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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.
Note that voltage levels of up to 850 V DC
may occur between terminals 88 and 89.
Tightening Torque, Power Terminals
Power and ground terminals must be tightened
with the following torques:
VLT
Terminals
2803-
Power line brake
Ground
{new-
line/}2875
2880-
Power line brake
Ground
{new-
line/}2882
Calculation of brake resistance
In lifting/lowering applications you need to be able
to control an electromagnetic brake. The brake is
controlled using a relay output or digital output (terminal
46). The output must be kept closed (voltage-free)
for the period of time during which the variable
frequency drive is not able to 'support' the motor,
for example due to the load being too great. Select
Mechanical brake control in parameter 323 or 341 for
applications with an electromagnetic brake.
When the output frequency exceeds the brake cut
out value set in par. 138, the brake is released if the
18
This requires that the installation is extended using
extra fuses and AC coils (see drawing below).
For load sharing 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
motor current exceeds the preset value in parameter
140. When stopping the brake is engaged when the
output frequency is less than the brake engaging
frequency, which is set in par. 139.
If the variable frequency drive is placed at alarm
status or in an overvoltage situation the mechanical
brake is cut in immediately.
Torque [Nm]
0.5-0.6
2-3
1.2-1.5
Access to control terminals
2-3
All control terminals are located underneath the
protective plate on the front of the adjustable
frequency drive. Remove the protective plate by
sliding it downwards (see drawing).
VLT® 2800 Series
89
Loadsharing
-
+
NOTE
This application is only for lifting/lowering
without a counterbalance.
MG.28.A8.22 - VLT is a registered Danfoss trademark
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