Control Of Mechanical Brake - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide
The adjustable frequency drive does not produce motor torque during an AMA. During an AMA, it
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is imperative that the application does not force the motor shaft to run, which is known to happen
with e.g. windmilling in ventilation systems. This disturbs the AMA function.

Control of Mechanical Brake

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For hoisting applications, it is necessary to be able to control an electromagnetic brake. For controlling
the brake, a relay output (relay1 or relay2) or a programmed digital output (terminal 27 or 29) is
required. Normally, this output must be closed for as long as the drive is unable to "hold" the motor, e.g.
because of too big load. In par. 5-40 (Array parameter), par. 5-30, or par. 5-31 (digital output 27 or
29), select mechanical brake control [32] for applications with an electromagnetic brake.
When mechanical brake control [32] is selected, the mechanical brake relay is closed during start until
the output current is above the level selected in par. 2-20 Release Brake Current. During stop, the
mechanical brake will close when the speed is below the level selected in par. 2-21 Activate Brake Speed
[RPM]. If the adjustable frequency drive is brought into an alarm condition, an overcurrent, or overvoltage
situation, the mechanical brake immediately cuts in. This is also the case during safe stop.
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
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"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.
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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.
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Introduction to FC 300
MG.33.B3.22 - VLT is a registered Danfoss trademark