ABB ACS480, Hardware Manual, Page: 71 / 180

1. Stop the drive and do the steps in section Electrical safety precautions (page 14) before
you start the work.
2. Make sure that the resistor cable is connected to the resistor and disconnected from
the drive output terminals.
3. At the drive end, connect the R+ and R- conductors of the resistor cable together.
Measure the insulation resistance between the conductors and the PE conductor with
a measuring voltage of 1000 V DC. The insulation resistance must be higher than
1 Mohm.
R-
R+
ohm
PE
1 kV DC,
> 1 Mohm
Earthing system compatibility check – North America
This section is valid for the UL(NEC) drive types. For the IEC drives types, see Earthing
system compatibility check – IEC (page 53) .
￭ 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.
￭ 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 .
￭ When to disconnect ground-to-phase varistor, or connect EMC filter
The table below 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.
Electrical installation – North America 71
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