3 Installation
3.5 Electrical installation
DB1 variable frequency drive
11/20 MN040031EN
Eaton.com
67
3.5.1.2 Connecting the motor cable
The shielded cables between the variable frequency drive and the motor
should be as short as possible.
Figure 36: Connection on motor side
▶
Connect the screening, on both sides and across a large area
(360° overlap), to the protective earth (PE)
.
The power screening’s protective ground (PES) connection should be in
the immediate vicinity of the variable frequency drive and directly on the
motor terminal box.
▶
Prevent the screen ground shielding from becoming unbraided, i.e. by
pushing the separated plastic covering over the end of the shielding or
using a rubber grommet on the end of the shielding. Connect the shiel-
ding braid at the (PES) end across a large area.
Alternatively, you can twist the screen braid and connect it to the protec-
tive earth with a cable lug. In order to prevent EMC interference, this
twisted shielding connection should be as short as possible (recommen-
ded value for the twisted cable screen: b
≧
1/5 a).
Screened, four-wire cable is recommended for the motor cables. The green-
yellow conductor in these cables must be used to connect the motor’s and
variable frequency drive’s PE terminals, minimizing the loads on the cable
screen (high equalizing currents).
The following figure shows the construction of a four-wire, shielded motor
cable (recommended specifications).
Figure 37: Screened connection cable in motor circuit
15 mm
(0.59’’)
PES
a
b
PES