Hoist Mechanical Brake - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide
Step-by-step Description
In hoisting/lowering applications, it must be possible to control an electro-mehanical brake.
• To control the mechanical brake any relay output or digital output (terminal 27 or 29) can be
used. If necessary use a suitable contactor.
• Ensure that the output is switched off as long as the frequency converter is unable to drive the
motor, for example due to the load being too heavy or due to the fact that the motor has not
been mounted yet.
• Select Mechanical brake control [32] in par. 5-4* (or in par. 5-3*) before connecting the me-
chanical 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 frequency converter carries out a stop command.
NB!
For vertical lifting or hoisting applications it is strongly recommended to ensure that the load
can be stopped in case of an emergency or a malfunction of a single part such as a contactor,
etc.
If the frequency converter is in alarm mode or in an over voltage situation, the mechanical
brake cuts in.
NB!
For hoisting applications make sure that the torque limits in par. 4-16 and 4-17 are set lower
than the current limit in par. 4-18. Also it is recommendable to set par. 14-25, Trip Delay at
Torque Limit to "0", par. 14-26, Trip Delay at Inverter Fault to "0" and par. 14-10, Mains
Failure to "[3], Coasting".

Hoist Mechanical Brake

The VLT Automation Drive FC 300 features a mechanical brake control specifically designed for hoisting
applications. The main difference compared to the regular mechanical brake control, where a relay func-
tion monitoring the output current is used, is that the hoist mechanical brake function has direct control
over the brake relay. This means that instead of setting a current for release of the brake, the torque
applied against the closed brake before release is defined. Because the torque is defined directly the setup
is more straightforward for hoisting applications.
By using the Proportional Gain Boost (par. 2-28) a quicker control when releasing the brake can be ob-
tained. The hoist mechanical brake strategy is based on a 3-step sequence, where motor control and
brake release are synchronized in order to obtain the smoothest possible brake release:
Introduction to FC 300
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MG.33.B8.02 - VLT is a registered Danfoss trademark
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