The correct way to use can extend the life of Emerson inverters
In modern industrial control systems, more choices of microcomputer or PLC control skills, in the process of system planning or transformation, certain Pay attention to the disturbance of the inverter to the microcomputer control panel. Because the user's own computer control board is generally poor in process level and does not comply with EMC international standards, the conduction and radiation disturbances that occur after the Emerson frequency converter is selected often result in abnormal operation of the control system. Therefore, the following necessary measures are required.
1. Good grounding. The grounding wire of the strong electric control system such as motor must be grounded firmly through the grounding busbar, and the shielding ground of the microcomputer control board should be grounded separately. For some occasions where the disturbance is severe, it is proposed to connect the sensor and the I/O interface shielding layer to the control ground of the control panel.
2. Add power supply to the control panel of the microcomputer to install EMI filter, common mode inductor, high frequency magnetic ring, etc., which can effectively conduct conduction disturbance. In addition, in the case of severe radiation disturbance, such as the presence of GSM or perhaps the PHS base station, a metal mesh shield can be added to the microcomputer control panel for shielding.
3. Add EMI filter to the input end of the inverter, which can effectively control the conduction disturbance of the inverter to the power grid, install input AC and DC reactors, improve power factor and reduce harmonic pollution. Inductive effect is good. In the case where the distance between some motors and the inverter exceeds 100 m, it is required to add an AC output reactor on the inverter side to deal with the leakage current protection due to the distribution of the output conductors to the ground and to reduce the external radiation disturbance. An effective way is to use a steel pipe to thread or perhaps shield the cable, and connect the steel casing or cable shield to the ground. It is worth noting that when the AC output reactor is not added, if the steel pipe is used to thread the cable or the cable is shielded, the output capacitance of the output to the ground is increased, and overcurrent is likely to occur. Of course, in practical applications, one or several methods are generally adopted.
4. Electrically shield and block the imitation sensor detection input and the imitation control signal. In the planning process of the control system composed of Vertiv frequency converter, it is advocated that the imitation control should not be used as much as possible, especially in the case of the control distance greater than 1m, across the control cabinet device. Since the inverter generally has multi-speed setting and switching frequency input and output, it can meet the requirements. If it is necessary to use the imitation quantity control, it is recommended to use the shielded cable, and realize the remote grounding on the sensor side or the inverter side. If the disturbance is still severe, the need to achieve DC / DC blocking measures. Can choose the standard DC / DC module, perhaps use the v / f conversion light barrier, and then select the frequency setting input method.