KEB COMBIVERT F5-A, Applications Manual, Page: 183 / 552

Motor data and controller adjustments of the asynchronous motor
© KEB, 2012-10 COMBIVERT F5-A, -E, -H Page 7.5 - 21
7
7.5.2.3.3 Additional trimming
dr.48 motor identification
Bit Description Value Function
0...4 Measurement
0: off
Detection of the no-load torque at different switching fre-
quencies. During operation this torque is subtracted from
torque display ru.12.
14: Torque detection 2
kHz
15: Torque detection 4
kHz
16: Torque detection 8
kHz
17: reserved
18: Torque detection
16 kHz
19: Current offset de-
tection
Detection of the current offset in phase U and V
20: Voltage pulse Only for synchronous motor
7.5.2.3.3.1 Torque detection (dr.48 = 14...18) / only for F5H-M
For applications with particularly high demands on the accuracy of the torque display, this can be calibrated.
As a standard, the torque display does not display a value of 0 in encoderless operation during no-load opera-
tion. The reason for this is switching frequency-dependent losses in the inverter and friction losses due to the
application.
If the torque display has to be corrected for this offset, the torque offset of the whole drive can be calibrated with
dr.48 = 14...18 for the various switching frequencies.
Thereby the drive accelerates in stepwise with the adjusted ramp in dr.49 to maximum 1,3-fold synchronous
speed. The speed limits set in the oP-parameters remain operative during this phase.
The calibrated no-load torque is stored as correction characteristic. During operation, the display of the actual
torque in ru.12 is corrected using this characteristic.
The torque offset-characteristic can be read with parameter dr.58/ dr.59.
The characteristic is not part of the data backup created by read out of a complete list.
This should be executed only if the application really requires increased torque accuracy. Since the trimming
values are not contained in the complete list, porting the data to a different inverter is labour-intensive.
7.5.2.3.3.2 Current offset detection (dr.48 = 19)
As a standard, the current offset from the inverter is permanently ascertained and balanced, as long as the
modulation is switched off. Therefore, the current offset-detection via dr.48 is usually not required.
In some cases, one achieves more accurate current offset values if one carries out the trimming with current
in the motor.
If dr.48 = 19 is selected, the inverter provides a test signal to the motor and so carries out the trimming once.
A disadvantage of this current offset detection is that it is carried out only once and therefore temperature and
ageing effects are not taken into account.
To preserve the identified offset, automatic measurement is deactivated with dr.48 = 19.
ATTENTION! Since the automatic measurement can only be reactivated by the KEB service personnel, the
current offset detection should preferably be carried out only in consultation with KEB.