Delta MS300 Series User Manual page 402

compensation can automatically adjust the output voltage according to the load and keep the air
gap magnetic fields stable to get the optimal operation.
 In the V/F control, the voltage decreases in direct proportion with decreasing frequency. The
torque decreases at low speed because of a decreasing AC resistor and an unchanged DC
resistor. The auto-torque compensation function increases the output voltage at low frequency to
get a higher starting torque.
 When the compensation gain is set too high, it may cause motor over-flux and result in a too
large output current of the drive, motor overheating or trigger the drive's protection function.
 This parameter affects the output current during operation. The low-speed zone has less impact.
 Set this parameter higher when the no-load current is too large, but the motor may vibrate if the
setting is too high. If the motor vibrates when operating, reduce the setting.
07-27

Slip Compensation Gain
07-72
Slip Compensation Gain (Motor 2)

07-74
Slip Compensation Gain (Motor 3)

07-76
Slip Compensation Gain (Motor 4)

Settings
 IMSVC control mode only.
 The induction motor needs constant slip to produce electromagnetic torque. It can be ignored at
higher motor speeds, such as rated speed or 2–3% of slip.
 However, during the drive operation, the slip and the synchronous frequency are in reverse
proportion to produce the same electromagnetic torque. The slip is larger with the reduction of
the synchronous frequency. Moreover, the motor may stop when the synchronous frequency
decreases to a specific value. Therefore, the slip seriously affects the motor speed accuracy at
low speed.
 In another situation, when you use an induction motor with the drive, the slip increases when the
load increases. It also affects the motor speed accuracy.
 Use this parameter to set the compensation frequency, and reduce the slip to maintain the
synchronous speed when the motor runs at the rated current in order to improve the accuracy of
the drive. When the drive output current is higher than Pr.05-05 (No-load Current for Induction
Motor 1 (A)), the drive compensates the frequency according to this parameter.
 This parameter is set to 1.00 automatically when Pr.00-11 (Speed Control Mode) is changed
from V/F mode to vector mode. Otherwise, it is automatically set to 0.00. Apply the slip
compensation after load and acceleration. Increase the compensation value from small to large
gradually; add the output frequency to the [motor rated slip × Pr.07-27 (Slip Compensation
Gain)] when the motor is at the rated load. If the actual speed ratio is slower than expected,
increase the parameter setting value; otherwise, decrease the setting value. 

0.00–10.00
Chapter 12 Descriptions of Parameter SettingsMS300
393
Default: 0.00
(Default value is 1 in SVC
mode)