Danfoss VLT AutomationDrive FC 300 Programming Manual page 59

Parameter Descriptions
2-15 Brake Check
Option: Function:
NOTE
The brake resistor disconnection function is tested
during power-up. However the brake IGBT test is
performed when there is no braking. A warning
or trip disconnects the brake function.
The testing sequence is as follows:
1. The DC link ripple amplitude is measured for
300 ms without braking.
2. The DC link ripple amplitude is measured for
300 ms with the brake turned on.
3. If the DC link ripple amplitude while braking is
lower than the DC link ripple amplitude before
braking + 1%: Brake check has failed by
returning a warning or alarm.
4. If the DC link ripple amplitude while braking is
higher than the DC link ripple amplitude
before braking + 1%: Brake check is OK.
[0] Off Monitors brake resistor and brake IGBT for a short-
circuit during operation. If a short-circuit occurs,
warning 25 appears.
NOTE
Remove a warning arising in connection with [0] Off or [1]
Warning by cycling the mains supply. The fault must be
corrected first. For [0] Off or [1] Warning, the frequency
converter keeps running even if a fault is located.
This parameter is only active in frequency converters with
an integral dynamic brake.
2-16 AC brake Max. Current
Range: Function:
100 % [ 0 - 1000.0 %] Enter the maximum permissible current
*
when using AC brake to avoid
overheating of motor windings.
NOTE
2-16 AC brake Max. Current will not have effect when
1-10 Motor Construction = [1] PM, non salient SPM.
2-17 Over-voltage Control
Option: Function:
Over-voltage control (OVC) reduces the risk
of the frequency converter tripping due to
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VLT AutomationDrive Programming Guide
2-17 Over-voltage Control
Option:
[0] Disabled
[1] Enabled (not
[2] Enabled
NOTE
OVC must not be enabled in hoisting applications.
2-18 Brake Check Condition
Range:
[0] At Power Up
2-19 Over-voltage Gain
Range:
100 %
3.4.3 2-2* Mechanical Brake
Parameters for controlling operation of an electro-
magnetic (mechanical) brake, typically required in hoisting
applications.
To control a mechanical brake, a relay output (relay 01 or
relay 02) or a programmed digital output (terminal 27 or
29) is required. Normally this output must be closed during
periods when the frequency converter is unable to 'hold'
the motor, e.g. due to an excessive load. Select [32]
Mechanical Brake Control for applications with an electro-
magnetic brake in 5-40 Function Relay, 5-30 Terminal 27
Digital Output, or 5-31 Terminal 29 Digital Output. When
selecting [32] Mechanical brake control, the mechanical
brake is closed from start up until the output current is
above the level selected in 2-20 Release Brake Current.
During stop, the mechanical brake activates when the
speed falls below the level specified in 2-21 Activate Brake
Speed [RPM]. If the frequency converter enters an alarm
condition or an over-current or over-voltage situation, the
mechanical brake immediately cuts in. This is also the case
during safe stop.
NOTE
Protection mode and trip delay features (14-25 Trip Delay
at Torque Limit and 14-26 Trip Delay at Inverter Fault) may
delay the activation of the mechanical brake in an alarm
condition. These features must be disabled in hoisting
applications.
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MG33MG02 - VLT is a registered Danfoss trademark
Function:
an over voltage on the DC link caused by
generative power from the load.
No OVC required.
Activates OVC except when using a stop
at stop) signal to stop the frequency converter.
Activates OVC.
Function:
Brake check will be performed at power up
Function:
[0 - 200 %] Select over-voltage gain.
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