Electrical installation   17
4. Electrical installation
WARNING! Obey the safety instructions. See chapter Safety on page 5. If 
you ignore the safety instructions, injury or death can occur. If you are not a 
qualified electrician, do not do electrical work.
Make sure that the drive is disconnected from the input power during installation. If 
the drive is already connected to the input power, wait for 5 minutes after 
disconnecting the input power.
Checking the compatibility with IT (ungrounded) and 
corner-grounded TN systems
WARNING! Disconnect the internal EMC filter when installing the drive on an 
IT system (an ungrounded power system or a high-resistance-grounded [over 
30 ohms] power system), otherwise the system will be connected to ground 
potential through the EMC filter capacitors. This may cause danger or damage the 
drive.
Disconnect the internal EMC filter when installing the drive on a corner-grounded TN 
system, otherwise the drive will be damaged.
Note: When the internal EMC filter is disconnected, the drive is not EMC compatible 
without an external filter.
1. If you have an IT (ungrounded) or corner grounded TN system, disconnect the 
internal EMC filter by removing the EMC screw. For 3-phase U-type drives (with 
type designation ACS320-03U-), the EMC screw is already removed at the factory 
and replaced by a plastic one.
Pay attention to the screws! Do not confuse the EMC screw to the similar varistor 
disconnecting screw. Do not disconnect the varistor. The varistor protects the 
drive against power line voltage peaks.