Is an Extra EMC Filter Needed for Altivar ATV61/71 Variable Speed Drives When Used on IT Power Networks? ATV61/71...M3X ?

ATV61/71...M3X drives are delivered without EMC filter. These (M3X drives) can only be used on a 3-phase 230V supply, which is not a typical public network. M3 drives on the contrary can be used also on single-phase supply, hence 1x230V is usually part of the public network.

It is assumed that non-public network 3-phase 230V is created by a transformer, so it is absolutely up to customer if he creates TN or IT network on 230V volts. From the same point of view (non-public network) we cannot apply the IEC standards regarding the EMC. To sum up, the EMC requirements for non-public networks are not specified.

Back to your question, the need of an EMC filter depends on the requirement. If there are sensitive devices in the same 3x230V network, the filter is needed. EMC filter in general is not only about its connection to the ground. Above all, EMC filter filters high-frequency conductive emissions in each phase (emissions in current) and emissions in line-to-line voltage between each phase.

The problem with additional EMC filters is that they are automatically connected to the ground by their metal body and so difficult to isolate them from the ground. On IT network it is forbidden to use grounded EMC filters. As mentioned in ATV extract, the only solution with an additional EMC filter is to use an isolation transformer and to make an autonomous TN or TT network for assembly: transformer secondary+EMC filter+ATV+motor. The primary side of the transformer with the rest of the devices will be part of the IT network.

Whenever the network perspective current at the point of ATV installation is greater than the value of the max prospective current defined in ATV catalog for a dedicated drive, it is mandatory to add a line choke.

ATV630..N4 drives have a max Isc of 50kA, so for you network with SCCR 80 or 100kA you have to use line choke. With line choke, you can be sure that max Isc at ATV inputs will always be below 50kA, despite whatever high SCCR upstream the line choke.

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