Double-girder bridge hoist cranes are mainly composed of bridges, carts, trolleys, and electrical equipment. According to the use of different degrees, divided into A5, A6, A7 three levels of work. Hook bridge crane maneuvers are all completed within the driver. In order to ensure the normal working process, the electric hoist crane has need to be set kinds of safety device. And do you know the zero protection for overhead hoist crane?
The three working mechanisms of the double girder hoist crane, such as lifting, vehicle running and trolley running, are controlled by three operating devices, and zero protection must be set. The protection function is that as long as there is a mechanism of the controller is not zero, all institutions can not start; only in the case of the first position of the mechanism controller is zero, the working mechanism of the motor is possible to start.
The zero protection of electric hoist crane is used to prevent the driver from starting the main switch without thinking preparation when the crane starts to run or when power is restored after power loss. The accidental injury caused by sudden operation of one or several mechanisms. In addition, all kinds of hoist cranes must be equipped with an emergency switch or device that can quickly disconnect the main power supply in case of an emergency and be set in a place where the driver can operate easily.
Interlock protection, travel limit, zero position protection, emergency switch, etc. are often combined in the control circuit of the crane. As long as one device is in an abnormal state, the crane cannot start or stop running in a dangerous direction.