KEB COMBIVERT F5-A, Applications Manual, Page: 243 / 552

Torque display and -limiting
© KEB, 2012-10 COMBIVERT F5-A, -E, -H Page 7.8 - 5
7
Picture 7.8.2.2a Field weakening range 1/x reduction
Istfrequenz [U/min]
Moment [Nm]
dr.17 dr.18 2 * dr.18
dr.15
dr.16
0,5 * dr.16
1 / x Absenkung
ds.03 "Feldschwächkennlinie" = 0: aus
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“.
dS.03: Current-/torque mode
Bit Meaning Value Explanation
1
Field weakening characte-
ristic
0: off
Activation of the active current limitation in the
field-weakening range
2: on
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 frequency = 50Hz
rated torque 36Nm M
rated
/ M
breakdown
= 2.5
selected value for DASM field weakening speed (
dr.18): 1500 rpm
Data sheet value for breakdown torque of the motor at rated
frequency: 2.5 * 36Nm = 90Nm
Safety reserve 25% = 22.5 Nm
dr.16 „DASM max torque corn. sp“ = 90Nm – 22.5Nm = 67.5Nm