Control Of Mechanical Brake; Thermal Motor Protection - Danfoss FC 302 Instruction Manual

FC 300 Instruction Manual

Control of Mechanical Brake

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In hoisting/lowering applications, you need to be able to control an electromechanical brake.
Control the brake using any relay output or digital output (terminal 27 or 29).
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• 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.
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The brake is released when the motor current exceeds the preset value in par. 2-20.
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The brake is engaged when the output frequency is less than the frequency set in par. 2-21 or
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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 FC 300 is able to control several
parallel-connected motors. The total current
consumption of the motors must not exceed the
rated output current I
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 calls for a higher voltage at start and at low rpm values.
The electronic thermal relay (ETR) of the FC 300 cannot be used as motor protection for the individual motor
in systems with motors connected in parallel. Further motor protection must be provided, e.g. thermistors
in each motor or individual thermal relays. (Circuit breakers are not suitable as protection).
NOTE
When motors are connected in parallel, parameter 1-02 Automatic motor adaptation (AMA) cannot
be used and Parameter 1-01 Torque characteristics must be set to Special motor characteristics.
For more information, see VLT AutomationDrive FC 300 Design Guide.

Thermal motor protection

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The electronic thermal relay in FC 300 has received the UL-approval for single motor protection,
when parameter 1-26 Motor thermal protection is set for ETR Trip and parameter 1-23 Motor
current, I is set to the rated motor current (see motor nameplate).
M, N
How to Install
for the FC 300.
INV
MG.33.A4.22 - VLT is a registered Danfoss trademark
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