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1. Frequency signal parameters of paper machine inverter
Set the operating frequency of the inverter: The general-purpose inverter can obtain the operating frequency from the following aspects.
(1) Operation panel
There are frequency increase and frequency decrease buttons on the display panel of the inverter, through which the operating frequency of the inverter can be changed. Operating frequency, therefore, its application range is limited. It can only be used in occasions where a single motor is driven and the running frequency is not frequently modified.
(2) Analog terminal general-purpose inverter
There are basically two types of analog terminals: voltage input and current input. Voltage input includes 0~5VDC, 0~10VDC, -5~5VDC, -10~10VDC, etc.; current input basically has 0~20mA and 4~20mA. One or more of the inputs can be set arbitrarily, and the inverter uses more than 10-bit A/D to convert it into a digital quantity. Using this method to set the operating frequency of the inverter can realize external control operation, and can be modified in real time on the spot, but it is well known that the analog quantity is easily disturbed during the transmission process, especially the voltage signal, which is more susceptible to interference, resulting in unstable system operation. , the current signal is recommended here; in addition, the running frequency is set by the analog quantity, and the speed synchronization problem must be solved in the paper machine transmission control system.
(3) Digital terminals
This way of setting the frequency, various brands of inverters are called differently, such as ABB inverters are called electric potentiometers, and Fuji inverters are called up/down functions, etc., which actually use the multi-function of the inverter itself. The digital input terminal is used to change the running frequency of the inverter, and the speed of acceleration/deceleration is adjustable. This method is most typical in the application of the eight-cylinder paper machine in the transmission system of the paper machine.
(4) Communication method
This way of setting the operating frequency of the inverter by serial communication is the most widely used in the transmission system of large paper machines. Common ones are RS-485 or CAN bus. Of course, among the frequency setting methods of general-purpose inverters, the above four methods are commonly used, and these four methods do not exist independently. They can be used in combination. For example, ABB800 series inverters can use analog when setting frequency The algebraic sum of multiple analog quantities, the maximum value of multiple analog quantities, the minimum value of multiple analog quantities, the product of analog quantities, the sum of analog quantities and communication quantities, etc., should be flexibly used according to the actual situation in use.
2. Control command of paper machine inverter
It includes controlling the start/stop of the motor, the running direction of the motor, etc.
When the system is ready (power on), the frequency converter is in a standby state and the motor is not running. To make the system run, a start command must be given to the frequency converter. There are three ways to start the inverter: operation panel; external terminal, which can be fixed level or pulse signal; communication mode. You can choose any of them according to the actual situation. When the inverter is stopped, it is exactly the same as when it is started, but the action is reversed.
(2) The running direction of the motor
The AC motor changes its rotation direction by changing the phase sequence of any two phases of its input three-phase power supply. In frequency conversion, it only needs to give it a level signal to automatically adjust its two-phase phase sequence, thereby changing the rotation direction of the motor. In the design of the transmission system, one-way or two-way operation is determined according to the process requirements. In the paper machine transmission system, it is all in one direction, and the rotation direction can be specified by the inverter parameters.
3. Limiting parameters of paper machine inverter
Limiting is the parameter range that specifies the normal operation of the system, such as maximum torque, current frequency, etc., the settings are different for different systems. In addition to the above three types of parameters, there are output signal type, constant speed type, acceleration and deceleration time and so on.