4-34
n55
Motor Current with No Load
Setting range 0 to 99 (%) Factory setting 40 (%)
Unit of setting 1 (%)
•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 thermal 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 n54 and n55.
n54 = (Synchronization speed – rated motor revolution)/synchronization speed x 100
Synchronization speed = 120/P f
P: No. of polls
f: Rated frequency
n55 = (Output current with no load/rated current of the motor) x 100
•The compensation frequency (fc) can be obtained from the following.
If the output frequency is lower than the constant set in n26 for the maximum voltage
frequency, use the following formula to obtain the compensation frequency (fc).
fc = n26 x n54 x [output current – (n31 x n55/100)]/[n31 – (n31 x n55/100)]
If the output frequency is equal to or higher than the constant set in n26 for the maxi-
mum voltage frequency, use the following formula to obtain the compensation fre-
quency (fc).
fc = output frequency x n54 x [output current – (n31 x n55/100)/[n31 – (n31 x
n55/100)
n26: Maximum voltage frequency (Hz)
n31: Electronic thermal reference current (A)
Note 1. The slip compensation function does not work if the output frequency is lower
than the constant set in n29 for the minimum output frequency.
Note 2. The slip compensation function does not work if the Inverter is in regenerative
operation.
Note 3. The slip compensation function does not work if 0.0 is set for the electronic ther-
mal reference current.
Preparing for Operation Chapter 4
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