64
Note
When the FWD (REV) run command is input in the status where
the accel/decel prohibit command is input, the baseblock status is
continued and the motor does not operate.
The motor will operate at the frequency set in constant No. 25 (fre-
quency lower limit) when No. 25
≥
No. 07 (minimum output fre-
quency).
2-8-27 Slip Compensation Speed Control
Item name
Constant to be set
Factory preset
Slip Compensation Function
No. 57
0%
Motor No-load Current
No. 58
30%
Torque Compensation Filter Time Delay
No. 59
---
•
The slip compensation function keeps the rotating speed of the
motor constant if the load is heavy. Without this function, the
motor will slip and the rotating speed of the motor will decrease if
the load is heavy.
•
If the output current of the Inverter is equal to the electronic ther-
mal reference current (i.e., the rated current of the motor), add
the compensation frequency equivalent to the rated slippage
value of the motor to the output frequency.
•
Refer to the following formulas to obtain the constants to be set in
no-57 and no-58.
no-57 = (Synchronization speed – rated motor revolution)/syn-
chronization speed x 100
Synchronization speed = 120/P f
P: No. of polls
f: Rated frequency
no-58 = (Output current with no load/rated current of the motor) x
100
•
The compensation frequency (fc) can be obtained from the fol-
lowing.
If the output frequency is lower than the constant set in no-04
for the maximum voltage frequency, use the following formula
to obtain the compensation frequency (fc).
fc = no-04 x no-57 x [output current – (no-19 x
no-58/100)]/[no-19 x no-58/100)]
If the output frequency is equal to or higher than the constant
set in no-04 for the maximum voltage frequency, use the follow-
ing formula to obtain the compensation frequency (fc).
fc = output frequency x no-57 x [output current – (no-19 x
no-58/100)/[no-19 – (no-19 x no-58/100)
no-04: Maximum voltage frequency (Hz)
no-19: Electronic thermal reference current (A)
Note
1. The slip compensation function does not work if the output fre-
quency is lower than the constant set in no-07 for the minimum
output frequency.
Description of Functions and Constants
Section 2-8
