Technical information

motor at that speed and resume normal operation. Please
refer to description of 1-70 PM Start Mode for
recommended settings.
Current limitations of the Flystart Principle used for PM
motors:
•
The speed range is up to 100% Nominal Speed or
the field weakening speed (which ever is lowest).
•
PMSM with high back emf (>300VLL(rms)) and
high winding inductance(>10mH) needed more
time for reducing short circuit current to zero and
may be susceptible to error in estimation.
•
Current testing limited to a speed range up to
300Hz. For certain units the limit is 250Hz; all
200-240V units up to and including 2.2kW and all
380-480V units up to and including 4kW.
•
Current testing limited to a machine power size
up to 22kW.
•
Prepared for salient pole machine (IPMSM) but
not yet verified on those types of machine.
•
For high inertia applications (i.e. where the load
inertia is more than 30 times larger than the
motor inertia) a brake resistor is recomended to
avoid over-voltage trip during high speed
engagement of the fly-start function.
1-77 Compressor Start Max Speed [rpm]
Range: Function:
0
rpm*
[0.0 -
max
output
speed]
The parameter enables “High Starting Torque”.
This is a function, where the Current Limit and
Torque Limit are ignored during start of the
motor. The time, from the start signal is given
until the speed exceeds the speed set in this
parameter, becomes a “start-zone” where the
current limit and motoric torque limit is set to
what is maximum possible for the frequency
converter/motor combination. This parameter
is normally set to the same value as
4-11 Motor Speed Low Limit [RPM]. When set to
zero the function is inactive.
In this “starting-zone” 3-82 Starting Ramp Up
Time is active instead of 3-40 Ramp 1 Type to
ensure extra acceleration during the start and
to minimize the time where the motor is
operated under the minimum speed for the
application. The time without protection from
the Current Limit and Torque Limit must not
exceed the value set in 1-79 Compressor Start
Max Time to Trip or the frequency converter
will trip with an alarm [A18] Start Failed.
When this function is activated to get a fast
start then also 1-86 Trip Speed Low [RPM] is
activated to protect the application from
running below minimum motor speed e.g.
when in current limit.
1-77 Compressor Start Max Speed [rpm]
Range: Function:
This function allows high starting torque and
use of a fast starting ramp. To ensure the
build-up of a high torque during the start,
various tricks can be done through clever use
of start delay / start speed / start current.
NOTE
1-77 Compressor Start Max Speed [RPM] will not have effect
when 1-10 Motor Construction = [1] PM, non salient SPM.
1-78 Compressor Start Max Speed [Hz]
Range: Function:
Size
related*
[ 0.0
- par.
4-14
Hz]
The parameter enables “High Starting
Torque”. This is a function, where the Current
Limit and Torque Limit are ignored during
start of the motor. The time, from the start
signal is given until the speed exceeds the
speed set in this parameter, becomes a “start-
zone” where the current limit and motoric
torque limit is set to what is maximum
possible for the frequency converter/motor
combination. This parameter is normally set
to the same value as 4-11 Motor Speed Low
Limit [RPM]. When set to zero the function is
inactive.
In this “starting-zone” 3-82 Starting Ramp Up
Time is active instead of 3-41 Ramp 1 Ramp
Up Time to ensure extra acceleration during
the start and to minimize the time where the
motor is operated under the minimum speed
for the application. The time without
protection from the Current Limit and Torque
Limit must not exceed the value set in
1-79 Compressor Start Max Time to Trip or the
frequency converter will trip with an alarm
[A18] Start Failed.
When this function is activated to get a fast
start then also1-86 Trip Speed Low [RPM] is
activated to protect the application from
running below minimum motor speed e.g.
when in current limit.
This function allows high starting torque and
use of a fast starting ramp. To ensure the
build-up of a high torque during the start,
various tricks can be done through clever use
of start delay / start speed / start current.
NOTE
1-78 Compressor Start Max Speed [Hz] will not have effect
when 1-10 Motor Construction = [1] PM, non salient SPM.
Parameter Description
VLT
®
HVAC Drive Programming Guide
MG11CD02 - VLT
®
is a registered Danfoss trademark 45
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