product is specially designed for lifting scenarios, with a built-in dedicated lifting control algorithm, featuring high starting torque and strong overload capacity. Relying on vector control technology, the whole machine has better mechanical properties, more stable operation and faster response speed. It can adapt to heavy load and impact load working conditions, reduce mechanical loss, reduce faults, save energy consumption, and significantly improve safety and stability. It is applicable to multiple mechanisms such as lifting, traveling, luffing, slewing and grab, realizing stepless speed regulation, making lifting operations safer, more efficient and more worry-free.
After the transformation, the crane's start-stop acceleration and deceleration are smoother, positioning is more accurate, and operation is safer. The motor has a smaller starting current, less heat generation, and a longer service life; the brake performs low-speed braking, resulting in lower wear. The variable frequency speed regulation has strong adaptability and obvious energy-saving effect, with a measured power saving of about 20% and a significant reduction in operation and maintenance costs. It comes with multiple protection functions, ensuring higher reliability. It can even increase speed under light loads, significantly improving work efficiency.
