What’re the control principle for cabin of overhead crane?
Overhead crane moving system controlled by cabin has three kinds of speed: 45m/min, 60m/min and 75m/min.
When the crane moves at a speed of 75m/min, moving system is driven by ZDR tapered wound rotor induction motor whose rotor connects the resistance to ensure smooth start, cam control operation, only the cam controller handle is in zero position, it can be started (zero position protection), connect bells before operation to send work guard signal to ground workers, press down start button to make general contactor work, then all systems begin running; when cam controller handle changes from zero position to forward moving or backward moving direction, motor immediately connects the rotor according to corresponding order and makes resistance change in different levels, thus the crane gradually reaches rated moving speed to ensure smooth moving.
When crane moves to the limit position, a pair of contacts of travel switch is opened, the system power is interrupted, then the crane can be re-started and moves backward only when cam controller handle is in zero position. As same with that in ground control, the system travel switch should not be regarded as a power off switch in the normal operation.Safe voltage 36v is usually used, if 380v voltage needs to be used, the users should tell us before placing an order. Protective device should be set to avoid damping if the crane will be used in the open air.
