The frequency converter of HVLS Fans is composed of electronic components, computer chips, etc. Many HVLS Fans customers are worried that the frequency converter will interfere with factory equipment, especially some high-precision factories. So will the frequency converter of HVLS Fans interfere with other equipment?
The rectifier circuit of any industrial frequency converter will produce harmonics, and the inverter circuit of the frequency converter will also produce harmonics. When the frequency converter generates harmonics, due to its large power, it can be regarded as a powerful interference source. Its interference channels are similar to general electromagnetic interference channels, such as conduction, radiation and secondary radiation, electromagnetic coupling, conduction and radiation, etc.
Harmonic interference generated by the frequency converter: First, conduction interference, causing electromagnetic noise of the direct drive motor and increasing iron loss and copper loss. At the same time, the conducted power also affects other sensitive equipment connected to the power input; the second is radiation interference, which interferes with surrounding electronic receiving equipment; the third is magnetic coupling to other lines laid parallel to the inverter, which may interfere with the inside of the inverter. computer chip.
If the low-voltage distribution network connected to the HVLS Fans inverter is connected to other electrical equipment at the same time, the harmonic current generated by the inverter will be shunted to the parallel loads and power supplies of the power grid system according to their respective impedances, causing adverse effects on various types of equipment. . If a compensation capacitor is connected, parallel resonance and malfunction may occur. Therefore, when using a large-capacity inverter, it is recommended to set up a dedicated transformer connected to the high-voltage system.
For normal HVLS Fans, the capacity of the frequency converter is very small, and the interference generated is basically negligible. However, for some factories that use large quantities of precision instruments, measures need to be taken to suppress interference from frequency converters when installing fans. Conducting interference through a shared ground wire is the most common way to suppress interference.
Separating the ground wire of the power cord from the ground wire of the control wire is the fundamental way to cut off this path, that is, connect the ground terminal of the power supply unit to the ground wire, and connect the ground terminal of the control device to the metal shell of the equipment panel . When the signal line is close to a conductor with interference source current, interference will be induced in the signal line, causing the signal on the signal line to be interfered. Cabling separation effectively eliminates this interference. In fact, high voltage cables, power cables, control cables should be routed separately from instrument cables and computer cables.
Adding an Lc passive filter before the frequency converter can filter out high-order harmonics. The filter may include multiple stages, with the first stage filtering out corresponding higher harmonics. The 5th and 7th harmonics are usually filtered out, but this method depends entirely on the power supply and load and has little flexibility. Typically, active compensators connected in parallel with the load and power supply are used to eliminate forward harmonic currents in the power supply and load by automatically generating filtered currents in opposite directions.
In addition, the HVLS Fans inverter itself is shielded by an iron shell, and the output line is shielded by a steel pipe. Pay attention to laying it separately from other weak current signal lines. Other nearby sensitive electronic equipment must also be shielded. The power line should use an isolation transformer or power filter to avoid conduction. In order to reduce electromagnetic noise, an output filter can be configured; in order to reduce pollution to the power supply, a power filter can be installed at the input end of the inverter when the requirements are high, and a zero-sequence reactance can be installed when the requirements are not high.
