Frequency converter electric winch
The frequency converter is used in the electric winch
1, Introduction
Winch is used to charge the important equipment transported to the blast furnace transporting ore material to blast furnace feeding or mine inclined shaft, China’s small and medium-sized blast furnace are basically using the skip hoist as standard feeding equipment. Meet the following requirements: there is sufficient transport capacity, both feeding speed can meet the requirements of blast furnace production; reliable operation. Durable, to ensure continuous production of blast furnace; can realize automatic feeding; has the advantages of simple structure, convenient maintenance.
Hoist the work characteristics are: starting speed, torque, speed smooth, parking is steady, accurate. The traditional control method is: using the wound rotor asynchronous motor, through the collector ring and carbon brush in the rotor circuit in series into several segments with resistance, resistance into how to control the speed controlled by the contactor.
However, the following shortcomings:
(1) the series resistance speed, the speed change is jumping, the gear reducer, the pulley, wheel and rail car, between the bridge, in the deceleration stage by the impact force, equipment damage, wire rope fatigue, resulting in large amount of maintenance, maintenance costs increase.
(2) the series resistance speed range is small, the car speed is slow after the stop mutation, there is still a high speed, adjust the precision of the brake and the limit switch with high requirements, and prone to offside and off road accidents affecting the production.
(3) the series resistance speed, the car starting and deceleration, most power consumption in the resistor; when the motor is in the voltage drop, lower torque, slip increases, serious when car doesn’t start, prone to accidents.
(4) high energy consumption, low mechanical properties of soft. Because the speed is decreased by the rotor external resistance energy consumption to achieve, and the lower the speed, the mechanical characteristics of soft, resistance in energy consumption in the proportion is bigger, not economic, the grid voltage has great effect on speed.
With the rapid development of inverter technology, manufacturers have introduced a special frequency converter for special conditions, the use of dedicated inverter transformation system, can solve the above problems
2, use the inverter should pay attention to the problem
In order to ensure that the hoist can be safe and reliable operation, to prevent the inverter jump failure, the tub down “slip car”, need to add a set of security system. In the outside of the inverter, a set of DC brake plus hydraulic brake brake system, once the inverter jump fault, issued by the inverter fault signal, control the DC braking circuit, the motor stator winding to apply low voltage DC current, Slow down the “slip car” speed, while the hydraulic brake clinging hoist drive wheel. After the fault is removed, the normal operation can be resumed.
3, concluding remarks
It is proved that the hoisting hoist adopts the special speed control scheme of the special frequency converter developed by Putong Science and Technology. It is simple, reliable, energy saving, high efficiency and full protection function (over current, over voltage, under voltage, grounding, overheating , Short circuit), to facilitate the best control of automatic programs, can replace the traditional control mode, with a very high promotion value.