able frequency drive and the motor. The shield con-
nections are to be made with the largest possible
surface area (cable clamp). This is enabled by different
installation devices in different adjustable frequency
drives. Connecting with twisted shield ends (pigtails)
is to be avoided, as these spoil the shielding effect at
high frequencies. If it is necessary to break the shield
to install a motor isolator or motor relay. The shield
must be continued at the lowest possible HF impe-
dance.
Brake connection
NOTE
Voltages up to 850 VDC occur on the ter-
minals.
No.
81 82 Brake resistor
R- R+
terminals
Connect the brake resistor wiring to drive terminals 81
and 82. The connection cable to the brake resistor
must be shielded/armored. Connect the shield to both
the ground of the drive and the brake resistor by means
of cable clamps. Dimension the cross-section of the
brake cable to match the brake torque.
Ground connection
Since the leakage currents to ground may be higher
than 3.5 mA, the adjustable frequency drive must al-
ways be connected to ground in accordance with ap-
plicable national and local regulations. To ensure that
the ground cable has good mechanical connection to
terminal 95, the cable cross section must be a mini-
mum 7 AWG (10 mm
2
). To improve protection even
further, a Recidual Current Device (RCD) can be fitted
to ensure that the adjustable frequency drive cuts out
when the leakage currents get too high. Also see RCD
Application note MN.90.GX.02.
Load sharing
Load sharing provides the facility to connect several
frequency converters' DC intermediate circuits. This
requires that the installation is extended using extra
fuses and AC coils (see drawing below). For load shar-
ing parameter 400 Brake function must be set to Load
sharing [5].
Use 6.3 mm Faston Plugs for DC (Load Sharing).
Contact Danfoss or see instructions no. MI.50.NX.02
for further information.
No.
88 89 Loadsharing
- +
VLT
®
2800 Series
20 MG.27.A2.22 - VLT
®
is a registered Danfoss trademark
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