The belt sway switch and pull cord switch would be arranged to each belt conveyor of the coal conveying system in the thermal power plant, but owing to the incomplete technology, the coal conveying system could not carry out the one-to-one identification and positioning function to the belt sway switch and pull cord switch. When the on-site open switch is in action, the operators should troubleshoot each device to find out the fault location, then conduct the essential maintenance, for the operators, it’s extremely taking up their physical strength and time. It can be accepted, if it is a single belt conveyor with short conveying distance in the thermal power plant; however, if it is a long conveying distance (for example, more than 2 or 3 hundred meters), that will be a disaster to the operator.
A new technical solution for the belt sway switch is put forward: there will be a power line positioning system used to the device, including the power supply device, PLC control system, belt sway switch & pull cord switch which evenly mounted to the belt conveyor side, and the remote control signal transmission system which transfers the action signal from the belt sway switch & pull cord switch to the PLC control system. Its features are that the remote control signal transmission system includes the main control device and the cable, the connection method between the PLC control system and the main control device is the communication mode or the hard-wiring communication way, while the cable of the main control device will connect to the belt sway switch & pull cord switch. In this solution, the mechanical actuator and the intelligent communication module are made up the belt sway switch & pull cord switch, and the intelligent communication module will check the action state of the mechanical actuator through the communication interface of the I/O encode. Their switches are connected by the I/O communication interface and the cable, and the connection method between the PLC control system and the main control device is the communication way, which connected by another interface module. Among them, there will be more than one main control device setting up the remote station with a third party interface module, to connect to the cable through the terminal.
Since the belt sway switch uses the power line positioning system: 1. The one-to-one identification & positioning problem is solved out in the thermal power plant; 2. Monitoring action state of the belt sway switch & pull cord switch in real time; 3. Adopting the power line fieldbus technology, the anti-interference ability is greatly improved, and the interrupted signal and transmission delay are not going to happen, which yielding great benefits (saving the investment cost and manpower) for the thermal power plant. The fault switch will display in the coal handling program control room, it is convenient for the operator to find and lighten the workload, time-saving, simple and easy. In addition, the system has a quick response when connecting to the coal handling program control room, to guarantee the stable running of the belt conveyor system.