Crane maintenance notice, crane electrical equipment protection measures
In order to protect the safety of crane electrical equipment and staff, the crane electrical control system should be set up necessary electrical protection measures.
1. Main isolation switch. Maintenance inspection of electrical equipment should generally be carried out in the case of power failure. Therefore, there should be isolation switches or other isolation measures between electrical equipment and the power supply network. When the isolation switch is off, it shall have the necessary disconnect distance and obvious disconnect point so that maintenance personnel can intuitively confirm that the power circuit has been disconnected. Special attention is: air switch and iron switch in the disconnect position, there is no obvious disconnect point, can not be used as isolation switch.
2. Short circuit protection of the total power supply. When the insulation of the electrical equipment on the crane is damaged, the short circuit protection device of the main power supply should act quickly and cut off the fault power supply. The main power short circuit protection shall be completed by the fuse breaker.
3. Voltage loss protection of the main power supply. The loss voltage protection of the main power supply means that the main power supply circuit can be automatically disconnected after the power supply is interrupted; When the power supply is restored, the main power loop cannot be switched on by itself without manual operation. Generally, the automatic reset button is strung into the general power contactor coil or the automatic circuit breaker's voltage loss trip coil loop to realize the voltage loss protection of the general power supply.
4, zero protection. The mechanism motor is controlled by a controller that cannot reset automatically. In order to prevent the controller handle is not in zero position, the crane power supply after voltage loss and restore power, resulting in the wrong start of the motor, the crane is equipped with zero position protection. Check method of zero protection:
4.1. The mechanism motor is directly controlled by CAM controller; Turn off the main power supply and turn one controller handle away from the zero position to switch on the main power supply. The main power supply should not be switched on. Only when all controller handles are placed in the zero position can the main power supply be switched on.
4.2 If the mechanism motor is controlled by the master controller and contactor, turn off the main power supply, turn the master controller away from the zero position, and connect the main power supply. When the main power supply is connected, the mechanism motors cannot start at the same time.
5. Overload protection of motor. If the rated power of the motor on the crane is greater than 1KW, overload protection should be set separately. Overcurrent protection is the motor overload protection method commonly used in cranes at present.
6. Emergency power off switch. The crane must be equipped with an emergency power switch that can quickly disconnect the main power supply in case of emergency, and located in a place convenient for the driver to operate. Emergency power failure should not be automatically reset. There are two ways to judge whether the emergency power switch is qualified:
6.1 Check whether there is a total power contactor on the crane. The crane must be equipped with a total power supply contactor, and the power cord of all institutions must be connected from the outlet end of the power supply contactor.
6.2 Turn the emergency power off switch, the main power contactor or the circuit breaker with the loss voltage trip coil to cut off the main power of all mechanisms and stop the operation of all mechanisms. At the same time, meet the above conditions can be judged to be qualified emergency power switch.
7. Safety interlock protection of passageway. The crane shall be equipped with an interlock switch of the passageway, which is used to disconnect the main power supply when the passageway is opened. The trolley of the bridge crane is powered by the naked slide line, which can prevent the staff from getting on the platform from getting electric shock by mistake, and also prevent the sudden start of the mechanism from causing crushing injury and falling accident.
8. Limit protection. In order to prevent the accident that the spool top to the upper supporting structure, break the wire rope and make the spool fall due to the negligence of the work, the lifting limit position limit device should be installed. Common types are hammer type and screw (or worm gear worm) type two. In addition, electrical protection and travel protection and grounding protection.
keyword： Crane maintenance notice, crane electrical equipment protection measures