ZENER 8000-V Installation Manual
IM00165
21
Can I add an EMC filter on the AC line to the drive?
There is no issue from a drive point of view; however the majority of packaged EMC filters available in the
market have substantial capacitors connected between the phase conductors and earth which is acceptable in a
TN supply system, but likely to be problematic in an IT supply system. EMC filters for IT supply systems should
be specifically designed for that environment.
What are the implications for touch potential around the installation?
The flow of leakage currents around the installation will naturally cause small voltage differences between the
ends of conductor(s) involved. We suggest that these be checked against the requirements for the particular
operating environment. General information on this topic is provided in AS/NZS 60479
Effects of current on
human beings and livestock
and AS/NZS 60990
Methods of measurement of touch current and protective
conductor current
Can pilot earth circuits be used in cables associated with 1000V VFDs?
There is no inherent reason that prevents the use of pilot earth (AKA “earth check”) systems, however the
electrical environment inside a VSD motor cable and to some extent associated AC line cables, is challenging
from an interference point of view. Pilot earth relays designed without specific consideration of this
environment are highly likely to be problematic.
What happens if the earth connection to the motor is disconnected?
In the event that earth connection to the motor frame is disconnected it is likely that the capacitive leakage
currents between motor winding and motor frame will result in the motor frame being hazardous to touch.
Other potential hazards for consideration include being a possible source of ignition in hazardous area
situations and hazards associated with capacitive leakage currents flowing in alternative circuits and / or
structures.
The integrity of the motor frame earthing arrangement is an important safety consideration and should be
specifically considered as part of the safety risk assessment of the installation design and included in ongoing
maintenance / inspection arrangements.
