Inverter Interference (VFD Interference)
The very fast voltage transitions at a frequency converter's output producing broadband electromagnetic noise, and that noise stressing the immunity limit of the radio receiver. The most effective and cheapest measure is to move the receiver and its antenna away from the inverter and the motor cable.
An inverter produces the motor voltage by switching at high frequency. Because the switching edges are very steep, the spectrum produced is broad and extends up to the MHz range. This energy is both radiated from the motor cable and conducted through the earthing and the supply.
- Symptom: the remote's response being delayed or interrupted while the inverter is running, and the problem disappearing entirely when the inverter stops.
- Order of measures: 1) move the receiver and antenna away, 2) use a shielded motor cable and terminate the shield through 360°, 3) separate the power and control cables, 4) add a ferrite ring and, if necessary, a line filter.
- Verification: for diagnosis, switch the inverter off and try the remote at the same distance; if the difference is clear, the source is here.
Antenna placement is especially decisive in this picture: moving the antenna outside the enclosure, positioning it vertically and keeping it a few centimetres away from large metal surfaces often produces a noticeable improvement on its own.
Context in which this term is used: 433 MHz or 2.4 GHz?