C-15
Compliance
AC30V series Variable Speed Drive
Increasing Motor Cable Length
Because cable capacitance and hence conducted emissions increase with motor cable length, conformance to EMC limits is only guaranteed
with the specified AC supply filter option up to a maximum cable length as specified in the Cabling Requirements for EMC Compliance C-17.
This maximum cable length can be improved using the specified external input or output filters.
Screened/armored cable has significant capacitance between the conductors and screen, which increases linearly with cable length (typically
200pF/m but varies with cable type and current rating).
Long cable lengths may have the following undesirable effects:
Tripping on ‘overcurrent’ as the cable capacitance is charged and discharged at the switching frequency.
Producing increased conducted emissions that degrade the performance of the EMC filter due to saturation.
Causing RCDs (Residual Current Devices) to trip due to increased high frequency earth current.
Producing increased heating inside the EMC ac supply filter from the increased conducted emissions.
These effects can be overcome by adding chokes or output filters at the output of the VSD.
WARNING
Ensure that all wiring is electrically isolated and cannot be made “live” unintentionally by other personnel.
The drive is suitable for use with IT and TN supplies when fitted with an internal ac supply EMC filter. When used on a IT supply the
filter efficiency is reduced resulting in only achieving Category C2 limits.
EMC Motor Output Filter
This can help the drive achieve EMC and filter thermal requirements. It also ensures longer motor life by reducing the high voltage slew rate and
overvoltage stresses. Mount the filter as close to the VSD as possible.
Output Contactors
Output contactors can be used, although we recommend that this type of operation is limited to emergency use only, or in a system where the
drive can be inhibited before closing or opening this contactor.
