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Maintenance is not in place lead to the end of the elevator squatting analysis

2014/1/21 8:40:40

A : accident phenomena described v
A hotel has an elevator , load 1000kg, speed of 1.75m / s, 9 layer 9 station , 13VTR host , serial communication, Yaskawa inverter using 676GL5 inverter. Usually run frequently, there are 12 people in the car at the time , from the 4th floor staircase intend to enter a building, which happened when the elevator at the moment the elevator door closing quickly slipped directly squatting at the end, the old man has a serious knee dislocation , several people were injured. According to the duty officer described v. Hall building was as if an earthquake .
Second : Lift -site inspection of a site measuring equilibrium factor of 25% ; 2 brake is a spring on both sides of the size found more than 80mm and uneven shoe wear serious ; 3 overspeed governor does not act, the scene speed . verification , mechanical movement speed is not the action ; 4 weighing system failure , the car weighed at the end of the five put a full load in the elevator switch found no input ;
Three: Accident Analysis
Now expand on the analysis of the problems , that the elevator maintenance unit ( not a manufacturing company maintenance ) in the usual routine maintenance is the very place in which to do , at least they did not in the following areas are required to do :
1 . Should first determine the equilibrium factor is how much lift to see the car in the end there is no change in weight . GB provides balance factor of 0.4 to 0.5 . In fact, after the elevator car decoration , car quality increased as much as 200 kg , that is now the elevator balance factor of 20 % to 30% , so invisible to reduce the heavy weight 200 kg, while is a necessary condition for the re- traction rope and rope sheave grooves produce friction , now undoubtedly the most important conditions for the destruction of ;
2 , followed by brake adjustment is in place ? This is very important, according to process requirements, brake adjustment amount should be set at 125% load upstream or downstream off more than half the floor off , watching gliding distance to determine whether the brake adjustment in place , according to the rated speed and rated load to determine the final spring brake adjustment , referring to the use of on-site maintenance manual , where a spring brake size is certainly no adjustment in place .
(3) There is also little downside is that the process has been governor electrical switch action, but the mechanical movement speed of the speed governor has not disengaged by pulling the safety gear to make the action , then that governor - safety gear linkage there are problems.
4 Again sedan weighing bottom switch is valid. According to the site super- loaded test, found that the elevator weighing system problems, even under full load , did not detect the weighing input . And the elevator system as a starting torque compensation weighing system , it is through the inverter analog input 676GL5 provided by the elevator car at the end of the five load switch can know the elevator load, the load switch inputs by weighing plate converted into a voltage 0-10V analog input , and provide the appropriate start to the drive torque at startup ( to explain, even in the maintenance state , the drive also can detect the weight of the car ) . When this failed when the judge , this time again in full load , but the system is still considered the process of load , load down the elevator in the energy state of the system is to give a driving torque , if it is loaded , then it should be given brake torque , here just to backwards, so to come out of the system downstream of the overload torque plus ( + cab loaded with its own weight ) to slip down the moment , along with making the car accelerate downward . This time , the system will detect the velocity anomalies , and stop the output torque , while falling brake , stopping the elevator , but here 's brake adjustment not get bit , zero speed elevators can only brake when the car is too big downside momentum when there is no effective brake hold the elevator , so the car began to fall , and because of the decline of inertia, faster and faster, brake shoe wear was also more smooth, so a vicious cycle, took place at scene.



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