Mitsubishi FR-A800

(H) Protective function parameter
PARAMETERS
351
5
GROUP
H
Adjusting the stall prevention operation signal output and output timing
(OL signal, Pr.157)
• If the output current exceeds the stall prevention operation level and stall prevention is activated, Overload warning (OL)
signal will turn ON for 100 ms or more. The output signal turns OFF when the output current falls to the stall prevention
operation level or less.
• Pr.157 OL signal output timer can set whether to output the OL signal immediately, or to output it after a certain time
period.
• This function also operates during regeneration avoidance operation (overvoltage stall).
NOTE
• OL signal is assigned to the terminal OL in the initial status. The OL signal can be assigned to other terminals by setting "3
(positive logic) or 103 (negative logic)" in any of Pr.190 to Pr.196 (output terminal function selection).
• If the stall prevention operation has lowered the output frequency to 0.5 Hz and kept the level for 3 s, the stall prevention stop
(E.OLT) is activated to shut off the inverter output.
• Changing the terminal assignment using Pr.190 to Pr.196 (output terminal function selection) may affect the other
functions. Set parameters after confirming the function of each terminal.
Setting for stall prevention operation in the high-frequency range (Pr.22,
Pr.23, 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
• When Pr.23 ="9999" (initial value), the stall prevention operation level is constant at the Pr.22 level up to 590 Hz.
Pr.157 setting Description
0 (initial value) Output immediately.
0.1 to 25 Output after the set time (s).
9999 Not output.
Stall prevention operation level (%)
in the high-frequency range
=A + B [
Pr.22 -A
]  [
Pr.23 -100
]
Pr.22 -B 100
Where, A =
Pr.66 (Hz)  Pr.22(%)
,B=
Pr.66 (Hz) Pr.22(%)
Output frequency (Hz) 400 Hz
Overload state
(OL operation)
OL output signal
Pr.157
Set time(s)
Output frequency (Hz)
Pr.22
Always at the Pr.22 level
when Pr.23 = "9999"
Pr.66
400Hz
Stall prevention operation level (%)
Stall prevention operation level
as set in Pr.23
Output frequency (Hz)
Setting example (Pr.22 = 150%, Pr.23 = 100%, Pr.66 = 60Hz)
18
0 10060 200 300 400
24
36
72
120
Stall prevention operation level (%)