Mitsubishi Electric FR-A820-00046 (0.4K), Instruction Manual

Page: 531 / 1218

Parameters (H) Protective function parameter
FR-A800 5 - 329
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.
Fig. 5-141:
Stall prevention operation level
I002597E
Fig. 5-142:
Stall prevention operation level when
Pr. 22 = 120 %, Pr. 23 = 100 % and Pr. 66 = 60 Hz
I002598E
Stall prevention operation level (%)
in the high-frequency range
= A + B × [
Pr. 22 – A
] × [
Pr. 23 –1 00
]
Pr. 22 – B 100
Where A =
Pr. 66 (Hz) × Pr. 22 (%)
, B =
Pr. 66 (Hz) × Pr. 22 (%)
Output frequency (Hz) 400 (Hz)
Always at the Pr. 22 level
when Pr. 23 = "9999"
Stall prevention operation
level as set in Pr. 23
Stall pr
ev
enti
o
n
oper
a
tion
level
(
%
)
Pr. 22
Pr. 66
400 Hz
Output frequency (Hz)
18
0 100 60 200 300 400
24
36
72
120
Stall pr
ev
enti
o
n
oper
a
tion
level
(
%
)
Output frequency (Hz)
Setting example (Pr. 22 = 120 %, Pr. 23 = 100 %, Pr. 66 = 60 Hz)