Danfoss FC 300 Programming Manual page 135

Parameter Descriptions
3.15.2 14-1* Mains On/Off
Parameters for configuring mains failure monitoring and
handling. If a mains failure appears, the frequency converter
will try to continue in a controlled way until the power in the
DC link has been exhausted.
14-10 Mains Failure
Par. 14-10 Mains Failure is typically used where very short mains
interruptions (voltage dips) are present. At 100% load and a short
voltage interruption, the DC voltage on the main capacitors drops
quickly. For larger drives it only takes a few milliseconds before the
DC level is down to about 373 V DC and the main IGBT cuts off and
looses the control over the motor. When the mains is restored, and
the IGBT starts again, the output frequency and voltage vector
does not correspond to the speed/frequency of the motor, and the
result is normally an overvoltage or overcurrent, mostly resulting in
a trip lock. Par. 14-10 Mains Failure can be programmed to avoid
this situation.
Option: Function:
Function: Select the function to which
the frequency converter must act when
the threshold in par. 14-11 Mains
Voltage at Mains Fault has been
reached.
Par. 14-10 Mains Failure cannot be
changed while motor is running.
Controlled ramp down:
The frequency converter will perform a
controlled ramp down. If par. 2-10 Brake
Function is Off [0] or AC brake [2], the
ramp will follow the Over Voltage
Ramping. If par. 2-10 Brake Function is
[1] Resistor Brake the ramp will follow
the setting in par. 3-81 Quick Stop Ramp
Time.
Controlled ramp down [1]:
After power-up the frequency converter
is ready for start. Controlled ramp down
and trip [2]: After power-up the
frequency converter needs a reset for
starting.
FC 300 Programming Guide
14-10 Mains Failure
Par. 14-10 Mains Failure is typically used where very short mains
interruptions (voltage dips) are present. At 100% load and a short
voltage interruption, the DC voltage on the main capacitors drops
quickly. For larger drives it only takes a few milliseconds before the
DC level is down to about 373 V DC and the main IGBT cuts off and
looses the control over the motor. When the mains is restored, and
the IGBT starts again, the output frequency and voltage vector
does not correspond to the speed/frequency of the motor, and the
result is normally an overvoltage or overcurrent, mostly resulting in
a trip lock. Par. 14-10 Mains Failure can be programmed to avoid
this situation.
Option:
®
MG.33.M9.02 - VLT is a registered Danfoss trademark
Function:
1. The power is back before the
energy from DC /moment of
inertia from load is too low.
The frequency converter will
perform a controlled ramp
down when par. 14-11 Mains
Voltage at Mains Fault level
has been reached.
2. The frequency converter will
perform a controlled ramp
down as long as energy in the
DC link is present. After this
point the motor will be
coasted.
Kinetic back-up:
The frequency converter will perform a
Kinetic back-up. If par. 2-10 Brake
Function is Off [0] or AC brake [2] , the
ramp will follow the Over Voltage
Ramping. If par. 2-10 Brake Function is
[1] Resistor Brake the ramp will follow
the setting in par. 3-81 Quick Stop Ramp
Time.
Kinetic Back-up [4]: The frequency
converter will keep on running as long
as there is energy in the system due to
the moment of inertia produced by the
load.
Kinetic Back-up [5]: The frequency
converter will ride through on speed as
long as the energy is present from
moment of inertia from the load. If the
DC voltage goes below par. 14-11 Mains
Voltage at Mains Fault the frequency
converter will perform a trip.
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