What failure will the frequency power supply cause to other equipment? how to prevent
Frequency conversion power supply is mainly used for testing and debugging of imported and exported electrical products and power supply of precision instruments, widely used in household appliance manufacturing, electronic manufacturing, IT industry, computer equipment, etc. However, the installation and use of variable frequency power supply will affect other equipment in the system, and sometimes even cause other equipment to malfunction. What are the specific manifestations? What precautions should be taken?
What kind of failure will the variable frequency power supply cause to other equipment? how to prevent
On the issue of high-order harmonics in the power supply. Since almost all variable frequency power supplies use PWM (Pulse Width Modulation) control mode, when the variable frequency power supply operates and distorts the voltage waveform, this type of modulation will generate higher harmonic currents on the power supply side, resulting in voltage fluctuations Waveform distortion, causing adverse effects.
We recommend that you use the following method to prevent this from happening: Use a special transformer to power the variable frequency power supply and isolate it from other power systems. Install a filter inductor or multiple rectifier bridge circuits on the input side of the variable frequency power supply to reduce high-order harmonic components. For phase capacitors, high-order harmonic currents will increase the capacitor current and generate a lot of heat, a choke coil must be connected in series upstream of the capacitor to reduce harmonic components, and the inductance of the choke coil must be correctly analyzed and calculated to avoid the formation of inductance and capacitive oscillations.
Question about motor overheating and operating range. If some companies retrofit existing motors with frequency conversion and speed control, the cooling capacity of self-cooling motors will be reduced during low-speed operation, causing the motor to overheat. In addition, the high-order harmonics contained in the output waveform of the variable frequency power supply will increase the iron loss and copper loss of the motor. Therefore, after confirming the state of charge and the working range of the motor, it is recommended to take the following measures: the specification level of the motor, using a dedicated motor for frequency conversion, limiting the working range and avoiding low-speed areas.
Regarding the effect of peak voltages generated by high-frequency switching on motor insulation. The output voltage of the variable frequency power supply contains high-frequency overvoltage, and these high-order harmonic pulse voltages will reduce the insulation resistance of the motor winding, especially in the case of variable frequency PWM control power supply. The following measures can be taken: Minimize the wiring distance between the variable frequency power supply and the motor. Suppress the surge voltage with blocking diodes to handle the output voltage of the variable frequency power supply, and for variable frequency power supplies, try adding filtering on the motor input device.
