The structure and function of the air compressor PLC product upgrade

The structure and function of the air compressor PLC product upgrade

The CPU is mainly composed of arithmetic units, controllers, registers and data, control and status buses that realize the connection between them. The CPU unit also includes peripheral chips, bus interfaces and related circuits.

　　" PLC defined by the International Electrotechnical Commission (IEC): PLC (Programmable Logic Controller) is an electronic system operated by digital operations, specially designed for applications in industrial environments.

It uses programmable memory to store instructions for performing logic operations, sequence control, timing, counting, and arithmetic operations in its internals, and through digital and analog input and output, it can control various types of machinery or production process. The programmable controller and its related equipment should be designed according to the principle of being easy to form a whole with the industrial control system and easy to expand its functions. "

　　Modular PLC includes CPU module, I/O module, power module, memory, backplane or rack, these modules can be combined and configured according to certain rules.

The structure and function of the air compressor PLC product upgrade

The CPU is the core of the PLC and has the function of the nerve center. A set of PLC must have at least one CPU, which receives and stores user programs and data according to the functions given by the PLC system program, and collects the data transmitted from the field input device by scanning. The status or data is stored in the specified register.

　　At the same time, it diagnoses the working status of the power supply and PLC internal circuits and the syntax errors in the programming process. After the system runs, the instructions are read from the user program memory, and after analysis, corresponding control signals are generated according to the tasks specified by the instructions to realize the command to the relevant control circuits.

　　 The CPU is mainly composed of arithmetic units, controllers, registers and the data, control and status bus that realize the connection between them. The CPU unit also includes peripheral chips, bus interfaces and related circuits.

　　 Memory is mainly used to store programs and data, and is an indispensable unit of PLC. The controller of the CPU controls the work of the CPU, which reads instructions, interprets instructions, and executes instructions. But the working rhythm is controlled by the oscillating signal. The arithmetic unit is used for digital or logical operations, and it works under the command of the controller. The register participates in the operation, but also stores the intermediate result of the operation, and its work is also under the command of the controller.

　　Control system and electrical wiring

1 Control System

　　1) Motor starting (reduced voltage or Y starting)

During the start of the motor, the intake valve is fully closed and the relief valve is fully opened. At this time, the intake side becomes a high vacuum. The coolant required for the compression chamber and bearings is guaranteed by the vacuum in the compression chamber and the atmospheric pressure difference in the oil drum. .

　　2) Motor full pressure operation (full pressure or △ operation)

After the control cuts into full pressure operation, the relief valve is fully closed. At this time, the pressure in the air barrel gradually rises and the intake valve gradually opens. Therefore, the pressure in the oil barrel rises rapidly, the intake valve is fully opened, and the compressor starts to be fully loaded. Operation, when the pressure reaches 0.45MPa, the pressure maintaining valve is fully opened and air is output.

　　3) Heavy load/no load operation

When the exhaust pressure reaches the upper limit of the control system, the control system cuts off the power supply of the relief valve, the relief valve opens, and the intake valve closes, expelling the air in the oil tank to the atmosphere. At this time, the compressor is in a no-load state. Down operation. When the vehicle is empty, the pressure of the system is maintained at about 2kg/cm².

　　4) Shutdown

　　 When the stop "OFF" button is pressed, the relief valve opens to exhaust the air in the oil tank to the atmosphere, and at the same time close the intake valve. When the pressure in the tank drops to a certain value, the motor stops.

　　5) Emergency stop

If the exhaust temperature exceeds 100°C, or the overcurrent protection device is running due to overload of the motor, the overcurrent protection device will automatically cut off the strong current control, the control panel will display an overload alarm, the motor will immediately stop and the relief valve will open, and the intake will The valve is closed, preventing the coolant from continuing to spray out of the compressor. Only when a special emergency situation occurs during the operation of the unit, the emergency stop button is allowed to be pressed, otherwise it may cause system failure or air inlet spray.

　　6) Automatic shutdown system without load for too long

If the air volume of the system decreases, the compressor keeps running under no-load conditions. If the no-load operation time exceeds the set time, the air compressor will automatically stop and the motor will stop running. When the air volume of the system increases, The system pressure will be reduced, customers can set according to their needs, the air compressor will automatically start to supplement the air volume. The time setting limit for the shutdown time of no-load operation for too long is based on the principle that the number of starting times of the motor should not exceed twice per hour. Since there is no prompt for automatic starting, please pay attention to safety when selecting this function to avoid personal injury.

　　 Do not start the motor too frequently and cause the motor to burn out.

2 　　 electrical wiring

　　 The electrical control of the air compressor can be divided into two systems, one is the internal control system; the other is the starter part.

　　Starting disk is a Y-△ starting control commonly used in general machinery. The control part is controlled by a microcontroller. Because the internal circuit and control of the micro-controller are more complicated, we will not introduce it in depth in this chapter. If there is any damage or malfunction, please contact the service units of Fusheng directly and replace the circuit board directly.