Phase failure protection of electric hoist
Electric hoist is widely used in machinery, chemical, light industry, railway and other industries due to its simple structure, convenient operation and low cost. Due to the particularity of this type of crane, the ground operator often has one person and several roles, and at the same time assumes the tasks of operation, rigging, and command. There are many hidden dangers in operation. One of the protection measures is open-phase protection.
When the electric hoist removes the power cord of the hoisting motor during the repair process, when the power cord is reconnected, the power cord may be connected in a wrong phase, so that if the "down" button of the flashlight door is pressed, the spreader rises , And the ascent limit position limiter does not work, so it is easy to cause accidents. This is because after the three-phase power line of the motor is out of phase, the steering of the motor is exactly the opposite of that before the disassembly. Pressing "up" will turn the spreader down, and pressing "down" will turn the spreader up, which can easily cause accidents.
In order to prevent accidents, the new standard requires shop assistants to install phase-break protection devices.
