2-17 Over-Voltage Control
Option:
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.
[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.
NOTE
If Resistor Brake has been chosen in
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 the frequency converter trips or a
coast command is given. Furthermore, it activates when
motor speed is ramped down below the speed set in
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.
CAUTION
If start delay time has passed, and
motor current is below
Release brake
current
, frequency converter trips.
2-22 Activating Mechanical Brake
Range:
Function:
If the motor is stopped using ramp, the
mechanical brake is activated 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.
Parameter Descriptions
VLT
®
Micro Drive FC 51 Programming Guide
20
MG02C602 - VLT
®
is a registered Danfoss trademark
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4