6 major precautions for using inverters with automatic control systems

1. For the frequency given signal, the international standard signal of 4-20 mA should be used as much as possible. Pay attention to the shield grounding of the signal line to avoid introducing interference signals into the inverter. There are interference signals at the production site, and the interference signals will affect the stability of the control. Therefore, the input filter should be enabled and its setting range is 0.00-5.00s. If you use the built-in PID function of the inverter, you also need to enable the feedback filter to increase the stability of the built-in PID control. The setting range is 0.0-60s. However, it should be noted that the filter time is set too long, the control is stable, but the system response is poor; the filter time setting is too short, the system response is fast, but the control is unstable; therefore, the filter time should be long and short according to the actual situation on site. Make adjustments.

2. Set the corresponding manual and automatic switching operation functions. Manual, automatic, and forced manual functions of the Communicator can be selected. If necessary, the redundant operation function of the current and voltage can be considered, that is, the frequency setting signal of the inverter is set by the current when it is normal, and the voltage is set by the abnormal manual. That is to add a potentiometer to set the frequency of the inverter, so that the frequency given signal of the inverter has two kinds of current signal and voltage signal. Since two frequency setting signals are input into the inverter, the redundancy is improved. degree.

3. Be sure to set the “inspection switch”, that is, set the “in-place maintenance switch” next to the rotating equipment. When the switch is turned to the “inspection” position, it is equal to cutting off the running signal loop of the inverter, in case someone accidentally operates. Equipment can not be transferred to ensure the safety of mechanical equipment maintenance personnel.

4. Make full use of the input and output control terminal functions of the inverter to perform some alarm and interlock functions to reduce wiring and improve reliability.

5, for a single machine or a simple control system, you can make full use of the built-in PID control function of the inverter to reduce control system equipment and reduce investment.

6. Some inverters have control power input terminals R0 and T0. Therefore, the control power should be connected to the R0 and T0 terminals of the inverter before the main power supply, so that the inverter still has the display function after tripping, in order to analyze the cause of the fault. Take countermeasures.