Flying Start - Danfoss VLT 5000 Series Operating Instructions Manual

Function no. 5
The digital input activates the mains failure function,
regardless of whether the unit receives any supply
voltage. See the different functions in parameter 407.
Function no. 6
The mains failure function is activated when the
intermediate circuit voltage has dropped to a given
value. The selected function in case of mains
failure is selected in parameter 407.
Function no. 7
The digital input activates both the quick discharge and
the mains failure function, regardless of the intermediate
circuit voltage level and regardless of whether the
motor is running. First the mains failure function will be
active; subsequently there will be a quick discharge.
Function no. 8
Quick discharge and mains failure function are activated
when the intermediate circuit level drops to a given level.
First the mains failure function will be active;
subsequently there will be a quick discharge.

Flying start

This function makes it possible to "catch" a motor
that is spinning freely and for the frequency converter
to take control of the motor speed. This function can
be enabled or disabled via parameter 445.
If flying start has been selected, there will be four
situations in which the function is activated:
1. After a coast has been given via terminal 27.
2. After power-up.
3. If the frequency converter is in a trip state and
a reset signal has been given.
4. If the frequency converter releases the motor
because of a fault state and the fault disappears
before a trip, the frequency converter will catch
the motor and go back to the reference.
94
®
VLT 5000 Series
1. Flying start is active.
2. Flying start is active.
The search sequence for the spinning motor depends
on Rotation, frequency/direction (parameter 200). If
only clockwise is selected, the frequency converter will
start looking from Maximum frequency (parameter 202)
down to 0 Hz. If the frequency converter does not find
the spinning motor during the search sequence, it will
carry out a DC braking so as to try to bring the speed
of the spinning motor down to 0 rpm. This requires that
the DC brake is active via parameters 125 and 126. If
Both directions is selected, the frequency converter will
first find out in which direction the motor rotates and
then search for the frequency. If the motor is not found,
the system assumes that the motor is at a standstill or
is rotating at a low speed, and the frequency converter
will start the motor in the normal way after searching.
MG.51.A9.02 - VLT is a registered Danfoss trademark