| 摘要 |
The invention relates to an RFI filter used for avoidance of mains retro-action in the form of radio noise. RFI filters are connected to frequency converters in order to reduce radio noise transmitted via conductors. These filters comprise large noise-decoupling capacitors which are connected to earth, and during start up of the frequency converter the capacitors cause leakage currents to earth. This gives rise to problems in those circumstances, where a circuit breaker is connected to a frequency converter and an RFI filter, because the leakage current is higher than the trigger current for the circuit breaker. The solution to this problem is to place a resistor in series with the noise-decoupling capacitor and parallel with the resistor to place a switch, which can be opened or closed with a control signal from a controller. The invention also concerns a method for activation of an RFI filter.
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