Electric hoists represent their own machinery, strength, and toughness, while the stage is elegant, flowing, and soft, with conflicts and collisions between the two.

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Brief Explanation :

Selection of Double Limit Control Form for Chain Electric Hoists

Category : W12 Stage Inteligent hoist

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Selection of Double Limit Control Form for Chain Electric Hoists

For cranes with a steel wire rope electric hoist as the lifting mechanism, a double limit is generally formed by using a fire switch and a heavy hammer or pressure plate height limit.

After the ignition switch is activated, it cuts off the power supply between the output end of the lifting or lowering contactor and the input motor; The height limit of the heavy hammer or pressure plate type is achieved by turning on or off the control circuit of the lifting contactor to connect or release the lifting contactor, thereby preventing the crane from hitting the top. The two types of double limit combinations used in the wire rope electric hoist are both operated through different electrical components (i.e., the fire switch and lifting contactor) to achieve safety protection. When one electrical component fails, the crane also has a safety redundant electrical component for safety protection. However, for cranes with a lifting mechanism consisting of a chain link electric hoist, due to its unique structural form, the chain link electric hoist is not suitable to use a fire switch as a height limit. Generally, a double limit is composed of a heavy hammer type and a pressure plate type height limit. The above analysis shows that both forms of height limit are connected or released through the control circuit of the lifting contactor to provide safety protection. So in practice, there is a situation where the weight type height limit and the pressure plate type height limit jointly control the lifting contactor. Because Document No. 16 does not specify the control requirements for the double limit, this method cannot be judged as unqualified. However, from the perspective of obtaining a safer control effect, it is safer to control the lifting contactor and the upper level contactor separately, which can avoid the adhesion and failure of a single contactor Accidents caused by damage.