KEB COMBIVERT F5-A Applications Manual page 243

Picture 7.8.2.2a Field weakening range 1/x reduction
Moment [Nm]
dr.15
dr.16
0,5 * dr.16
The "max. torque FI" (dr.15) is depending on the maximum inverter current and can not be changed.
At default setting the maximum torque in the field weakening is reduced to a 1/x function - because of flux
reduction.
The physical breakdown torque characteristic of the motor is a quare characteristic, i.e. also the maximum
active power in the field weakening range must become smaller.
The square limiting characteristic must be activated if the motor shall be driven to its limits. This is done with
value 2 in point "field weakening characteristic" of parameter dS.03 „current/torque mode".
Bit Meaning
Field weakening characte-
1
ristic
The limiting characteristic is adapted to the motor with parameter dr.16 „DASM max torque corn. sp" .
dr.16 = breakdown torque of the motor (at speed dr.18) - safety reserve
Example:
a motor shall have the following rated data:
rated speed: 1470 rpm
rated torque 36Nm
selected value for DASM field weakening speed (dr.18):
Data sheet value for breakdown torque of the motor at rated
frequency:
Safety reserve
dr.16 „DASM max torque corn. sp" = 90Nm – 22.5Nm = 67.5Nm
© KEB, 2012-10 COMBIVERT F5-A, -E, -H
Torque display and -limiting
1 / x Absenkung
ds.03 "Feldschwächkennlinie" = 0: aus
dr.17 dr.18
dS.03: Current-/torque mode
Value Explanation
0: off
Activation of the active current limitation in the
field-weakening range
2: on
rated frequency = 50Hz
M / M = 2.5
rated breakdown
2 * dr.18
Istfrequenz [U/min]
1500 rpm
2.5 * 36Nm = 90Nm
25% = 22.5 Nm
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