Eliminating interference with central air conditioning frequency converters
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I have a central air conditioning supply fan; it was originally driven at the power frequency, but the manager said the noise level was too high, so it is now controlled by an inverter (Yaskawa inverter). The current problem is that there is interference in the temperature measurement signal, which affects the startup and shutdown of the compressor. Let’s see which expert can help me come up with a solution. Thank you for this!
This post was last edited by h20090630 on 2020-5-31 16:41. It’s not a serious problem, but it’s quite troublesome. 1. The frequency converter must be reliably grounded; the grounding wire should have a cross-sectional area of at least 4 square millimeters. It is best to provide a separate grounding connection, as the frequency converter can contaminate the power supply. 2 If the temperature signal is a thermal resistor, three wires must be used, and a shielded wire should be employed; the grounding of this shielded wire should be connected to the instrument ground. 3 It is advisable to use an isolation module for instrument signals; the power supply for the instruments should preferably come from another source. If it is necessary to use the inverter’s power supply, an isolation transformer should be used for isolation. However, isolation transformers are ineffective against high-frequency harmonic interference.