The influence of PLC on elevator work


In the operation control, the operation conditions must […]

In the operation control, the operation conditions must be met first, then the operation contactor is closed, the brake is powered on and the brake is released, the PC sends out the operation command, and starts the uplink and downlink output. When the normal feedback information from the inverter is obtained, the speed command is issued; When the stop command arrives, the PC will stop running and output. When the zero-speed signal arrives, the running program will be delayed and the running contactor will be cut off. The system is in a stopped state. PLC module design The functions of the PLC software system in the escalator control system are divided into: input and output signal conversion; direction signal processing; status setting; operation control; fault detection; automatic lubrication control.
   Input and output signal conversion The input signal and output signal are respectively fixed in the internal memory M for processing, and then input and output conversion is performed. The determination of the direction signal In this program, it mainly completes the collection of the input signal, then determines the upward and downward directions, and uses the software to complete the conditional storage and memory of the signal. The status setting determines the correct operation mode of the elevator according to the status of the system working status switch. The system has three operating states: overhaul, normal speed and slow speed. The PLC determines the normal speed and the slow speed through the input signal of the photoelectric switch, and sets the time before and after conversion to ensure the normal operation of the conversion. Operational control. Fault detection Various fault detection points are input in parallel. In order to avoid the loss of fault signals, M03B7 is incorporated as fault self-protection. Later, I learned that the screw and gears of the elevator were lubricated with lubricating oil. Between the 2nd and 3rd floors of the elevator it tested, the operation was relatively small, and the resistance between the gears was relatively large. Among the factory parameters of the inverter, there is a parameter MAK-25, which is a parameter equivalent to the locked-rotor protection function (the locked-rotor protection function is a parameter in this type of inverter, which is mainly to prevent the inverter from Over current is output when running. If you select this parameter to act, when the output current of the inverter reaches its alarm upper limit, the inverter will keep the current output frequency running, which is during acceleration or deceleration; or lowering The current operating frequency is when the inverter is running at a steady speed. When the current is normal, the inverter will operate normally. However, this parameter cannot be used in some occasions, such as processing machinery, grinders and other occasions that require machining accuracy. Easy to use, because the frequency changes, it will affect its processing accuracy). In view of the above situation, because the actual output current was checked with an oscilloscope to be around 6A, this parameter was changed to 0 (no detection).