Mitsubishi Electric FR-A820-00046 Instruction Manual page 531

Parameters
Setting for stall prevention operation in the high-frequency range (Pr. 22, Pr. 23, Pr. 66)
Pr. 22
Setting example (Pr. 22 = 120 %, Pr. 23 = 100 %, Pr. 66 = 60 Hz)
120
72
36
24
18
● When operating at the rated motor frequency or higher, acceleration may not be made because
the motor current does not increase. Also, when operating in the high-frequency range, the
current flowing to the locked motor becomes less than the rated output current of the inverter;
and even if the motor is stopped, the protective function will not operate (OL).
In a case like this, the stall prevention level can be reduced in the high-frequency range to improve
the motor's
operating characteristics. This is useful when operating up to the high speed range, such as when
using a centrifuge. Normally, set Pr. 66 "Stall prevention operation reduction starting frequency"
to 60 Hz, and Pr. 23 "Stall prevention operation level compensation factor at double speed" to
100%.
● Calculation formula for stall prevention operation level
Stall prevention operation level (%)
in the high-frequency range
Where A =
● When Pr. 23 = "9999" (initial value), the stall prevention operation level is constant at the Pr. 22
level up to 590 Hz.
FR-A800
Always at the Pr. 22 level
when Pr. 23 = "9999"
Stall prevention operation
level as set in Pr. 23
400 Hz
Pr. 66
Output frequency (Hz)
0 60 100 200 300
Output frequency (Hz)
Pr. 66 (Hz) × Pr. 22 (%)
Output frequency (Hz)
Fig. 5-141:
Stall prevention operation level
Fig. 5-142:
Stall prevention operation level when
Pr. 22 = 120 %, Pr. 23 = 100 % and Pr. 66 = 60 Hz
400
Pr. 22 – A
= A + B × [ ] × [
Pr. 22 – B
Pr. 66 (Hz) × Pr. 22 (%)
, B =
400 (Hz)
(H) Protective function parameter
Pr. 23 –1 00
]
100
I002597E
I002598E
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