￭ EMC filter
The drive has an internal EMC filter as standard. However, for the UL(NEC) drive types,
the filter is disconnected as default. The filter is typically not needed in North American
installations.
If you are concerned with EMC issues, and install the drive to a symmetrically grounded
TN-S system, you can connect the internal EMC filter. See Disconnecting
ground-to-phase varistor, or connecting EMC filter.
Note: When the internal EMC filter is disconnected, the electromagnetic compatibility
of the drive is reduced.
WARNING!
Do not install a drive with the internal EMC filter connected to an earthing system
that the EMC filter is not suitable for (for example, an IT system). The supply
network becomes connected to ground potential through the internal EMC filter
capacitors, which can cause danger or damage to the drive.
￭ Ground-to-phase varistor
The drive is equipped with an internal ground-to-phase varistor as standard. For frame
sizes R1, R3 and R4, the varistor is connected as default. For frame size R2, the varistor
is disconnected as default.
A drive with the ground-to-phase varistor connected can be installed to a symmetrically
grounded TN-S system. If you install the drive to another system, you may need to
disconnect the varistor. See When to disconnect ground-to-phase varistor, or connect
EMC filter.
WARNING!
Do not install the drive with the ground-to-phase varistor connected to a system
that the varistor is not suitable for. If you do, the varistor circuit can be damaged.
￭ When to disconnect ground-to-phase varistor, or connect EMC filter
The table shows different earthing systems, and when to disconnect ground-to-phase
varistor, or connect EMC filter, ie, maintain or remove the factory default EMC screw or
VAR screw.
WARNING!
Failure to remove the metal VAR screw, when indicated in the table, can cause
danger or drive failure.
90 Electrical installation – North America
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