Control Of Mechanical Brake; Parallel Connection Of Motors - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide

Control of Mechanical Brake

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Control an electromechanical brake in hoisting/lowering applications.
Control the brake using any relay output or digital output (terminal 27 or 29).
•
• Keep the output closed (voltage-free) as long as the adjustable frequency drive is unable to
"support" the motor, for example due to the load being too heavy.
Select Mechanical brake control [32] in par. 5-4* for applications with an electromechanical brake.
•
The brake is released when the motor current exceeds the preset value in par. 2-20.
•
The brake is engaged when the output frequency is less than the frequency set in par. 2-21 or
•
2-22, and only if the adjustable frequency drive carries out a stop command.
If the adjustable frequency drive is in alarm mode or in an overvoltage situation, the
mechanical brake immediately cuts in.

Parallel Connection of Motors

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The adjustable frequency drive can control
several motors connected in parallel. The total
current consumption of the motors must not
exceed the rated output current I
adjustable frequency drive.
This is only recommended when VVC
selected in par. 1-01.
Problems may arise at start and at low RPM values if motor sizes are widely different because small motors'
relatively high ohmic resistance in the stator requires a higher voltage at start and to operate at low RPM values.
The electronic thermal relay (ETR) of the adjustable frequency drive cannot be used as motor protection for
the individual motor of systems with parallel-connected motors. Provide further motor protection by e.g.
thermistors in each motor or individual thermal relays. (Circuit breakers are not suitable as protection).
NOTE
When motors are connected in parallel, par. 1-02 Automatic motor adaptation (AMA) cannot be
used, and par. 1-01 Torque characteristics must be set to Special motor characteristics.
How to Install
for the
INV
plus is
MG.33.B3.22 - VLT is a registered Danfoss trademark
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