Bridge cranes are commonly used loading and unloading equipment in industrial and mining enterprises. They work in harsh environments and often need to be started and braked frequently under heavy loads, resulting in large impact currents and vibrations. In traditional electrical control systems, contactor contacts are easily burned out due to impact currents, which requires large maintenance and high costs. In addition, the speed control system has poor comprehensive indicators and is difficult to meet industrial production needs. Nowadays, the FRECON FR500A series of special inverters for cranes provide a new electrical control solution with simple control circuits, stable operation, and less maintenance, becoming the mainstream in the industry.
The structure of a bridge crane mainly includes a bridge, a trolley moving mechanism, a trolley, a lifting mechanism and an operating room. The bridge is a basic component, consisting of a main beam, an end beam, a walkway, etc. The main beam spans above the span.
The trolley moving mechanism consists of an electric motor, a transmission shaft, a reducer and other components, which drives the crane to move along the length of the workshop.
The trolley is placed on the bridge rail and can move along the width of the workshop. It is driven by the trolley motor.
The lifting mechanism consists of a lifting motor, a reducer, a drum, etc., and is used to lift heavy objects.
The control room is the cabin for operating the crane, which is equipped with various mechanism control devices and protection devices.
Bridge cranes can realize vertical, horizontal and longitudinal movement of heavy objects in three-dimensional space. The trolley motor drives the trolley to move forward and backward along the tracks on both sides of the workshop. The trolley and lifting mechanism are driven by the trolley motor to move horizontally left and right along the tracks on the bridge frame. When lifting heavy objects, they are driven by the lifting motor to move vertically up and down.
The trolley, car and hoisting transmission system on site all use FR500A series hoisting-specific inverters. In the control system, the trolley and car are each independently controlled by an inverter, and the anti-sway and anti-sway function is built in. The inverter output frequency is adjusted through a specific mathematical model to control the operating speed of the mechanism and suppress the swing of the lifting main hook. The lifting mechanism adopts a one-to-one control mode. In order to ensure smooth transition when the crane starts and stops lifting and prevent the hook from slipping, the FR500A inverter has a built-in lifting-specific brake logic. The brake signal will be output only when the frequency and current meet the set conditions, thereby ensuring the stability of the motor start and stop, and fully meeting the special needs of lifting operations.
FRECON's FR500A high-performance vector inverter has excellent operating results. It supports synchronous and asynchronous motors, and has built-in application macros that can set parameters with one click; dedicated hoisting brake logic allows the equipment to be hoisted without slipping hooks, and hovering and starting without alarms; anti-sway and sway reduction functions eliminate swaying; and zero servo function ensures safe shutdown. It also has complete protection functions, with an overload capacity of 150% rated current for 60S, which can effectively respond to a variety of abnormal conditions, ensure stable and reliable system operation, and win high trust from users.
