Chziri ZVF200-M User Manual page 74

Motor Cable
1. The electromagnetic field (EMF) caused by fundamental curr ent has
weaker effect on electric field coupling and magnetic flux inductive
coupling of the parallel cable. While the EMF produced by the higher
harmonic current has stronger effect on electric field coupling.
2. Radiated interference.
3. Due to the existence of distributed capacity, there is high frequency
earth leakage current and inter phase leakage current in the cable,
which may le ad to malfunction of some leakage protection devices such
as circuit breaker, relay and other equipment. DO attach importance to
these things.
Propagation Diagram of Motor Cable's Interference over External Equipment
Solutions
1. The basic solutions are the same with the defense of electromagnetic
countermeasures of a power cable.
2. Install an output wireless noise filter and keep the sensitive equipment
away from the motor cable; or the motor cable adopts a well grounded
shielded cable and insert this cable in a metal pipe.
3. Use an insensitive leakage protection breaker for the inverter system
only; reduce carrier frequency of the inverter; or use an AC (output)
reactor to solve this kind of problems.Relay, contactor and other
electromechanical elements:Instantaneous current and voltage surge
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Appendix
will be caused by the close and open of the switch devices such as relay,
contactor and etc, which may result in discharging radiation and conductive
surge noise. This instantaneous noise must be prevented when designing
the peripheral circuit of the inverter, as shown in the figure below
As for a 24VDC controlled relay a shunt winding continuous current diode
should be inserted at both ends of the coil and pay attention to the polarity
of diode. As for a 220V AC controlled contactor; an over-voltage suppressor
should be mounted at both ends of the coil (i.e., RC network). Also, the
protection of switch contact can not be ignored. This can be realized by
forming a shunt winding RC or RCD buffered network, as shown in the
figure below
Appendix
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