2-17 Over-Voltage Control
Option: Function:
Use Over-voltage Control (OVC) to reduce the risk of the fre-
quency 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.
[0]
*
Disabled The OVC is not active/required.
[1] Enabled, not at stop OVC is running unless a stop signal is active.
[2] Enabled OVC is running, also when a stop signal is active.
NB!
If Resistor Brake has been chosen in par. 2-10
Brake Function
the OVC is not active
even though enabled in this parameter.
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 speed set in par. 2-22,
Active Brake
Speed
.
2-20 Release Brake Current
Range: Function:
0.00 A
*
[0.00 - 100 A] Select motor current at which mechanical brake releases.
If start delay time has passed, and motor current
is below
Release brake current
, frequency con-
verter trips.
2-22 Activating Mechanical Brake
Range: Function:
If the motor is stopped using ramp, the mechanical brake is ac-
tivated when motor speed is less than
Active Brake Speed
.
Motor is ramped down to stop in the following situations:
• A start command is removed (stand by)
• A stop command is activated
• Quick-stop is activated (Q-stop ramp is used)
0 Hz
*
[0 - 400 Hz] Select motor speed at which mechanical brake activates when
ramping down.
Mechanical brake automatically activates if frequency converter
trips or reports an alarm.
VLT Micro Drive FC 51 4. Parameter Descriptions
MG.02.C2.02 - VLT
®
is a registered Danfoss trademark
29
4
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