Danfoss VLT Micro Drive FC 51 Series Programming Manual page 24

VLT Micro Drive FC 51
4.3.3. 2-1* Brake Energy Function
Use the parameters in this group for selecting dynamic braking parameters.
2-10 Brake Function
Option:
Off
*
[0]
[1] Resistor Brake
[2] AC Brake
2-11 Brake Resistor (Ohm)
Range:
*
5 [5 - 5000 ]
2-16 AC Brake, Max Current
Range:
*
100.0 % [0.0 - 150.0 %]
2-17 Over-Voltage Control
Option:
Disabled
*
[0]
[1] Enabled, not at stop
[2] Enabled
NB!
If Resistor Brake has been chosen in par. 2-10
4.3.4. 2-2* Mechanical Brake
For hoisting applications an electro-magnetic brake is required. The brake is controlled by a relay, which releases the brake when activated.
The brake activates if frequency converter trips or a coast command is given. Furthermore, it activates when motor speed is ramped down below the
Active Brake Speed
speed set in par. 2-22,
Function:
Resistor Brake:
The resistor brake limits voltage in the intermediate circuit when the motor acts as generator. Without brake
resistor, the frequency converter eventually trips.
The resistor brake consumes surplus energy resulting from motor braking. A frequency converter with brake
stops a motor faster than without a brake, which is used in many applications. Requires connection of external
brake resistor.
An alternative to the resistor brake is the AC brake.
NB!
Resistor brake is only functional in frequency converters with integrated dynamic brake. An
external resistor must be connected.
AC Brake:
The AC brake consumes surplus energy by creating power loss in the motor.
It is important to keep in mind that an increase in power loss causes motor temperature to rise.
No brake function.
Resistor brake is active.
AC brake is active.
Function:
Set brake resistor value.
Function:
Enter max. permissible current for AC-braking to avoid overheating of motor.
100% equals motor current set in par. 1-24.
Function:
Use Over-voltage Control (OVC) to reduce the risk of the frequency converter tripping due to an over voltage
on the DC link caused by generative power from the load.
An over-voltage occurs eg. if the ramp down time is set too short compared to the actual load inertia.
The OVC is not active/required.
OVC is running unless a stop signal is active.
OVC is running, also when a stop signal is active.
Brake Function the OVC is not active even though enabled in this parameter.
.
MG.02.C4.02 - VLT is a registered Danfoss trademark
4. Parameter Descriptions
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