Mitsubishi Electric 800 Series Instruction Manual page 262

 Setting for stall prevention operation in the high-frequency range (Pr.22,
Pr.23, Pr.66)
V/F V/F V/F Magnetic flux Magnetic flux Magnetic flux
Always at the Pr.22 level
when Pr.23 = "9999"
Pr.22
Pr.66
• 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
Pr.66 (Hz) × Pr.22 (%)
Where,
A =
Output frequency (Hz)
• When Pr.23 ="9999" (initial value), the stall prevention operation level is constant at the Pr.22 level up to 590 Hz.
Stall prevention operation level
as set in Pr.23
400Hz 590Hz
Output frequency (Hz)
Pr.22 - A Pr.23 - 100
= A + B × [ ] × [
Pr.22 - B
Pr.66 (Hz) × Pr.22 (%)
, B =
400 Hz
Setting example (Pr.22 = 120%, Pr.23 = 100%, Pr.66 = 60Hz)
120
72
36
24
18
0 60 100 200
]
100
5.7 (H) Protective function parameter
300 400 590
Output frequency (Hz)
5. PARAMETERS
3
4
5
5
5
6
7
8
9
10
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