Eight safety protection device of electric wire rope hoist
1, the main isolation switch
Electric wire rope hoist with the main isolation switch into the line, switch off the main switch crane without electricity, in order to ensure the safety of maintenance personnel. Small single girder crane ground operation (low headroom electric hoist crane) not to set the main isolation switch.
2, the emergency switch
Emergency switch should be installed within reach and position in the driver, (some point magnetic crane switch and the emergency switch with a type of control electromagnetic disc, when the electromagnetic disc control switch can not and emergency switch installed side by side) to prepare for an emergency, immediately disconnect the power, ensure the safety of personnel and equipment.
3, short circuit protection
Commonly used short circuit protection device with automatic air switch, fuse, two. Should be set up in the power supply circuit, short circuit protection to do total power circuit.
4, zero protection
In order to prevent the controller failed to institutions in the zero position, the vehicle suddenly start the accident send electric crane driver, the controller is provided with a zero protection.
5, the loss of excitation protection
No current in his shock excitation winding DC motor's armature current will increase, resulting in failure. And as the crane hoisting mechanism with eddy current speed regulation, the eddy current brake magnetic loss leads to load descending overspeed phenomenon. In the two place, should set the excitation loss protection.
6, over current protection
Over current relay on the armature circuit in AC motor stator loop, DC motor. When the current exceeds the allowable value, the relay action of the motor power, the motor protection.
7, interlock protection
The door, the access door to crane cab on the hatch door, ascending or escalator mouth, travel switch, the switch is opened, automatically cut off the power supply, the crane can not start, to protect the safety of personnel.
8, grounding protection
For preventing crane metal structure is charged by electric shock injury, setting the ground protection.
Ground connection to use a section of not less than 150mm2 or 10mm2 flat copper wire, connected by welding. Is strictly prohibited for current zero line grounding wire. By the rectifier power supply AC power lifting electromagnet, electric should be reliable connection between the shell and the crane. Suspension type control button (electric hoist crane hand switch) should also be reliable electrical connection between the metal shell and the crane. Crane and rail office ground resistance point shall not be less than 4.